my nieghbors atc 110 with yz125 piston .

[RIDE-RED 250r]

All I know is George's 110 revs out much higher than my 110! LOL!

But I think DOHC is likely correct about it being a "short timer".....

[effort=results]

ok found out today that the piston was made for a "ttr yamaha 125" . from wiseco.

[C.J]

The TTR is a 4-stroke. Means it's got an oil scraper ring. The only thing the bottom ring is there for on a 4-stroke is to keep oil from being burnt and fouling the plug. Actually would help a high revving engine to burn some oil. Your top ring(s) are just for compression. So no,, it wouldn't hurt the longevity of the engine to run a 2 stroke piston, you'd just burn oil. And if you're running a low compression engine you'll need a big cam with short duration to run high revs. 110's don't mind being shifted under power so long as the clutch is in good shape, the larger rear sprocket helps with taking some load off it though. Stock the gearing is 14/52 if I remember right (I haven't messed with a stock front sprocket in a while)? I know I dropped 3 teeth in the rear from stock to a 49 rear and it's still pretty low geared.

I say George builds HIS engines how HE wants and runs them as long as they will run and I'm sure he will have a grin no matter what.

Thanks for sharing with us E/R and George!

[DohcBikes]

So no,, it wouldn't hurt the longevity of the engine to run a 2 stroke piston,

Yes it will.

[effort=results]

well i was wrong anyhow. its a ttr piston 4 stroke. but for us guys goin big bore this will be a fresh supply for the 110's. thanks to george for figuring it out. also george is 56 so he wont be riding every weekend . but when he does .......it will get down. plus with his hoard,jugs are easy to come by.

[just ben]

The oil ring holds oil to lubricate the cylinder Its not just to keep oil from the compression rings. The title did say it was a break in video. If George assembles a 4 poke like I do, they will smoke for a while from the assembly lube.

[DohcBikes]

well i was wrong anyhow. its a ttr piston 4 stroke. but for us guys goin big bore this will be a fresh supply for the 110's. thanks to george for figuring it out. also george is 56 so he wont be riding every weekend . but when he does .......it will get down. plus with his hoard,jugs are easy to come by.

Ya thats awesome!! So does he just bore it out 2 mm or does he sleeve it? I dont know anything about 110's but this stuff always interests me. Has he cc'd the setup to see what kind of CR he's getting? What's the advertised CR of the piston he got? Is it the 11:1 piston? Race gas?(duh) Any more questions he'd like to answer lol....

[effort=results]

hahahah ya i had to shoehorn what piston he used out of em. he did temperture cycle the motor for a while and whet u see is the first ride around the yard. i do know he didnt sleeve it and just bored it out. hes the lead mechanic at treaders tnt motorcycle shop in quincy il .so u may call and see if u can get more from him. he knows what hes doin and is always workin on mowers and wheelers at his shop at home. so he knows what hes doin. heck the lil bit of smoke could be old oil deposits in the muffler. my guess on what he used is this.
http://www.ebay.com/itm/00-08-Yamaha...-/330618660761

[DohcBikes]

Just had a thought, they make that piston up to 1mm oversize too....55mm bore possible on a 110? That would make it a 117cc.

[C.J]

Seeing as though a 110 is a lay down engine that gets plenty of oil to the crank shaft area, revving it THAT MICH is GOING TO get oil to the sleeve and in turn will oil between the piston and sleeve. Plus if you drill oiling holes in the piston (if it doesn't have it already) then it will get plenty of oil to the skirt.




And don't say you can't drill oiling holes in 2-stroke pistons because we do it on our fullbore/big bore LT's to help keep the exhaust bridge cool

[C.J]

BUT George's bike has a TTR225 piston which is a flat top but it doesn't have oil holes in it. I say a 2-stroke piston can be ran in a 4-stroke engine fine, it's just going to smoke and you'll need to add oil holes to it. (Damn how many times am I going to say oil holes) But until we can test that, we are just going to have to call this an impasse, my trike brothers.

So we wait

[C.J]

Ok,,, stock 90/110 piston. ~28mm from center of wrist pin to top of dome, BAPP 12:1 piston 30mm, Rocky 12:1 30mm. 90 piston is 14mm wrist pin, 110 is 15mm wrist pin. So you take and measure the TTR225 piston center of wrist pin to top of the dome, compare to those measurements mentioned before, and make a little equation thing with Y over X = Y2 over X2 and do some multiplying, divide,,, boom boom bam there's your compression ratio.

Im willing to put money on George's bike having a ported head at the very least. Maybe a bigger carb or the stock carb opened up some. At the very least.

[DohcBikes]

Ok,,, stock 90/110 piston. ~28mm from center of wrist pin to top of dome, BAPP 12:1 piston 30mm, Rocky 12:1 30mm. 90 piston is 14mm wrist pin, 110 is 15mm wrist pin. So you take and measure the TTR225 piston center of wrist pin to top of the dome, compare to those measurements mentioned before, and make a little equation thing with Y over X = Y2 over X2 and do some multiplying, divide,,, boom boom bam there's your compression ratio.

Im willing to put money on George's bike having a ported head at the very least. Maybe a bigger carb or the stock carb opened up some. At the very least.

No, because as you mentioned, the tt-r piston is a flattop. Not to mention that stated CR and measured CR are not always the same. My question was from one engine builder to another. I'd like to know if he cc'd it to find out the true CR.

Your 2 stroke piston theory is bunk, brother. Theres absolutely no reason to use one, and it would not last as long, period.

[C.J]

It'll get you in the ball park,, but yes cc'ing it is the proper way to find actual CR


And why is it bunk? Just because you don't agree with it and it's different?

I KNOW 90/110's. Maybe not as well as Pat, or Mike, or 90Guy, or anyone else who's been into the 90's for forever and a day. But I say it could be done. Maybe not with a YZ125 piston. But I say it could be done. And if you ask any of the guys who HAVE been around the 90/110's, they will tell you a built engine won't last long being ran hard anyway. ( I just realized I looked up a piston for a TTR225 not 125 give me a second to fix that)

[DohcBikes]

Lets forget that it will not last as long as a four stroke piston, because that's already been explained clearly(by members here and by the industry NOT doing it).

Tell me WHY you would do it.

2 stroke or 4, a piston is just a damn slug thats intended to create pressure in a cylinder. 4 stroke pistons are built the way they are for a reason. That reason is because if they were built like 2 stroke pistons, the engine would not last as long.