03 blaster blew up can u bore the stock cylinder?

Karen Tracy

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Feb 25, 2016
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i have a 03 blaster 200 and the oem piston finally came apart and I was wondering if I can just bore the stock sleve and run a bigger piston? if so what size should I run?
 
U have to send ur cylinder out to get bore to a piston and if piston came apart u have to take apart the whole bottom end and clean out metal fragments
 
If you can't find a good local shop, then send it out. Cyl has to be measured for new bore/piston. X2 on clean out. Hopefully piston pieces didn't blow the cases out.
 
The size of the new piston will be determined by the amount of material that has to be removed to clean up the bore to make it round, strait and with no taper. The amount removed will have to be enough to get rid of gouges, scrapes, and scars.

As for brand of piston? Pick one.
Everybody will say, or tell you wiseco, I disagree... I prefer a quality cast piston over a forged piston (wiseco) any day of the week.
If you go the wiseco route be sure to warm up the engine properly before riding, or else certain areas of the piston will expand at different rates and give you a "four corner seizure". This doen't always happen, but "could" happen if you don't warm up the engine/piston before use. A great piston if treated properly.

A cast piston is what your blaster came with from the factory as well as other makes of quads and motorcycles.
A cast piston will give you piece of mind if you rush the warm up. It also runs tighter tolerances in the bore and is a bit quieter while running. A great piston and what I like to run.

Either choice will do.

As mentioned above... time to get your hands dirty and disassemble that lower end and inspect. While your at it, rebuild the crank, and reassemble with quality seals and gaskets. After that run a QUALITY two stroke oil like Maxima Super M, or one of your choice. DO NOT run echo weed wacker two stroke oil or any lawn care two stroke oil.
 
Just ask your local shop or call ken oConnor, he's well know, he does cheap work but high quality work. It's only 50-60 for him and around 60-100 anywhere else depending on where you go and get a wiseco piston, I have the high compression series, don't get cast
 
Just ask your local shop or call ken oConnor, he's well know, he does cheap work but high quality work. It's only 50-60 for him and around 60-100 anywhere else depending on where you go and get a wiseco piston, I have the high compression series, don't get cast

Spewing misinformation all over. See above post. There are advantages and disadvantages of both cast or forged.
My machinist charges $48 bore/none.
 
and get a wiseco piston, I have the high compression series, don't get cast

I say ... Hmmmm
Where do you get your information?
Pretty ignorant.
I'm still trying to find that "High Compression" wiseco pro lite piston you have.
I must have missed it on wiseco's web site. I did see the 10 over sizes of pro lite pistons available for the Yamaha YFS200 Blaster though. However,no high compression ones.


A cast piston works fantastic. Always has.
A forged piston will handle detonation a bit better, but why would you let your engine continue to detonate.


What modifications have you done to your blaster?

A lean condition will kill either a forged or cast piston.


 
Always laugh at that too.

FYI guys, ONLY way to increase compression on a two stroke is modded head or dome change. Depending on engine. Seeing there is only .040-.050" clearance between crown of piston and squish area (normally) no possible way to change the piston much. Can't put a bump like a 4choker high comp piston because a smoker doesn't have time to cool the piston.

This is only an advertising gimic to make a sale.
 
I say ... Hmmmm
Where do you get your information?
Pretty ignorant.
I'm still trying to find that "High Compression" wiseco pro lite piston you have.
I must have missed it on wiseco's web site. I did see the 10 over sizes of pro lite pistons available for the Yamaha YFS200 Blaster though. However,no high compression ones.


A cast piston works fantastic. Always has.
A forged piston will handle detonation a bit better, but why would you let your engine continue to detonate.


What modifications have you done to your blaster?

A lean condition will kill either a forged or cast piston.
Sorry miscommunication, I have a wiseco pro lite with a high compression series gasket. Didn't mean high compression piston, but namura does make a high compression piston, wouldn't recommend running a namura though
 
Always laugh at that too.

FYI guys, ONLY way to increase compression on a two stroke is modded head or dome change. Depending on engine. Seeing there is only .040-.050" clearance between crown of piston and squish area (normally) no possible way to change the piston much. Can't put a bump like a 4choker high comp piston because a smoker doesn't have time to cool the piston.

This is only an advertising gimic to make a sale.

This is not completely true Larry. Compression is increased (slightly) just by boring the cylinder, so I guess they can advertise an oversize piston as "High Compression". I do see what you're saying. Compression can also be increased (other than cutting the head or chamber) with cylinder head and base gasket thickness, cylinder base machining, cylinder top machining, case machining, and crankshaft stroking.
 
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Never thought of it in that aspect. Couple extra cc of displacement compressed into same cc combustion chamber.
Guess I'm so used to seeing numbers such as 10 1/2 : 1 .
Obviously methods such as decking aren't quite as common, in respect to " average " builds.
 
Why not run a Namura? Please explain.

A namura is cast, I never like to run cast. They break apart when they're bad unlike forged but warm up easier than forged, and namura also usually blow up within a few hours on blasters. Just search on YouTube Yamaha blaster namura
 
Stop with the ignorance. Your making yourself look dumb.
I'm fully aware that Namura is a cast piston as well as ART, ProX, WSM, Vito's, Vertex, etc, etc.
You don't like to run cast. Just an opinion. I get it, but you don't know much about pistons.
They don't blow up in just a few hours in blasters. Ignorance
Seriously? Wow.
 
A namura is cast, I never like to run cast. They break apart when they're bad unlike forged but warm up easier than forged, and namura also usually blow up within a few hours on blasters. Just search on YouTube Yamaha blaster namura
So, why is it that if they are so bad that they last until the bore and piston are so worn that you can actually hear the wear ? PISTON SLAP?. They break because they are well past the service limit ( poor maintenance)

I just Google searched, and a stock YFZ450 uses a cast piston, and they spin nearly 11,000 rpm.
First gen Hyabusa uses cast, and Busa cast pistons are 15 grams lighter than Wiesco.
 
So, why is it that if they are so bad that they last until the bore and piston are so worn that you can actually hear the wear ? PISTON SLAP?. They break because they are well past the service limit ( poor maintenance)

I just Google searched, and a stock YFZ450 uses a cast piston, and they spin nearly 11,000 rpm.
First gen Hyabusa uses cast, and Busa cast pistons are 15 grams lighter than Wiesco.
It's just a personal preference I don't prefer me, just the other day after 1-2 hours on a rebuild my blaster blew up
 

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