Exhaust Gasket sealant advice V7 Racer

[jcb72]

Hi

I recently fitted new PipeMaster muffers to my V7 racer, it was an easy job and the bike ran a lot smoother than when I had the El cheapo shorties I had on it previously.
But then I installed a Stuchi Crossover pipe which meant I had to remove the exhaust from the gasket and here is when my pain began :(

Ever-since this change the bike just does not feel right I reckon Ive lost some power too, and it idles horribly at around 750 rpm to the point it feels like its going to stall, I add some choke to around 1000RPM but it just does not feel the way it did (sounds weak)

Ive had to take off the pipes from the manifold twice as teh first time I did not add any gasket sealant and the bike backfired and was noisy as hell, second time I aapplied gasket sealant to both sides of the O ring the back firing stopped, but I think ive still got a small leak, I sprayed some soapy water between the manifold and pipe and noticed some micro bubbles, I could not see a leak anywhere else.

Ive also noticed gold colouring on other areas of the pipes that where not there before I only had Blue colouring.

Can some recommend what Permatex sealant I should be going with ? the website mentions with or without gasket, but I'm not sure if the O ring would be classed as one.

Also can someone please provide some advise for the best way to apply the sealant i.e steps, does it need to be applied both sides of O ring, do I need to leave it to set for 1 hour before applying some torque ?.

one other thought could it be the crossover pipe?

I have a power commander and autotune running also.

thanks in advance.

[Vasco DG]

By o-rings do you mean the gaskets between the header pipes and the heads? These shouldn't have or need any sealant, just careful, even, torquing.

The fact that the bike is now running badly would seem to me to indicate that you have messed something else up. Is this a single lamda or twin lamda bike? Is or are the sensors connected and working properly?

Pete

[jcb72]

yes the O ring gasket, I was not sure if it was classed as a gasket as they are normally of paper like material and the O ring is more Tin like material.

Strange that there is not supposed to be any sealant, when I first removed the pipes there seemed to be a white coloured material on it (cement type) are you sure it should not have any. the first time I did not apply any sealant and the leaks where very evident and also noisy, and the bolts that tighten the pipes to the manifold would always come loose no matter how many times I tightened ?.

Its a single Lamda that has always been disabled as i am running PCV and Autotune which still seems to be working.

[Vasco DG]

Sounds like you've over tightened the nuts and stripped the studs out of the head.

Pete

[jcb72]

It could be but I dont think so as the threads look ok, I can also tighten further If I wished but by doing so I probably would damage the thread.

Any other suggestions :)

[Vasco DG]

Nope. The laws of physics and engineering always win. If you have a problem with gas leakage at the port it's because the sealing gasket is buggered or you can't get sufficient clamping force. Replace the gaskets, torque correctly, if you still have a problem then it's elsewhere.

Pete

[jcb72]

But isnt that what a sealant help with ?

[Vasco DG]

No, it's a horrible kludge to cover up a mechanical or engineering failing. There are some places where sealants are useful. An exhaust port where temperatures can be greater than 800*C? With a compound tht is basically an organic plastic? Maybe not so much...

Pete

[rbm]

Maybe it's me but I think there are two different gaskets being talked about.

Inbetween the header pipe and the cylinder head exhaust port on each cylinder, there is a copper gasket.  It looks like this:

There is one of these gaskets for each cylinder.  Both of these gaskets needs to be replaced if the header pipes (i.e. manifold) is removed from the engine.  These get crushed on first use and are not reusable once crushed.  The exhaust port clamp screws are tightened evenly to cause the crush.  The clamp nuts are known to loosen and need to be checked for tightness (or wired in place using racing wire).

There are also gaskets used where the muffler joins the header pipe near the crossover, down around the footpeg area.  This gasket looks like this:

This gasket seals the joint between these two parts to prevent gas leakage. I've found that this gasket can be reused so long as it does not have any damage.

When I read the OP's first post, I thought he was talking about this second gasket.  It might be possible that this gasket can be substituted with a gasket forming material that can withstand high heat, such as muffler cement, but it's not recommended.  No such gasket forming material is ever used around the copper gasket at the exhaust port.

However, with Pete's questioning, the focus of the discussion shifted to the copper gaskets.  If that is truly the case, the I guess I was mistaken.

[Cam3512]

Different gasket at the head on my'14 Special.  It's a flat, very thin washer.  Not sure what it's made of, but it's almost paper-like with a metallic center.

[jcb72]

ahhhahh Thats the problem, i did re-used the O ring lol, I'll buy 2 new ones,

Mine is more like this one Athena Exhaust Manifold Gasket (8452857) http://www.rawpowermotorcycles.co.uk/PBSCProduct.asp?ItmID=13057416 is this still a crush gasket ?  as it already looks pretty crushed

so there is no way it could also be a combination of the exhaust leak (even though its a minor leak)  and the new crossover as its half the size of the original.

cheers lads.

[rbm]

One possibility could be that the PC-V/AT equipment you have attached is learning the correct fuel changes necessary to compensate for the reduced size crossover.  It takes time for the Power Commander to adjust for new conditions because there is a programmed limit on the range of change for any trim map cell value; 20%, I believe, as set by the Max Enrichment/Enleanment Trim variables.  This can be altered in the AT configuration so that the final map values converge quicker at the risk of losing your safety net.  The AT manual also offers troubleshooting tips that suggest trim map values which could point to exhaust leaks.

[jcb72]

Thanks Robert I'll have a look at it on the weekend.