Does My Cylinder Need Bored Or Not

[Surfrjag]

exhaust wont cause that low compression but if you didnt kick it till the guage stopped it would. whats a wsm piston?


edit- its a cast piston. i hope we wont be seeing a carnage thread from you....

 

[quadsrus1]

I hope so to lol

 

[quadsrus1]

D#*# well i just went and tried to cancel the order for the wsm kit but i can't so what should i do do you think the piston will last for this winter and ill get it out and bored and stuff soon as possible

 

[sicivicdude]

D#*# well i just went and tried to cancel the order for the wsm kit but i can't so what should i do do you think the piston will last for this winter and ill get it out and bored and stuff soon as possible

The only way to know for sure if that piston will work in your cylinder is to measure your cylinder bore!

You can get the stuff to measure you own cylinder on the cheap from Harbor Freight for about $30 (and have the ability forever more) or you can carry your cylinder by a machine shop and they can measure it for you. I'll say it again, the service manual (downloadable version available for FREE in the general support section of this forum) has the process to properly measure your cylinder bore, taper, and out of round. Once you know those numbers you can compare them to the specs in the manual to see if your cylinder does, in fact, need boring.

Digital Calipers - Save on these 6 Inch Digital Calipers

6 Piece Technical Measuring Set

A WSM piston kit is one made by ART, the original caster for stock yamaha pistons. Cast pistons are fine for "normal" (read : not highly tuned) engines as long as there are no air leaks (lean conditions cause all pistons to go boom but it causes cast pistons to disintegrate) and the cylinder to piston clearance is within specifications (the forging process aligns molecules of aluminum into directional "chains" which lend some strength to the skirts) . If you measure your cylinder (or have it measured) and it found to be out of spec, you can sell the piston kit (piston, rings, wrist pin, and circlip) and then purchase the correct size (probably .010" oversize looking at the condition of your bore) and take the piston and cylinder to a machine shop to get it bored. The finished product will have a fresh hone and, provided the shop doesn't have their head in their posterior, be the correct size for the new piston.

 

[sicivicdude]

Or, if you feel like spending another $5 this set of gauges is MUCH easier to use and even slightly more accurate:

6 Piece Telescoping Gauge Set

 

[quadsrus1]

Ok thanks i do appreciate it im not trying to be a noob

 

[sicivicdude]

Ok thanks i do appreciate it im not trying to be a noob

it's NO problem as you take the recommendations and work with them.

Helping out is the best part of a forum with an active knowledgeable membership. Trust me, everyone has to start somewhere.... and it's usually asking silly noobish question...

Either pick up some measuring tools or find a local machine shop and have them measure the current bore size, out of round, and taper. Then you'll know what you've got and where you need to go instead of guessing. Guesswork generally ends up in people having to click on the bottom link in my signature

 

[Blaaster]

If you are not sure than ask questions, that is what you have done, that's not noobish that's normal.

Have that cylinder measured and if it comes within specs, hone it and put in your new piston.
If it is sloppy have it re bored and fit another piston.

You should have no trouble selling the surplus piston.

 

[quadsrus1]

Ok sounds good to me

 

[sicivicdude]

If you are not sure than ask questions, that is what you have done, that's not noobish that's normal.

Have that cylinder measured and if it comes within specs, hone it and put in your new piston.
If it is sloppy have it re bored and fit another piston.

You should have no trouble selling the surplus piston.

X2. I highly recommend getting your own measuring tools and learning how to measure your cylinder vs paying a machine shop to measure. You think "I only need one cylinder measured this one time so why buy the tools?" but I PROMISE you, you get comfortable working on blaster engines and you'll run up on a deal on Craigslist where someone's trying to dump one that "blew up" and you can get it cheap enough to make it worth it. You'll wind up kicking yourself for not getting the measuring tools the first time and having them waiting around for you for later.

 

[quadsrus1]

Yea i see what you mean

 

[chumley1/17/96]

sounds to me to go with new piston rings. and i got a question what cc is a 66mm bore?

 

[Blaaster]

195cc with std stroke. Am I right bore x stroke.

Edit:: I am having an out of brain experience this morning, did I get the formula correct.

If the guy just puts in new rings without checking for cylinder wear he is courting disaster, and speaking from experience, disaster is not a nice Lady!

 

[quadsrus1]

Im not only putting new rings in im putting new piston,ring,gaskets,clips, everything

 

[blasterman2323]

I had the same problem but i have a scuff in my if i hone it with a rigid hone will that be good enough???