1. Husqvarna Motorcycles Made In Sweden - About 1988 and older

cylinder swap?

Discussion in 'Vintage/Left Kickers' started by disonny, Jan 31, 2016.

  1. disonny Husqvarna
    AA Class

    Location:
    upstate ny
    Husqvarna Motorcycle:
    73 360 wr/rt, 75 wr250 78 cr250,
    Other Motorcycles:
    83 wr250, 84 wr400
    I just picked up a 75 wr250. It needs a rod and a cylinder. I was wondering if a CR crank will work in this motor? I think they have different size crank ends. would I just need a CR flywheel to make it work?
    Also, will a CR top end work on it too?
  2. Jeff B Husqvarna
    AA Class

    Husqvarna Motorcycle:
    1975wr 250
    Other Motorcycles:
    yamaha ty 175,
    I have a 75 wr 250 also. This, for the most part it is a 1974 CR 250 mag. You can use a CR crank, but if I recall the crank ends might be different to accept different ignitions. This would be a good time to install a MZB, so it wont matter which crank end you have . 1975 wiring is too old to be reliable. Mine failed, so MZB time. The pistons are the same, as is the rod. I have been told the cylinder is the same. I don't know for sure, but it will bolt on. I have a 74 CR cylinder done by Tom Boyd waiting to put on mine. Your 75 head is radial and bolts down with 4 studs and two bolt holes. The 74 CR cylinder has four studs only and a non radial head. It will work fine. A lot of people put the 75 head on the 74 cylinder and don't worry about the the bolt holes. Your 75 WR is a great find and will be a fantastic vintage racer. Any other , let me know. Good luck and have fun. Jeff
  3. disonny Husqvarna
    AA Class

    Location:
    upstate ny
    Husqvarna Motorcycle:
    73 360 wr/rt, 75 wr250 78 cr250,
    Other Motorcycles:
    83 wr250, 84 wr400
    I actually have a spare PVL that fits the case. So that will go on it but I will have to do a new rod if I keep the wr crank. It came with no top end so I'm trying to figure out what top end I can use ( and also find). I saw a CR crank on ebay but I wasn't sure it would fit.
  4. Jeff B Husqvarna
    AA Class

    Husqvarna Motorcycle:
    1975wr 250
    Other Motorcycles:
    yamaha ty 175,
    I looked on Halls Husqvarna site, they have parts listings. The part number is the same for the cylinder...74, 75, 76 CR and WR 250. I think the crank end is only different because of different ignitions. They do not show rods. I believe they are the same. As I said before the 75 WR 250 is basically a 74 CR 250 mag. 75 WR...6 speed, heavier fly wheel with lighting coil (points...you don't want points), high breather air box..(it is crap), I think the exhaust is different...(you can buy a LOT BETTER) small front hub, (I am using the 400 cross front wheel. same rear brakes as the rear.). The 74 CR 250...5 speed, motosplat, lighter fly wheel I think, round air cleaner cover. 75 WR and 74 CR share... frame, swing arm, suspension front and rear, same plastic and seat. WR bigger gas tank.

    Attached Files:

  5. Jeff B Husqvarna
    AA Class

    Husqvarna Motorcycle:
    1975wr 250
    Other Motorcycles:
    yamaha ty 175,
    Note....the 74 and 75 WR 250 engines are totally different. I let that slip. The 74 CR and 75 WR cylinders are the same. The 74, 75, and 76 CR is the same as the 75 and 76 WR. Reed valve. Jeff
  6. disonny Husqvarna
    AA Class

    Location:
    upstate ny
    Husqvarna Motorcycle:
    73 360 wr/rt, 75 wr250 78 cr250,
    Other Motorcycles:
    83 wr250, 84 wr400
    Thanks Jeff. That's a lot of valuable info. Now I can start getting some parts and get going on this bike. That's an awesome bike you have. What pipe is on it? Mine came with the stock WR pipe. I have the same air box but it's discolored. I was going to change the front hub too. Those brakes are small. I think I may have another hub with bigger brakes. I have a DLS hub but there has to be a lug on the fork for the brake stay arm. I would stick that on if I could.
  7. Jeff B Husqvarna
    AA Class

    Husqvarna Motorcycle:
    1975wr 250
    Other Motorcycles:
    yamaha ty 175,
    I t Is a Proform pipe. I had to move the petcock because it hit the pipe. I am using a DG on the end of it. Runs much better than stock. I use a CR tank rather than the WR. You don't have to move the petcock with a CR tank. Never ran out of gas. The stock bike turns like a well prepped Harley. Great for the desert but not so good on the trails we ride today. I guess trails back in 1975 were more open. Stock shocks are 12 inches...almost. I put 13.5 Progressives on the back. I have heard people say "If you have only 4 inches of travel, it better be good travel"....Well...there isn't a whole lot of difference between 4 inches of good vs. 4 inches of bad travel. Eight inches of bad vs eight inches of good is a big difference. So I went for the Progressives vs Works. I also slid the forks up an inch. The bike handles great. The air cleaner cover came from DC plastics. It is for the for the 74 WR 250. With trimming it works. I used Huskyjunk for advise and parts source. He specializes in the 74 CR 250 Mag. I used the MZB because it makes better fire at low RPM. The kick ratios is very slow. One slow kick nets almost 3 turns. Unlike an Ossa which one slow kicks gets maybe 4 or 5 turns of the crank. Also MZB has a lighting coil. BTW my bike is not a garage queen. Jeff
  8. disonny Husqvarna
    AA Class

    Location:
    upstate ny
    Husqvarna Motorcycle:
    73 360 wr/rt, 75 wr250 78 cr250,
    Other Motorcycles:
    83 wr250, 84 wr400
    Is the pipe specific for the 75? I have a couple extra pipes from other bikes. I'll try them for fit when I get the motor together. I have a set of fox shocks I plan to use. I think they are 13 or 13 1/2. I was going to try and fit a 76 seat since the stock seat doesn't meet the tank real close. My bike will be a rider too. No matter what 4 inches isn't good. What triple clamps do you have? That's a 76 front fender right? How does it mount?
  9. Jeff B Husqvarna
    AA Class

    Husqvarna Motorcycle:
    1975wr 250
    Other Motorcycles:
    yamaha ty 175,
    The pipe is for the 74 250 Mag. Anything for a 74 mag will bolt on. My Proform hit the petcock on the WR tank. So a welder friend of mine cut out the bung, patched the hole and welded it in a place that worked. The CR tank should not give that problem. The Proform is lighter, makes more and better power, and the kick starter is easier to get your foot in position. The can that comes with the Proform is too loud, that is why I went to the DG can. My triple clamps are stock. The front fender is a later front fender. I folded a small piece of stainless steel and drilled holes to mount it under the bottom clamp, using the holes where the original fender is mounted. Then, drilled four holes in the fender with matching holes I drilled in the plate. The fender is wider. One thing about the WR, it is geared VERY tall. Think desert racing. I am using 10 x 56 final drive. You can't tell in the photos but the rear brake arm on my bike has been extended about a half inch. The rear brake cam that spreads the shoes apart is not on a spline. Now, new shoes for the rear has a thinner liner. So you can't get the best adjustment. Two things can be done. Get the shoes relined to proper thickness and you will be good. What I did was machine a new brake cam thicker so that I have better position of the brake arm when I put on new shoes. I got my brakes from Huskyjunk. I have also used Vintage Husky, and Forest Stahl for parts. When you work on the forks , do not drain the oil from the bottom screws. The sliders are fragile and easy to strip. If you are working on the forks, drain them from the top. The 75 WR is almost a cheater it is so good, but it legal. Mine starts first or second kick cold. Hold the kill button and kick about four times, then kick it. Jeff
  10. Kartwheel68 Husqvarna
    Pro Class

    Location:
    Newnan, Georgia
    Husqvarna Motorcycle:
    82 125XC, 250XC, 430XC, 430WR, 250CR
    Other Motorcycles:
    83 175WR , 76 250WR, 74 250 Mag
    The PVL will not fit the WR crank, the crank end is too large. The small PVL rotor can not be machined enough to fit that crank end which is why only the MZB is available for the bikes with the big crank end.

    Also, the 75 250WR is NOT legal for AHRMA Sportsman vintage clsss. Many people mistakenly assume it is but it is not.
  11. disonny Husqvarna
    AA Class

    Location:
    upstate ny
    Husqvarna Motorcycle:
    73 360 wr/rt, 75 wr250 78 cr250,
    Other Motorcycles:
    83 wr250, 84 wr400
    Kartwheel, I just read the rules for AHRMA and the 75 is listed as like design for sportsman class. It's more about suspension than anything else in those years. HUsky's first lay down shock bikes were 76. They would run in historic. My PVL is off my 76 wr 360. I will have to check the shaft size. The wr was the large crank end. I can always buy another flywheel for the application.
  12. Kartwheel68 Husqvarna
    Pro Class

    Location:
    Newnan, Georgia
    Husqvarna Motorcycle:
    82 125XC, 250XC, 430XC, 430WR, 250CR
    Other Motorcycles:
    83 175WR , 76 250WR, 74 250 Mag
    It is poorly worded, the 75 is not legal. The same notation says the 75 CR is legal and it is not because that was the first year of the lay down shocks, not 76.. It also says 75 YZs are legal and they are not. The reason why the 75 250WR is not legal is the 6 speed transmission, which makes it not a like design. Because of the very poorly written rule many people think the 75 250WR is legal, but it is not legal. It is highly unlikely you will ever be protested but if you were you would lose the protest.
  13. disonny Husqvarna
    AA Class

    Location:
    upstate ny
    Husqvarna Motorcycle:
    73 360 wr/rt, 75 wr250 78 cr250,
    Other Motorcycles:
    83 wr250, 84 wr400
    I guess it is poorly worded. I never thought the trans would make a difference. I didn't know the 75 was first year lay down shocks. Mine is like the 74 suspension. I'm going with what I have. I'm not sure I would do good enough to be protested anywho. Thanks for shedding light on it.
  14. Kartwheel68 Husqvarna
    Pro Class

    Location:
    Newnan, Georgia
    Husqvarna Motorcycle:
    82 125XC, 250XC, 430XC, 430WR, 250CR
    Other Motorcycles:
    83 175WR , 76 250WR, 74 250 Mag
    The WR got the lay down shocks in 76 but the CR got it in 75,hence the Mikkola replica name. The 75 YZ was the first year of the monoshock so you know it can't be Sportsman legal. I don't think the 6 speed transmission is a big deal but AHRMA does.
  15. disonny Husqvarna
    AA Class

    Location:
    upstate ny
    Husqvarna Motorcycle:
    73 360 wr/rt, 75 wr250 78 cr250,
    Other Motorcycles:
    83 wr250, 84 wr400
    I had a 76 WR. I just sold it a few months ago. I have a 78 cr250 that I like a lot. I ride that most of the time. I was looking to improve a little on my 73 wr/rt 360 so I picked up this 75.
    Bill502 likes this.
  16. Jeff B Husqvarna
    AA Class

    Husqvarna Motorcycle:
    1975wr 250
    Other Motorcycles:
    yamaha ty 175,
    I wanted to find out for sure. I have seen this come up before. So I called one of the Cross Country leaders. The 75 Husky WR 250 is vintage legal. It is more about the suspension. As for the 75 CR. Maybe they just aren't aware. I did not check on anything other than the 75 WR.
  17. disonny Husqvarna
    AA Class

    Location:
    upstate ny
    Husqvarna Motorcycle:
    73 360 wr/rt, 75 wr250 78 cr250,
    Other Motorcycles:
    83 wr250, 84 wr400
    Will a CR crank work in the wr cases?
  18. Jeff B Husqvarna
    AA Class

    Husqvarna Motorcycle:
    1975wr 250
    Other Motorcycles:
    yamaha ty 175,
    My understanding. The cases are the same as the 74 CR250. I believe the cranks are the same except the stub on the right side. Ignition side. Who do you have lined-up to build the crank? . Jeff
  19. Kartwheel68 Husqvarna
    Pro Class

    Location:
    Newnan, Georgia
    Husqvarna Motorcycle:
    82 125XC, 250XC, 430XC, 430WR, 250CR
    Other Motorcycles:
    83 175WR , 76 250WR, 74 250 Mag
    The only difference in the cranks is the magneto side snout.

    On the '75 WR, I believe you when you say you were told that it is legal, but putting the 6 speed transmission in the '74 Mag is not legal for Sportsman, it must remain a 5 speed. I'm not sure how a bike that came stock with that transmission can be legal. About 6-7 years ago there was even a submission for a rule change to allow the '75 WR in Sportsman and it was rejected by the rules committee.
  20. Jeff B Husqvarna
    AA Class

    Husqvarna Motorcycle:
    1975wr 250
    Other Motorcycles:
    yamaha ty 175,
    Kartwheel68 I hope I did not offend you. I have seen this come up before and simply called to find out. This was from their mouth not the book. I looked at the rule book first and the 75 CR and WR are listed. I agree this should be illegal for the CR....lay down shocks, they most likely don't know. But the gear box is not listed. The spirit of vintage is using the suspension from 1974 according to the rule book. If it bothers you that I checked, I am very sorry. I have already gone through the problems of putting together my WR and simply offering help. I guess that the rules committee felt that there was not an advantage to the 1975 WR.