Lean miss?

[Stevej's wing]

So I got the engine from the parts bike I bought installed and running, WOW!
Now I am working out the bugs. So I have this miss above 4000 rpm, and changed plugs and checked them out today.
Looks like it is running lean and may have to rebuild the set of carbs that came with the parts bike.
Could a lean mixture cause a miss like that, bugs me!
Boy but what a difference on the smoooothness of this engine, and oil pressure, WOW, shifting WOW.
Now just work the bugs out. :headscratch:

 

[zman]

Not sure, did you try pulling the choke when it happens?

 

[joedrum]

yes ... its probably lean mixture from leaking air .. try what zman said and post what happens

 

[Stevej's wing]

Leaking air on all four cylinders?
Will try the choke number tho thanks.

 

[Stevej's wing]

Choke did not change things.
Put a pint of MMO in gas tank took it out on the freeway and let her rip. Will see how it goes this week on my commute.
I think it is the carbs, started getting a hint better out on the freeway with the MMO
Will keep you posted!

 

[Stevej's wing]

Found the problem. Spark plug wire pulled out of boot on one spark plug just enough to cause a miss under load.
Wow now I can enjoy some smooooth ridding! :heat:

 

[joedrum]

great nice when its simple

 

[AApple]

DOH!!!! I hate it when that happens!!

:good: :clapping:

 

[Steve83]

Cool - an easy, cheap fix!