Topic: I think I found my carb problem!

[DammitDan]

I always thought that the engine of the SC model and the std model on the 1982 CB650 were mechanically the same.  However, when I got to thinking about it, I did a little research and found this...  http://home.wi.rr.com/kgebauer/cb650history.htm

Turns out std carbs have a 120 main with a #100 main air jet, while SC carbs have a 118 main with #80 main air jets.  This may be the solution to all of my problems!

My bike is an '82 CB650 std with stock pipes and carbs, and SC engine and airbox.  If the main air jets are too large, then that would create a seriously lean issue when running at 1/4-1/2 throttle, right?  And that's where I'm having all of my problems.  And yes Buffo, I did a plug chop.  Idle to 1/8 is just a TAD on the rich side (pilot screw adjustment?), while 1/4 is on the lean side, and higher just gets worse.

Now, how do I fix the main air jets on the '82 CV carbs?  I hadn't even heard of them before now.

[DammitDan]

Guess the easiest/cheapest solution is to buy SC carbs... looks like replacing the main air jets would be major undertakings!

Fortunately I've found a set for $30.  We'll see how they fare.

[Buffo]

I know the carbs are different but I have an 82 yamaha Vision and it has removable air jets...i  just pulled mine out ond put the new ones in...they were dirt cheep...from the dealer...I am not sure aabout your airs thou...

Hey...your making progress!!! 

Buffo The Magnificent