• Husqvarna Motorcycles Made In Sweden - About 1988 and older

  • Hi everyone,

    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.

    When he passed, I worked with his kids to gather the necessary credentials to keep this site running. Since then (and for however long they worked with Coffee), Woodschick and Dirtdame have been maintaining the site and covering the costs. Without their hard work and financial support, CafeHusky would have been lost.

    Over the past couple of weeks, I’ve been working to migrate the site to a free cloud compute instance so that Woodschick and Dirtdame no longer have to fund it. At the same time, I’ve updated the site to a current version of XenForo (the discussion software it runs on). The previous version was outdated and no longer supported.

    Unfortunately, the new software version doesn’t support importing the old site’s styles, so for now, you’ll see the XenForo default style. This may change over time.

    Coffee didn’t document the work he did on the site, so I’ve been digging through the old setup to understand how everything was running. There may still be things I’ve missed. One known issue is that email functionality is not yet working on the new site, but I hope to resolve this over time.

    Thanks for your patience and support!

Road racing a 390

H

Husky390

Husqvarna
AA Class
Hi all, This is my first post after looking around at all the impressive history and knowledge about here.
I am putting together a period 5 historics road racer using a 79 390 WR motor that came from a wrecked bike. The attraction is good power to weight ratio and excellent build quality, six speed box etc. It can be raced here in Australia in pre 1982 and a variety of races for European makes.

Now the 1st question. I am up to the point where I need to build an expansion chamber. I have worked out some measurements for cones and was wondering if anyone here has any data on road race pipes for these engines to compare with what I have worked out before I get cracking?
I am working on the assumption these engines ran to about 7500rpm standard and the exhaust port duration is 176 degrees?
Any advice appreciated as I am working in a vacumn here.
Cheers
Russ
 
You're not going to find road racing ones.

The pipe you will want would be a mid to top end pipe as you'll be in the revs most of the time. And as far as that kind of pipe goes your best bet truly would be to call uptite husky and request them to make you a pipe for your application. There will be no guides out there for this other then the actual exhaust someone may have and even at that it may not be a mid-top end pipe.

And when making an expansion chamber you may want to figure out the exact port timing you have before you just guess. On a 2 stroke port timing and expansion chambers are extremely important, and if you get it wrong the powerband of the motor will be terrible.

One question I do have is what's wrong with the stock pipe? If you're running in a pre '82 class under 500cc's with this motor it'll be faster (acceleration wise) than a lot of other bikes out there. Even with the motor in stock form.

If you want a true monster though, give the top end to uptite Husky and have them change the port timing, extrude hone it, modify the cylinder head, and build you a custom expansion chamber. Also add a larger carb. Then it'll be an even nicer motor.
 
There a lot of experts on here, and I am not one of them! I do think for road racing you want to look for a CR top end. The WR has a tendency to be a milder motor with good mid range but is pretty flat on top. If you are going to port and build a custom pipe you might not want to start with the WR jug.
 
THANK YOU 87 500XC, Firecracker kid and Huskydoggg for giving me your advice. Much appreciated.
I measured the cone angles and tuned length of a beaten up standard pipe I have and the tuning looks to be aimed at about the 5000rpm region (fat midrange) with gentle taper on the reverse cone (wide over rev but milder power) as standard. My new pipe is aimed at a tuned length for 7500rpm with cone tapers to offer reasonable mid range but I am hoping someone will have done a similar thing to compare to. The revs I need are 5000 to 7500 with gearing for 100 to 130 miles per hour flat out. I will avoid getting too boring with the numbers. Huskydoggg, That report 14 looks very interesting but I don't seem to be able to access it so a copy would be fantastic. I presume you can email it?
Cheers
Russ
 
A fella in Colorado, sorry no name or link but I'll search. I think he has made some custom pipes for your intended use.
 
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