Topic: leaky intake manifold

[cadler]

Anybody ever have a leaky intake manifold. Does not matter what bike, but that is where I am going next to debug this cb450.
if anyone has had one, what were your symptoms?
Thanks

[edbikerii]

Bike runs like @$$.

Spray intake, including the surface that mates with the head, with WD40.  If the idle improves (or changes at all, really), then you have a leak somewhere.

[cadler]

this is what i get.  a nice idle at 1000rpms,then give it gas and idle sticks at 3000rpms.
when i spray carb cleaner around manifold it will knock it back down to 1k.

[Bar50]

Look for cracks in the manifold/boots.  If you can narrow it down to one or two with the Wd-40 it helps, but, if you got to replace them, I would put them all on.  Some times you can rev up the bike and chock out each carb buy hand(over the carb opening with the air filters off) if it has trash in it, sometimes it will suck the gunk through...not much help with an intak leak though. 

[cadler]

I think I found the problem, there are no gaskets behind the manifolds. I guess i did not expect something like that because the bike had only 14000 miles. Why would someone remove them?
Craig

[edbikerii]

Maybe PO had no business turning a wrench.  I've seen dumber than that, for sure.  Consider yourself lucky the PO didn't try to seal that surface with epoxy or roofing tar or something stupid like that.  Are they supposed to be o-rings like the CB550, or just flat gaskets?

I think I found the problem, there are no gaskets behind the manifolds. I guess i did not expect something like that because the bike had only 14000 miles. Why would someone remove them?
Craig

[cadler]

I will let you know, I just ordered them from David silvers. I think they are flat gaskets.

Do you know if I should put on  non hardening gasket sealer or just use the gaskets?

[edbikerii]

On my 550 those were o-rings and I used Hylomar HPF(?) non-hardening sealer.

I will let you know, I just ordered them from David silvers. I think they are flat gaskets.

Do you know if I should put on  non hardening gasket sealer or just use the gaskets?

[midnightrider]

On my 550 those were o-rings and I used Hylomar HPF(?) non-hardening sealer.

Did this work out well for you?  Did you check it for leaking after?

[edbikerii]

Yes.

On my 550 those were o-rings and I used Hylomar HPF(?) non-hardening sealer.

Did this work out well for you?  Did you check it for leaking after?

[MoMo]

I will let you know, I just ordered them from David silvers. I think they are flat gaskets.

Do you know if I should put on  non hardening gasket sealer or just use the gaskets?

Flat gaskets on the CB450 dohc and you should not need to use any sealer-I never have on any of the ones I owned...Larry