Quick question, I'm looking for a cylinder to use for a big bore. I can get a 248 stock cylinder, or a 292cc KLX-300 cylinder. Reckon I'd be better off using the larger one as a base?

 

Unless you find someone who's done the exact same thing on the 300 cylinder, you'd probably be better off e-mailing Bill or whoever your source will be to insure the 300 cylinder will work. My guess is that it won't matter. I'll bet the water jacket design is identical on both cylinders. I'm sure Bill knows without question if there's a difference or advantage.

 

I'm about to have a 2009 KLX250 cylinder available, if you're in need of one. It has less than 1000 miles on it.

 

Yes I'll do that. The reason I ask is that Kustomkraft offer a 330 kit based on a 300 cylinder which can be bored, or sleeved.
The kit based on the 250 cylinder is sleeved only. This suggests more "meat" on the the 300 cylinder.
Not sure if it'll make a difference or not.

Edit: 250 based cylinder is a new unit, I assume sleeved?

 

I'm not totally clear on your statement here, but I'll throw this out. Be aware that KK also offers "plated" cylinders which are different from liner/sleeved style cylinders. Maybe you already know this, and I just missed what you were saying here. A plated cylinder has no sleeve. The material that lines the cylinder is sprayed or "blown" by a high tech electrical process right onto the aluminum. But yeah...the more I think about it, the more possible it seems that the two cylinders might have some subtle differences. However, I did an OEM 300 cylinder on my '06 KLX250, and while I had the two cylinders sitting side-by-side, I did various visual comparisons and couldn't detect any notable differences beside the bores. My X-ray vision wasn't working too well that day, so I can't swear as to the sizing of the internal water jackets.

Please let us know what you find.

 

I considered the cost of the KustomKraft Nikasil, and the warranty on it. Higher cost than a sleeve, and one year on the Nikasil as opposed to 5 years on the sleeve.

I'm going Bill Blue Sleeve...

 

Yes I know the difference between sleeving and plating, and there are many opinions regarding which is better.

My comment was about this:
http://kustom-kraft.com/KAWASAKIKITS.html

I read this as the 330 kit (using a 300 cylinder) can either use sleeving OR plating. My personal choice would be sleeving.

Now, considering boring and plating to 330 is possible with the 300 jug, but not the 250 jug, it means that the cylinder wall is thicker on the 300, or at least larger outer diameter. So, if a 330 sleeve is fitted, more of the original cylinder material remains.
Probably doesn't make a lot of difference, but just wondered.
Makes sense?

 

Yeah, reading the "More Details" section on the 250, it does sound like there's a notable difference between the two cylinders. I see what you mean. However, the "more meat" issue in the 300 cylinder probably does not really translate into any performance or strength issue in a sleeve/liner system. The only benefit to the 300 cylinder is its ability to be coated instead of sleeved. The external size of the 250 and 300 cylinders are the same. If anything the info on the KK site might suggest to me that the water jackets in the 300 cylinder may be smaller to accomate the additional material. Even this, however, probably does not guarantee any additional cooling benefit to the 250 cylinder...at least as it applies to increased water jacket size or cooling improvement. At a certain point, a well designed cooling system is more than adequate, and the KLX250/300 systems seem to fill that bill. I have a Vapor instrument panel with an inline temp sensor and going to the 300 cylinder didn't produce any change in temp swings compared to the 250.

Both the 250 and 300 OEM cylinders are coated. I would think that the Kaw engineers designed both cylinders with about the same amount of material between the bore and the water jacket to maintain proper heat transfer/dissipation between the water jackets and piston bore. Having a notable difference in material thickness in the cylinder wall would seem to affect cooling/heat transfer, so I just have to guess that both cylinders are pretty similar in this area. Since the 300 has a bigger bore, getting to 330cc is possible with the material present. Obviously the 250 cylinder wouldn't have the necessary material for a 330cc bore assuming that the material between the bore and water jackets is about the same as the 300 cylinder. In fact it's possible that the 330cc plated 300 cyclinder might be getting a bit thin, but what's adequate and what's not may only be known by an engineer. Apparently using a sleeved/liner system doesn't require that much material left in the bore area, because the liner itself is obviously one stout chunk of steel...especially when compared to aluminum...and apparently having the liner extend into the water jacket isn't an issue in regards to durability or reliability.

One other issue is that portion of the cylinder or liner that extends into the engine case. The 250 cylinder may just have less material at this point to prohibit a 330cc overbore with plating, so the sleeve may be the only solution. I really think that this part of the cylinder may be the factor that dictates the biggest difference between the 300 and 250 cylinder.

Of course we're doing a bit of speculation here, and one would have to wonder if you'll even get a straight answer from the suppliers of these big bore kits as they have a vested interest in selling a product...and I'm not saying they wouldn't necessarily shoot straight. When it's all boiled down, I seriously doubt there's a major issue with using any of these kits. How much heartburn do we hear from any users of any of these kits concerning failures, problems, or cooling issues? I can't think of or recall any. We may just be overthinking the whole deal, but it's at least it's somewhat interest thinking as it applies to engine and cylinder design.