036 ring end gap

[flatsfisher]

good morning. I'm installing a NOS top end on my 036 today. the service manual makes no mention at all about ring end gap that I can find. as a lifelong MX bike rider and former racer this is a big deal in that world. I've installed new top ends on 2 strokes and had to file many rings that came new way out of spec.

I've done a search and found nothing definitive. one guy says .002 per inch of bore and another guy says .006 per inch of bore. I know what wiseco says for dirt bikes per inch of bore but that is for water cooled 2 strokes with forged pistons.

anyone have a source for this spec?

 

[Mad Professor]

good morning. I'm installing a NOS top end on my 036 today. the service manual makes no mention at all about ring end gap that I can find. as a lifelong MX bike rider and former racer this is a big deal in that world. I've installed new top ends on 2 strokes and had to file many rings that came new way out of spec.

I've done a search and found nothing definitive. one guy says .002 per inch of bore and another guy says .006 per inch of bore. I know what wiseco says for dirt bikes per inch of bore but that is for water cooled 2 strokes with forged pistons.

anyone have a source for this spec?

There were threads on this but the search function here sucks.

I can't recall myself. Check it anyway, you need "enough".

A Husky piston scoring guide gives a wear limit of 1.0mm/0.040"

 

[flatsfisher]

did some further reading on other forums. .004" gap per inch of bore seems to be the consensus. there is also a "how to" on the wolf creek saw shop that recommends .004" per inch of bore diameter.

 

[flatsfisher]

in this case it turned out to be a non-issue as the new rings had a .011" gap.

 

[Mad Professor]

PITA to check the gap as P/C sets and piston/ring sets come with the rings installed.

 

[flatsfisher]

true. I took the rings off and measured the gap. just have to be careful taking them off and putting them back on. they can snap in half if you bend them too much.

 

[Mad Professor]

true. I took the rings off and measured the gap. just have to be careful taking them off and putting them back on. they can snap in half if you bend them too much.

Or they break your fingernails.

 

[Captain Bruce]

There were threads on this but the search function here sucks.

I can't recall myself. Check it anyway, you need "enough".

A Husky piston scoring guide gives a wear limit of 1.0mm/0.040"

Nothing here helps answer the question? Whats the point of typing....

 

[BrettS]

There were threads on this but the search function here sucks.

It's not the only thing on here sadly...

 

[Chevboy0167]

I got to use this little guy on the 141 I did a few weeks ago. Only a 40mm piston mind you. Worked great!

https://www.ebay.com/itm/295049881113?hash=item44b257e619:g:Y0cAAOSw8S1ir6hC

 

[Mad Professor]

Nothing here helps answer the question? Whats the point of typing....

Point being if you have nearly no gap bad things are going to happen when it runs. The OP has rebuilt engines and has a ballpark idea of correct gap. I provided a "worn out" value from a Husqvarna piston analysis guide to use as a comparison..

So how have You helped? Not a bit besides whining.