"Customer service is priority #1 at Rocky Mountain ATV/MC. We value our customers and strive to be the best shopping experience- when you buy from us, you are buying lifetime service."
-Dan Thomas, CEO and Founder
Returns
We take pride in offering no hassle returns. In the event of a return, please call, email or chat with us to receive a solution to the problem. For apparel that doesn't fit quite right, Click here to see our Fit Guaranteed Program.
Warranties
We will stand behind all products we sell with regards to manufacturing defects in workmanship and material. Most products are limited to the manufacturer's warranty. However, we will do everything in our power to take care of the problem.
Have questions?
(Leave email if after hours) Email: sales@rockymountainatv.com Call us: 1 800 336-5437 7am-7pm Mon-Fri 8am-4pm Sat (Mountain Standard Time)
People who have viewed this item have also viewedSee all Pistons
Ive used wiseco before and have had great results, fit and finish are great, nce breakin is done ill let you know on durability, but anticipate success.
Great product, but be very careful, with break in procedure and if your riding in cold weather be sure to let the bike warm up to operating temps before ripping it around due expansion differences between cast and forged aluminum, broke a chunk off the crown of the piston, luckily it got kicked out the exhaust port!
I have bought hundreds of wiesco kits in the past, always top quality parts and good price.
First one arrived without a wrist pin, so I called Rocky Mountain customer service. They got shots of wiesco immediately and sent me a whole other kit, wrist pin included this time. Got it the next day.
Ive always used Wiseco and always will. Never had a single issue with a forged piston. Much stronger than cast and hold up to the abuse. My only complaint was this didnt come with a wrist pin bearing so you'll have to purchase that separately
Excellent so far! After installation and heat cycles compression test read 120 could have went a little more. No wristpin bearing just so you are aware.
I haven’t really used many other products due to I have never had any issues with there products were other products have failed I inspect my 2t pistons often and the normal areas that have problems I haven’t seen in there pistons
fitment was spot on have was easy to install have not yet ran the bike as it is still winter in the northeast so can comment on durability but have used wiseco before and have never had an issue
Bought the Wiseco piston for 89 YZ250WR. Compression was at 170 - and I had never done a top end before. Fairly simple procedure - so if you have not done it - give it a try. Great videos on the site. Bike has tons of power now. Went up from 69mm cylinder bore to 68.5mm. Took to machine shop to have bored to match piston. Took small jewelers file to chamfer the ports in the cylinder. Bike runs awesome!
This piston is easy to install and very durable. I replace this piston in a cr125 once a year and it hasn't failed us yet. When replaced after 40+ hours, the ring still looks decent and piston still looks pretty good. I purchase a wiseco piston for all of our bikes including a kx85 and kx65. Can't beat them.
Bike was torn down ready to go back together and there were no rings in the box. It was disappointing and I ended up getting new rings through local bike shop to expedite the process at my own expense.
I haven't bought a wiseco piston in almost 10 years for a bike. I decided to try one again! If it lasts and performs as good is it looks it will be a winner. I did a couple heat cycles on it and ripped around the field some seems pretty good runs like a ktm 250sx should.
A beautiful piece of aluminum! good price, clearance was good, instalation was a breeze and bike has awesome power with it. Generally very pleased with this piston, will buy the same for my girlfriends KX85.
Perfect fit and went together great. Awsome instructions on messing end gap and ring placement and even had notches cast in piston to keep rings in place while installing head first wiseco piston I have bought and this will be what I buy from now on
BEST ANSWER:Just piston, rings and circlips. You will need to buy a separate gasket kit. I would recommend ordering and replacing the wrist pin also while it's tore down.
BEST ANSWER:Just piston, rings and circlips. You will need to buy a separate gasket kit. I would recommend ordering and replacing the wrist pin also while it's tore down.
BEST ANSWER:Rudy, It is just Weisco's design. Other manufacturers try different things to make their product different or better. It's a great piston. Weisco teflon Coates their pistons for extra protection. I have never had one not make it to the next overhaul.
BEST ANSWER:Rudy, It is just Weisco's design. Other manufacturers try different things to make their product different or better. It's a great piston. Weisco teflon Coates their pistons for extra protection. I have never had one not make it to the next overhaul.
BEST ANSWER:Your piston should have a clip on both sides just like the piston you will receive. There is a little groove on each side of the piston and you have to remove one clip to get the wrist pin off of the rod. I always put one in the piston before I put the piston back on the rod so I only have to put one clip back in once the piston is in the machine.
BEST ANSWER:Your piston should have a clip on both sides just like the piston you will receive. There is a little groove on each side of the piston and you have to remove one clip to get the wrist pin off of the rod. I always put one in the piston before I put the piston back on the rod so I only have to put one clip back in once the piston is in the machine.
No just make sure you have a clip in properly on both sides also some Pistons only have a single ring and that is sufficient. Certain brands have dual rings I find that they last a little longer
just to make sure I'm getting the right piston for my cylinder , when the description states "standard " (xx.xmm) does that mean the piston is that size or thats the piston for that bore? i caliperd my bore and its 66.4mm
I want to rebuild top end over the winter. I want to go bigger.
Where do I see a chart of sizes which are available so I can see how big I can go?
A shopper
on Sep 5, 2017
BEST ANSWER:On a 2016 the only way to go bigger is to buy the big bore kit. You can't bore the factory cylinder without putting a sleeve in it which would cost the same as the big bore kit with a new cylinder
BEST ANSWER:On a 2016 the only way to go bigger is to buy the big bore kit. You can't bore the factory cylinder without putting a sleeve in it which would cost the same as the big bore kit with a new cylinder
There is a lot of cost and uncertainty when you mod your engine as I have done several. sometimes it works out well and most time just a huge headache . I recently bought a TM mx 300 two stroke was more $$ up front but cost comp to Ktm & husky. I am 6'2" and the Tm is first bike I have ever owned that didn't feal too small I am more comfortable on the bike than I have ever been and the bike is very durable and the only parts I changed were the handle bars and the throttle tube. My best advice is to put a fresh top end (stock set) and when you are ready to trade up spend the extra money buy 300 2 stroke (find that suits you best) at the end of the day they cost up front or in the long haul .
Go on Wiseco's website and look to see what is available for your bike. Rocky Mountain typically only carries standard sizes. You may wanna call Millineum to see what they suggest as to how big to go on your cylinder.
For a 2007 Yamaha yz 125 there are 4 different piston sizes to choose from. This piston only has one size when I enter my bike. Will it work or should I order OE?
BEST ANSWER:You should alway check the piston size that came out of you machine to insure proper fit although most bikes have the metric size it is easy to figure out if it is a 65mm piston and you want it .020 over then it is 65.5 or to make it 66mm then it’s .040 over std size
BEST ANSWER:You should alway check the piston size that came out of you machine to insure proper fit although most bikes have the metric size it is easy to figure out if it is a 65mm piston and you want it .020 over then it is 65.5 or to make it 66mm then it’s .040 over std size
You need to know what size piston is in your bike. If it has ever been bored out, the stock size will not work. Piston with be marked. Once you know the size, these pistons are great.
BEST ANSWER:As long as the cylinder is standard bore and the plating is good, this piston will work great in your bike. Always do a light hone to the cylinder whenever doing a piston replacement. It helps the rings seat and wear correctly. These pistons are one of the best on the market. I hope this helps.
Thanks Matt. I appreciate the feedback back. Since my 450 has the Nikasil coating they told me not to hone it as that could cause the plating to come off and I'd have to replate it. Any sense out of that or are they wrong?
BEST ANSWER:As long as the cylinder is standard bore and the plating is good, this piston will work great in your bike. Always do a light hone to the cylinder whenever doing a piston replacement. It helps the rings seat and wear correctly. These pistons are one of the best on the market. I hope this helps.
Thanks Matt. I appreciate the feedback back. Since my 450 has the Nikasil coating they told me not to hone it as that could cause the plating to come off and I'd have to replate it. Any sense out of that or are they wrong?
The Wiseco piston kits are great. You will not need to bore your cylinder but make sure you hone it. As long as you cylinder is in spec these Pistons will last well.
BEST ANSWER:it really depends on how the bike is being used; small bore with a fast kid racing 8hrs +/-, 250 race mode 25hrs,250 old slow guy 50-100hrs.
BEST ANSWER:it really depends on how the bike is being used; small bore with a fast kid racing 8hrs +/-, 250 race mode 25hrs,250 old slow guy 50-100hrs.
BEST ANSWER:Stock positions usually have a letter on the piston indication what size piston is in the bike you will have to look up factory piston with letter indication which size you have usually in parts breakdown will have 2-3 pistons with letters indicating size hope this helps
BEST ANSWER:Stock positions usually have a letter on the piston indication what size piston is in the bike you will have to look up factory piston with letter indication which size you have usually in parts breakdown will have 2-3 pistons with letters indicating size hope this helps
89 YZ 250 - Bought new Wiseco piston - Prolite .020 (68.5MM), for 1989 YZ250WR. Bike has original bore (68mm - cast iron sleeve) - no score marks. Ring end gap was excessive on old rings, but no blow by on stock piston. Had 170 compression. Bike was getting hard to start. Was told to bore to next size up so that is why bought this piston. Took to machine shop today with new piston. Also brought cylinder head with me and they said that they do not need the cylinder head? I thought that the inside radius of the cylinder head needed to be opened up to accommodate the new piston/bore size? Also asked if they would champher/round edges on all ports inside cylinder after bore? They said no need to? Also wondering if power valve will need to be shaved? Anyone have any answers? Any suggestions?
BEST ANSWER:Your machine shop is correct, the piston does not protrud the top of the cylinder. Also correct on rounding the edges, no need to. As far as the power valve goes I would check on reassembly.
BEST ANSWER:Your machine shop is correct, the piston does not protrud the top of the cylinder. Also correct on rounding the edges, no need to. As far as the power valve goes I would check on reassembly.
you need a different machine shop. They are correct about not needing the head, but you do want to get it chamfered. that's only if you want any kind of lifespan on that new piston.
I have the 2000 ktm mini adventure which is a reedless motor. Is ur 39mm piston have a window on intake side? The reedless motor requires a solid piston and I've bought a few wrong ones already. Thanks for info
The wiseco piston has a window on the intake side this is because wiseco is a forged piston and improved so that it has better acceleration response than the original and you will not have problem of power or installation I hope and my answer will help you in your Doubts
Penn, KTM offers group II piston kits for cylinders with 50+ hours or 1000+ miles. They are slightly larger to tighten up the fit. I have used hundreds of Wiseco pistons over the years and they appear to be replacements for OEM original equipment. If your cylinder is worn enough that you can see a ring ridge at the top I'd suggest replacing the cylinder or having it relined and going back with the Wiseco. If it looks good I'd again suggest the Wiseco.
BEST ANSWER:I checked into this for you and unfortunately, we do not carry the 90.5 mm piston for your machine. However, Wiseco does have it for your machine on their website. I'm sorry for any inconvenience this may cause.
BEST ANSWER:I checked into this for you and unfortunately, we do not carry the 90.5 mm piston for your machine. However, Wiseco does have it for your machine on their website. I'm sorry for any inconvenience this may cause.
will it fit my rm 125 2 stroke?, didnt know double ring could fit in my bike
A shopper
on Jan 23, 2018
BEST ANSWER:This picture is generic and doesn't necessarily represent the actual product you will receive. If your machine is listed in the drop down menu, it will fit.
BEST ANSWER:This picture is generic and doesn't necessarily represent the actual product you will receive. If your machine is listed in the drop down menu, it will fit.
BEST ANSWER:To see if this part will fit your machine please enter the make, model, and year into our "Choose a vehicle" drop down boxes found above the product image. If your machine is not listed, we may not carry the right item for your application. If you have a 2017 year model but don't see your machine as an option, please contact a tech via Live Chat or call us at 1-800-336-5437 for assistance.
BEST ANSWER:To see if this part will fit your machine please enter the make, model, and year into our "Choose a vehicle" drop down boxes found above the product image. If your machine is not listed, we may not carry the right item for your application. If you have a 2017 year model but don't see your machine as an option, please contact a tech via Live Chat or call us at 1-800-336-5437 for assistance.