MRP pipe/ jetting question

skip! · Post by **skip!** » Mon May 11, 2009 12:26 am

So, finally splurged and picked up an expensive MRP pipe. I installed it on my Blur and took off for work. It ran pretty good on the way there but started sputtering at high revs on the way home and actually died on me at one point. I got it home (still ran great at 10mph and below) and ordered some jets from Scooterworks. Long story short, I've tried a 105, 108, 115, 120 and now I currently have a 130! in the carb and the bike still sputters at high revs! Starts great, great acceleration but after 10 or 15 mph it runs like crap. Any suggestions, I'm stumped. Could it be the piston? Variator got too hot and melted? Any help would be greatly appreciated.
Thanks, Skip!

p.s. the pipe looks really sharp on the Blur and the bracket is very well made

Lostmycage · Post by **Lostmycage** » Mon May 11, 2009 2:48 am

You might have the wrong type of main jet. The best I've been able to tell, the jets on the PGO version of the Keihin carbs use a slightly different size jet.

Sputtering at high revs is indicative of being too rich.

Check out this <a href="topic10679.html#136701">Thread</a>. In the posts a few below, it shows some sources.

So that you're not looking and looking, the jet style is 99101-116xxx (xxx=jet size). Stock is a 102. I've had good experiences running up to a 110 with the stock exhaust (slightly rich) and even better with a 105. I think for my area, a 105 main with a 1mm needle shim is pretty much spot on.

Let us know how it works out! Don't forget some pics.

mozart2k · Post by **mozart2k** » Mon May 11, 2009 3:42 am

I think I might cuase over rev. I could be floating valves and hit piston. please try to check for valves leak.

skip! · Post by **skip!** » Mon May 11, 2009 3:48 am

mozart2k wrote:I think I might cuase over rev. I could be floating valves and hit piston. please try to check for valves leak.

How do I check for valve leak?

mozart2k · Post by **mozart2k** » Mon May 11, 2009 2:10 pm

skip! wrote:
mozart2k wrote:I think I might cuase over rev. I could be floating valves and hit piston. please try to check for valves leak.
How do I check for valve leak?

You should do a compression testing (Std. for 150cc 11Kg/Cm @ 650 rpm)

1. Warm up engine
2. Replace spark plug with compression guage
3. Fully open the throttle and using start motor drive engine until guage stop rising then read compression guage

Lower compression shown cuase bent valve or worn piston ring and sleeve

Higher compression shown cuase carbon deposit

If you can take cylinder head out you can test by pour gasoline into intake port and looking for leak gasoline from combustion chamber
and then do the same with exhuast port

^^' even if it leaky take out valve for bent check

PS. Sorry for my terrible english

skip! · Post by **skip!** » Sun May 17, 2009 2:24 am

So, I took off the MRP pipe, put the stock pipe back on with a 105 jet and she rides like a dream again. Is there something wrong with the 400 dollar MRP exhaust?

Lostmycage · Post by **Lostmycage** » Sun May 17, 2009 3:59 am

There's something wrong with a $400 exhaust, that's for sure.

I missed your question before, but a needle shim is used to richen the mixture in the midrange. This shouldn't apply to you, as the first step is to get the main jet correctly selected. The needles in the CVK's that the PGO bikes use don't have clips (most other CVL carbs, at least the tunable ones, have several clips to control how deep the needle sits). To increase the mid range fuel supply, you can add a shim (.5mm-1mm washer) or two until you get the midrange performance that you're looking for. This should be done after the main jet is selected.

From what I've gathered, it almost sounds like the baffle has collapsed in the MRP exhaust. I'd be talking to my dealer for some answers (they get their answers from MRP). I really hope you don't get burned on this. Let us know what happens!

skip! · Post by **skip!** » Sun May 17, 2009 4:57 am

thanks a lot. I 'll let you know what happens

Lostmycage · Post by **Lostmycage** » Tue May 26, 2009 1:46 pm

Skip, have you gotten your Blur fixed yet? Any idea what was happening?

skip! · Post by **skip!** » Fri May 29, 2009 4:06 pm

Lostmycage wrote:Skip, have you gotten your Blur fixed yet? Any idea what was happening?

I finally gave up and brought it to my local Genuine Dealer (NoHo scooters in North Hollywood). I know the owner, so I feel pretty safe doing that. Well, the immediate diagnosis is that it's the STATOR! After all my jetting and re jetting and going back to completely stock, it's an electronic thing. They said that there is another Blur in the shop with the same problem. Ever heard of an ongoing stator problem with the Blurs. Wonder if it has anything to do with upgraded CDI? Too many revs? Got too hot? Anyway, before I blame the MRP pipe, (at this point, I think it is fine) I will wait on the part (80 dollars) and the installation and hope for the best. I'm also gonna post a new thread about stators if I can't find one.

Lostmycage · Post by **Lostmycage** » Fri May 29, 2009 4:44 pm

I'm glad you guys got it figured out. I don't think I've heard of this happening on a Blur before, but it's not surprising.

What CDI did you use?

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MRP pipe/ jetting question

MRP pipe/ jetting question

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