Hey guys I have a stock 89 250s that I am trying to rebuild into a 300ex as$ kicker... I am planning on boring it out two sizes over if possible and I have a Slip-on form a Yamaha R1 street bike for it. My question is.. how do I tell if its running too lean or too rich? It has a stock carb with a 110 main jet. Id love to put a bigger carb on it but when ready the other post, its seemed very complicated to put that 32 mm carb on. Plz help.. I love rebuilding the past.
CGriff

 

well if the bottom of the plug is white your running lean or if it puffs white smoke your running lean. If your running rich the bottom of the plug is all full of gas/or you faul your plugs often. Its also puffs blue/black smoke if your running rich. I bored mine out .40 over and still got the stock main jet and it runs mint.

 

Are you also running an after market pipe on your zuki? The reason i ask id because i was always told if you put a high flow filter and pipe on you will need to rejet.. wether it be just fine tunning or replacing jets. Also where did you get the piston and rings for your bor job?

 

i ordered the piston from suzuki there are no weisco pistons for them which sucks. I am also running with a uni foam filter. I redid my stock pipe because i do not want it loud. Too bad your so far from me because the guy that rebuilt my engine did a great job it cost 440$ for all the parts and labour and he redid everything and checked everything over.

 

Id love to get more details on the rebuild you got done.. what size piston did u end up putting in? how much did you have to bore the cylinder out?
CGriff

 

I think its bored out 0.40mm the less you bore it the better. My bore job cost f*ck all just go to a machine shop. I have no idea what size of piston i got put in.