Rebuild problems

[dmple1230]

So I have an 85 atc250r with a lot of parts from different years I recently rebuilt top end and found out I have a long rod so I bought a spacer plate and put it together after rejetting I had very low power did a compression test and got 80psi sprayed cleaner on gaskets no idle change put oil in cylinder and got 10 more psi so new rings are on the way is there something I'm doing wrong?

[dmple1230]

Any help would be greatly appreciated

[350for350]

Hopefully, you had the cylinder honed and installed new rings the last time. Did you bore the cylinder last time? If not, there may be a lot of wear in the cylinder and if that's the case, you need to bore it and go with a larger piston.

[dmple1230]

Had an 89 cylinder on and got an 85 cylinder freshly bored and honed to 68mm new rings Pistons gaskets and spacer plate I might've tweaked a ring on install though

[ATCKevin]

I've had a ring slip past the locating pin in the groove and I didn't know it. Very frustrating!

[dmple1230]

When I was slipping jug on bottom ring popped out and got a little bent but I flattened it as best I could so that's the only culprit I can come up with for the low compression I also checked it with two different testers so new rings will be in soon so I really hope that it fixes my issue

[ironchop]

When I was slipping jug on bottom ring popped out and got a little bent but I flattened it as best I could so that's the only culprit I can come up with for the low compression I also checked it with two different testers so new rings will be in soon so I really hope that it fixes my issue

Do a compression test. If that ring isn't completely flat, the top corner on the bent side is what will contact the cylinder wall instead of the flat face giving you way less seal than the full width of the ring on the flat sides. You'll always have less contact patch there than elsewhere on the ring.

As cheap as a set of rings are, I would consider just getting another set.

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[dmple1230]

Also I was wondering if my spacer plate is to thick it is 3/16 when I didn't have it the piston would hit dome

[ironchop]

Also I was wondering if my spacer plate is to thick it is 3/16 when I didn't have it the piston would hit dome

No that's the size you need.

If you run the TRX piston with the long rod crank, it won't need one because I think the TRX wristpin is located higher in the piston than the ATC piston but I could be wrong


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[ironchop]

Also I was wondering if my spacer plate is to thick it is 3/16 when I didn't have it the piston would hit dome

Here....read post #6...."acecarlos" is the owner of BDT Motorsports so he's knows his liquid R's and how to build them.

https://r.tapatalk.com/shareLink?url...6&share_type=t

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[dmple1230]

I ordered new rings and did a couple comp tests got 80 psi then put a little oil in cylinder and got 10 more pounds so that must be my issue

[dmple1230]

Thanks and yes I'm running a long rod with 85 piston before I tore it down I was unaware of some mods and didn't realize my old jug was an 89 jug so I bought the spacer plate so now I have an 85 jug with spacer plate and an 89 dome

[dmple1230]

I really appreciate all the input guys I've been mad as hell that I'm not out riding yet but hopefully once these rings and new base gasket come in I'll be good to go I'm using a 3 piece metal gasket on dome I've heard of drilling out rivets and making it one piece is this a good idea?

[dmple1230]

Also is there any compression difference running this set up?

[ironchop]

I really appreciate all the input guys I've been mad as hell that I'm not out riding yet but hopefully once these rings and new base gasket come in I'll be good to go I'm using a 3 piece metal gasket on dome I've heard of drilling out rivets and making it one piece is this a good idea?

Drilling out the rivets and using only one piece boosts the compression ratio. I'm not sure how much boost.

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