I just put a new fmf pipe and 35mm Keihin on my 87 tecate, and it is bored .060 over. When I start it, it smokes quite a bit and it won't idle. It also looks like there is a little oil coming out of the head where the exhaust mounts up. I checked the main jet and it is 160. I am thinking it is running too rich. It seems to run alright at the higher rpms, but boggs a little at the lower rpms in first and second gear. I pulled the spark plug and it is pretty black. Should I change the jetting?

 

You should rejet after doing anything to alter the airflow of an engine. If you don't you could ruin the engine resulting in costly repairs. Since it runs good at higher rpms, you need to adjust the needle and pilot jet.

 

J, you need to lower your needle by raising the E-clip one postion, should take care of the smoke, but make sure you have the right main jet in it.

 

you need to open up that airbox and go bigger all carb settings to get the full effect.

 

Thanks for the replies. I think I have the right main jet as it runs great from about 1/4 throttle on up. I will adjust the needle position one setting and see if that helps. I also have holes in the top of the airbox with a k&n.

 

Under 1/4 throttle is most influenced by the pilot jet. Probably going to need around a 52 pilot, do you know what size you have in there now?Try going down a size or two...

 

Bear with me, I hope this doesn't sound too stupid. How do you get to the pilot jet? I know how to get to the main jet but have never checked the pilot jet.

 

u need to take off the bowl, and get a small screwdriver to take it out. It sits in a "straw" near the main.
What controls the throttle positions:
idle to 1/4, PILOT JET
1/4 to 3/4, Needle Jet
3/4 to full throttle, MAIN JET

 

I took the pilot jet out and it is a 68. I think that is my problem. I was thinking I need around a 52/54. What do you think?

 

Yes, being bored try the 54, but keep checking plugs to make sure that the other throttle positions are not too lean or too rich. The pilot circut wont damage the motor if a little lean, the main and the needle will! If it is very hard to start you have too lean a pilot. If it revs really high when you start it you have it too rich!!! Good Luck