Topic: 1981 CB900c exhaust backfire

[yellowjacket]

Have any of your worked with a cb900c?  Picked it up about a month ago and have it running fairly well with exception of the exhaust backfiring(popping).  Tried to get some help on the DOHC board but they do not support modifications to bikes.  The bike has CV carbs jetted 125/74 with air pods.  It has what I believe to be a Jardine 4 into 2 exhaust.  The bike runs strong thru all the gears.  The plugs when pulled are dry with a whiteish tan look to them.  Any input would be appreciated.  Thanks.

[MikeSimon]

For one thing, I have never used pods on a bike with CV carbs. The re-jetting required to get these to run right is a nightmare.
But I am not trying to lecture you on what you should do or not.
One other problem area on the DOHCs are the inlet manifolds between cylinder head and carbs. They harden real bad and have air leaks, which could be the cause for the popping. Check whether all the clamps are tight.

[yellowjacket]

I have heard the comments on the carbs with pods.  I plan on trying for a while.  Thanks for the input.  I should replace the inlet manifolds, they pretty dang hard.  it took two of us to get them back on.  I believe they are sealed though because I have no fluctuation when at idle and I spray carb cleaner on the joints.  I am replacing the exhaust gaskets next to see if this helps.

[eigenvector]

If it's anything like my CB750 Limited with the aluminum slide carbs - that bike is REALLY vacuum sensitive.

That said, there are rumors of guys who do run them with pods and they work just fine.  But they may also live with some popping on decel too.

For the record, if it's the same site - I didn't find them to be particularly nice to anyone.  Their way or the highway attitude.

[MikeSimon]

That said, there are rumors of guys who do run them with pods and they work just fine.  But they may also live with some popping on decel too.

For the record, if it's the same site - I didn't find them to be particularly nice to anyone.  Their way or the highway attitude.

They probably do...and I think I know what site you are talking about....a few primadonnas who "have done everything" and are above any critique. Most of the others are hamfisted hackers who worship on their altar...

[MoMo]

If you need a set of boots, I have an extra brand new set.  The 900c does not support mods and doesn't do much well other than cruise all day long down the highway.  Never understood the use of a "10 speed"     How is your rear brake? ....Larry