38mm carb

[thecoon]

just finally got what ive been wanting a 89 250r and my question is i put a 38mm air stryker on it runs like crap . motor piston is one size over stock boysen reeds bills pipe and no lid on air box . at sea leval what should i start with as far as jetting and needle old carb had a 168 in new carb has a 170 runs like **** . its been a long time since i messed with 2 strokes thanks for the help

[DnB_racing]

did it run good with old carb? are you sure its a fuel issue and not electrical?

and at what throttle position is it running poor,

before you start jetting, you need to make sure of all the pre tuning preparations.....
new gas, new plug gaped properly, clean air filter, air tight intake boot,

is the carb new, if used check for wear on the slide, and make absolutely sure its clean and free from damage,

2 strokes and 4 stroke carb jetting circuits are the same, its throttle position not rpms that determines what jetting needs attention,

[thecoon]

ya ran ok with old carb . the guy i bought it from put a new cdi,coil,stator on it when he rebuilt it about 8months ago but its not oem stuff could this be a problem? runs bad off idol bogs and pops no air leaks fresh gas and plug starts easy idols great just bogs and pops then revs up . carb is like new new pilot and main slide looks good thanks again for the info should i just go straight to the cr ignition since the electrial is not oem and its all some ebay stuff ?

[DnB_racing]

I wouldnt condemn your existing electrical components just yet... if it ran good with old carb then its more then likely the new carb, and from what your describing it sounds like it could be the pilot circuit,

does it clear up over around 1/2 throttle? if so your main is in the ball park,

bogging and popping are 2 different things, if its bogging like hitting a false rev limit, then its too rich, if it pops and breaks up then its too lean..


have you ever tried doing a plug chop?
they can be helpful if you know what to look for, but if not it can be deceiving with the synthetic oils and race fuels and ratios it can be tough to get a good reading unless youve done them before, and have seen what different combinations will leave for results