Jet sizes

Post by **Lostmycage** » Mon Apr 27, 2009 5:46 am

Hi folks.

I just wanted to get a quick little topic going because I'm curious.

On a stock (engine unmodified) Blur, I found that at close to sea level (central VA) the Stock blur really likes a bigger main jet.

I'm curious if anyone else has checked into their jetting on their stock bike. I actually got up to a 110 main jet with the stock engine/exhaust. I think that might have been just on the cusp of too large, but never made up my mind which I liked better. Both the 105k and the 110k seemed to produce a little more power than the stock jet (102k) without any sputtering or other mal-effects.

The reason I'm bringing this up is that at the moment, there are a few Blur's in my local shop with engine problems. The kind associated with running them too lean.

Has anyone pulled the plug and looked to see how they're running with the stock 102k jet? I'm pretty curious about this now. The trick to the Blur engine is that it's got a little more advanced camshaft in it than the Buddy 150.

I'd appreciate any input that anyone has on this, as it's mainly my curiosity that's driving this train of thought for now.

The stock exhaust on the Blur is a pretty impressive little feat of engineering. It's supposed to give back pressure at lower RPMs (for torque) and less at higher RPMs (for an easier time pulling the engine at full load). But I think the exhaust (if it really functions like that) causes some issues with proper jetting.

If you want to help out, pull your plug and post your results. If you want to try something a little silly (and possibly rewarding) try rejetting it with a bump up to a 105k.

Thanks for taking the time to read this. It really is just a little ponderment that I'm having.

charlie55 · Post by **charlie55** » Mon Apr 27, 2009 1:05 pm

I'm at the Jersey Shore, which is just about as sea-level as you can get, and everything on mine is stock. I've pulled the plug quite a few times over the last year, and each time it's been that nice cafe-au-lait shade of tan than falls into the "normal" category on spark plug color charts.

I'm wondering if a lot of folks are noodling with their idle mixture and running it too lean. Granted, this only has an effect when you're, well, idling, but in stop-and-go traffic that can add up to quite a bit of time.

Post by **Lostmycage** » Mon Apr 27, 2009 3:09 pm

That's very true too. I'm mainly just curious at this point. I'll ask around at my shop and see if the folks who had their Blurs in admitted to any noodling.

I like that term.

mozart2k · Post by **mozart2k** » Mon Apr 27, 2009 8:53 pm

I'm a new user in this board

I've G-MAX 150 in thailand (I think all the same with Blur 150) today I've installed iridium spark plug and adj carb setting 1 turn (Pretty rich mixture) after test run I think stop 'n' go is much better.

^_______________^

Post by **Lostmycage** » Mon Apr 27, 2009 9:06 pm

Welcome to MB!

I think they're pretty much the same bike.

Which iridium plug did you end up going with?

And thanks for the input!

babblefish · Post by **babblefish** » Mon Apr 27, 2009 10:41 pm

I'm wondering if the Blurs are jetted lean on purpose in order to meet U.S. (well, California anyway) smog standards. If this is true, I should think about increasing my jet size. I haven't actually pulled my plug yet, but next chance I get, I'll do that and see if it's a nice crispy white (lean) color!

I've also thought seriously about changing the stock carb altogether for either a 28 or 30mm unit (stock is 24mm). I decided to give up on the electric supercharger thing because the stock electrical system won't be able to handle the current draw.

Post by **Lostmycage** » Tue Apr 28, 2009 2:13 am

I was able to get up to a 110 main jet without fouling the plug. It really liked the extra fuel. I'm not saying my results would be typical because of a million different variables, but it's worth it to spend the $5 for a 105 jet. If you get a chance, pull your plug and let us know how she looks.

Your statement about the smog tests is pretty much what I was thinking. I know I've read of several manufacturers who lean their bikes to pass C.A.R.B. testing.

davelhunter · Post by **davelhunter** » Tue Apr 28, 2009 4:49 am

Hey guys. I just pulled my plug. My Blur is all stock right now except for dr. pulley 12g sliders. My plug is crispy white. It is definately running too lean. I just ordered a 105 & 110 main. I will post results as soon as get the jets.

charlie55 · Post by **charlie55** » Tue Apr 28, 2009 1:54 pm

Where are you ordering your jets from, and what's the Keihin part number? Been to a few sites, but the numbering scheme is kind of confusing to me.

Thanks

Post by **Lostmycage** » Tue Apr 28, 2009 2:08 pm

I get them at my local dealer Scoot Richmond. It's a little more expensive, but i get them right away and the price with tax comes to about the price with shipping, plus I give a great shop a lil business.

Jetsrus, ebay, there's a few places that carry them.... Scooterworks should...

I'll do some digging for the exact part number/model lines (it's been on my list of things to research for the FAQs), but they're Keihin main jets for the 24mm CVK Carb. Any reputable motorcycle shop should have them.

More later...

mozart2k · Post by **mozart2k** » Tue Apr 28, 2009 8:47 pm

I think many reason to reduce jet cuase they want to meet emission standard (thailand is going to euro6 soon) and about economic consumption for brand image

ps. I do planing to mod my G-MAX and do article later

mozart2k · Post by **mozart2k** » Tue Apr 28, 2009 8:55 pm

babblefish wrote:I'm wondering if the Blurs are jetted lean on purpose in order to meet U.S. (well, California anyway) smog standards. If this is true, I should think about increasing my jet size. I haven't actually pulled my plug yet, but next chance I get, I'll do that and see if it's a nice crispy white (lean) color! I've also thought seriously about changing the stock carb altogether for either a 28 or 30mm unit (stock is 24mm). I decided to give up on the electric supercharger thing because the stock electrical system won't be able to handle the current draw.

I think high compression head piston and re jet is ideal for more acceleration.

fs8gbe · Post by **fs8gbe** » Tue Apr 28, 2009 9:24 pm

sigh, i wish i knew what all of this meant. i keep reading posts like these in hopes that one day it *clicks*

so far, no clicky

guess i will have to wait for the faq

Post by **Lostmycage** » Tue Apr 28, 2009 11:26 pm

If you've got questions or suggestions on how to make some of that stuff more relateable, I'm all ears.

charlie55 · Post by **charlie55** » Wed Apr 29, 2009 12:31 am

OK, I just got a reply back from jetsrus. Assuming that the following picture is a correct representation of the jet's geometry:

with an overall length of 8mm and a head diameter of 6mm, then they can be ordered from this page:

http://www.jetsrus.com/a_jets_by_carbur ... 28-xxx.htm

The Keihin part number prefixes for this jet series is either 99101-393 or N424-36. They both have the same geometry, but the N424's are plated for watercraft usage so as prevent corrosion. I believe (but don't quote me) that the actual jet's part number is made up of the prefix, plus the jet size, followed by a zero. For example, a #105 would be 99101-393-1050.

LMC, think you could verify the jet dimensions from one of your "extras" please?

The Blur's stock size is #102, so I'm thinking of getting a #105 and a #108 to diddle around with.

Thanks all

Post by **Lostmycage** » Wed Apr 29, 2009 12:45 am

charlie55 wrote:OK, I just got a reply back from jetsrus. Assuming that the following picture is a correct representation of the jet's geometry:

with an overall length of 8mm and a head diameter of 6mm, then they can be ordered from this page:

http://www.jetsrus.com/a_jets_by_carbur ... 28-xxx.htm

The Keihin part number prefixes for this jet series is either 99101-393 or N424-36. They both have the same geometry, but the N424's are plated for watercraft usage so as prevent corrosion. I believe (but don't quote me) that the actual jet's part number is made up of the prefix, plus the jet size, followed by a zero. For example, a #105 would be 99101-393-1050.

LMC, think you could verify the jet dimensions from one of your "extras" please?

The Blur's stock size is #102, so I'm thinking of getting a #105 and a #108 to diddle around with.

Thanks all

OK, that's the right geometry (from the pic). Now for the measurements:
Length: 7mm
Head (non threaded portion) Diameter: 5mm
Head Height (thickness): 3mm
Thread Diameter (outside thread to outside thread): 3.85mm
Thread length 4mm

I'd say the jet they measured for you is close, but it's a little off. Let me see if I can find the right part number...

OK, it looks like the model number is 99101-116 or N424-35.
<a href="http://www.keihin-us.com/am/_media/pdf/ ... ">Keihin's jet chart</a> lists it as the second number above.
<a href="http://www.jetsrus.com/a_jets_by_carbur ... Jetsrus</a> has the 99101-116 jets, but it looks like they stop at 102. Their <a href="http://www.jetsrus.com/main_page.htm">chart</a> shows that they also have a 100, 105, 110, 115 and 120, but it doesn't appear on the order page.

A quick search on Google with the jet model number lead me to:
<a href="http://www.motorcyclecarbs.com/Keihin_M ... rbs.com</a>

I'm sure there's others out there.

Hope that helps!

charlie55 · Post by **charlie55** » Wed Apr 29, 2009 1:10 am

Wow, this is getting weirder and weirder. I specifically asked for Keihin CVK24 jets. If you check out the following link, it shows that the 99101-393 series is for CVK type carbs, while 99101-116's are for PB type carbs.

http://www.motorcyclecarbs.com/Keihin_M ... ac34bf3642

But, if what you've got fits correctly, then that's the way to go.

Thanks

charlie55 · Post by **charlie55** » Wed Apr 29, 2009 1:29 am

LMC - you're absolutely, 100% correct on the jet specs and part numbers. I had forgotten that I had the G-Max parts list, and here's what I found:

For the M2-150-4V, the stock main jet is a #105 bearing a part number of 991011161050, which corresponds exactly to the 99101-116-xxx0 pattern.

For the M2-125, the stock main jet is a #102, part number 991011161020.

Now, the G-Max Service manual lists the M2-125 and M2-150 (no 4V designation) as both using a CVK24 carb, and both using a #102 main jet.

So, when it comes to the 150, it looks like they only went to a #105 with the 4-valve option.

In any event, thanks for the legwork. I'm gonna pick up a couple of #105's (one as an offering to the god of dropped and lost tiny parts, and one to actually install) and give em a whirl.

Post by **Lostmycage** » Wed Apr 29, 2009 2:07 am

charlie55 wrote:..one as an offering to the god of dropped and lost tiny parts, and one to actually install...

That made me chuckle! That's a pretty good plan.

charlie55 · Post by **charlie55** » Wed May 20, 2009 11:04 pm

Ran it through the wringer (mostly WOT) for 15 minutes and chopped the plug as soon as I got home (burned my wrist on the %@!&$#%! exhaust). About 5/6 of the circumference of the insulator ranges from cafe-au-lait to an ashy brown. The remaining sixth is an ashy grey. And this is with the stock (102) main jet. So, no evidence of overheating here.

I've got a bit more carbon on the plug threads than I've seen in the past, but I tend to run the idle mixture a bit on the rich side. And now my MPGs have been breaking the 80 mark as well. Guess my baby's a late bloomer since it really seems to have gotten more responsive since it passed the 6000Km mark.

In any event, I picked up a 105 jet and will probably install it when I have some time just to see what effect it has.

charlie55 · Post by **charlie55** » Tue Jun 02, 2009 1:57 pm

Did some poking around and found this review on an Australian forum for their version of the G-Max 150 (Bolwell). Long story short, they also mention the possibility of lean jetting on the 150's (jet size 102).

http://www.scootersales.com.au/ScooterC ... fault.aspx

My plug looked pretty good with a 102, but I think I'm gonna install the 105 tonight just to be on the safe side.

fs8gbe · Post by **fs8gbe** » Tue Jun 02, 2009 2:39 pm

so, keep in mind the closest i have come to any voodoo is a windshield...be gentle.

so a more sizable jet would increase performance. is this top end, accelaration, a little of all?

also, let's say i bought a jet size 105 and installed it. would i need to change anything else on the bike? would it have the potential to cause any issues? would regular maintenance be changed, i.e. would i have to up my oil changes, etc?

Post by **Lostmycage** » Tue Jun 02, 2009 4:10 pm

I ran across that Bolwell site a while back. It was one of the places that lead me to start thinking that this might be an across the board issue. They've got some good stuff there (their download manual section is just plain fantastic).

Changing your jet only changes the air/fuel mix. It won't increase your performance unless you're running lean in the first place. Oil changes, maintenance, etc would be unaffected.

Going too rich will cause it to bog down, but I don't think going from a 102 to a 105 would run it too rich if it were correctly jetted in the first place. Running slightly rich is much more preferable to running slightly lean. The best way to tell is to check the plug and see how it looks.

If you were to change it out, you *might* need to adjust the air/fuel mix to compensate at idle (but not by much at all). The idle speed might jump up a little as well, but that's a much easier adjustment.

MDMason · Post by **MDMason** » Thu Jun 04, 2009 3:00 am

My blackjack came wiith a 90 main. Scooerworks suggested a 92. Whats up with this?

Post by **Lostmycage** » Thu Jun 04, 2009 1:59 pm

It's hard for SW to suggest a fit's all solution for a main jet. There's several factors that come into play. Larger jets will cause a hit in fuel economy which no one likes. Also, the US spands quite a few thousand feet in elevation, which will call for different jets. Then there's the minor differences between engines due to the nature of how they're produced and then broken in.

I think the 92 is the "minimum" that should be installed (they suggest that with the Prima pipe). I also think that the 92 suggested is for the Buddy 125 (the engine that the pipe was originally designed for). They're in the middle of doing some reworking of their website, so some of the info is out of date. Then again, some of the info is just pain wrong. That's one of the reasons I suggest going through your dealer or emailing/calling SW before placing an order online for anything where a mix up can occur.

How positive are you that the BJ came with a 90? I was under the assumption that the Buddy 150 came with at least a 95 jet (I can't remember what I pulled out of my Italia when I re-jetted last Summer). I put in a 105 Jet on the 150 Buddy (with the Prima) and it liked that a lot.

charlie55 · Post by **charlie55** » Sat Jun 06, 2009 11:11 pm

Finally got a chance to rejet today, and took the opportunity to give the carb the once-over. So, I get the 105 in and it runs like crap. Put the 102 back in and it still runs like crap. The it dawned on me that I had taken the slide out in order to try shimming the needle, then decided to try without the shim for a while. Pulled the slide and needle and, of course, I had put the needle THROUGH the plastic spider, not UNDER it. Dumbass Charlie!

Straightened out the needle issue, then put the 105 back in. Voila, success.
As LMC had said, there's no real noticeable diff in performance (well, maybe a little, but that could just be a matter of wishful thinking).

I'm gonna run it this way for a couple of days, then do a plug chop. I'm sure it'll be OK since the 102 already seemed to be working for me, but doing the upjet offers cheap insurance and peace of mind. I'd rather clean/change plugs than have to re-do the top end.

BTW: I took the opportunity to pull the starter and grease its' pinion gear - it was BONE dry. Also, the starter motor sort of sits in a plastic trough. There was a ton of road dreck wedged in there and the casing of the motor was starting to rust. A good dustoff with compressed air might be a wise addition to the regular scheduled maintenance.

babblefish · Post by **babblefish** » Thu Sep 03, 2009 9:51 pm

Ok, so I pull the sparkplug (NGK CR7HSA) from my stock Blur and it's mostly black and wet. The gap was about 1mm (too much, should be .6 - .7mm). I also pull the air filter and I find a small puddle of gas residue at the bottom of the intake tube as well as at the bottom of the air filter housing. The filter itself is a little dirty, but not horribly so - I can clearly see light through it when holding it up to a light source. I'm at sea level, so this is a little odd to me. I installed a new CR7HSA and tried to ride without the air filter in place. Besides the really loud intake noise, it ain't going nowhere. Idles OK, but as soon as the throttle is cracked open the engine bogs and wants to die. Too lean of a mixture without the air filter in place. This is actually good news from my point of view. Could be the stock air box/filter is so restrictive that hidden horsepower is available by getting rid of the stock air box/filter and installing an aftermarket filter and rejetting the carb. To this end, I've ordered some bigger jets from Jetsrus (thanks Charlie55!) in sizes 105, 108, 110 and 112. Now to go find an aftermarket filter. I'm also going to try a hotter plug - CR6HSA. I'll post info when I finish my experiments.

I should probably just wait for the new G-Max 220.....

Post by **Lostmycage** » Thu Sep 03, 2009 10:15 pm

That reminds me... I've been meaning to replace the stock filter with a uni filter, but not directly attached to the carb (so it's not as susceptible to atmospheric changes and the like). My idea is to cut the paper element out and replace it with 40 or 60ppi Uni material. I of course haven't gotten around to it, but you might want to order slightly larger jets. In addition to that, there's a small snorkel in there that can be removed as well as the tiny drain hole drilled out (similar to the Mod Scootertrash posted about).

At near sea level that mix really likes a 110 jet. I've been meaning to go back to a 105 but with a 1mm shim on the needle to see how that compares to the current set-up as well. That's been on the back burner because I'm procrastinating about installing a Mikuni TM24 flat slide carb: same intake and output as stock so it can be used without re-routing vacuum lines or switching to a Uni-type filter that could possibly make it un-rain worthy.

Another note, specifically for you Babblefish, is that the Red CDI works really well, but I think the headlight needs to be re-routed off the kill-switch circuit to take it out of that loop so it doesn't cut out at idle. That's another project I've let sit for a while. I need to look up the Buddy wiring schematics sometime and see how that's routed through.

Glad to see you back 'round these parts.

babblefish · Post by **babblefish** » Thu Sep 03, 2009 11:25 pm

Yeah, I've been away from MB for awhile traveling down one of life's little side roads.

I've been studying the electrical schematics for the Blur to try and figure out why the CDI would effect the headlight, but haven't come to any solid conclusion yet. There's a chance that the particular CDI we have is designed for a DC generator system rather than an AC like the Blur has. The fix could be as simple as putting a diode between the generator and the CDI unit. Something else on my to-do list!

I already have a few jets on order and am looking for an air filter. Ran across a dual layer UNI filter at www.scootertronics.com that I might try. Do you happen to know the O.D. of the stock carbs' intake?

Of course, I may just forget about hopping-up my Blur and just wait for the 220EFI.

Post by **Lostmycage** » Fri Sep 04, 2009 12:11 am

Funny thing about that is that Kaos and Djelliot are both running the same CDI. The measurements for the in and out of the carb are: Intake: 44mm OD Output: 30mm OD. I think the 1.75" (double check that, it's just off memory!).

I'm seriously thinking about the 220i, but there's still no solid news on it showing up (really good speculation, though) and there's no price. Makes it a tough choice. It has made me reconsider doing anything drastic like a big-bore.

I've seen the dual layer stuff and I was giving it some thought... I forget where, but I'v e definitely seen it cheaper than Scootertronics.

babblefish · Post by **babblefish** » Fri Sep 04, 2009 1:00 am

Lostmycage wrote:I've seen the dual layer stuff and I was giving it some thought... I forget where, but I'v e definitely seen it cheaper than Scootertronics.

Yeah, Scootertronics is kinda expensive. I found it for $18.50 at www.partsforscooters.com. It has a 44mm inlet.

babblefish · Post by **babblefish** » Wed Sep 09, 2009 7:24 am

Just received my UNI air filter from Parts For Scooters (really quick delivery) and am just waiting for my new jets to arrive. I'll post info on the conversion and performance results when I'm done.

BTW: If anyone else is interested in getting one of these filters, I found it cheaper at www.powersportsuperstore.com. I paid about $18.50 for mine and as of 9/8/09, Power Sports Super Store has it for $12.35. Rats. The P/N is UP-4182AST.

goshort · Post by **goshort** » Wed Sep 09, 2009 6:00 pm

Would you mind posting a pic of the air filter once installed?
I'm curious how it looks. Good luck!

Post by **Lostmycage** » Wed Sep 09, 2009 7:05 pm

I'm curious about fitment. I'v got a 4" Uni filter and although I've never gotten around installing it, I put it up three in a dry fit and it looks tight.

Then there's the airbox... it's molded into the rear fender. The hose has to be removed for the Uni to fit (assuming a direct placement on the carb) or the box has to be removed so the Uni can be fitted to the hose end (this is supposed to be better for atmospheric changes and the like).

I've just held off on doing anything else because my Blur purrs just right as it is... I dunno if I'd have the patience to retune it to get it to run this smoothly after changing the intake around. Of course I would, but every time I think about it I decide to just put it off till later. Well, I also put it off till I install that Mikuni Flatslide... I'll likely kick myself for waiting once I finally get around to it, lol.

Irishrover · Post by **Irishrover** » Wed Sep 09, 2009 7:35 pm

Uni filters are great so long as you don't get them soaking wet, we have one on my sons mini bike, but if he goes through puddles off road it causes the engine to bog down, I normally coat the black foam part with K&N filter oil and find that helps.

babblefish · Post by **babblefish** » Wed Sep 09, 2009 9:47 pm

I plan to remove the plastic tube that now goes between the carb and the air filter box. The UNI filter will then be mounted directly onto the carb and stay enclosed within the body work thereby keeping water off of it. The filter box will stay in place mainly because the scooter will look weird if I removed it and left a big ol' hole sitting there. I'll take pictures and post.

babblefish · Post by **babblefish** » Thu Sep 10, 2009 7:44 am

Just got my new jets today - guess I know what I'll be doing this weekend!

Er...unless I happen to get tickets for the Giants game....

charlie55 · Post by **charlie55** » Thu Sep 10, 2009 11:56 am

Correct me if I'm wrong, but doesn't the airbox/intake tube combination also help support the carb? Granted, the elbow from the carb to the head is rigid, but do you see any harm coming from letting it be supported from that side alone?

Post by **Lostmycage** » Thu Sep 10, 2009 12:22 pm

charlie55 wrote:Correct me if I'm wrong, but doesn't the airbox/intake tube combination also help support the carb? Granted, the elbow from the carb to the head is rigid, but do you see any harm coming from letting it be supported from that side alone?

Ha, you're right. I'd completely forgotten, but that was another reason I didn't install the Uni.

Since it's not a rigid intake, once you take off the other side, the carb becomes free floating. With the vibrations of the engine and the movement from the engine/swingarm assy, I just don't know how long that manifold would last.

I think that's why I decided to go with the stock air filter replacement instead; it retains the carb/intake mounting points.

babblefish · Post by **babblefish** » Thu Sep 10, 2009 6:49 pm

charlie55 wrote:Correct me if I'm wrong, but doesn't the airbox/intake tube combination also help support the carb? Granted, the elbow from the carb to the head is rigid, but do you see any harm coming from letting it be supported from that side alone?

This won't be an issue. The attachment at the front of the carb is more than enough to support it - it doesn't weigh very much. This is done all the time with dirt bikes (and they get bounced around a lot more than our scooters) plus a lot of street bikes are modified with after market air cleaners that just hang off the carb.

Post by **Lostmycage** » Thu Sep 10, 2009 6:56 pm

Well then the only excuse I have left is procrastination

babblefish · Post by **babblefish** » Thu Sep 10, 2009 10:20 pm

Lostmycage wrote:Well then the only excuse I have left is procrastination

+1

Post by **Lostmycage** » Fri Sep 11, 2009 3:09 am

What range of jets (Ha! pulled it back to the original topic!) are you thinking you'll need? If I were a guessing man, I'd say you'll need about a 120 main, 2mm bump on the needle, and maybe a 40 pilot.

I'd be really curious about how accurate my guess is once you've got it all installed and purring.

I've still got to get the motivation to get some tinkering jets for the flat-slide and get that installed and dialed in. It's really hard to do when the weather is in the 70-80's... just too much riding that needs to be done!

babblefish · Post by **babblefish** » Fri Sep 11, 2009 5:28 am

Hmmm...the biggest jet I bought is a 112 and I,m hoping I don't have to do anything else other than maybe moving the needle up a bit. Guess we'll see when I get to it. Like you said, the weather's just too good right now!

babblefish · Post by **babblefish** » Fri Sep 11, 2009 9:47 am

Lostmycage wrote:Then there's the airbox... it's molded into the rear fender. The hose has to be removed for the Uni to fit (assuming a direct placement on the carb) or the box has to be removed so the Uni can be fitted to the hose end (this is supposed to be better for atmospheric changes and the like).

I just read your post a little more carefully (actually, I paid attention this time

) - the airbox is not molded into the rear fender. Look carefully and you'll see that it's a separate assy. But, if it is removed, there will be a big hole exposed that might look goofy. I'll take if off anyway and have a gander at it.

And I'm not sure if atmospheric changes are an issue since dirt bikes as well as street bikes do it all the time with no ill affects.

Post by **Lostmycage** » Fri Sep 11, 2009 12:17 pm

Doh, I could have worded that better... but, yes, I think we're saying the same thing - with it not on, it's going to look like something's missing. Next time I'll try reading my posts better, hehe.

It was a brisk 50 degrees this morning. Ain't no modding happening this weekend, the weather's PERFECT!

babblefish · Post by **babblefish** » Mon Sep 14, 2009 11:07 am

It's been raining this weekend, so all I got done was to install some 11g sliders and install the UNI air filter just to see if it'll fit within the engine compartment. Yes it does, perfectly. Also, removing the stock airbox and leaving it off is not an option - it's part of the support for the rear fender. Without it, the fender just flops around doing silly things against the tire. I'll try to change the main jet on Monday; if it's neccessary.

babblefish · Post by **babblefish** » Tue Sep 15, 2009 1:03 am

charlie55 wrote:OK, I just got a reply back from jetsrus. Assuming that the following picture is a correct representation of the jet's geometry:

with an overall length of 8mm and a head diameter of 6mm, then they can be ordered from this page:

http://www.jetsrus.com/a_jets_by_carbur ... 28-xxx.htm

The Keihin part number prefixes for this jet series is either 99101-393 or N424-36. They both have the same geometry, but the N424's are plated for watercraft usage so as prevent corrosion. I believe (but don't quote me) that the actual jet's part number is made up of the prefix, plus the jet size, followed by a zero. For example, a #105 would be 99101-393-1050.

LMC, think you could verify the jet dimensions from one of your "extras" please?

The Blur's stock size is #102, so I'm thinking of getting a #105 and a #108 to diddle around with.

Thanks all

I can tell you that those "K28" jets that are from Jets R Us is not the correct size for the Blur. They're too big; almost twice the size. I now have 4 very small paperweights that I hope I can return to them. After removing the carb and taking it apart, I had to put it all back together again with the original airbox.

Looks like Lostmycage is right; the 99101-116 part number is correct and JetsRUs shows up to size 108 can be ordered.

Oh well, at least I know how to do it quickly the next time around...and I replaced the phillips head float bowl screws with SS allen screws which will make taking off the bowl a lot easier the next time.

Post by **Lostmycage** » Tue Sep 15, 2009 2:49 am

babblefish wrote: I can tell you that those "K28" jets that are from Jets R Us is not the correct size for the Blur. They're too big; almost twice the size. I now have 4 very small paperweights that I hope I can return to them. After removing the carb and taking it apart, I had to put it all back together again with the original airbox.

Looks like Lostmycage is right; the 99101-116 part number is correct and JetsRUs shows up to size 108 can be ordered.

Oh well, at least I know how to do it quickly the next time around...and I replaced the phillips head float bowl screws with SS allen screws which will make taking off the bowl a lot easier the next time.

Yeah, the Blur's use an off the wall jet size... I recall being able to get them in 102 (stock) 105, 110, 115 and 120. I've heard rumors of a 108, but I I don't recall seeing any. As a precaution, I bought 1 of each a while back for testing purposes. 115 with a mostly stock airbox, stock filter and a Prima Exhaust was too rich. I'm running a 110 with a slightly modified airbox, stock filter (brand new as of 500 miles ago) and stock exhaust and mine purrs. I don't *think* I have the needle shim still in place... I'd check, but that procrastination's a real butt-kicker.

You know about the drain screw on the carb right? Makes jet changes a breeze, plus you can recover the fuel. And I friggin LOVE my allen screws on the carb, the standard/stock ones strip like a sunnuvabich!

babblefish · Post by **babblefish** » Tue Sep 15, 2009 4:18 am

Where did you buy your jets from? JetsRUs sells theirs for $2.79 each, but I think they makeup the price difference with their shipping cost which was $7.50 for 4 jets.

Modern Buddy

Jet sizes

Jet sizes

just read my plug

Upjet Completed