82 cr250 cylinder

I just purchased a 82 cr250 cylinder. The wrist pin backed out and grooved the wall. It needs a sleeve.

My point is I ordered a sleeve from Andy at HVA. It says it has two extra exhaust ports. I’m waiting to get it I just ordered it today. Does anyone know anything about this cylinder with the extra two exhaust ports? My cylinder has the two extra intake ports in the reed box. Two more exhaust ports sounds interesting?

im sure andy could tell you the specifics about it

I believe in 83 Husky started using winglet exhaust ports.All the jap bikes had them,but they where power valve activated. In order to take advantage of them you will have to grind port tunnels into the exhaust port.

Bill, those two extra exhaust ports are what make the 83CR and 84WR cylinders different from the earlier ones. We've already talked about this like a hundred times.

I read to use this sleeve in a cr cylinder the ports have to be made to match plus the two extra exhaust ports need to be added. Sorry if I bore anyone.

Well Andy at HVA has shipped my sleeve already. My hats off to Andy. His fast service. The cr250 cylinder is on its way too. I just ordered all the new tranny bearings too. I have a bottom end waiting here.

The Liner with the 2 small extra exhaust sub-ports is the upgrade part.

If you don't want to use them, you don't have to dremel the material from the cylinder if you don't want to, but worth the effort.

Also, depending on what liner you have, you may also decide to open up the main exhaust port - depending on what you find when you press out the old one...

Heat the cylinder to press in or out and be careful to use something flat against the whole of the top of the liner on the way in - or you may break it.

Make sure you align the liner rotationally as you will only get one go

Hope this helps,

Andy.

Thanks Andy. I purchased it for a 82 cylinder liner I purchased from eBay. The wrist pin backed out and grooved the wall. I wanted the two extra ports. It’s probably the most power out of a Cr250 ac.
Thanks Andy for your fast shipping. I’ll be back soon.

I had a wrist pin move into the cylinder wall when I missed a circlip on my father's MR 250 . First my father chewed me out. He had my tear down the top end to inspect the damage.I showed him how deep the drag was so he told me to make sure I had both circlips in and reassemble. After a few days of riding he came to me and told me that groove in the cylinder gave a a stronger mid range. During the time period (70's), there was experimentation with micro porting. I inadvertently created microporting by omitting a circlip on the safer side of the cylinder wall.

The groove is another transfer port? I purchased this cylinder from eBay cheap. At the same time I ordered the 84 a.c. sleeve from HVA with the two extra exhaust ports. Probably it might be a tad louder. Have to repack the silencer.

Not necessarily but it might not hurt to try it, Depends on what the groove intersects.

The sleeve from ANDY AT HVA showed up today. The two extra exhaust ports are over the side transfer ports. Neat the exhaust has more flow. I’m going to have the sleeve installed and ported to a cr cylinder. I gather this is a 84/250 wr sleeve with the extra two exhaust ports. This is why my ‘84/250wr is so pipey. Another task for Ken OConner racing. I need to draw up prints on what I need done. So many things that can be done to increase the flow. This engine also has the crank that Ken rebuilt too.

How much improvement is the vee force reeds over boyzeen reeds. The UFO is going in the carb too.

This is a ‘83/cr250.

the big problem...is the husky primary kick engine is limited in port size by having studs run the whole way through the jug..the transfer ports are tiny. theres no working around that.

I just want this 250 to be all it can be.

You want it to grenade itself? It does not need top end, it needs the wider powerband that was only achieved with power valves.

I figure this is bench racing or close to it. Be all it can be for what rider and what terrain?

food for thought
How about stuffing the crank as they call it in the chainsaw world. I think around 2004 the Husqvarna 250 bikes got magnesium inserts to fill the crank, probably the 125 within a few years of that perhaps earlier. Then experiment with spacing the reed block back which may or may not get more of the characteristics you desire. Then the pipe, If one was to come out farther before making that bend I suspect gains are to be had there if you can avoid hitting the wheel.

How about the piston, If it is like the 430 and 500 the distance from the ring to the crown changed with the change to liquid cooling (at least it appears this correlates from what I have disassembled). Can you get pistons for air cooled? The aftermarket pistons and most of the NOS stuff for the 430 and 500 have the ring the distance from crown at the liquid cooled spec.

I have posted it before, the Yamaha Rd400 twin (350 before that and I think the banshee quad) have the through studs like Husky and folks have experimented making them all they can be. There must be a wealth of experience in that regard.

There is a lot more room inside the stud circle on the 250 than the 86mm bore versions. The fact the cylinder is air cooled may be more of a limiting factor than the port area for high power output on a continuous basis.

There is a way around that, just like it sounds a passage that goes around. I do not know the evolution of the 250 but by 1988 the reed cage connects to the transfer ports.

Cleaning and matching the ports and stuffing the balance holes in the crank in my 1970 Yamaha CTI 175 yielded about 3 hp over the entire powerband. Kept it's lowend and got a nicer midrange surge. Just remember the balance between performance and reliability.

Power valves give more bottom end but they take away more from the top end to put it on the bottom.

Fran hit the nail right on the head ! BENCH RACING .