Cracked skirt

[JB]

Just imported a engine from the US to Australia because they are getting very hard to come by over here, ended up costing about $3500 USD all up including postage and import tax, which isn't too bad for over here because engine was supposed to be in brand new condition.
I'm guessing any crack in a piston is bad



Was going to contact the seller to see what he is going to do about it, can anyone recommend a good piston that would suit road riding, looking for something that will last rather than performance.

Thanks

[Tharrell]

Since I've owned mine, I've heard a lot about the 500 cracking skirts over time. Mostly on this site.
Good thing you checked it.
Some of the guys will chime in but, I would think a forged piston would be good. That's what I always use for all my rebuilds.

[redrocket190]

Raced my CR480R several times before I took a peek up the intake...

[2strokeforever]

if everything is done right you should get plenty of life out of a cast piston.... other than running dirt thru the engine i havent had any issues and i put a ton of hours on.... and it sees the sunny side of 10 000 every ride and coolant temps over 285.... not to mention the intentionaly lean jetting

[JB]

Seller has said he will give me a piston kit free of charge, which is a resonable outcome i think, as long as the bore isn't to flogged out.
Still trying to decide on a piston though, is wiseco the only forged piston?

[fmikhele]

http://www.wossnerpistons.com/products ... 89-mm-bore

[TYSTYX]

I like cast pistons myself.

[AlisoBob]

Just drill it, and keep running it. Those cracks aint nothing to worry about.

[JB]

Not a bad idea Bob, if i do that all i need to do is find a way of building up to the bore to bring it back up to spec, have seen some photo's of people using metal putty like this, seems like i good idea.

[JB]

Pulled the cylinder and measured up, 89.13mm spec is 89.07 max, out of round by .14mm spec is .05mm. Big end side clearence all good at .75mm.
Going to see if anyone local has the gear to bored it when my piston turns up.

[2strokeforever]

Going to see if anyone local has the gear to bored it when my piston turns up.

or you can send it to someone who knows what their doing and get it done right the first time...

[JB]

Any Aussie's know of a good machinist preferably in Queensland

[gregrobo]

Going to see if anyone local has the gear to bored it when my piston turns up.

or you can send it to someone who knows what their doing and get it done right the first time...

why do you assume that his machinist doesnt know what he is doing?

[2strokeforever]

a better question would be: "Why would you assume his machinist knows what he is doing?"

[freeride588]

a better question would be: "Why would you assume his machinist knows what he is doing?"

I know your young and have some good knowledge and good riding skill but you have got to stop coming across like a dick head. Not trying to start a big thing here just commenting on what i see. Advice given by someone being a dick about it is hardly listened too.

[AlisoBob]

a better question would be: "Why would you assume his machinist knows what he is doing?"

x491

[gregrobo]

if everything is done right you should get plenty of life out of a cast piston.... other than running dirt thru the engine i havent had any issues and i put a ton of hours on.... and it sees the sunny side of 10 000 every ride and coolant temps over 285.... not to mention the intentionaly lean jetting

and if your going to talk shit at least make it believable

[2strokeforever]

and if your going to talk shit at least make it believable

what part isnt believable?

every few months (pretty regularly) a guy gets his cyl bored by someone who dosent specialise in cr500s, and then there here asking why did my bike seize 10 minutes into the first ride.....

[Rhino89523]

Think he is talking about the 10,000 rpm rev, temp claims, and lean jetting....doesn't know about your ignition and roosty mods or your temp gauge, and lean is mean.

You may not like what 2 stroke has to say or maybe the way he says it but I have not seen him present things as a guy totally full of shit.......you can still keep that hydro clutch though

[exackery]

Along the same lines>>> I've been experimenting to see how long I could run the cast piston in my '98. I did a top end job in 2001 (its first) and that was just a deglaze and a new stock piston. Every year in the spring I pull the reed cage and check for cracks>> Finally got one this year so I rebuilt the top end. I average 75-100 km per ride and ride 15- 20 Sundays a year (long freakin winters). So lets say 87 km x 17 rides for 10 years (took 2 years off 2005 & 2011) which equals 14790 km or 9190 miles per piston crack. No too shabby for a cast piston. Riding is an amazing mixture of WFO gravel road/open trail to first gear mud infested rock riddled goat paths (dont' worry the goats died long ago) with temps from just above freezing to 85 degrees depending on the month.

Oh and I use "chain saw oil" >>>>castrol gran prix 2 stroke oil (I bought 6 cases years ago for $1.18 liter/quart and I still have a fair bit left).

Kept the same sparkplug for 6 years (my conscience finally got the upper hand)

[JB]

While i am waiting for my cylinder to get bored i thought i might get a decompression valve put in the head, company in Melbourne, Australia doing the work.

Looks similar to Roosty's but is closer to the edge of the squish band and has a larger hole, the machinist said they drill them 1/8.
$145 plus postage
Any thoughts on the hole size and position??

[JB]

I got my cylinder bored at wiseco's australia's distibutor Serco. And it come back bored at .0025" clearance (which was recommended on the piston box) and ring end gap of .029" (wiseco recommend .014")
Sent an email regarding my concerns with the small clearance and big ring end gap and they said 'with correct run in proceedure all should be good'
Haven't started it yet, but my af build should be finished soon and i'm a little nervous on the piston clearance on first startup.

[Kuma]

That doesn't sound right for clearance, just going from memory, if you knew me that would be a funny statement, I thought it was more like .004"? what exactly does the wiesco instructions say? I know that in the past they would give a number and then you increase based on the piston size.

[JB]

From what i've read on here sounds like .004" is what everyone else runs with wiseco's. Printed on the box the piston comes in has a clearance distance stated what wiseco recommend. The ring end gap is .004"per inch piston diameter = .014 for a 3.5" piston.