Help/advice installing 250R piston (Installing new piston)

[KASEY]

looks like your screwed,,, you will have to get a short rod piston,,,, cause a long rod piston won't go all the way to the top of the bore,,,,,,,,,,,

[SYKO]

hey man I havea stroker base spacer you can have if it will help, let me know..

[250r'en +TCB]

looks like your screwed,,, you will have to get a short rod piston,,,, cause a long rod piston won't go all the way to the top of the bore,,,,,,,,,,,

WTF?!?!?! I would need a longer rod so the piston could complete the stroke, right? Did you get those 2 mixed up???

Would a spacer plate be enough??? Or do i need to buy an 88 or 89 rod???
Please somebody tell me what i have to get to make this work!!! Any pics you need I can get........

[Billy Golightly]

You need a piston that same diameter with the wristpin located 5mm lower or whatever the difference is between the short and long rods, if there is such an animal. Alternatively you COULD cut 5mm off the piston skirt and the bottom of the jug but I dont know how well that would work out...

[250r'en +TCB]

You need a piston that same diameter with the wristpin located 5mm lower, if there is such an animal. Alternatively you COULD cut 5mm off the piston skirt and the bottom of the jug but I dont know how well that would work out...

The guy swears on his life this was the piston run in the quad with this kit. the piston is a match to the cylinder for sure...... I'm waiting for him to answer me if it was used on an 88/9 engine.

This piston has defiantly been ran before, so something must work......... Maybe I would have to shave 5mm off the skirt, but that's obviously a last resort...... Hate to have to break out the bench grinder!!!

[deathman53]

first, what rod do you have, does it say ha5 on it? I use long rod cranks and 86 pistons, I have 5mm spacer plates on my motors. Most of you big bore pistons are 86 pistons(if not all). Esr sellls a spacer plate kit, that includes everything you need. And yes, the head stay mount does work. I believe 87-89 pistons stop at 68mm or 80 over, 86 pistons go to 76mm bores, maybe78mm?

[250r'en +TCB]

Here's what the guy said to me, looks like he knows his stuff thank god lol:

"The window in the piston indicates that it is the long rod, the short rod piston have a half moon at the bottom, thats why i had the oiston positioned with the window showing. if you have a shortrod motor the cheap way would be to grab a crank and rod off ebay i see them for as little as $40.00"

Is this what i'll have to do?

[Pete]

you need the '85/86 version of that piston or an 87+ crank. I'd do the piston over the crank, that way you don't have to split the cases.

[ChrisD]

Well I guess if you wanted to wait another 6 or so months, you could get a good crank for $40. Then have to dig into your bottom end. Why don't you go to wiseco's page to see if they make the same size piston for the short rod motor?

I looked at LA Sleeve's site. They have them from Pro-X and Wiseco.

[Pete]

I haven't seen a 310cc 88/89 piston in a long time, is this a Pro-X cylinder you're installing, and are you sure the bore size is 72-73.5mm?

[deathman53]

I thought the big bores only came in 85/86 pistons.

[3WW Star-Yamahondaman]

Ohh...my ..... God !!!.........

[gasmask]

my question when was the bottom end rebuilt. if you don't know that the go ahead and rebuild it complete. add more compression can cause the rod bearing to end up on top of the piston. ebay: crank bearing, complete gasket kit , complete seal kit under $100.00 a small price to pay for years of riding. since the crank halfs are the same order a 87 to 89 trx crank rod and rebuild the crank... that's what i do. also i coat the cylinder and piston with WD40 when i'm putting it back together...

[gasmask]

my question when was the bottom end rebuilt. if you don't know that the go ahead and rebuild it complete. add more compression can cause the rod bearing to end up on top of the piston. ebay: crank bearing, complete gasket kit , complete seal kit under $100.00 a small price to pay for years of riding. if the crank halfs are the same order a 87 to 89 trx crank rod and rebuild the crank or ebay again. also i coat the cylinder and piston with WD40 when i'm putting it back together...

[250r'en +TCB]

Well I guess if you wanted to wait another 6 or so months, you could get a good crank for $40. Then have to dig into your bottom end. Why don't you go to wiseco's page to see if they make the same size piston for the short rod motor?

I looked at LA Sleeve's site. They have them from Pro-X and Wiseco.

No another 6 months of wating isn't in my schedual Here's the wiseco page http://www.wiseco.com/PDFs/Catalogs/CB06/HondaATV.pdf This cylinder is on it's 2nd to last bore, so what do I get for a bore size??? I don't see anything that's close to 72mm, if that is what I need..... There all a few more CC's than stock (262cc max)...... So would i have to send this cylinder in to get a custom piston? That won't be cheap....

The only brand label on the cylinder is on the left side of the intake, it's an HM with a circle around it. Anybody know this brand?

I've been thinking, why can't I just cut the needed amount off the piston skirt like billy suggested???? The pistons look the same except for the half-moon cresent on the bottom. Can this be done?