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Old 10-18-2014, 11:43 AM   #1
Tinker1980 OP
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1977 Husqvarna - Time to do some work.

For the past 12 years or so, I've had this somewhat worse for wear '77 Husqvarna WR250 "Cross Country". Great sentimental value to this machine.

It's always ran, and for quite a while ran pretty decent. But recently, I've been noticing low compression, lack of power, harder to start, so on and so forth. Along with the lack of brakes, bad suspension, etc etc etc.

So it's time to fix up my old bike. Shop says the cylinder hasn't been bored before, and I should go to the first oversize due to a scratch. I'm thinking wiseco has the piston kit I need. What else should I look at doing, while I have the top end off? Anything I should pay special attention to?

Lastly, when I pulled the head off, there didn't seem to be an o-ring or a head gasket. Is this normal, or is this machine so old and decrepit that I just didn't notice the head gasket?











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Old 10-19-2014, 08:37 AM   #2
Ever Onward
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If you not splitting the cases, then your kinda limited to what you can see with the top end off......IE , rod wobble and end play. At least measure your rod play so you have a basic idea of crank / rod wear .

I personally would try to source a OEM type piston.......I dont know if OEM was cast or forged. The Wiseco's are forged, and expand differently when heated than a cast piston. Whichever you go with, make sure the macinist is really talanted with a boring bar, hone and has the finess to chamfer ALL those ports !

Thats a crazy amount of porting in that jug. Lotsa labor to do a rebore correctly there.

Since Im not a Husky guy, gotta wonder if those are simple steel sleeve, or some kind of plated liner ?
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Old 10-19-2014, 01:05 PM   #3
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I don't know about the newer Husky motorcycles but back in the era of your bike the stock pistons are forged. They didn't use a head gasket . The cylinder and head are lapped together with rubbing compound, the same way old aircooled VW heads were sealed to the cylinder.
I would look into replacing the crank seals if they can be replaced without splitting the cases, if aren't splitting the cases.
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Old 10-19-2014, 04:55 PM   #4
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I'm going to hit up my favorite machine shop about the boring job. A bit of work with calipers confirms that it hasn't been bored. I've only pulled apart a couple of two strokes, and never have I seen this many ports in the cylinder.

Fortunately I have lapping compound leftover from a recent valve job. I will wait until I have the jug back from machining before I lap it to the head.

Still trying to decide if I want to split the cases. Bearings all seem ok, and I think I can replace the seals with the engine in situ. Assuming I can find said seals.

I'm thinking about replacing the bing carb with a mikuni... anyone know which jets I should get?
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Old 10-19-2014, 05:09 PM   #5
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If the bottom end was fine before I would probably leave and just replace crank seals..but that's me.

Sudco can probably sell you one jetted for your bike. Probably wouldn't be a bad idea to get a few richer and leaner from them as well
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Old 10-19-2014, 06:00 PM   #6
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I liked the Bing carbs back in the old days.
But probably harder to find parts now
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Old 10-19-2014, 10:12 PM   #7
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I liked the Bing carbs back in the old days.
But probably harder to find parts now

I'm sure it was a great carb - back in the 70's. Now it's just a leaking, dripping chunk of aluminum. IF I could find the pieces for it (float, float needle, seat, etc) I'd be willing to use it - simply because it works. I think the next year for this particular bike (1978) they went to a mikuni carb anyway.
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Old 10-21-2014, 03:39 PM   #8
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Bing carbs

Quote:
Originally Posted by Tinker1980 View Post
I'm sure it was a great carb - back in the 70's. Now it's just a leaking, dripping chunk of aluminum. IF I could find the pieces for it (float, float needle, seat, etc) I'd be willing to use it - simply because it works. I think the next year for this particular bike (1978) they went to a mikuni carb anyway.
Do your research, Bing carbs and all their parts are stii being manufactured here in the states. Their current use includes ultralight aircraft so you know that they can be reliable and rebuildable. John at Vintage Husky prefers their use for his restorations. Wonder why?
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Old 12-17-2014, 04:39 AM   #9
rick danger
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I put a Lectron flat slide on my '77 390 cr back in the day. Made a huge difference in starting. I recently put a new float bowl on it. They are clear plastic. I was surprised to see they were still available
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Old 12-17-2014, 08:10 AM   #10
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I hope you didn't get dirt into the motor, kinda nasty to be working on.
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Old 12-17-2014, 12:54 PM   #11
Scootern29
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To replace the wet side seal you have to split the center cases.
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Old 12-18-2014, 10:09 AM   #12
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I thought the machine shop would need the piston before doing any boring ???
(To insure the proper clearances )
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Old Yesterday, 03:26 PM   #13
slideways
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I would send it to Eric Gore not only will he bore it for you and match up a piston he will clean the porting and sort the head.

http://www.eric-gorr.com
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Old Yesterday, 03:40 PM   #14
jm-2008
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[QUOTE=daviethebiker;25318058]I don't know about the newer Husky motorcycles but back in the era of your bike the stock pistons are forged. They didn't use a head gasket . The cylinder and head are lapped together with rubbing compound, the same way old aircooled VW heads were sealed to the cylinder.
I would look into replacing the crank seals if they can be replaced without splitting the cases, if aren't splitting the cases

+1
Been a while since I had one apart but if memory is correct they used Mahle pistons
Wiseco were around then and often used for their larger than stock sizes ie +1 and 1.5mm oversize
Pull the magneto cover off and check the crank bearings for slack (usually a sign of dust getting past the airfilter and definately replace seals on both sides.
The magneto side seal leaking will make them run lean and erratic, the primary drive side leaking will foul plugs.
Bing carbs were prone to wearing out slides, needle jets and needles (like the Spanish AMAL carbs) were not good in water as it came in through the tickler button and generally sucked for long term consistant performance.
I'd go with a Mikuni or Lectron.

Almost forgot - they don't need a lot of lapping of the head, ensure the area has cleaned up wipe clean and reassemble, they don't usually leak

Great bike wish I still had my 450 Desert Master

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