Sealing a leaky exhaust manifold

[3WW Star-John_Neary]

Since day one the pipe on my Rotax has leaked at the exhaust manifold as it has no type of seal or o-ring and while the pipe fits snug over it they do not make a proper seal and it make a mess. Any ideas on how to seal this better?



I was thinking of getting a over sized o-ring and sliding it over the manifold so the pipe is pressed against it once the springs are snug.

[El Camexican]

Not sure if you want to start changing much on that particular trike, but if the spigot is thick enough you could get a groove cut on a lathe to hold an o-ring like some do on the Tri-Z cylinders.

The be all end all is the current KTM method of two O-rings on the exterior of the pipe collar that then slides inside a spigot on the cylinder. Not a drop of oil has escaped on the ones I've seen that are 2 years old. I'd love to convert mine to that set up some day.

[3WW Star-John_Neary]

The manifold is 3mm thick so not a huge amount of metal there to cut grooves in.

[barnett468]

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Since day one the pipe on my Rotax has leaked at the exhaust manifold as it has no type of seal or o-ring and while the pipe fits snug over it they do not make a proper seal and it make a mess. Any ideas on how to seal this better?

yup

I was thinking of getting a over sized o-ring and sliding it over the manifold so the pipe is pressed against it once the springs are snug.

thats in the right direction, unfortunately, the springs will either cause the o ring to squeeze out or it will smash it to smitherines because they are not designed to work that way.


here's just a few of options.

1. make sure the flange on the pipe is perfectly square with the flange when it is installed.

2. with the piper brackets loose but the springs installed, pull on the headpipe with one hand . . if you can pull it away from the cylinder, the springs are too loose . . get stiffer springs or shorten yours.

3. get one of the gasket types below and install that over the flange.

4. install the springs then tighten the brackets.


If the flange on the pipe is thick enough, you can have an inside 0 ring groove cut as El Camexican suggested for cylinder flange, and use an 0 ring there.

If you don’t care about the appearance of the flange on the head, you can weld a 5/16 tall ring on it and use one of the copper gaskets inside.

You can also, make it around the same height and use a copper gasket, or cut o ring grooves in the od of your pipe or do both.

you can get these at some motorcycle shops and industrial hardware supply stores . . dont know if home depot has them though.


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[barnett468]

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there will still likely be some amount of leaking if you just use a gasket over the flange but it will be greatly reduced . . using o rings as El suggested, will seal the best . . the copper gaskets are designed to be crushed with a bit of force.


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[3WW Star-John_Neary]

manifold is 48mm OD so ill see what i can find, im buying new springs and waiting to measure stuff once the pipe is back on the bike but that is a ways off still

[onformula1]

If you don't o-ring use- exhaust assembly paste.

http://www.ebay.com/itm/Wurth-Exhaus...470059&vxp=mtr

Works wonders and is very popular in the UK were emissions are very strict, if you have a leak you fail.

The exhaust will come off with a small twist.

[3WW Star-John_Neary]

I ordered this

http://www.ebay.com/itm/HONDA-YAMAHA...-/170860620080

but i might get that paste as well

[onformula1]

Copper gaskets are made to go in the exhaust pipe and seal against the exhaust flange with pressure from the pipe springs, that one looks to big at 49mm and will go over the exhaust manifold all the way to the bolt on plate.

Keep in mind any gasket that spaces the exhaust out will give you more low end power and less top end power, but that gasket looks fairly thin so you may not notice a difference.

[barnett468]

manifold is 48mm OD so ill see what i can find, im buying new springs and waiting to measure stuff once the pipe is back on the bike but that is a ways off still

if the flange leaks at the head, you can find one of these gaskets to fit . . you can place a piece of 180 - 220 sand paper on a granite counter top or on a window next to a frame and rub the flange on it to see if it is flat or not.

if you want to just put sealer between the flange and pipe as suggested, you can also try ultra high temp copper filled silicone for just $6.00 . . you could put some on the gasket below also.

http://www.amazon.com/Permatex-81878.../dp/B0002UEOPA
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[3WW Star-John_Neary]

the flange seals good so ok there, the plan for the copper gasket i ordered was to wedge it up into the pipe and have it mash down tight onto the manifold with some new springs

the OD of the gasket is 1mm more than the ID of the pipe so with a little work it should be a snug fit, the ID of the gasket should be around 44mm so it wont slide over the manifold and a few more MM of headpipe would do that powerband some good...very pipey bike as i recall it

[onformula1]

^ if you want, put in a envelope and send it to me, I will turn it down on a lathe.

The paste is the way to go, copper is soft but not so soft pipe springs will "crush" it to seal, but the carbon from the exhaust will probably make it seal at some point.

[nd4speed]

Since you said the pipe and flange have a good mating fit, you may want to just try Red Loctite. I used it back in the day to seal my pipe to my silencer. The only down side was, they were like welded together until the stuff wore out. I wanted to take my silencer off once and it would not budge, so I gave up and left it.

[onformula1]

Since you said the pipe and flange have a good mating fit, you may want to just try Red Loctite. I used it back in the day to seal my pipe to my silencer. The only down side was, they were like welded together until the stuff wore out. I wanted to take my silencer off once and it would not budge, so I gave up and left it.

If you heat it up to 500 degrees the Loctite will turn to liquid and it will come off.

Sent from my SM-G386T1 using Tapatalk

[Joseph Farrow]

Good info. I am running into the same problem with my RD bike.

This is what I currently have.....


This is what I am used to coming from my 250R. It has the grove and metal O Ring.


Onformula1 thanks for the tip on the sealer. Probably what I a going to use.