Hi all.

need some help.

i changed the cylinder head cover on my 89 cbr600fh as the old one had a screwdriver driven through it (dont ask). Anyway. Before I started, i started the bike and it ran fine.now With the new cover on it is back firing. As far as i can tell i touched no other parts. I thought the ht leads were in wrongly but they seem to be fine. I put new sparks plugs a week or two before i changed the head and everything im reading would suggest that the carbs may need reset. This certainly seems logical as when i pulled the choke out it stalls but with it in it only idles around 1k rpm (around 2k) before. However i didnt go near the carbs so i dnt see how they would need reset.

any other suggestions?

 

Is the bike backfiring through the carbs or the exhaust?

 

Hi

its backfiring through the exhaust

 

That indicates a lean situation. Since you say that you didn't touch the carbs, I'd begin by looking at the headers. Are they torqued down correctly? when reinstalling them, are you sure the o-ring/gasket for each cylinder got installed properly?

 

I guess the gasket could have slipped as i put the gasket on due to the angle of the cylinders. I shall check this and get back to you.

cheers much

 

Mark,

Not clear what you did here. Did you change the head? There are a lot of things that could go wrong if you changed the head. Your post says "cylinder head cover".

Assuming everything is together right then a lean condition is likely the cause. Loose, cracked or leaky carb boot(s), dirty pilot circuit in one or more of the carbs. These carbs are very sensitive to the crap gas we have now. If it sat with fuel in the bowls they likely needs to be cleaned. Running without air cleaner and cover also can cause lean burning...you get more air to the engine with it off and thus there isn't enough fuel in the mix.

Your description of how it runs with the choke on is symptomatic of dirty carb pilot circuit again assuming everything else is put together correctly.

Dennis