Jetting - 150 Italia

Benzo Mike · Post by **Benzo Mike** » Sun Aug 24, 2014 9:49 pm

OK, a little background. Motorcycle guy here, I have 4. I'm an engineer, for what that's worth. I build motors, and do a lot of racing. Road racing, drag racing, and land speed record racing. I picked up a 150 Italia recently for the wife to ride, we'll see how that goes. It has 900 miles on it, I've gone over it thoroughly and cleaned it up. Did a FULL service, everything. Absolutely mint condition, 100% stock.

Well, I rode it around some and immediately made a couple observations. Most notably, as built, it runs CRAZY lean, has crappy throttle response, and the top speed is pretty low (53 MPH GPS on a looooooong flat run). Tucked in, behind a Prima windshield.

Plug is snow white, I've never seen anything like that. It sounds lean when wound out, kind of crackly, Sluggish throttle response. Excellent MPG. Classic lean symptoms. Confirmation (try this). Pull off the pet carrier, put it up on the center stand. Start it, warm it up, then hold the throttle WFO and let it wind out all the way (you won't break anything). It won't pull anywhere near the rev limiter. Now, put a finger or two in front of the air intake tube, choke it a little. Now, you would EXPECT it to slow down, as you're starving it for air. Nope. It revs up BIG time, maybe another 2000-3000 RPM, and the exhaust note gets mean. Hmmmm...

This thing wants fuel, big time. When you choke it, the vacuum signal gets stronger and you pull more fuel up the main jet/emulsion tube.

So, time to get tuning...

KrispyKreme · Post by **KrispyKreme** » Sun Aug 24, 2014 9:59 pm

Welcome to the forum. I don't have an answer for you, I just wanted to say I am very jealous that you have this...........

Benzo Mike · Post by **Benzo Mike** » Sun Aug 24, 2014 10:00 pm

Some reference information...

For a 2009 150 Italia, stock jetting is:

Main jet Keihin type 99101-116 size #92
Pilot jet Keihin type N424-21, size #38
Float height 18.5 mm
Pilot screw 2.25 turns out from seat

OK, a couple of oddities...

The carb is equipped with an accelerator pump. A functioning accelerator pump. If you pull the float bowl off and stroke the pump, you will get a high-pressure needle of gasoline in the eye. However, the outlet (in the carb throat) is plugged, it looks like a little cap is soldered/brazed on. So no accelerator pump function.

Also (and it has been claimed here before), the OEM pilot jet fitted from the factory (a 100% legit looking Keihin #38) is MUCH smaller (the orifice) than a replacement Japanese genuine Keihin #38. Much smaller. Weird. So if you replace or otherwise go swapping pilots, be aware of this and adjust accordingly (smaller pilot or run fuel screw in some). Swap in a genuine #38 and leave the fuel screw in the same position, it will not idle. It will just load up the plug and stall.

Benzo Mike · Post by **Benzo Mike** » Sun Aug 24, 2014 10:00 pm

Wait for it, Krispy...

Post by **jrsjr** » Sun Aug 24, 2014 10:08 pm

Benzo Mike wrote:The carb is equipped with an accelerator pump. A functioning accelerator pump. If you pull the float bowl off and stroke the pump, you will get a high-pressure needle of gasoline in the eye. However, the outlet (in the carb throat) is plugged, it looks like a little cap is soldered/brazed on. So no accelerator pump function.

Okay, now I have a dumb question. Could that little cap be machined off with something as simple as a Dremel moto tool, or does the opening need to be precision shaped (as a jet)?

Interesting thread, BTW. Welcome to Modern Buddy!

Benzo Mike · Post by **Benzo Mike** » Sun Aug 24, 2014 10:18 pm

So, the solution...

I ordered up a huge assortment of pilots and mains. PJmotorsports.com, I get all of my jets from them. OK price, outstanding customer service, fast shipping.

I've been working on this pretty solid for about a week, finally got it sorted to my satisfaction today. Yes, I have a wideband, etc...

Went all the way up to a #105 main jet. Yes, I know that's a huge increase from stock. No, I haven't modified the exhaust or intake. All stock. The wideband and plug both indicate this is a little bit too big. But a #100 was definitely too small. So really a #102.5 (which doesn't exist as far as I can tell) would be ideal. The #105 gave best top speed and throttle response, plus it satisfied the "finger in front of intake tube" test, any obstruction now slows the motor down.

Put in a genuine Keihin #38 pilot. This required the fuel screw to be set at 1.5 turns out to get it to idle properly. It's still a little fat, will probably run it in a little more. Also had to back off the idle speed screw. In truth, this pilot is a little too big, a smaller one with the fuel screw back out would maybe be better. Tip-in is nice, though, so I'm going to stick with it.

Put 2x0.50 mm shims (the infamous Radio Shack washers) on the needle. The stock needle has a nice taper, but sits too low. This thing REALLY wants fuel.

With this jetting/carb set-up, I can now pull 62 MPH GPS on a long, flat run. It gets up to 50 MPH GPS in a hurry, then takes a while to rev out. It will pull 49 MPH GPS uphill (a steep one), and I saw 71 MPH GPS on a long gentle downhill run today (chasing/drafting a Porsche 911S), it still had a little in it but I had to lift to avoid running into the dude. It will cruise at 50 MPH GPS with just a little throttle, maybe 25% open. Stock, I had to pin it to hold 50 MPH GPS.

Oh, almost forgot - with the stock jetting it would actually run faster at about 7/8 throttle, classic lean condition.

For those that care about such things the fuel mileage is now pretty poor, maybe 70 MPG. Exactly as you would expect.

Benzo Mike · Post by **Benzo Mike** » Sun Aug 24, 2014 10:23 pm

I would bet that the accelerator pump squirter could be opened up. Maybe as simple as hitting it with a torch and melting the solder (if it is indeed soldered). The size of the shot is controlled by pump stroke and a jet right at the bowl-to-body junction. Usually when the pump is disabled, that jet is plugged (a #0 jet). In this case, there is a legit jet in that position, ready to go, and the tip of the squirter is plugged.

Next thought - do we need an accelerator pump? I don't get any lag when the throttle is yanked open, so with my current setup, I would say "no".

An accelerator pump can be cool. It can also cause you to have to walk home when some moron (possibly yourself) works the throttle several times when parked, especially hard yanks on the throttle. Flood the motor, no start.

KrispyKreme · Post by **KrispyKreme** » Sun Aug 24, 2014 11:20 pm

Benzo Mike wrote:Wait for it, Krispy...

Nah, I have different priorities. Still love that Daytona.

MYSCTR · Post by **MYSCTR** » Mon Aug 25, 2014 1:41 am

Interesting thread yet I wonder how much variance there is between model years or even the same year of a certain motor in production and assembly. This is because our 2009 150 Italia with just under 400 miles on it hit 78 bmph and we have had 2 150's and 1 125 that easily run 75 bmph on the flats. Last time I rode our daughters 2009 125 through Dallas I was drafting an 18 wheeler showing 82 bmph and hardly on the throttle.

We have seen others who picked up a used Buddy state on here that their top end was much lower then any Genuine Buddy scoot we have had which makes no sense as all but one was ridden stock short of the Prima pipe on the 150's.

We have two 170's in the mix now and have not pushed them yet so we don't know where they will end up. The Ozarks are calling...

Benzo Mike · Post by **Benzo Mike** » Mon Aug 25, 2014 1:58 am

Good question/point. I certainly can't hit those kinds of speeds. Full-sized dude here, 6'2", 210 lb. Maybe that has something to do with it. I imagine a tiny woman might go faster, 120 lb is 25% lighter scooter/rider combo, quite significant? Don't know...

MYSCTR · Post by **MYSCTR** » Mon Aug 25, 2014 2:52 am

Yes - weight does play a factor but has to be minimal for the 125/150's as at that time I was about 185 and the past year bouncing around 200-205.
The 125 with a rider weight at 110 'riding like a girl' she was pulling 107 mpg and had no problem keeping up with me on a 150. The wife weighs just a tad more and rides a 150 - yet it was me on my wife's new scoot that pulled those speeds coming back from the North Texas Lakes Rally that year.
The girls don't ride that fast or aggressive on their own and always get better gas milage than I do. Not sure if any of this helps your carb work.

Benzo Mike · Post by **Benzo Mike** » Mon Aug 25, 2014 3:03 am

Nope.

It's a Taiwanese scooter. What you gonna do?

In the motorcycle world, a 10 MPH top speed difference between stock bikes would burn the internet to the ground and immediately trigger a buyback of ALL units. Oh well.

How accurate is your report? Just saying, there are a couple "top speed" threads on here and your numbers are WAAAAAY out on the long tail of the bell curve for a stocker.

PeteH · Post by **PeteH** » Mon Aug 25, 2014 3:48 am

Buddy mph (bmph) are typically GPS + 10% or more

Benzo Mike · Post by **Benzo Mike** » Mon Aug 25, 2014 3:55 am

Accounting for that. I am now making max power for a stocker and can pull BMPH 55 (uphill), 69 (flat), and at least 80 (downhill). Dude is still claiming some impressive MPH relative to what I'm seeing (and generally reported experience). Kind of pissing me off, if these numbers are genuine (no pun), and I have no reason to believe they are not. Top speed is the whole game here in the Midwest, pretty much defines where you can and can not go. Not sure.

skipper20 · Post by **skipper20** » Mon Aug 25, 2014 4:28 pm

Benzo Mike wrote:So, the solution...

I ordered up a huge assortment of pilots and mains. PJmotorsports.com, I get all of my jets from them. OK price, outstanding customer service, fast shipping.

I've been working on this pretty solid for about a week, finally got it sorted to my satisfaction today. Yes, I have a wideband, etc...

Went all the way up to a #105 main jet. Yes, I know that's a huge increase from stock. No, I haven't modified the exhaust or intake. All stock. The wideband and plug both indicate this is a little bit too big. But a #100 was definitely too small. So really a #102.5 (which doesn't exist as far as I can tell) would be ideal. The #105 gave best top speed and throttle response, plus it satisfied the "finger in front of intake tube" test, any obstruction now slows the motor down.

Put in a genuine Keihin #38 pilot. This required the fuel screw to be set at 1.5 turns out to get it to idle properly. It's still a little fat, will probably run it in a little more. Also had to back off the idle speed screw. In truth, this pilot is a little too big, a smaller one with the fuel screw back out would maybe be better. Tip-in is nice, though, so I'm going to stick with it.

Put 2x0.50 mm shims (the infamous Radio Shack washers) on the needle. The stock needle has a nice taper, but sits too low. This thing REALLY wants fuel.

With this jetting/carb set-up, I can now pull 62 MPH GPS on a long, flat run. It gets up to 50 MPH GPS in a hurry, then takes a while to rev out. It will pull 49 MPH GPS uphill (a steep one), and I saw 71 MPH GPS on a long gentle downhill run today (chasing/drafting a Porsche 911S), it still had a little in it but I had to lift to avoid running into the dude. It will cruise at 50 MPH GPS with just a little throttle, maybe 25% open. Stock, I had to pin it to hold 50 MPH GPS.

Oh, almost forgot - with the stock jetting it would actually run faster at about 7/8 throttle, classic lean condition.

For those that care about such things the fuel mileage is now pretty poor, maybe 70 MPG. Exactly as you would expect.

Welcome to the MB forum. Your technical expertise is most impressive and I'm sure those of us with carbureted scoots will benefit from your experience. But, and with all due respect, what's with your fist in the face avatar?

Bill in Seattle
'09 150 Buddy Blackjack
'12 170i Buddy Italia
'87 150 Honda Elite (currently for sale)

Benzo Mike · Post by **Benzo Mike** » Mon Aug 25, 2014 4:53 pm

Really? Are you serious?

That fist does not belong to me. It belongs to a 13-year-old British actor. I'm a 47-year-old brewer.

Cool movie, though. Check it out.

MYSCTR · Post by **MYSCTR** » Tue Aug 26, 2014 12:58 am

We are two weeks from Scoot the Ozarks - will get a few rides to push the max on the 09 150 (just under 14K miles) and 14 170 (just hit 1,000 miles).

KrispyKreme · Post by **KrispyKreme** » Tue Aug 26, 2014 2:42 am

Benzo Mike wrote:Really? Are you serious?

That fist does not belong to me. It belongs to a 13-year-old British actor. I'm a 47-year-old brewer.

Cool movie, though. Check it out.

The actor? The movie?

You come on a bit strong. I like your style, but we are a peaceful bunch here. Maybe you can teach us and we can you?

Pics and /or videos would be cool.

Post by **ericalm** » Tue Aug 26, 2014 4:26 am

Some carburetor functions and adjustments may be disabled to meet EPA/DOT/CARB requirements.

That could be why the accelerator is plugged over. They also cap or use special screws on the air/fuel adjustment.

Duggle · Post by **Duggle** » Tue Aug 26, 2014 2:48 pm

KrispyKreme wrote:The actor? The movie?

Too easy, I just discovered that there is such a thing as online reverse image recognition software now for finding out where images originate from.

http://www.imdb.com/name/nm2129938/

What I used. https://www.tineye.com/

CapnK · Post by **CapnK** » Tue Aug 26, 2014 2:54 pm

Good point, eric. On the Sym Wolf, the first thing many non-Californians do is to remove all the junk which makes the bike CARB compliant. The result is smoother starting and general better and more responsive running. I never gave a thought to the fact that my Buddy has been treated this way - and so am very interested in finding out what could be done to de-CARB it and 'let it run free'.

Looks like to me the kids fist has a tattoo on it - will Google Image search it, see if I can figure it out. Personally I don't see the avatar as being overly aggressive or any of that... Kind of funny, actually, a little kid with attitude, like Spanky in Little Rascals of *long* ago...

Edit: Duggie posted as I typed my own.

Duggie - you can also use Google - go to Images, click the camera icon in the Search text box, and then paste in the URL of the picture you want to search about. It returns pretty good results (as does TinEye).

Movie synopsis: A story about a troubled boy growing up in England, set in 1983. He comes across a few skinheads on his way home from school, after a fight. They become his new best friends even like family. Based on experiences of director Shane Meadows. It's from the movie "This is England": http://www.imdb.com/title/tt0480025/?ref_=nmmd_ph_tt1

Duggle · Post by **Duggle** » Tue Aug 26, 2014 3:19 pm

CapnK wrote:Personally I don't see the avatar as being overly aggressive or any of that...

Yeah, he's just doing the '60s/'70s British youth thing, like the "Benzo" in his name (mods, Quadrophenia, etc). Perfect for a scooter forum.

Benzo Mike · Post by **Benzo Mike** » Tue Aug 26, 2014 6:11 pm

Previous post notable for active imagination and incorrect assumptions. You guys are entertaining, I'll give you that. Good times.

Duggle · Post by **Duggle** » Tue Aug 26, 2014 7:27 pm

Ok, my mistake. I thought Benzo was for Benzadrine.

Benzo Mike · Post by **Benzo Mike** » Wed Aug 27, 2014 1:17 am

That's one whopper of an assumption, for sure. I'm going to let this go without additional comment.

HowHH · Post by **HowHH** » Wed Aug 27, 2014 3:00 pm

All this talk of jetting and top speed has piqued my interest.

Rejetted my Blackjack to a 100 main jet earlier this summer, but had some nagging performance and starting issues, that ended up being due to a failing auto fuel valve. Finally got that replaced (took a while to get the part delivered). Cleaned up the gas that had been flooding everywhere and readjusted the carb for idle and mixture.

It's now running really strongly. Good off the line and pulls well throughout. In a tuck, on the flat, it'll hit a hair over 70bmph. I assumed I was doing maybe 63-65 but never confirmed with GPS as it felt fast enough for 10" wheels and kept up with traffic on the highway when needed.

Anyways, I installed a GPS speedo app on (Ulysses Speedometer) my phone and went for a few runs. Hit 71 or 72bpmh. When I pulled out my phone and checked the app I was surprised to find it reported a top speed of 70mph!?

Can this be right? I have no idea how accurate such apps are. I will have to try a couple other "real" GPS devices to check this out.

By the way - It was good movie.

scootERIK · Post by **scootERIK** » Thu Aug 28, 2014 4:42 am

^I have been running the Ulysses Speedometer for quite a few miles and it seems pretty accurate.

tiii · Post by **tiii** » Sat May 09, 2015 4:40 pm

I've not seen another post mentioning the accelerator pump in the Buddy carbs. Has anyone unplugged theirs?

BuddyRaton · Post by **BuddyRaton** » Sat May 09, 2015 11:34 pm

tiii wrote:I've not seen another post mentioning the accelerator pump in the Buddy carbs. Has anyone unplugged theirs?

Yes. The only difference is that sometimes I need to work the throttle until it warms up. Maybe 2 mins

tiii · Post by **tiii** » Sun May 10, 2015 6:24 pm

Okay, thank you, BuddyRaton.

So, no performance gained? Or, the only down-side is that you can't idle before it's warmed up?