Wiseco Piston Kit

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Displaying parts for your 2004 KTM 300 EXC

Wiseco Piston Kit
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Wiseco Piston Kit Pro-Lite Standard (72 mm)

Fits: 2004 KTM 300 EXC
Part# 1038400236

Our Price: $120.56

MSRP: $192.00 - You save $71.44 (37% off)

Get $2.41 in Quick Cash

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5+ In-Stock

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Additional Videos

How To - Rebuild A Two Stroke Top End

How to - check piston ring end gap

How to - Four-Stroke Top End Rebuild (Part 2)

How to - rebuild the top end on a motorcycle or atv (Part 2)

How To - Hone A Cylinder

How to - rebuild the top end on a motorcycle or atv (Part 1)

RM YouTube Channel

Details

  • Lightweight forging for instant throttle response and maximum torque .
  • Computer engineered piston skirt profiles provide minimal cylinder wall friction .
  • Piston kit includes piston, rings, wristpin and circlips.

Wiseco Piston Kit Reviews

Each review submitted enters you into a
$100 gift card monthly drawing and a
$500 gift card quarterly drawing!
 
4.8 / 5.0
422 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Stars
370
41
5
4
2
Value
4.8 / 5
Durability
4.8 / 5
Fitment
4.9 / 5
Performance
4.9 / 5
Recommend it?
Yes (131)
Value
5 / 5
Durability
5 / 5
Fitment
5 / 5
Performance
5 / 5
Recommend it?
Yes
Great quality
As always great quality from wiseco. The only brand parts I buy when doing a top end.
February 20, 2018
Stockton , CA, US
Purchased
2 weeks ago
Value
5 / 5
Durability
5 / 5
Fitment
5 / 5
Performance
5 / 5
Recommend it?
Yes
Trusted
Always run these in all our bike never had any issues. We run nationals on a 125 havent had one fail
February 19, 2018
Pittsburgh , PA, US
Age: 15-24
Purchased
2 weeks ago
Gender:
Male
Weight:
131 - 160 lbs.
Height:
5'7 - 5'9
Value
5 / 5
Durability
5 / 5
Fitment
5 / 5
Performance
5 / 5
Recommend it?
Yes
Great piston company.
I have been using Wiseco pistons for years, I have tried others but always come back to Wiseco. For me they are the best.

-m-2016 YAMAHA YZ250X--
February 13, 2018
Chapel Hill , TN, US
Age: 45-64
Purchased
3 weeks ago
Gender:
Male
Weight:
221 - 250 lbs.
Height:
5'10 - 6'0
Value
5 / 5
Durability
5 / 5
Fitment
5 / 5
Performance
5 / 5
Recommend it?
Yes
Great pistons
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
February 8, 2018
Hazen, ND, US
Age: 25-44
Purchased
over 2 years ago
Gender:
Male
Weight:
131 - 160 lbs.
Height:
5'10 - 6'0
Value
5 / 5
Durability
5 / 5
Fitment
5 / 5
Performance
5 / 5
Recommend it?
Yes
Great piston
Great pistons with a great price

-m-2012 KAWASAKI KX450F--
February 8, 2018
Wagoner, OK, US
Age: 25-44
Purchased
1 month ago
Gender:
Male
Weight:
161 - 190 lbs.
Height:
5'10 - 6'0
Value
5 / 5
Fitment
5 / 5
Recommend it?
Yes
Good
Was as described. Always had good luck with Wiseco
February 6, 2018
Evansville , IN, US
Purchased
3 weeks ago
Value
5 / 5
Durability
5 / 5
Fitment
5 / 5
Performance
5 / 5
Recommend it?
Yes
Perfect fit and great quality!!!!
Great product at a great price. Thank you Rocky Mountain for your fast processing and shipping!!!
New piston installed and ready for the head. Piston and rings fit perfect!!!  Thanks Rocky Mountain
New piston installed and ready for the head. Piston and rings fit perfect!!! Thanks Rocky Mountain
February 1, 2018
Havre , MT, US
Purchased
1 month ago
Value
5 / 5
Durability
4 / 5
Fitment
5 / 5
Performance
4 / 5
Recommend it?
Yes
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
January 25, 2018
Corning , NY, US
Purchased
1 month ago
Value
4 / 5
Durability
4 / 5
Fitment
5 / 5
Performance
5 / 5
Recommend it?
Yes
!989 YZ250
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!

-m-1989 YAMAHA YZ250WR--
January 24, 2018
North Port, FL, US
Age: 45-64
Purchased
1 month ago
Gender:
Male
Weight:
161 - 190 lbs.
Height:
5'7 - 5'9
Value
4 / 5
Durability
4 / 5
Fitment
5 / 5
Performance
5 / 5
Recommend it?
Yes
Good quality product.
Good product for the money. I’ve used this brand on everything from dirt bikes and atv application as well as automotive performance with no issues.
January 16, 2018
Trenton, AL, US
Age: 25-44
Purchased
1 month ago
Gender:
Male
Each question or answer submitted enters you into a:
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$500 gift card quarterly drawing!
Start typing your question and we'll check if it was already asked and answered. Learn More
Browse 37 questions Browse 37 questions and 80 answers
Does this kit include all the gaskets needed as well as the piston?
Brandon P on Mar 26, 2017
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.
why doesn't the top of this piston have the 4 circles?
Rudy P on Sep 13, 2017
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.
Does this kit also come with the piston pin bearing?
A shopper on Dec 4, 2017
BEST ANSWER: No, it doesn't. The Pro-X bearing is Japanese made, good price. I always use them.
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
Michael G on Jan 19, 2018
BEST ANSWER: It means it is for that bore or it is a standard size cylinder hasn’t been touched it is stock
If you have re sleeved the cylinder with a steel sleeve will the rings work?
SAMUEL M on Dec 24, 2017
BEST ANSWER: I apologize, I don’t have an answer to that. I assume so as long as the bore is correct.
will this fit a 2001 cr80? stock bore
james b on Sep 14, 2017
BEST ANSWER: Yes, the standard 47mm pro-lite piston is meant as a stock bore replacement with unmatched reliability from wiseco's race proven pistons
I have a 89 yz 80 the cylinder is 49mm what size piston will fit. The 48.5mm or no?
Chris T on Sep 5, 2017
BEST ANSWER: As long as its a standard bore and hasnt been altered by replating or sleeving the piston that wiseco reccomends will be the correct size.
I have a 2016 yz250 x

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: 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 .
it's for 2 times?
A shopper on Jun 20, 2017
BEST ANSWER: That's a vague question at best. But it is the second oversize bore from the stock piston if that's what u mean
Does this piston come coated or plain? Does it come with a TiN coated ring or plain ring?
Alexander H on Jun 15, 2017
BEST ANSWER: Mine was plain got it for my 2001 kx 125.
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?
Charles B on Jun 10, 2017
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
Will this fit my 04 trx450 bored to a 96mm.?
armando s on Apr 4, 2017
BEST ANSWER: Select the correct size of piston upon checkout. Be aware must hone cylinder before installation of this piston.
Will this work good for 08 kfx450r rebuild? Any boring needed to be done?
Michael F on Mar 14, 2017
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.
I have a 2006 trx450r what is the compression rating for this piston on my atv?
Tyler A on Mar 4, 2017
BEST ANSWER: As long as it's not the high compression piston, it's the same as stock which I believe is 11:1
Is the standard Raptor 250R piston stock compression or the higher 10:5-1?
Jeff P on Oct 20, 2016
BEST ANSWER: If it's standard then it's stock compression
Why are there two size options for a stock replacement? Which one is right?
Jeff H on Feb 18, 2018
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?
Brian W on Jan 2, 2018
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.
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
michael l on Jun 8, 2017
BEST ANSWER: I went and checked on the piston that we have in stock and it does have a window on the intake side.
i see that KTM has a "Size I" and a "Size II". which is this?
Penn W on Oct 12, 2016
BEST ANSWER: This would be equivalent to the size II piston which is made for a rebuild/honed cylinder rather than a brand new cylinder.
Does anybody know if I can get a 90.5 mm piston for my 2001 CR 500?
ERIK B on Feb 10, 2018
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.
What size is the piston?
Travis o on Jan 7, 2018
BEST ANSWER: To see that size of the piston you will need to enter in a machine in the drop down boxes above the product image.
Would this fit a 2001 rm 125?
A shopper on Sep 24, 2017
BEST ANSWER: Yes, this will fit. You will need to enter in your machine in the drop down boxes above the product image.
Will this fit a 2010 kx 85?
Tyler s on Aug 5, 2017
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.
For a 2001 YZ125 does this include a wristpin? I'm aware that some kits do not have wristpin for 2 strokes
Braydon C on Jul 31, 2017
BEST ANSWER: This kit will include the wristpin but you will need to purchase the wristpin bearing separately.
What is the next bore size for a 2001 yz250 ?
A shopper on Jul 25, 2017
BEST ANSWER: I show that we only carry standard bore sizes for the 2001 YZ250. Standard is 66.35mm. The Wiseco Pro-Lite is 66.4mm.
Will a 75mm fit my 1998 Honda fourtrax 300?
Dustin T on Jun 14, 2017
BEST ANSWER: I show that a 75mm piston is .040 mm over size from the stock piston. We do have this listed for your machine.
I need a Wiseco piston 80mm + 10 + 20+ 30 with rings material High silicone? please get back to me.
John D on Jun 3, 2017
BEST ANSWER: I would be happy to look into this. Could you please let me know the make, model, and year of the machine this will go on?
What comp piston is this for a 2005 trx450r?
Jake P on May 18, 2017
BEST ANSWER: Compression ratio for this piston in a 2005 TRX450R is 10.5:1
I have a 08 KTM 300 xcw there is A and B sizes i have a 71.95mm size B that is bigger than standard .What you have for sale is a Standard bore that is 72.00mm this looks like a size C ?
john d on Apr 16, 2017
BEST ANSWER: The actual bore size of this piston is 72.00mm which is essentially a size C piston for this bike.
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