TRX250R.ORG
Workshop => Engine and Bottom End => Topic started by: rjt500r on April 19, 2016, 02:42:03 PM
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Looking for some info/feedback on this cylinder I found in my stash of parts. Its a stock cylinder with a big bore sleeve, the piston is a 72.95mm. It has Trinity 11 engraved on the cylinder as well. Online research tells me the stock cylinder with the big bore sleeve is not worth the trouble and the Trinity 11 engraving means a play port in the cylinder. (http://forums.trx250r.org/vbulletin_imports/901_7602_2017-04-18_3441.jpg)(http://forums.trx250r.org/vbulletin_imports/901_7603_2017-04-18_9702.jpg)(http://forums.trx250r.org/vbulletin_imports/901_7604_2017-04-18_5452.jpg)(http://forums.trx250r.org/vbulletin_imports/901_7605_2017-04-18_3393.jpg)(http://forums.trx250r.org/vbulletin_imports/901_7606_2017-04-18_9971.jpg)(http://forums.trx250r.org/vbulletin_imports/901_7607_2017-04-18_7531.jpg)(http://forums.trx250r.org/vbulletin_imports/901_7608_2017-04-18_5631.jpg)
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is not worth the trouble and the Trinity 11 engraving means a play port in the cylinder.
the only trouble is getting a head gasket to seal, and you never know how it will seal until you mount it up. even if u have issues u could have the head recut and oringed.
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the only trouble is getting a head gasket to seal, and you never know how it will seal until you mount it up. even if u have issues u could have the head recut and oringed.
a copper gasket would probably solve the leaking issues. I know a guy who does copper cylinder head gaskets (Hussey Performance) and he could probably cut one.
John
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Make sure cylinder and head are flat.
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Good luck. All good advice above but still no guarantee of reliable seal. If you dont need to invest much to try it out go ahead. If much cost starts to be involved investigate the available 310 kits that work before hand and then decide if the gamble is worth it or if you should just invest in something else.
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Thanks for the feedback. I'm going to give it a shot, the setup is a freebie sitting in a box on a shelf. I'll have the head resurfaced and o-ringed and re-ring it, bolt it on and see what happens. More or less I'm just curious how the 310 performs, if I was going to spend money on a big bore cylinder, it would not be a 310. Sphynx or Puma or even the ESR four stroke killer set up intrigues me. Always on the hunt for a 250r setup to keep up with my 500's.
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Head gasket sealing was the reason we never produced this kit for the public. We had head gasket sealing problems on about 10 to 20% of our test engines. This is an area that needs to have a 99% or better sealing success regardless who assembles the engine.
There was not enough room between the bore and the studs for using a viton or silicone 0-ring that was commercially available around 1988. We tried composition type head gaskets with the stainless steel fire ring, copper gaskets and without any gasket.
We had about the same success rate using a copper gasket as be did using not using any gasket at all. Even the very soft copper gaskets did not have enough resilience to flex and follow the distorting surfaces due to the normal heat and combustion pressure. The key to getting either one of these methods to seal was the type of sealer used between the head and cylinder or applied to both sides of the copper gasket. Case bond or gasket cinch seemed to be about as good as any sealer we tried.
The big bore sleeve required a lot of material to be removed from the inner casting wall where the head studs anchor to the aluminum sleeve that surrounds the iron sleeve and supports the flange of the iron sleeve. The removal of all of this material left the stud anchors essentially attached to a very thin aluminum sleeve that surrounds the iron sleeve. Lack of a sufficiently strong aluminum structure in these key areas left the iron sleeve flange sitting on top of a beer can thick aluminum sleeve that had to support the clamping force needed to make a head gasket seal. Lack of aluminum support in this area also caused the bore and the head gasket surface of the cylinder to distort to the point it was difficult for the head gasket and the rings to seal properly.
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Is it just me ? Or does your spark plug hole in the head look oblong ???? That looks like an accident waiting to happen! I had a 295cc kit like this....I used the COMETIC Gasket and it sealed up good....it was a fibre gasket with an inner steel ring....I think you can order them online from them directly.
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If interested I have an esr head that I had a dome made for a stock jug big bore cylinder I would sell you. Has the orings in the head. Sealed 100% and never had a problem. Cylinder I had ran every bit as good as a esr 310 unfortunately the cylinder cracked around the base studs a big problem with these
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Thanks for the feedback. I'm going to give it a shot, the setup is a freebie sitting in a box on a shelf. I'll have the head resurfaced and o-ringed and re-ring it, bolt it on and see what happens. More or less I'm just curious how the 310 performs, if I was going to spend money on a big bore cylinder, it would not be a 310. Sphynx or Puma or even the ESR four stroke killer set up intrigues me. Always on the hunt for a 250r setup to keep up with my 500's.
If you want that a puma will do that no issue.
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I have had a 310 sleeve installed in my stock cylinder and I regret it everyday. The cylinder is at 67.5mm and it's junk now, the shop that installed the sleeve cracked the water jacket above the exhaust port. Once the engine got warm the coolant would start leaking, I had the cylinder cut for O-ring and used a gasket with threebond which sealed the head extremely well.
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I run a bhp ported factory bb cylinder, and have zero leaking problems running a comitec copper gasket. If ran, definitely want to run a larger radiator though. I would put this cylinder up against any 310 kit.