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Exhaust Leak

Started by Diablo007, September 19, 2020, 12:15:59 AM

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Diablo007

So the project RD350 has an exhaust leak.  Actually 'leak' doesn't quite describe it.  It's more like the exhaust isn't sealed at all judging by the smoke coming out of the junction.  The exhaust gaskets are brand new, from a gasket set from India.  I did a quick comparison with some factory Yamaha ones I had and they seemed the same.  The clamp seems to be flush against the cylinder so I'm guessing the gaskets were not thick enough.  The bike is a 'bitsa' so I don't know if the clamps are for the headers if there were different ones.  They seemed to fit properly but they also seem to have a curve which I didn't notice until I inspected the junction after firing the engine up.  There is a tiny gap in the middle while the sides look flush with the port.  The clamp did not slide off the end of the header so it seemed to be the correct size, and the bolt holes also lined up perfectly.

Has anyone seen this before.  What would a solution to the problem be?  Doubling exhaust gaskets seems like it would be too thick.  If the Indian gaskets were incorrect they were close enough in size to the Yamaha ones that there was no noticeable difference so using a Yamaha gasket seems an unlikely solution.
2 stroke junkie:
Too many motorcycles to list.  The highlights:
1973 Yamaha RD350 Cafe Racer project; 1983 Suzuki RG250 YammaGamma project; 1988 Yamaha YSR50/80 project; 1984 Yamaha RZ350; 1984 Yamaha RZ500

quocle603

 Do not double up on the gasket.

I would try putting some of the "the right stuff" gasket maker with your exhaust crush gasket to see if that helps with your issue. I've used all sorts of different exhaust crush exhaust gaskets,  ranging from Chinese to factory ones and they all sealed up properly.
Do not underestimate the power of a two-stroke.

1975 Yamaha RD350 (modified), 1973 Yamaha RD350 (stock), 1971 Suzuki T500, 1981 Yamaha XS650 HS2, 1982 Honda MB5, 1980 Puch Maxi, 1979 Puch Magnum, 1993 Tomos Bullet, 2003 Malaguti Firefox F15 LC

Evans Ward

Also, to add to the above; a cure time of 24 hrs after application of "Permatex- The Right Stuff" is optimal before starting it after tightening your flange bolts/ nuts.
1984 Yamaha RZ350
1976 Suzuki GT750
1972 Kawasaki H2 750 Mach IV

Striker1423

The Right stuff works, but I opted for the orange high temp version. Stinks to high heaven, but once cured... no leaks!

Diablo007

Thanks for the input.  I have to go to O'Reilly's today anyway so I'll grab some 'The Right Stuff'.  Permatex's website shows black, grey, and red, in different applicators.  I'll see what the local store has in stock and choose from there.
2 stroke junkie:
Too many motorcycles to list.  The highlights:
1973 Yamaha RD350 Cafe Racer project; 1983 Suzuki RG250 YammaGamma project; 1988 Yamaha YSR50/80 project; 1984 Yamaha RZ350; 1984 Yamaha RZ500

Diablo007

The black 'The Right Stuff' seems to have worked.

That being said; I noticed that both the Indian and Yamaha gaskets seem to 'choke' the exhaust port.  Say for giggles I turned some aluminum 'gaskets' on my lathe out of aluminum bar stock that did not choke the ports and used 'The Right Stuff' to seal everything up; what would the possible problems be?
2 stroke junkie:
Too many motorcycles to list.  The highlights:
1973 Yamaha RD350 Cafe Racer project; 1983 Suzuki RG250 YammaGamma project; 1988 Yamaha YSR50/80 project; 1984 Yamaha RZ350; 1984 Yamaha RZ500

quocle603

Glad that suggestion helped out! :)
Do not underestimate the power of a two-stroke.

1975 Yamaha RD350 (modified), 1973 Yamaha RD350 (stock), 1971 Suzuki T500, 1981 Yamaha XS650 HS2, 1982 Honda MB5, 1980 Puch Maxi, 1979 Puch Magnum, 1993 Tomos Bullet, 2003 Malaguti Firefox F15 LC

pidjones

Quote from: Diablo007 on September 22, 2020, 02:05:19 AM
The black 'The Right Stuff' seems to have worked.

That being said; I noticed that both the Indian and Yamaha gaskets seem to 'choke' the exhaust port.  Say for giggles I turned some aluminum 'gaskets' on my lathe out of aluminum bar stock that did not choke the ports and used 'The Right Stuff' to seal everything up; what would the possible problems be?
Many other bikes use hollow copper o-ring exhaust gaskets. You might try getting the right diameter of them and try. Whichever, always check carefully that previous gaskets have been removed. I once found three gaskets compressed into each port on a GL1000.
"Love 'em all.... Let GOD sort 'em out!"

quocle603

BAHAHAHA I can hear the exhaust leak now.
Do not underestimate the power of a two-stroke.

1975 Yamaha RD350 (modified), 1973 Yamaha RD350 (stock), 1971 Suzuki T500, 1981 Yamaha XS650 HS2, 1982 Honda MB5, 1980 Puch Maxi, 1979 Puch Magnum, 1993 Tomos Bullet, 2003 Malaguti Firefox F15 LC

Diablo007

@quocle603

Elaborate please.  Was your comment directed at using the copper gaskets found in 4-strokes, or regarding turning aluminum spacers and using 'The Right Stuff'.  If it's the latter, similar has been done by a noted tuner acquaintance.  In their case they JB welded the spacers in for one of their builds, currently they weld up the recess and use copper/silicone gasket sealer.  I'm hesitant to use JB weld or weld up the recess on a street bike as it would be hard to reverse.  They replied to my email after my last post.
2 stroke junkie:
Too many motorcycles to list.  The highlights:
1973 Yamaha RD350 Cafe Racer project; 1983 Suzuki RG250 YammaGamma project; 1988 Yamaha YSR50/80 project; 1984 Yamaha RZ350; 1984 Yamaha RZ500

85RZwade

I thought he was referring to the Gold Wing with three gaskets per port. :umm:
I post waayyy too much

Diablo007

DOH...that makes more sense.  I thought there might be a reason for not using a round/tube copper gasket in a 2-stroke, or bad experience with using a spacer and sealer instead of a crush gasket.
2 stroke junkie:
Too many motorcycles to list.  The highlights:
1973 Yamaha RD350 Cafe Racer project; 1983 Suzuki RG250 YammaGamma project; 1988 Yamaha YSR50/80 project; 1984 Yamaha RZ350; 1984 Yamaha RZ500

quocle603

Laughing at the goldwing.
Do not underestimate the power of a two-stroke.

1975 Yamaha RD350 (modified), 1973 Yamaha RD350 (stock), 1971 Suzuki T500, 1981 Yamaha XS650 HS2, 1982 Honda MB5, 1980 Puch Maxi, 1979 Puch Magnum, 1993 Tomos Bullet, 2003 Malaguti Firefox F15 LC

Diablo007

@quocle603
Thanks for the clarification.  Wanted to make sure I hadn't missed something important with my plan as I'm thinking of doing this for the next engine that needs new gasket and seals.
2 stroke junkie:
Too many motorcycles to list.  The highlights:
1973 Yamaha RD350 Cafe Racer project; 1983 Suzuki RG250 YammaGamma project; 1988 Yamaha YSR50/80 project; 1984 Yamaha RZ350; 1984 Yamaha RZ500

quocle603

Do whatever works. People are all up in arms about things when it comes to doing it the RIGHT WAY.
Do not underestimate the power of a two-stroke.

1975 Yamaha RD350 (modified), 1973 Yamaha RD350 (stock), 1971 Suzuki T500, 1981 Yamaha XS650 HS2, 1982 Honda MB5, 1980 Puch Maxi, 1979 Puch Magnum, 1993 Tomos Bullet, 2003 Malaguti Firefox F15 LC