Perplexed in Iowa

[DAM shop]

Okay folks need some help. We have a ATC 90 Bored 5mm over, stroked, ported head, bigger cam, heavy duty valve springs. The machine smokes bad, runs good, idles good, good compression. We’ve had the top end off 4x now. The trike is actually dripping oil out of the exhaust. We have Inspected rings (new rocky) without taking off piston and no obvious signs of breakage. We’ve inspected the valve guide with no obvious signs of breakage. We thought after our last pull off that we had found the problem with us forgetting to put in a stud guide where the oil seal goes. That didn’t solve the issue either. We did have a bad tick and that was caused by the intake valve hitting the piston we have fixed that. We have rebuilt 50 of these or so and have never had one smoke like this before. We are now leaning towards a bad exhaust valve guide. Any thoughts as to what we could be missing here?

[ATC King]

Any oil leaks besides the exhaust? :naughty:

Is the crankcase venting properly? Vent tube pinched or has it been modified with an extra vent?

Dirt daubers here will plug any and everything up so I start looking in holes right off. Do y'all have any of those there (AKA mud wasp)?

[DAM shop]

Any oil leaks besides the exhaust? :naughty:

Is the crankcase venting properly? Vent tube pinched or has it been modified with an extra vent?

Dirt daubers here will plug any and everything up so I start looking in holes right off. Do y'all have any of those there (AKA mud wasp)?
We considered that and it did not have a vent. So we vented the head this last time.

[Shep1970]

Who put the 2-stroke gas/mix in the Atc 90 gas tank.......just Kidding

shep

[DAM shop]

Who put the 2-stroke gas/mix in the Atc 90 gas tank.......just Kidding

shep
I wish it was that easy.

[shortline10]

Is it a one piece oil ring ?
I’ve see plenty of bad sets of rings back in the day .

[DAM shop]

Is it a one piece oil ring ?
I’ve see plenty of bad sets of rings back in the day .
It is Mike, also with a leaky head as in guide I would think oil would burn off after a few minutes of run time. Honestly, we have never had one of these start so well, idle and throttle up and smoke so bad.

[shortline10]

I would lightly hone the cylinder and get a different set of rings .
Back in the day we built a lot of these motors and new which ring sets not to use and the sets with the one piece oil rings always smoked like a freight train lol . Rocky and big Al’s were the worst !

[ATC King]

That one piece oil ring makes sense to me because there's one gap with no way to stagger anything like with the three piece sets being able to stagger the gaps in both rings and the expander.

I've worked on some older Honda motorcycles, but never came across a one piece oil ring. Was a good day; learned something new.

[DAM shop]

I would lightly hone the cylinder and get a different set of rings .
Back in the day we built a lot of these motors and new which ring sets not to use and the sets with the one piece oil rings always smoked like a freight train lol . Rocky and big Al’s were the worst !

i would love to find a 3 piece ring set if i knew of a brand that would fit I'm wondering if Honda rings fit the Rocky pistons/

[shortline10]

Some OEM Honda rings fit . Years ago I had plenty of just about every size in stock .