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Bigatc
03-14-2012, 02:04 AM
I recently sent my motor out to get the cases machined for a big bore 350 kit. When i got the bike back it blubering real bad on acceleration. I was told to start the jetting at 192 for break in and might have to lower to 190 or 188. Took it to the guy that designed the kit. He then installed the 188 and no change. he even leaned it out to 182 still the same. He stated that with the higher compression that he think the compression is puting the spark out. He told me to leave it with him. I called him back a week later and he stated that he tried a new cdi box and stater and still no change. He was then waiting for a flywheel and a wiring harness to throw at it. Isnt there ohms checks that can be done to figure out if the stater or wiring harness are bad? Or do you think it might be a porting isuue? I never had this problem before i blew the bike up. The old cylinder was a stock cylinder that was ported to the max so i would want to say the compression was high as well. I am going friday to pick the bike up. Any suggestions.:wondering

RIDE-RED 250r
03-14-2012, 04:17 PM
It could still be jetting on the pilot circuit or needle height.

There are electrical specs in a service manual that could be checked. I don't know the link, but member MonroeMike usually pops in with links to downloadable service manuals.

Also, heavy porting doesn't have an effect on compression ratio. It's all in the combustion chamber dome profile in the head. You can have a heavily ported cylinder that runs on pump fuel.

What dome did you get with your 350 cylinder kit? Pump gas or race gas? As long as you are running the recommended fuel for which ever head you got compression would not be your problem.

rjs89ia
03-15-2012, 12:38 PM
had the same problem with my 310 from esr i put it on and when i rode it it would spit and sputter and cut out at anything over half throttle. i changed everything on the electical side and that didnt fix it i ended having to switch to an airbox delete and that fixed it right away. dont know if your running a stock airbox on the 350 but check your airflow.

Bigatc
03-15-2012, 04:20 PM
Thanks guys, I hve the esr air box elimination kit. RIide red, not sure what dome, he set the motor up to run 50/50 gas and race gas. Im running 110 octane set the needle height to 4 where he said and gave me a new pilot jet. This guy made his name from 250r and not just some joker.

RIDE-RED 250r
03-15-2012, 04:47 PM
Just curious.... Who did the build for you if you don't mind my asking??