Finding a Pro X piston kit

[ATV_Chick08]

Ok, I thought it would be pretty strait forward to order a piston kit, but apparently not. I'm rebuilding the top end on my 88 because it's past due. I had my guy at the Honda shop check out the cylinder and piston, and he told me to replace it with the same .25 Pro X piston that's in it, however I can't seem to find one...

I'm gathering that the standard piston size is 66mm, is that correct? So I need a 66.25? The markings on the inside of the piston are CR25088, but even when I look for a piston for a CR 250 I'm not finding a 66.25. I've got to call Duncan Racing to order reeds and packing kit for my silencer but they aren't open again til Tuesday. They don't even have the piston kits listed now, it says to call for availability. I just looked the other day and it said they were $129.99 which seemed a little high.

[Dezsled]

No that price is the norm. Loren bored my national ported cyl and found a woessner piston kit for it for the same price. I used to work at a cycle shop and a Wiseco was $49.99 so I really feel the prices are rediculous these days. I'm not familiar with the sizing any more, sorry I'm not any help

[ATV_Chick08]

No that price is the norm. Loren bored my national ported cyl and found a woessner piston kit for it for the same price. I used to work at a cycle shop and a Wiseco was $49.99 so I really feel the prices are rediculous these days. I'm not familiar with the sizing any more, sorry I'm not any help

Maybe Duncan's not using Pro X pistons now, it's been 3 or 4 years since they rebuilt my 88 motor. The Honda shop could only get a .50 over Pro X piston. Somehow in owing a 250R for 18 years I've managed to never have to order a piston kit. I don't want to get something different without knowing for sure what I need. Hopefully Duncan will have the Pro X or something equivalent.

[Pumashine]

I'm rebuilding the top end on my 88 because it's past due. I had my guy at the Honda shop check out the cylinder and piston, and he told me to replace it with the same .25 Pro X piston that's in it.

If your top end is past due and its got a .25 over in there then you need to get the next size up and go to .5. Or is he saying it is stock and you need to just go .25 over?

[Dezsled]

I was told that it's not like in the hay day when everything was trx250r. Loren said he would have locate a piston kit for me and he normally uses only certain brands. It's not like the manufacturers are going to have xxxx quantity of each size made any more. I have afew new oem pistons laying around but it's 85-6 stuff.

[C-Leigh Racing]

Breezy,
For the 87 to 89 cylinders, a Wiseco 66.25mm piston kit, is a number 526MO6625, but being on the STD bore, you really need to have the cylinder bore measured to be sure that 66.25mm will be big enough. Normally on the first time boring the cylinder, they will be worn enough that it will need to be taken to the 66.50mm size, to clear up the wear in the bore.
Now LA Sleeve offers a Pro-x cast piston in a 66.25mm, a part number 4321 piston kit, but after that size it is a Wossnor brand, part number 8189D050 , 66.50mm kit. My new catolog, does not list any larger sizes of the Pro-x cast piston larger than a 66.25mm, but LA probably still has larger sizes of the Pro-x pistons on hand, just not listed in this new catolog I have.

For the OEM TRX cylinders, you cheapest route for a new piston is on e bay, just find the right size your needing.
The new Wossnor forged or the Wiseco would be best to use, leave the cast piston for stock play engines.
Neil

[ATV_Chick08]

Thanks for the info guys. We took the cylinder and piston to the Honda shop and had the one mechanic look at it. He's been there for years and has a 250R. He checked it out, looked at the piston and rings, and measured everything,and he said it didn't need bored. The piston that came out of it is a Pro X .025. The mechanic said that it looked good and just needed a ball hone run through it. He said they don't do honing any more and they take it to a local Harley shop or Car Quest.

I originally bought the cylinder new in 96 when I bought the quad. It was freshened up once when I was racing back then. Here about 3 years ago I sent the whole motor to Duncan to be rebuilt, and I'm going to assume that Loren is the one that took it up to .25.

When I say overdue, I just mean that I haven't really ridden the 88 much since I got the 86 set up for the woods. I only raced the 88 once or twice last year and didn't notice it was down on compression and power until I had the 86 motor rebuilt. There's nothing wrong with it, per se. I'm freshening up the Duncan motor so I have the 88 as a back up for the GP series.

[Jerry Hall]

Breezy,
For the 87 to 89 cylinders, a Wiseco 66.25mm piston kit, is a number 526MO6625, but being on the STD bore, you really need to have the cylinder bore measured to be sure that 66.25mm will be big enough. Normally on the first time boring the cylinder, they will be worn enough that it will need to be taken to the 66.50mm size, to clear up the wear in the bore.
Now LA Sleeve offers a Pro-x cast piston in a 66.25mm, a part number 4321 piston kit, but after that size it is a Wossnor brand, part number 8189D050 , 66.50mm kit. My new catolog, does not list any larger sizes of the Pro-x cast piston larger than a 66.25mm, but LA probably still has larger sizes of the Pro-x pistons on hand, just not listed in this new catolog I have.

For the OEM TRX cylinders, you cheapest route for a new piston is on e bay, just find the right size your needing.
The new Wossnor forged or the Wiseco would be best to use, leave the cast piston for stock play engines.
Neil

526MO6625 is 0.25 mm oversize for the 1985 and 1986

562M06625 is .025 mm oversize for the 1987 through 1989

[Jerry Hall]

...............,and he said it didn't need bored. The piston that came out of it is a Pro X .025. The mechanic said that it looked good and just needed a ball hone run through it. He said they don't do honing any more and they take it to a local Harley shop or Car Quest.

I am troubled by the experience level of someone that recommends using using a ball hone.

[C-Leigh Racing]

526MO6625 is 0.25 mm oversize for the 1985 and 1986

562M06625 is .025 mm oversize for the 1987 through 1989

Now figure that out. I was sitting there looking directly at the part number in the catolog & still put it in wrong. What is it called, that sickness you can get when you reverse numbers & put down words was suppose to be put in later.

I've just got this fixation on any TRX250R engine build, that its any year TRX cylinder, long rod crank, a spacer plate & old model 85/86 piston kit, so I guess the old model number came out even though I was looking at the new model piston kit.
Its just kinda abnormal, to me anyways, to see a 250R engine put together with all the parts that go together from each year model

I'll 2X on the ball hone idea. Most things have a place to be used, leave those ball hones to the auto industry.
Neil

[ATV_Chick08]

I'll 2X on the ball hone idea. Most things have a place to be used, leave those ball hones to the auto industry.
Neil

 
So are you guys saying that you should never hone a cylinder, but bore it every time you change the piston and rings? Both the Honda mechanic and the guy in the shop at car quest said the cylinder looks great. They are going to hone it (with something other than a ball hone) and mic it and make sure everything is to spec before I order a piston. The guy at car quest recognized the quality of the work done to the cylinder and commented on it, he seemed to be very knowledgable.

It also seems to no one makes the .25 piston any more but Wiseco, this is according to the guy at LA Sleeve. So as long as the cylinder is true I'm either just going to have to replace the rings on the Pro X piston or make sure Wiseco has the .25 kit. There web site says they do, but they were already closed before I could call.

[ATV_Chick08]

The guy who was going to hone the cylinder doesn't feel like he has the equipment or whatever to do it right, and no one makes a .25 over piston any more. I talked to Loren Duncan and I'm sending everything back to him and let him decide whether or not it needs bored.

[Jerry Hall]

...................I'll 2X on the ball hone idea. Most things have a place to be used, leave those ball hones to the auto industry.
Neil

I would not use a ball hone to clean sewer pipe.  A good hone will only touch the high spots and remove minor imperfections.  A ball hone makes the cylinder look a little better but follows all imperfections, making any bore it touches worse.

[Jerry Hall]

So are you guys saying that you should never hone a cylinder, but bore it every time you change the piston and rings? Both the Honda mechanic and the guy in the shop at car quest said the cylinder looks great. They are going to hone it (with something other than a ball hone) and mic it and make sure everything is to spec before I order a piston. The guy at car quest recognized the quality of the work done to the cylinder and commented on it, he seemed to be very knowledgable.

It also seems to no one makes the .25 piston any more but Wiseco, this is according to the guy at LA Sleeve. So as long as the cylinder is true I'm either just going to have to replace the rings on the Pro X piston or make sure Wiseco has the .25 kit. There web site says they do, but they were already closed before I could call.

If the bore looks good and measures within spec it should not need to be honed.  Anytime a cylinder is honed some material is removed from the bore, making the piston to cylinder wall clearance a little looser.  If your air filter does it's job and you run a lot of oil in the fuel it is not uncommon to be able to replace the piston many times without boring the cylinder.  If you hone the cylinder each time you replace the piston you will have to bore it more frequently.

Pistons need to be replaced frequently to keep the clearances tight.  Keeping the clearances tight makes the bore last much longer and the engine will produce more power.  Some of the seasoned racers understand this but the average guys lets the clearances get too loose and damages the bore requiring boring the cylinder to the next oversize each time the piston is replaced.

[The_Steve_Man]

How often do you recommend changing the piston?  I had Eric Gorr port my cylinder and bore it.  He sent the piston with it it is a 66.25 wiesco. It is on an 85 atc.