blowing exhaust from port

my exhaust seems to be blowing between the expansion chamber and the port is this a common thing ? its only blowing on one side . it has new gasket . please assist me with this thanks

I think many do leak in that area - if you mean between the exhaust manifold and expansion chamber. Mine does, and it's quite annoying as it spews black oil over the back of the front mudguard and down the frame down-tube.

I haven't got around to fixing mine yet, but I'll be trying stiffer springs and/or a little high temp silicon smeared around the inside of the expansion chamber where it joins the manifold - not too much though.

Also worth checking that your tailpipe packing isn't clogged up or spark arrestor caked up (if it has one fitted), i.e. that nothing's increasing the back-pressure.

yes its only on the ignition side that it blows from how annoying grrrrrrrrrrrrrr . i have a fresh silencer . just seem to blow from that side dont know why??? maybe a common fault between the manifold and expansion chamber. it may be due to the bracket on the frame ? i dont know . but hope some one comes up with a soloution in the future? thanks

It does on my '71 400...persistant problem..I just figure 'oh well'

If it's between the spigot and the pipe, rather than between the spigot and the cylinder, use hi temp black silicone when you assemble it. It doesn't get hot enough to cook it. It will be cleaner and run a tiny fraction better. Permatex makes the brand I use. Smear a bit inside the pipe and some on the spigot and stick it together. I do it all the time.

very helpful .

please can you post a picture of the tube of silicone . as i want to get the correct one. thanks. i bet we cant get it in uk ???

I used to have this problem.
The solution is "Permatex Ultra-Copper". It is a silicone based sealer, but is much thicker. Ideally suited for exhausts. It does not burn off, even at the head/primary pipe joint on 4 or 2 strokes.
It stay's where it is put, even in small holes in mufflers (my KLX250 has nearly rusted out).
It has totally cured the Husky stub leaking. Seems to be very difficult to get this stuff in the UK at the moment. Although it is still available in the U.S.
Comes up on ebay.com.

will this be ok?

is permatex ultra black ok do you think?

Not really. That is a gasket silicone. It will last a short while before it blows out.
There are some one fleabay at present in the US. Price is not bad either. But not much help if you want it tomorrow.

I wonder if Loctite Ultra Copper High Temperature RTV Silicone Gasket Resists Up To 350°C is the same product, as "Ultra Copper" seems to be a registered trademark, but see Loctite product sheet here



£6.75+vat from here but you could probably get it cheaper.

That loctite stuff is essentially the same and will work fine. And the cleaner the surfaces before applying, the better it will last (I know - stating the obvious!)

what do u rekon?

i have found some silicone/instant gasket at home .... 1 is high temp pro seal copper XS RTV withstands 371 oC but its orange in colour. and other is pro seal black RTV withstands 315oC. if i mix them up do you think it will be ok? as id like it to be black in colour. just incase it goes every where lol. thanks all

i cleaned up the two parts and smeared the orange /copper high temp silcone on the inside of exhaust. then reassembled . fingers crossed. im just a bit worried that i may of put too much on or too less? what can be the worst case sinario if i have applied too much ??? thanks

too much

dont worry too much will just blow out of end can/i have done mine twice with rtv but still leaks slightly.

chhers pat

thanks for that info pat

Good stuff guys ... I am soon to reassemble and will use the suggested Permatex ultra copper.

The joint between the manifold and pipe on my CR400 is not what I would call tight!

hello again. i just had a look down my expansion chamber and found some seriously bad welding on inside. maybe thats whats causing my leaky joint . the only problem is..... what sort of tool can i use to grind the inside down with ??? please help

The contour of the pipe can change causing a mis alignment at that junction. The red rtv silicone stuff and a day of waiting is standard for me. Do you have an allignment problem at that place? As for what tool, there are some quite small air powered die grinders, less than an inch in diameter and less than five inches long which could be attached to a pole or pipe or bent object if you were really dedicated. If one can't weld stuff like expantion chambers without having the molten puddle collapse one should use copper back up. Or most any kind of back up at least it won't stick to copper if you really get it hot. Is it possible the leak is from a crack? Would be quite easy to spot.

Fran

it is the bad welding inside of the expansion chamber causing problems. i have cut it to have a closer look. just hope the welder has a small grinding tool to grind it away and re weld neatly. what was you saying about the copper ? and please explain . thanks fran k