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Bit of a weird one , bike runs crapish, and gets worse each time

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Cr 125 07

 

1. First time took it to a track

Session1.the first 20mins it ran pretty good and was loving it

Session 2. the next 15 mins , starts bogging low down, but still rideable 

Session3.next time out , bogging like mad , to point  almost unrideable.

Piglet 50    Main 420.  plug was a 9 and nice and brown        As1.5 out   Needle stock clip3    Fuel 110ml to 5l        

 

2nd time took to  a track to test 

So changed pilot to 40 main 420.   plug 8  (looked wet and oily ). As 1.5 out needle stock clip 3 fuel 110ml to 5l

pretty much the same  happend as first time to tack, but the 3rd session out it got to point I didn't even do quarter of a lap, had to cut  the course as could barely ride it back to the van

compression and rings seem ok, checked v force reeds which are ok, clean filter , and all sounds satisfactory on the stand 

 

im slowly starting to fall out love with this mc,what you chaps reckon, should I just chuck the mukuni carb in the the bin and buy a 38mm keinhen, would the keinhen fit straight on without changing the boots.idealy I suspect should start from scratch, but it's a pita as have to take the bike to a track(which only get chance every 6weeeks)  and pay £35 to ride and an hr pissing about each time changing jets, so want to be in the ballpark before I next take it out

 

 

 

 

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Jetting doesn't suddenly change; there is an underlining issue. Is suspect a failing main bearings. This would intern cause seal failure, causing the bike to run rich. I'm not ruling out a worn out top end though. Heat can also bring on electronic gremlins as well.

 

 

 

 

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If you are dead set on changing the carb, if that is the issue, I would scrap both of those carbs and go with a lectron. Generally speaking a bike that runs worse as time goes on, it is a sign of more major problems than jetting.

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Sounds exactly like when my bike had a leaking trans-side crank seal.  Weekend trip, first day it fouled the plug if I didn't keep the revs high.  Second day, really hard to start then I would have to get on immediately and rip it.  Third day couldn't get it started to save my life.  

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Also it started to leak oil from around top of rhs casing , I'm not sure if there's significants 

IMG_1954.JPG

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I might add ,initially it was only playing up bottom end, once on the main jet it seemed fine, hence why I first thought it was pilot jet and went from 50 > 40 ,but on the last session it wouldn't even ride on the main, just spluttered as I rode it back to van, and that's when I noticed oil on the casing 

what does the tps do 

Edited by fakesy

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I'm not sure mate, as they came on the bike 

iv only had bike 5 months and done 2 rides 

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My money is a failed right side crank seal or failed reed petal.  Have you checked your coolant level/condition?  Drain your gearbox oil and inspect it; any coolant?

 

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Coolant level is ok, I have just ordered new 38mm airstrike , as that will illuminate the mukuni out, but suspect there could be an additional problem.im going to take it round a mate so he can have a look, he knows 10x more than me .

the keihen will come jetted for a cr250, so obviously I will have to swap jets needle , how about the 7mm slide ?

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