Rebuild needed?

[Cstewa37]

Hi all, I'm Chris from Scotland and I'm new to the forum and have recently bought a 2011 EC 250 as a project bike. This is my first 2 stroke so apologies if this is a stupid question!

I decided to take the cylinder head off to have a look at the piston and cylinder condition and I'm not sure if what I see is "normal" or acceptable to run?

I know the previous owner ran his premix at 40:1 and the jetting seems lean compared to standard (178, 40, N1EF on top slot) which could maybe explain the colour of the piston? Apparently the bike had a top end rebuild around 40 hours ago but nothing to prove this.

I cant see a cross hatch on the bore, more vertical lines although I can't feel any with my finger nail. Couple of small "particles" on the cylinder, some I could feel some I couldn't.

Any thoughts or comments?

Regards

Chris

 

[BrandonEc300]

If that were my cylinder I would send it out to get replated and then get the head machined while your at it. Here in the states Millennium tech is a great well known company that offers the service. Also I?d ditch that n1ef and put in a nedj.

 

[SS109]

Actually looks rich to me as there is definitely some piston wash (same with the head) going on. Cylinder looks to need a replate but wouldn't know for sure unless you pulled it, scrubbed the bore clean with a scotchbrite pad, and posted up better pics.

 

[(F5)]

As above, scotchbrite and clean to inspect. Plating is tough.

Also cut the needle in half so you dont use it, and but NEDJ, try clip 2 as starting point.

Measure ring end gap in bore pushed down about a cm with piston. Google tolerance. They dont wear much.

 

[Moto7man]

http://www.gasgasrider.org/forum/showthread.php?t=19892

This is a link to the rebuild on my 2011,scroll down a bit it has some info that might help you.

 

[Cstewa37]

Thanks all, I've got the cylinder and piston off now and will get some photos of it up when it's all clean. Trying to remove the power valve to give that a check over and a clean too.

Looks like I have a B cylinder as standard with a C piston currently fitted.

Chris

 

[Cstewa37]

Cylinder liner is definitely worn and can see some small "particles" in the cylinder wall. Piston doesn't look too bad but does have vertical wear marks I think, glad I decided to strip it!

 

[Cstewa37]

And the piston..

 

[Cstewa37]

So I guess my question now is, replate it and get a correct sized piston, or replace the cylinder and get the piston with it? Is there much price difference as I can see a S3 cylinder and piston kit is about ?400, the piston alone is ?120 or there abouts.

If I replate the existing cylinder, do I use a B size piston for this initial build and then use a C on the next rebuild?

Chris

 

[(F5)]

Pic one is the decider. Plate it and send them the new piston to match it to.

 

[Zman]

Yes, your plating is worn through to the aluminum cylinder casting.

A third option is to have your cylinder bored out and get a big bore piston.

The company that replates the cylinder will typically finish hone the cylinder to the piston size.

when you consider the shipping costs both ways it may be less expensive to get the S3 kit and sell your old cylinder.

 

[Cstewa37]

Good point, so option number 4 could be to fit a 300 cylinder/piston? Would I need to change anything else other than the jetting to compensate?

Chris

 

[Gasser Nate]

Buy an A piston and get it replated to suit.
That way you have somewhere to go with wear. That bore is 100% dead. A magnet is a good test to see if the plating is gone as well. The nikasil is slightly magnetic whereas the aluminium cylinder is not. But the giveaway is the discolouration around the exhaust port.

 

[Moto7man]

Go with an S3.

 

[(F5)]

Spend the money on cocaine and hookers.

Just, to put out a balance of options.

 

[SS109]

Spend the money on cocaine and hookers.

Just, to put out a balance of options.

Hookers and blow is always a valid option!

 

[Cstewa37]

Hookers and blow is always a valid option!

Chris