Hi I was wondering if any one had tried the MxPartsOnline 308cc big bore kit for our bikes? I think it's 500 bucks off eBay with free shipping all new parts plus the ad says they will pay you 100 bucks for your old jug. I know that's only a 150 less than bills 351 kit but thought I would ask.

 

Noooop. Never even heard of it.

Why go smaller when there's a 351cc available?! BIG OR BUST!

 

My thoughts exactly, and to add Bill has a great reputation on this forum and I personally use his 351 kit and it's AWESOME, I wouldn't settle for less. My bike has gone from a slug to a rocket.

I'd easily spend the 150$ for more, the quality is there and Bill is happy to help with any questions you have.

 

went looking for more info..... i dont see anything for the klx250
mxpartsonline: Kawasaki big bore

 

Yeah, I searched too and didn't see anything listed on their site. I did find a mention of a guy supplying the 308 on the ADV site, and he was from New Jersey. I did like the fact that the thread indicated that it was a nikasil coated cylinder. I don't think it's the end of the world of nikasil plated over steel liner, but I've liked the cooling efficiency of my OEM 300cc nikasil jug on mine. I think coated cylinders have a little advantage, but like I said, not the do-all-end-all by any means.

 

Thought I would at least ask. I'm leaning toward the 351 strictly because of Bills reputation. My bike is near perfect right now but it runs out of steam on the highway. It will do 75 all day long as long as there's no head wind or hills. I think the extra cc's would fix that problem if I went with either of the kits. I'm not worried about the coating or liner issue. Here is the ebay link if you are interested. Thanks for your replys!
KLX250 308cc 80mm Big Bore cylinder Kawasaki 11:1 CR wiseco piston KLX 250 | eBay

 

Yeaaahhhh..... wouldnt buy anything like that over ebay.... im going to have to advise against that.

 

The 308 kit is tried and true modification for the KLX300 (which is only 292cc in stock form) - it just doesn't seem to be very common. It uses an off the shelf 80mm (2mm or 0.080" oversize) Wiseco piston and off the shelf oversize Cometic gaskets.

A 300 cylinder could be sleeved or bored/plated to 80mm. A 250 can not be safely bored to 80mm - it would be left with extremely thin cylinder walls - sleeving is the only option for 250 cylinders.

The 80mm piston kit and gaskets can be had for something like $180 and the boring/replating around $200. If you throw in the cost of a used KLX300 cylinder (I've seen them actually sell on ebay for $40-$150, though many sellers have them listed for much more), the price of the 308 kit on ebay isn't outrageous...but it is a bit high in my opinion. Certainly there are bigger (sleeved) kits available for similar investment.

Buyer beware of any online engine work (replating in this case) without specific knowledge of the quality. If I were thinking about buying that kit, at a minimum I would definitely ask the seller what the core cylinder is (0.292l = KLX300, 0.249l = KLX250) and who actually did the boring, plating, and honing of the cylinder.

 

This is the type of useful information that I love about this forum!I have decided to save a few more dollars and when I have them Ill give my business to Bill. Have to admit it was tempting it would have put me closer to a bigger tank. Going to have to feed that big thumper don't ya know!

 

This is an interesting option for owners of the 250 EFI models. The stock injectors and mapping seem to work up to around 315cc. After that, from investigations on the various forums, the bigger kits, such as BB or KK open up a can of tuning worms and expenses for EFI owners.