• 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 The previous version was outdated and no longer supported.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!

Mikuni 38mm for 1979 250

E

Edward Rennie

Husqvarna
B Class
Hi guys, looking for a steer if any help is available!

I was racing an Enduro last weekend and there was a lot of flat out fast sections. The top end felt far too rich with noticeable loss of power. The main jet is a 430 and needle is 6DH3 (looks like that anyway!), the handbook spec is a 430 main but needle says Q8?

I’m in UK, so climate is cool / temperate and no riding above 1000ft.

Any suggestions? I guess the main jet could be worn, so maybe just replace with a new 430 and see what it’s like? Or are these generally regarded as too rich? How about needle and position?

Appreciate there are a lot of factors, but a general steer would be great!
 
In what rpm range was it running rich? 1/4 throttle, half, 3/4 or full? The Q8 is the needle jet size no the needle size. You said top end felt rich so probably safe to going to leaner main jet to begin. I have never had a 250 needing a 430 jet.

Marty
 
motomwo said:
In what rpm range was it running rich? 1/4 throttle, half, 3/4 or full? The Q8 is the needle jet size no the needle size. You said top end felt rich so probably safe to going to leaner main jet to begin. I have never had a 250 needing a 430 jet.

Marty
Click to expand...

thanks for coming back to me Marty. it's at full throttle that the bike is rich, the rest of the range feels pretty crisp to be honest. So I'll try dropping down a size or two on the main jet. Do you have any knowledge of what the needle size its self should be? Many thanks, Ed
 
All my 250's never had to run a 430 Main either.
78 250 CR Jetting
Needle 6DH3
Slide 2.0
Main. 390
Pilot. 35
this is my current jetting I'm at 800-1400 feet above sea level.
Bill
 
Edward Rennie said:
thanks for coming back to me Marty. it's at full throttle that the bike is rich, the rest of the range feels pretty crisp to be honest. So I'll try dropping down a size or two on the main jet. Do you have any knowledge of what the needle size its self should be? Many thanks, Ed
Click to expand...

Your # 6DH3 needle is correct. What fuel mix ratio are you using?

Marty
 
Excellent, thanks for the help guys. I’ll replace the needle anyway as I guess it could be worn.

I’m running 45:1 with 99 octane and Putoline fully synthetic - thoughts?!!
 
Edward Rennie said:
Excellent, thanks for the help guys. I’ll replace the needle anyway as I guess it could be worn.

I’m running 45:1 with 99 octane and Putoline fully synthetic - thoughts?!!
Click to expand...

Remember the original mix ratio back in the 70's was 20:1 so when you go 45:1 then the factory jetting specs will be rich. Replacing the needle is a good idea if you suspect it to be worn. The needle jet may also be worn.

Marty
 
motomwo said:
Remember the original mix ratio back in the 70's was 20:1 so when you go 45:1 then the factory jetting specs will be rich. Replacing the needle is a good idea if you suspect it to be worn. The needle jet may also be worn.

Marty
Click to expand...

thanks Marty, yep that makes sense
 
Thanks for your advice guys - was racing today and the bike was going like a train!!! Top end transformed, some real pulling power.

That was my last event of the season, so time to get some more jobs done on the old girl. Think I’ll look in to the 40mm fork upgrade (I’m on 35’s) and have to get the Works Performance shocks sent off for a rebuild.

Roll on next season
 
What did you do to change the outcome? Goes like a train as opposed to running rich at full throttle
I didn't think you could run the mix that lean(45to1) and not have to buy a piston!
 
DeathFromAbove said:
What did you do to change the outcome? Goes like a train as opposed to running rich at full throttle
I didn't think you could run the mix that lean(45to1) and not have to buy a piston!
Click to expand...
I’m running the jetting same as Bill, I’m at the same altitude or lower.
In regard to the mix ratio, I know there’s been a lot of conflicting recommendations on here. My take, as with all the guys I’ve spoken to who race in the vintage enduro series, is that the old manual recommendations of 30:1 or whatever was relevant to the oil quality available. With modern oil (I use fully synthetic Putoline) most of our guys are running 50:1. I’m just going on the slightly cautious end of that.
Most of the events im doing are pretty open terrain, so rarely am I thrashing the bike in slow going, it certainly hasn’t seemed to have got too hot so far…
Of course happy to listen to others opinions on the matter
 
Crashaholic said:
Heres an excellent read on two stroke oil for the vintage motorcycle.

http://www.klemmvintage.com/oils.htm
Click to expand...

thanks for that. Interesting article and certainly educational to me.

I'm not doing much sustained high RPM, just the occasional section of a track across open fields when i can let it rip properly - the suspension slows me down from going hard the whole time!!

Regardless of this, would the suggestion of other members on air cooled / older bikes be to use Maxima 927? I'm only doing 10 riding days a year so the additional cost wont really factor in to it.
 
Edward Rennie said:
thanks for that. Interesting article and certainly educational to me.

I'm not doing much sustained high RPM, just the occasional section of a track across open fields when i can let it rip properly - the suspension slows me down from going hard the whole time!!

Regardless of this, would the suggestion of other members on air cooled / older bikes be to use Maxima 927? I'm only doing 10 riding days a year so the additional cost wont really factor in to it.
Click to expand...

Opening a can of worms asking about oil!
Personally I wouldn't be comfortable running my bike on 50:1 though I know many people do with no problems. I ran fully synthetic racing oil from Westway Oils, a company in the UK for years at a ratio of 35:1. After three years of hard use I stripped the top end and found virtually no wear, I really don't see what advantage you get from running less oil.

For the last couple of years just really to try it, I switched to Maxima 927. I find it burns clean, smells great and when I lifted the cylinder a few weeks ago everything still looks like new. The only disadvantage is that it's harder to get it to mix with petrol, especially when it's cold. That said I'm not sure if I'll stick with it, I'm not convinced it's that much better that a good synthetic oil and it does cost a lot more.
 
Opening a can of worms asking about oil!
Click to expand...
True Statement. Ask 10 motorcyclists what the best 2 stroke oil is and you'll most likely get 10 different answers. The performance shop that wrote the article I posted above has been building their own race motors since the 70's. IMO they know vintage motor architecture well. The article is long and full of stuff not related to this thread so here's what I got out of it.

"A two-stroke engine actually has two very different kinds of lubrication needs. The lower end crank and rod bearings prefer a slow drip of a very heavy viscosity oil, while the top end parts wear best with a deluge of a very lightweight oil. Since these are two very opposite lubrication needs, you have to choose whom you want to please. For most two-stroke owners, it’s a no brainer. You can buy 100 cranks and crank bearings that will all offer the same performance, but every owner wants to do whatever can be done to preserve a good running piston / cylinder set. Given all this, heavier premixes of lighter viscosity oils are more desirable to most owners."

"The lesson here is that your premix ratio should be a function of the average operating rpm that your vintage two stroke runs at. If you are at peak rpm all the time, 20:1 is a good idea. However for recreational level riders that don’t “scream” their engines constantly, leaner premixes will yield excellent long term wear."

"For vintage machines that spend very little time held at peak rpm (in the higher gears), API-TC oils are the better choice. Among these oils, our favorites are Yamalube R, Kawasaki K2, and Maxima Super M."
 
Hey, my 80 390cr & 82 430CR both have this carb set up for years & years:

340 main, 50 pilot & 2.0 slide .... 32/1 premix

original Husky paper work on Jetting was way tooooo rich, they didn't
want bikes blowing up, NO matter how hard u were on them.

Husky John
 
Right - the above was a tester, I seem to be able to post again! Does anyone else get a server error?

Anyway, thanks for the input guys. On balance, seems folk run a richer oil mix than what I’m on. Shall richen the mix to 35:1 and see how the bike feels - if the difference isn’t noticeable shall just go with that for a while
 
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