I am looking to get a piston/ rings for my blaster, Any advice on a brand/ type to get? Also my dad wants to know if they sell rebuild kits for a topend.
Piston, Rings
- Thread starter LiftErUpTV
- Start date
yes they sell rebuild kits but not always the best way to go. I suggest weisco piston w/ oem gaskets. can find the piston on ebay and gaskets on cheapcycleparts.com or rockymountainatv.com you also need to take the cylinder to machine shop to have it measured to make sure you get the right sized pison and to see if it needs to be bored to the next size up. a real machine shop bores the cylinder to the new piston with the piston in hand only
The piston should be stock. Dont know why I would have to measure it. Dont they all come the same size? I need new gaskets for a piston/ring replacement? Ring brand? Thanks...
the bore size get's worn over time and if you put too small of a piston in it, the piston can slap from side to side, causing it to shatter. then you are really screwed. you can chose to listen or not.
K, I think there might be a little confusion here.
As A cylinder wears, the size naturally changes. and look at it like this, as time goes on. The cylinder needs to be honed or rebored. there fore, a larger size piston and rings are needed. to match that larger size cylinder.
A good mechanic / machine shop, wants the piston and rings, to match the bore / hone work to the size of the piston and rings and makes sure that the pistonring gap is correct and in spec.
Everyone prefers weiso. can't go wrong there. but for the budget and easy rider, not heavy racer. A WS kit or namura kit. works well.
My grandpa always said, son, if you got it to tight, you got junk, if you got it to loose, you got junk. its got to be just right !
Sporty
As A cylinder wears, the size naturally changes. and look at it like this, as time goes on. The cylinder needs to be honed or rebored. there fore, a larger size piston and rings are needed. to match that larger size cylinder.
A good mechanic / machine shop, wants the piston and rings, to match the bore / hone work to the size of the piston and rings and makes sure that the pistonring gap is correct and in spec.
Everyone prefers weiso. can't go wrong there. but for the budget and easy rider, not heavy racer. A WS kit or namura kit. works well.
My grandpa always said, son, if you got it to tight, you got junk, if you got it to loose, you got junk. its got to be just right !
Sporty
Ok, but that still doesn't answer my question, do I need new gaskets to replace my piston and rings?
yes you need new gaskets. you can anneal a head gasket but it sounds like this is your first rebuild so i won't go into that. have you owned the blaster since it was new? if not you have no clue what size piston is in there. if you go trying to just slap a piston in there you will have catastrofic engine damage. but what do i know. you seem to have it all under control.......
Is there anyway I can measure my cylander without having to take to a shop such as yamaha? I would rather not take it out of house to have stuff done to it...
the tools to properly measure a cylinder are expensive. theywill measure for free. don't go to a dealer. dealers don't do bore jobs usually. just search for machine shops in your area
How will I know if I need to bore it out? Also, the only place close to here is a chopper shop? Would that work?
Well our local yamaha dealer, does do machine work. And if they dont, they will recomend someone who does work.
I thought he might not know. So thats why I included that info.
But other than looking in yellow pages for your area. for machine shop to call around and ask.
My machine shop guy, charges $50 for bore & honed, checked, rings in piston and piston in cylinder, so all I have to do is just carefully, install the piston rod bearing and clips onto the rod and rod bearing and gaskets and bolt together.
I take him in the cylinder, he does a initial bore and then called me about a week later, with the size, to order the piston / kit. Cuz I find it cheaper then he can get stuff. then I take it back in to him,. so he can finish with the hone job and check everything and what I also just mentioned.
Dont go buying a piston kit, until you have it bored or know the size to get.
Also, My machine shop guy, he has people bring him in namura and WS piston kits all the time to use on there rebuilds. So if money is a factor, don't worry about the cheaper cast piston. but if you gonna run it wide open and race hard and not learn more about what you have and can do and check, then I would go with a weisco kit.
I thought he might not know. So thats why I included that info.
But other than looking in yellow pages for your area. for machine shop to call around and ask.
My machine shop guy, charges $50 for bore & honed, checked, rings in piston and piston in cylinder, so all I have to do is just carefully, install the piston rod bearing and clips onto the rod and rod bearing and gaskets and bolt together.
I take him in the cylinder, he does a initial bore and then called me about a week later, with the size, to order the piston / kit. Cuz I find it cheaper then he can get stuff. then I take it back in to him,. so he can finish with the hone job and check everything and what I also just mentioned.
Dont go buying a piston kit, until you have it bored or know the size to get.
Also, My machine shop guy, he has people bring him in namura and WS piston kits all the time to use on there rebuilds. So if money is a factor, don't worry about the cheaper cast piston. but if you gonna run it wide open and race hard and not learn more about what you have and can do and check, then I would go with a weisco kit.
You need to get the bore measured to find out if it is within specs.
If the bore measures good, then it will be ok to purchase a new cast piston, and have the bore honed.
Do not purchase a forged piston for a stockbore as they require the bore size to be matched, to keep them within tolerences, and may not suit an old bore.
If the jug needs machining, the machinist should be able to tell you what oversize you need to purchase, and should wait until they have piston in hand before reboring, especially in the case of a forged piston.
The choice of piston is yours, both types have their fors and againsts. Read up on cast versus forged pistons, they each have different warm up requirements.
If maintained properly, lubricated, jetted correctly and the proper proceedures followed, either type of piston will suit your needs.
You do need to get all new gaskets for a top end rebuild, do not entertain the idea of using old ones.
Do not use the blue/green paper composition gaskets, use only OEM or Cometic gaskets.
You really need to be dealing with an engine shop/builder who knows 2 strokes and preferably Blaster engines. Make sure the ports are chamfered after the cylinder is bored. When the engine is back together, be sure to do a leak down test, then heat cycles to break it in. There is threads and video's on doing both. I've owned 2 strokes all my life and until I got on this site I didn't know anything about these things. The good news is, Blasters are cheap to rebuild. The bad thing is, if you over look these things, you be doing rebuilds often.
Found this whilst browsing, have edited out brand names.
Something to consider regarding choice of piston type.
Pistons: Cast vs. Forged
We have all heard the advantages of forged pistons. However, when you consider the disadvantages of forged pistons it becomes very clear why cast pistons are the ultimate pistons for your rebuilding and repair projects.
The major disadvantages to forged pistons are actually a result of the forging process itself. Forging results in a piston that is considerably heavier, than cast pistons, and is limited in the aluminum alloys that can be used to produce the piston. Additionally, the forging process also limits the design configuration of the piston itself.
The forging process and its limited choice of aluminum alloys result in a dramatically higher expansion rate for the forged piston. This means that the set up characteristics are very different from the original engine manufacturers' and that break-in and warm up periods are crucial for the forged piston.
An example of the dramatic expansion of forged pistons is the piston skirt clearances in the cylinder. A typical forged piston has a skirt clearance of approximately .0007 to .0009. A cast piston has a skirt clearance of .005 to .007. The forged piston has 10 times more slop in the cylinder. This results in less ring stability against the cylinderical wall, more piston noise and extra blowby.
In all fairness, after the forged piston has reached operating temperature, its dramatic expansion makes up for these extra clearances. Can we expect the casual weekend rider to strictly observe the extended break in period and the critical warm up procedures required for a forged piston? Let your own experience answer this question.
Most forged pistons are quality products, but they are better suited to racing and professional applications.
Something to consider regarding choice of piston type.
Pistons: Cast vs. Forged
We have all heard the advantages of forged pistons. However, when you consider the disadvantages of forged pistons it becomes very clear why cast pistons are the ultimate pistons for your rebuilding and repair projects.
The major disadvantages to forged pistons are actually a result of the forging process itself. Forging results in a piston that is considerably heavier, than cast pistons, and is limited in the aluminum alloys that can be used to produce the piston. Additionally, the forging process also limits the design configuration of the piston itself.
The forging process and its limited choice of aluminum alloys result in a dramatically higher expansion rate for the forged piston. This means that the set up characteristics are very different from the original engine manufacturers' and that break-in and warm up periods are crucial for the forged piston.
An example of the dramatic expansion of forged pistons is the piston skirt clearances in the cylinder. A typical forged piston has a skirt clearance of approximately .0007 to .0009. A cast piston has a skirt clearance of .005 to .007. The forged piston has 10 times more slop in the cylinder. This results in less ring stability against the cylinderical wall, more piston noise and extra blowby.
In all fairness, after the forged piston has reached operating temperature, its dramatic expansion makes up for these extra clearances. Can we expect the casual weekend rider to strictly observe the extended break in period and the critical warm up procedures required for a forged piston? Let your own experience answer this question.
Most forged pistons are quality products, but they are better suited to racing and professional applications.
I prefer a CAST PISTON any day of the week.
They are very durable,as I've never had any issues in any two stroke engines.
I've had issues with forged pistons expanding too much even after the proper piston to cylinder clearance has been obtained.
They (forged pistons) make more noise too
I beat the crap out of my blaster's engines and NEVER had an issue. I've also do proper maintenance.
Just for the record,I've had properly clearances wiseco pistons crack too.
Read this thread here >>>
http://www.blasterforum.com/engine-13/joeak47s-thread-cast-piston-vs-wiseco-forged-piston-49255/
They are very durable,as I've never had any issues in any two stroke engines.
I've had issues with forged pistons expanding too much even after the proper piston to cylinder clearance has been obtained.
They (forged pistons) make more noise too
I beat the crap out of my blaster's engines and NEVER had an issue. I've also do proper maintenance.
Just for the record,I've had properly clearances wiseco pistons crack too.
Read this thread here >>>
http://www.blasterforum.com/engine-13/joeak47s-thread-cast-piston-vs-wiseco-forged-piston-49255/
