• Husqvarna Motorcycles Made In Sweden - About 1988 and older

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    As you all know, Coffee (Dean) passed away a couple of years ago. I am Dean's ex-wife's husband and happen to have spent my career in tech. Over the years, I occasionally helped Dean with various tech issues.

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'83 Husqvarna 250cr cylinder

Bigbill

Bigbill

Husqvarna
Pro Class
The last bike I built was a '83 250cr. The cr cylinder had two extra transfer ports on the base surface that ran verticle to in front of the reeds. This allowed more of the pressurized crankcase fuel mix to be forced into the cylinder when the piston is on its down stroke. These are two cutouts on the intake side where the base gasket is.

I'm posting this as a food for thought. Some don't know what they have.
 
I have the very same cylinder from the factory on my 84 250WR. It is very simple to add those ports as the web they go through is thin wall and the port goes down behind the liner on the 82 250WR cylinders I have . That is one of my 250 projects as I am not likely to be happy with a pipey 250 after spending more time on big bores
 
Your right but if one wants to improve a 250 those two extra transfer ports help. I admit once I rode the 390cr the 250 stayed parked. My weight loss program started with the 390. My '84 250wr ac does run a lot better than my '83 250wr's did probably because of those two extra transfer ports.
 
You say the transfer ports help the power. My 83 wr250 is weak on the lower end. Will those ports help?
 
It's the cr ported cylinder. Yes two totally different engines the wr std and the wr with the cr porting. Don't expect the hit like having a power valve but it's a lot more over the standard wr250.
 
Dale
The transfer port cylinders give more top but make the motor more of a MX power or at minimum more GNCC track power. in my opinion, the 82 WR is best smooth woods power cylinder for an AC primary kick woods weapon.
 
I'm not so sure about this. I think the 84 WR might have a smaller Exhaust Port. I recently re sleeved my 84 WR and I made the modifications as per the Husqvarna service bulletin intended for the 83 CR. The one where they use a WR liner and then port it back to CR specs but leave the smaller Exhaust port. My liner Cracked around the Transfers and was a complete failure so all I had was broken pieces to look at. But near as I could tell the Exhaust port was the same size as the specs in the service bulletin. So it looks as though the 84 WR might of come with the service bulletin all ready done. There is another Service Bulletin for the 84 CR and it is showing the Transfers being 49.5 mm from the top. There is no mention if they are raising them to 49.5 or if this is the way a CR comes. One way or another I had to raise mine to get to 49.5. Once again I was using broken pieces laying on my work bench to figure out the original porting. If anybody out there has an extra 84 WR Cylinder I'm looking for one.
 
The cylinder porting is not the same. After much research and looking at bulletins. The 84wr cylinder porting has 1 mm lower exhaust port. The sleeve produced by LA sleeve for the 84 250WR has the lower port. (Do not raise to match the CRs exhaust port. This will make more narrow.)

The boysen ports down behind the sleeve does and should add to both the lower and upper end. But because it gives more fuel volume and rush it too can give a pippey feel.

Based on the March Bulletin Husky also changes the exhaust port to a new three port style.
The bulletin has you cut even with new lower exhaustt port two additional tunnel ports to exhaust the gas. But these are cut lower not the higher 83 CR height. Tunnels really is just a drilled hole.

Question was Husky updating the 250 CRs in possible later model production runs and them shipped them ??? This is after March 83. Found no Evidence to support that so far.

Per Husky engine builders the 84 250wr was a one of a kind produced cylinder. That has as standard the lower exhaust port. The added tunnel exhaust ports. The added Boysen ports behind the sleeve down into the transfers.

But I do believe after the Bulletin we may find hundreds of ( how many survived ??) 250 owners who could have modified their cylinders. If its the higher exhaust its an 83
 
Please note the tests on the 84 250WR. Basically saying more power but still peaky.

Quote from engines builders seminar at Barber vintage event,

Horsepower is not good measure. 200 HP in narrow rpm range you go nowhere. You need
torque over a wide rpm range as possible. Period.
 
I rode an a/c before buying the l/c and was pleasantly surprised at how much better the l/c motor was. I found the a/c to start off with a low end run that suddenly stopped mid range before working up to short peaky squirt if revved. was hard to ride as I was always in the flat midrange area.
 
GaryM said:
Horsepower is not good measure. 200 HP in narrow rpm range you go nowhere. You need
torque over a wide rpm range as possible. Period.
Click to expand...

Exactly. This correlates with what I always tell people about putting bigger carburetors on engines. You MIGHT make slightly more peak HP, but probably not, and you will for sure kill the low end. That is the majic of the Husky 390/430 and why it is so good, its usable spread of HP must be wider than any other two stroke.
 
I ended up Porting my Cylinder to the 84 CR Bulletin specs. I race vintage with the bike and its only 5 laps. I would probably be much faster on my 82 XC Cylinder but I'm racing Vintage for the fun of it. And a high reeving fan the Clutch and lots of shifting makes for a fun ride. Well for 5 laps anyway. And if the Track has a long straight I can catch and pass....
 
85 WR is twin shock and same basic porting..... do believe the LC up and out pipe has alot to do with the change in power from the AC bikes. Same baci motor aside from the LC. the criss cross back and over AC pipe has less pipe tuning ability due to it having some design limitations. only thing I can think of whty the LC motors are more usable power than the AC ones
 
interesting as the power characteristics are quite different with the lc have a broad smooth almost linear power curve c/w the a/c. the lc always did something when you opened the tap.
 
As far as I know the early 1984 250 WR's were Air Cooled Twin Shocks. And mid Year they became Liquid Cooled Single Shock. So as far as I know there were no AC Twin Shock 85's.
 
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