Cr500 Piston and Bore pics

[utsman]

Hey Dirties,

I just pulled the pipe off my 500 after just 5 hours on a brand new motor and this is what I saw through the exhaust port

[utsman]

This ones a bad photo but there is some wear marks on the bore. And I wasn't expecting any blow by on the piston picture either.

I hav'nt seen a lot of new motors but does this look normal?? Am I being paranoid?

[gorby]

could be the flash and camera angle,but it looks like a very coarse hone was used on it?

[utsman]

The hone was all good,

It's more the brown marks on the piston and vertical bore marks I am seeing

[Hoony]

looks a bit like abrasive wear on the piston from grit being sucked in?

[utsman]

It's gotta be I suppose Hoony,but I havn't even ridden with anyone so the has been very little dust, and the filter has been kept clean.
I guess I will just keep riding eh.

[STW996]

Couple of things,

Is it a air or water-cooled bike?
Did you rebore or just hone?
How long did you run it in for? (if rebored)
The blow-by can only be leakage under compression and this can be from to much piston to bore clearence same to with the marks on the back of the cylinder or if the bike was rebored can be from little or no running in time.

The best way to view it is to remove the head and have a good look inside, if air cooled it is only time and if water-cooled costs you a head gasket.

Shane

[utsman]

Hey Shane Thanks for the Help.

It's water cooled. The bore was done at Serco and all the motor work done by a good 2 stroke mechanic who said Piston to Bore clearance was good.
To Run it in this is what I did as told by the mechanic.

Start bike let it warm up slowly blipping throttle a bit - shut down when hot.
Next Day - Start again -warm up slowly and ride at no more than third  throttle for ten minutes.
Next DAy, warm up slow again and away I went varying throttle but not flogging it, and only short bursts of half throttle. Rode for about half hour
After that I just rode but I never ride it at much above half throttle (it's a CR500) it certainly hasn't been flogged and I always warm it up slow.It's a bit of a bummer cause I did the full rebuild because of vibration. I thought the crank was shot. Turns out the engine was O.k and it still vibrates.
I'm not gonna do the bore and piston again yet thats for sure, I guess the bore job wasn't spot on. I thought Serco were the best.Still runs good. Better to be a bit loose than a bit tight eh

UTSMAN

[squirtmoto]

Don't have a panic attack just yet ol'mate
A couple of more questions need answering
What brand of oil and ratio you using?   I have found that most of todays
synthetic oils are too efficient and cause a premature varnishing of the cylinder as you describe, the rings can't bed-in if they arn't put under enough pressure. The cast lining on the cylinder will attract the oil and build up a glaze. This then causes the rings to slip and break seal and it compounds to what you now have!
"putting around" as you have been told to run it in, is a wank!!  If you dont get on the gas after about 30mins of "putting" it will glaze-up!  If it was going to have a mechanical failure it would have by now!.  Just give it a light rub with some 1000-1200 grit W&D ensuring to maintain the same cross hatch as the original rebore, then ride it like normal.  Most guys that ride 5-hungies don't get them up to the normal stressfull ranges that a 125 or 250 cops and normal riding a 500 is like running-in for a 125-250cc

As for the SERCO rebore, I use Al all the time and never had an issue with one of his rebores.  Have faith it will be the Oil and running-in procedure

Bill.
 

[utsman]

Bill I like your thinking,

It's the oil - it's too good- of course
I think I ran it in on Motul 8002T cause I had a bit left. Now I use the Silkolene Comp 2 Premix because it's much easier to get in my neck of the woods (Supercheap). Both are ester based oils. Run at 35mls per Litre (28:1 I think)

Thanks for all the replies.
Bill Yours is the best

Now it's off to EMU CREEK on Saturday for some FUN.

UTSMAN

[STW996]

Yep Bill is spot on, I stay with the old mineral based oils (personal choice for air cooled and water cooled) and have no problems, the running in done was a bit over the top for sure but would only cause glazing and not the friction marks. I just go another engine from the states and the marking on the cylinder/piston made your's look like a small scratch and a cleanup with the 1200 wet and dry and all is good (power wise) and as for Serco bores I have to rate them highly specially as Bill said our local (Brisbane) guy Alan.

You can really kill a 500 and the performance will still be A1 so get on it and enjoy the ride

[utsman]

Cheers guys,

Nuff Said

UTSMAN