I'm sure the Nikasil coating suffers much less wear than an un-coated surface, but the coating does not add any structural strength to the wall of the cylinder. Similar to a TiN coating on drill bits, it's just a thin (very durable) layer. We do a similar process where I work. Aluminum parts are "hardcoated" this adds a .002 - .003 thick layer of a hard anodize surface that we then grind or hone to a specific size and finish. If you are not careful with these parts the edges of the "hardcoating" will chip. Hard but brittle.
Dan

 

I honestly dont know if the bike overheated and caused the crack or if the crack bubbled out the coolant and caused the overheating. I noticed it when dealing with stop and go trafic up a hill caused by construction. maybe about 10min. I had had the fan come on before in same kind of situation so I expected it was normal when it came on. Then the red light came on about the time I cleared the construction. It went off when I got a little speed and I just went ahead and rode the 500yards to my house.

I also want to point out that the nikasil was definatly NOT the cause of failure. The bore of the cyl is very smoothe and rings look perfect. The wall of the cyl is pretty thin in my opinion. I think the bb351 has about same thickness and its steel so I expect it to hold up better. 10K may be OK to sum but that was less than a year of rideing and I dont want to have to swap in a cyl every year!
Another contributing factor may be I think I was slightly lean on the jetting. I will be correcting that also.
Cheers Jim

 

Well..you can't go by time on the calender, you have to go by time on the engine. If 10K is it, then 10K is it. That's a lot. Also, remember, you have a WAY over modified engine too. Normal big bore kits dont go 40%-50% overbore. Thats huge, plus your carb, etc. I've had my bike a little over 2 years and I put like 4K on mine and I considered that alot...and I don't live on an island!! lol

I think you did pretty well.

By the by, how did that beer turn out?

 

Beet Japan, who also offer a big bore kit (315cc), state that pre '97 models need extra modification. KK also show compatibility with 97~ models

The KK 330 kit based on a 300 cylinder is a 10% increase, not 40 ~ 50%.
Kits that size like Bill Blue's using a 250 cylinder are sleeved, not bored and plated.
Nearly 40% increase for the crank maybe, but his crank hasn't failed, and from what I can deduce about the KLX engine, the 250 and 300 bottom end is the same.

 

I was talking to bill yesterday. I have a 351 kit on its way. Bill says the crank and rod are huge compared to most or all other 250 engines, closer to a 400 size crank and rod.

My BMW has 123,000 miles on it. All original. 10K does not seem like a lot to me. I understand its not the same miles, but I do not think one case shows the service life of a motor. It cracked, stuff happens. The owner does not know what caused the crack and we probably never will. My guess is it overheated.

David

 

Ok. Now does the 300 and the 250 use the same wrist pin?

 

Sorry to hear about the blown cylinder. I was just thinking about the kk kit for my 2006. Maybe the BB kit wet sleve and all. Also new to the board.

 

I was doing quick math in my head. But now that I grabbed the calculator I'm a damn good guesser. 250 to 350 is 40%

The 300 head is not a true 300 if I remember, its a 282cc. 282 to 330 is like 20% Thats still a lot. Most big bore kits go like 10% or so. And also, don't forget, that was just one part of my reasoning. The other is its a small bore dirtbike engine ridden on the street. Thats a lot for that little engine.

I'd be happy with that. When you rebuild use some hardcore oil, like mobil 1 or something synthetic kawasaki brand.

 

yeah, the 300 is actually 292cc on the Kawasaki OEM version at least. The 300 and 250 do not use the same piston pin, but obviously the pin diameter is the same.

 

Jason the FrankenMarzen came out good............Reall good. Been using shell Ultra synthetic since ever since.

Note to all I was in contact with Bill Blue and even with the crack the original cyl can resleaved so I think it will end up a BB331 for the GF's I just have to iron out some details like whether I can keep the same piston and rering or is his piston different than KK.

Going to work on putting up photos now.