2005 ec200 top end- where do i go from here?

[paulos]

Ok, so I finally pulled the top end apart to check the state of play.

Head is original and unmarked, piston had some decent carbon buildup, I'm assuming due me running too lean trying to clear up the stutter at 1/4 throttle?

Initial solder squish measurements show 1.9mm at the outer edge and 2.6 at the limit of the solder being squashed (about 10mm in from the outside edge)

The barrel has a definite lip where the rings "finish" so I'm assuming a rebore and replate is in order?

My main questions are regarding the barrel, the need to send the head to be sorted is a given.

What is the plating used on the barrel and is there anything should know before handing it over to be rebored?

[paulos]

After closer inspection, could someone please tell me whether the lip at the top of the cylinder is original? It seems to be around the depth that the head inserts into the cylinder, and as the chrome looks fine I'm thinking it's not wear related.

[Jakobi]

New cylinders have no lips. If the groove is worn enough you can catch a finger nail on it then it indicates the bore has worn. You won't know how much the bore has worn unless if you get a gauge on it and spec it all up.

[paulos]

So are there any ramifications in reboring and replating in relation to the way the head "inserts" into the top of the cylinder?

[Zman]

If you need to have it replated they will resize the bore to match the new piston and the head will fit fine. Can you estimate/quantify how much ridge there is?

If the ridge is minor you may be able to diamond hone it and get the correct piston size to match it. Ryan Callies at Finishline Engines can hone it for you and if necessary he can get it plated at Millennium Technologies. http://www.finishlineengines.com/ He can also source Wiseco pistons. His prices are very reasonable and he is a racer himself.

[paulos]

Thanks mate. I spoke to a local re-plating mob who explained that they work back to the original bore size. I'm used to older engines where you just buy a bigger piston and rebore to suit. Cheers