nicasil vs steel concerns about hot running are more an issue in twostroke motors that see flame on the piston twice as often. A fourstroke with it's wasted stroke gives twice as much time for the heat to transfer. So I wouldn't be concerned about over heated motors. The big concern with a sleeve is it stays put, doesn't drop as the host cylinder heats up and expands. This can fall back to how well it was fit, and how well the host cylinder has the ability to hold it especially when hot). If it does move the problem usually shows up in a blown head gasket.

Another thing one might consider is piston availability. At one bore size I might be able to find pistons (and gaskets) from 4 or 5 manufactures, or maybe at another size they were one off builds that may be hard to find in the future. Been burned on this before.

 

Does anyone have a pic of a jug of each of the sizes? I see the 351 sleeve is into the water jacket. It's just me, but I don't like that. What's the 340 look like?

 

I believe even the 331 is even into the water jackets.

 

That is what I like about the 351, water is in direct contact with the steel liner, I have about 2000 hard miles on mine so far and it works great. would do again without question.

 

OK, here's something I've never really thought of or researched. In single or multi cylinder blocks, are the steel liner designs in contact with the water jackets as a common design element or not? I'm thinking Bill Blue's setup isn't an oddity, but to be honest I've never considered it before or studied cylinder liners and water jackets when I've had engines apart. Never really worried about it. Water jackets in engine cylinder heads were usually more of a concern on automotive engines, but you had to have those magnafluxed or such, because you usually couldn't see cracks with the naked eye. Anyone know or care to comment on the issue of steel liners being in direct contact with water jackets as a common or uncommon design in general watercooled engine design?

 

Liners or sleeves are common in diesels. You don't bore them out, just replace the piston and sleeve. always back to stock.

Wet sleeves have Orings on them and are tapped into the block and the head gasket or fire rings hold the liner in. Most common.

Old antifreeze can eat through the liner on a diesel. That is why they have a water filter with an anode in it like on a boat.

Dry sleeves are put in dry ice or pressed in to a dry cylinder. To remove dry sleeves, I weld a small bead or two in them. they shrink and fall out.



I have been reading this thread trying to decide my self If I want to go big or go home. 95% of my riding is on the street. I have heard the fan come on once when I let it idle till it did. Cooling shouldn't be a problem.

The bike runs really well the way it is. Dyno Jet kit and KDX snorkel. Lots of torque. No it won't lift the front wheel. I still get 62 mpg every tank.

It looks like gold valves for the front come first. Those screws do nothing that I can see.

David

 

David, you won't regret revalving the fork...or the rear for that matter. But you're right, the front is horrid with the stock piston. You know...I almost forgot about the o-ring/wet liner design. I haven't owned anything with that design that I've been into.

 

I'm going to GUESS and say it's the same sleeve, the 351 is just bored out a bit more than the 340. Just my GUESS.

 

I think the sleeve has a bigger OD and the blue guy has to bore the aluminum cylinder before installing the sleeve. This puts more of the sleeve in the water, but could make for less water flow. I don't know for sure, but I did look at the pics on his website. I keep thinking this 250 would be one hell of bike if it was a 350.

It would sort of defeat the purpose of buying the bike in the first place. I have a fuel injected BMW 1100. I bought this bike as a commuter and general zoom around bike. Its perfect. I must zoom around quite a bit because last night I went into town for gas (still 62 mpg) and the local cops stopped and waited till I filled up then followed me around so I went home. Living proof its already big enough to get me into trouble. Its a total hoot to ride. Every time I take it out its an adventure.

David

 

People might be surprised how much extra restriction that it takes to decrease flow through an increasingly small lumen. That tiny amount of encroachment into the water jacket probably doesn't decrease the total coolant flow at all...it might not even result in an increase in the driving pressure that it takes to move the coolant at it's regular flow rate.

As long as there are no leaks between the coolant and oil passageways, it should operate just fine...I guess that's a stupid comment....at least a "no duh!" comment. What I should say is that I don't see a problem cooling a 351 cc chamber with this stock cooling system.