Piston diameter / Cylinder bore size Identification Markings

madmcnish · Post by **madmcnish** » January 18th, 2008, 5:31 am

Just pulled the cylinder head off my '95 to replace a leaking gasket.
The crown of the piston and the outside of the cylinder barrell casing have no markings to indicate which over-bore the engine is on.
Does this mean the bike is still on the original piston & cylinder bore?
Piston to cylinder clearance looks fine and the cylinder walls also look good.
A couple of the cylinder head bolts and nuts look pretty shagged though, so i'll have to clean them up or replace them.
Cheers

fastkart · Post by **fastkart** » January 18th, 2008, 6:04 am

Do you have a way of measuring the cylinder? 89.00 mm is stock bore.

dannygraves · Post by **dannygraves** » January 18th, 2008, 9:23 am

I'd measure it, just so you know what bore its on, then put it back together and keep riding!

britincali · Post by **britincali** » January 18th, 2008, 9:55 am

If theres nothing on the crown its a stock cast piston.

Did you check the intake skirt for cracks? Being a '95 I would definatly rebore and slap in a new piston / rings.

iggys-amsoil · Post by **iggys-amsoil** » January 18th, 2008, 5:17 pm

britincali wrote:If theres nothing on the crown its a stock cast piston.

Did you check the intake skirt for cracks? Being a '95 I would definatly rebore and slap in a new piston / rings.

X2

Post by **AlisoBob** » January 18th, 2008, 7:38 pm

iggys-amsoil wrote:
britincali wrote:If theres nothing on the crown its a stock cast piston.

Did you check the intake skirt for cracks? Being a '95 I would definatly rebore and slap in a new piston / rings.
X2

X3

Pull that reed cage...

madmcnish · Post by **madmcnish** » January 20th, 2008, 3:44 pm

Pulled the crab and reed-cage to inspect the piston like you guys advised and...........
The Fu&*er's cracked!
I took a couple of photos, but am not sure how to attach them to this message.
How do I do it?
The crack itself doesn't look that big, less than 10mm long.
What's my next move?
If the bore's not worn over the required tolerance, can I get it honed and install a new original-sized piston?
BUGGER!

britincali · Post by **britincali** » January 20th, 2008, 3:48 pm

Use the img button above the post box then copy and paste your photo link then hit the img button again.

Get the next oversized piston and rings and get it bored out to suit.

lewisclan · Post by **lewisclan** » January 20th, 2008, 3:56 pm

britincali wrote: .

Get the next oversized piston and rings and get it bored out to suit.

Bingo!

Post by **AlisoBob** » January 20th, 2008, 4:33 pm

madmcnish wrote: If the bore's not worn over the required tolerance, can I get it honed and install a new original-sized piston?
BUGGER!

What do you think caused the crack?

Once the machine work is done, you'll have piece of mind that the motors good to go for a few YEARS, and the performance will be outstanding.

Loose , rattling pistons crack, are noisy, and dont make much power.

M.F.D.B. · Post by **M.F.D.B.** » January 20th, 2008, 10:50 pm

Send that stop signed jug to get it deck plate honed...see the sticky in drive tech...

If its a stocker and you dont ride hard just get a coated cast piston. If you ride real hard and want to do some power ups step up to a forged...JMHO

madmcnish · Post by **madmcnish** » January 21st, 2008, 1:56 pm

I'm looking at piston kits, comparing UK prices to US.
Wiseco forged - UK £120, US £70 Including postage to the UK.
PRO-X cast - UK £95, US £70 Including postage to the UK.
Why are the kits so much cheaper over there?
WWWHYYYYYYY?????
These are prices that I found just doing a brief search on ebay - I have not compared every dealer or supplier.
I mainly ride my local MX tracks (for fun only, no racing), and there's not a lot of space to get her WFO, so I don't think I'll be putting alot of stress on the motor.
If I was restricted to buying from the UK, I would go for cast PRO-X or VERTEX kits, as they are cheaper than the forged WISECO items.
However, if I get them posted from the US, the cost of forged Vs. cast are about equal and both are alot less than buying them over here.
I have read that a few people have had problems with WISECO pistons and they require drilling oil holes for proper cooling / lubrication.
Do any of the cast pistons require holes to be drilled?
As far as bridge relief work and transfer port grinding/ re-shaping goes, should this info. be included with the new piston?
There is no info on this in my Haynes workshop manual.
I'm not trying to start another forged vs. cast piston argument, but what do you guys think would be best suited for me, as I'm not trying to set any horsepower records???
Thanks again...

dannygraves · Post by **dannygraves** » January 21st, 2008, 2:05 pm

in your case, cast is probably the way to go. no need to drill holes. still need the releive the exhaust bridge. Cast pistons can fit nice and snug and if your mx or trail riding, you will get years of service from that piston. I run a forged piston because I hit the dunes and do a lot of extended WFO runs.

ISBB · Post by **ISBB** » January 21st, 2008, 4:14 pm

im runnin fine with no holes drilled in the sizeco.. just make sure the exhaust bridge is clearnced properly and you shoudlnt have any problems with either.

britincali · Post by **britincali** » January 21st, 2008, 4:15 pm

ISBB wrote:im runnin fine with no holes drilled in the sizeco.. .

I got $5 it'll squeek this weekend

ISBB · Post by **ISBB** » January 21st, 2008, 4:17 pm

If it was gonna squeek it would have done it 12 gallons of race gas ago!

britincali · Post by **britincali** » January 21st, 2008, 4:18 pm

M.F.D.B. · Post by **M.F.D.B.** » January 21st, 2008, 8:20 pm

I hope the only squeeking any of us heres this weekend is from my trailer...

But I put my money on Britt squeekin' over Nick any day!!

dannygraves · Post by **dannygraves** » January 22nd, 2008, 7:16 am

dannygraves · Post by **dannygraves** » January 22nd, 2008, 7:16 am

don't come a knockin' if MFDBs trailer is a rockin'!

M.F.D.B. · Post by **M.F.D.B.** » January 22nd, 2008, 9:10 am

dannygraves wrote:don't come a knockin' if MFDBs trailer is a rockin'!

LOL I doubt much of thats gonna happen as we will have company 90% of the weekend!!

100hp honda · Post by **100hp honda** » January 22nd, 2008, 9:33 am

M.F.D.B. wrote:
dannygraves wrote:don't come a knockin' if MFDBs trailer is a rockin'!
LOL I doubt much of thats gonna happen as we will have company 90% of the weekend!!

i took some bitch to sand mountain utah with me about 10 years ago. she wouldnt give me none either. i feel your pain bro

M.F.D.B. · Post by **M.F.D.B.** » January 22nd, 2008, 10:33 am

100hp honda wrote:
M.F.D.B. wrote:
dannygraves wrote:don't come a knockin' if MFDBs trailer is a rockin'!
LOL I doubt much of thats gonna happen as we will have company 90% of the weekend!!
i took some bitch to sand mountain utah with me about 10 years ago. she wouldnt give me none either. i feel your pain bro

ISBB · Post by **ISBB** » January 22nd, 2008, 12:46 pm

sounds alot like the same girl that i took to glamis.. drank all my beer smoked all my smokes and i didnt even get a thank you blowjob out of it!! She did sleep with my best friend though that weekend.

M.F.D.B. · Post by **M.F.D.B.** » January 22nd, 2008, 1:05 pm

ISBB wrote:sounds alot like the same girl that i took to glamis.. drank all my beer smoked all my smokes and i didnt even get a thank you blowjob out of it!! She did sleep with my best friend though that weekend.

OUCH!!

BannedCR500Riders.com

Piston diameter / Cylinder bore size Identification Markings

Piston diameter / Cylinder bore size Identification Markings