I need an exspert on jetting and tuning a 84 air cooled 250R!

[David komatina]

I have an 84 250r with a 72mm over bore carbon fiber boysen reeds and the stock kehien carb PE 30 i run a 32:1 mix i do not know what main or pilot is in it right now but i can find out if needed the place i took it last said they had too drill the main out i am not shur that it was the right thing to do?. It has been rejetted four different times by people that said they new what they were doing but its still not right it spits and sputers at low throttle and even at half. Three quarters too full it evens out but when you are on it for a strait strech it sometimes stuters and i halfto pump the throttle to get it to even out again and it will only even out in fifth gear if im in lower gears it spits and sputers again i would like a nice clean and smooth thottle through out the gears and power band . Im a pretty damn good mechanic i built the machine frame up so i know it well i want too tune it myself but i need a guy that realy knows what hes doing to help me out and give me some insight. Any help would be greatly apriciated! Thanks David

[WilliamJ]

David,

It is not a good idea to drill out your own jets. It sort of works but a drill is not a very precise tool - all carb jets are made to very precise sizes and finishes. I think you need to get stock jets and needle and try that. The fact that your engine is over-bored should not trouble the stock carb.

The carb does not know about the engine size or the reeds. All it sees is airand fuel, and the air pulls fuel from the jet at a rate to precisely match the volume of air as you open the throttle. If your engine is pulling more air than the carb can deliver, you will only find that out at high revs when the engine is trying to suck more air than the carb will allow. At that point you need to go to a larger carb. But the smaller carb will still do a good job up to that point.

Bill

[David komatina]

I didnt drill my jets the last place i took it too did and i have had it completely back too stock it ran way worse at stock. Keep it coming guys i need too tune this thing in corectly.

[Thorpe]

Read this thread....

http://www.3wheelerworld.com/showthread.php?55086-Carb-Jetting-101-Terms-Tips-and-Jetting-Theory

[David komatina]

Thanks man this should help alot!
Read this thread....

http://www.3wheelerworld.com/showthread.php?55086-Carb-Jetting-101-Terms-Tips-and-Jetting-Theory

[David komatina]

I have another question what is the diferance beetween the longer main jet or the shorter main jet can u use eather or should i stick with what was in it? My wheeler has a long one in it.

[Thorpe]

Whatever jet is pictured in the manual is the one I would use....