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 The previous version was outdated and no longer supported.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

1982 to ???? 250 Engines

I'm sorry, but I have to disagree, people are temped to go to bigger carbs and it is rarely the right way to go, especially on a 125. I love them, but there is no doubt the Swedish Husky 125s were anemic, they were over carburated with the 38 which is why Husky went down to the 36mm in '84 and it was still over carburated, a 34mm would have been best but the 38 is totally overkill. Changing jets and needles is irrelevant if the engine the carb is attached to can not generate enough vacuum signal to make it operate properly, which is the case with the 38mm on the Husky 125, it simply can not function properly with the weak signal the engine sends it. I also had an '85 Honda CR125 with a Pro Circuit ported engine, it used the stock 34mm Keihin (not a 36mm) and it was super fast. I now have an '84 KTM125 with a 36mm Delorto, the bike is a missile on the top but the carb is too big, the bike would run a lot better with a smaller carb, the body is the same size as a 36/38 Mikuni so a smaller Mikuni wont be easy to fit so I will get Lectron to build a 34mm in that body size. It was not until a few years ago that Yamaha put a 38mm carb on the YZ125, I have used both on my YZ125 and the 36mm works far better, it loses nothing on the top and pulls better in the midrange. Unless you are talking about a shifter kart or a GP road race 125, I would have to see some flow charts to believe any 125 was running out of CFM with a 36mm carb.

As to the needle jets, you are 100% correct, that is by far the most important part of the carb to get right and its the one the least often gets changed. I cant tell you how many bikes I have fixed a bike where someone has gone super-lean on the pilot jet trying to lean out the mid range and the needle/needle jet is what they should have changed. I have a big jet box I take with me every time I ride and 3/4s of the brass is needle jets, not mains or pilots. Most of the time when someone asks me to jet their bike and I take out the needle jet they say "I didnt even know that piece came out!!".
 
im starting to slowly warm to the lectrons..bought one for my 95 360, it really is a great performing carb..starts first or second kick, hot or cold. im starting to wonder whether i should even use the choke..only part that you really ever need to change is the metering rod, and they are supposed to be very versatile..
 
Kartwheel68 said:
I'm sorry, but I have to disagree, people are temped to go to bigger carbs and it is rarely the right way to go, especially on a 125. I love them, but there is no doubt the Swedish Husky 125s were anemic, they were over carburated with the 38 which is why Husky went down to the 36mm in '84 and it was still over carburated, a 34mm would have been best but the 38 is totally overkill. Changing jets and needles is irrelevant if the engine the carb is attached to can not generate enough vacuum signal to make it operate properly, which is the case with the 38mm on the Husky 125, it simply can not function properly with the weak signal the engine sends it. I also had an '85 Honda CR125 with a Pro Circuit ported engine, it used the stock 34mm Keihin (not a 36mm) and it was super fast. I now have an '84 KTM125 with a 36mm Delorto, the bike is a missile on the top but the carb is too big, the bike would run a lot better with a smaller carb, the body is the same size as a 36/38 Mikuni so a smaller Mikuni wont be easy to fit so I will get Lectron to build a 34mm in that body size. It was not until a few years ago that Yamaha put a 38mm carb on the YZ125, I have used both on my YZ125 and the 36mm works far better, it loses nothing on the top and pulls better in the midrange. Unless you are talking about a shifter kart or a GP road race 125, I would have to see some flow charts to believe any 125 was running out of CFM with a 36mm carb.

As to the needle jets, you are 100% correct, that is by far the most important part of the carb to get right and its the one the least often gets changed. I cant tell you how many bikes I have fixed a bike where someone has gone super-lean on the pilot jet trying to lean out the mid range and the needle/needle jet is what they should have changed. I have a big jet box I take with me every time I ride and 3/4s of the brass is needle jets, not mains or pilots. Most of the time when someone asks me to jet their bike and I take out the needle jet they say "I didnt even know that piece came out!!".
Click to expand...

according to kevin at lectron, that weak signal problem is severely diminished on the lectron design..much better atomization which helps it cope with elevation and weak signal off the line. wouldnt be surprised if the lectron pulled off a 36 well..altho my 360 only has a 38. i bet the 125 would have superb bottom end fueling with a 34 lectron..whats nice is for a small fee they will machine the carb flange and spigot to your specs..you can usually get away running your stocks boots
 
Yes, exactly. Lectrons are really excellent carbs, I cant figure out why more people dont use them. Typically, you can use a plus 2mm size in a Lectron because they counter the weak signal issues of doing that with a standard type carb, but even with a same size as stock venturi a Lectron will flow a lot more than a standard carb at WOT. Lectron will machine the carb to fit so you can go to a venturi size that would require a different size body, and different boots, in a Mikuni or Keihin, it really makes it easy to go to a smaller carb like in my '84 KTM so I can use the stock boots. On some older piston port bikes the carb has a female flange that clamps on a male spigot on the cylinder, Lectron can also build their carbs with that female type flange so it will bolt on like the stock Bing.
 
The needle jet is like a bath tub. The main jet meters what's
In the bath tub. The needle jet meters what goes in the engine and works with the taper of the needle. If your needle jet is too rich no main jet change can fix it. But by going smaller on the main jet can cause a lean situation. Remember to read your spark plugs color too.
It's all about metering the gas flow to the cfm' s of the carb to your engines needs.
 
Kartwheel68 said:
Yes, exactly. Lectrons are really excellent carbs, I cant figure out why more people dont use them. Typically, you can use a plus 2mm size in a Lectron because they counter the weak signal issues of doing that with a standard type carb, but even with a same size as stock venturi a Lectron will flow a lot more than a standard carb at WOT. Lectron will machine the carb to fit so you can go to a venturi size that would require a different size body, and different boots, in a Mikuni or Keihin, it really makes it easy to go to a smaller carb like in my '84 KTM so I can use the stock boots. On some older piston port bikes the carb has a female flange that clamps on a male spigot on the cylinder, Lectron can also build their carbs with that female type flange so it will bolt on like the stock Bing.
Click to expand...
didnt know that lectron also offered a female type flange...old sleds use those too. one thing for sure is that its nice to not worry or deal with pilots, needles, needle jets, mains, or keeping a box full of them..
 
Bigbill said:
The needle jet is like a bath tub. The main jet meters what's
In the bath tub. The needle jet meters what goes in the engine and works with the taper of the needle. If your needle jet is too rich no main jet change can fix it. But by going smaller on the main jet can cause a lean situation. Remember to read your spark plugs color too.
It's all about metering the gas flow to the cfm' s of the carb to your engines needs.
Click to expand...

Be careful reading plugs with modern pump fuel, they do not give the same color as old fuel or race fuel and the color can lead you the wrong direction. Unless you have race fuel, av gas, or some other kind of non-pump fuel rely on what the engine is acting and sounding like instead of the plug color.
 
justintendo said:
didnt know that lectron also offered a female type flange...old sleds use those too. one thing for sure is that its nice to not worry or deal with pilots, needles, needle jets, mains, or keeping a box full of them..
Click to expand...

Yup, they can basically machine you a carb to fit anything. I have one on my '77 Penton/KTM 400 that mounts to the male spigot on the cylinder, they also turned the airbox side to the size of the Bing so all I had to do was put it on, no messing around with adapters or different boots.
 
I recently purchased a Lectron for My Maico (1983) 250 and they told me not to compare there Carb Bore sizes to other brands. In other words a 38mm Kehin ( or any other brand) and a 38mm Lectron don't flow the same CFM. In most cases the Lectron will flow more so there for You can use a smaller Bore. I was split between a 38 and a 36 and decided on the 36 for my 250. Only one ride so far but pretty spot on right out of the box. This was the recommendation from Lectron.
 
All I can say is when I adapted the Mikuni 40mm carb to my '82 CR 390 the bike was an animal much worse than a stock 390 hit wise and power throughout the throttle. There was no dead areas with lack of power or jetting. I changed the needle jet and jetting the carb.

The guy who purchased the bike got injured on it. These 390's stock aren't for new riders.
 
It sounds like the lectron carb is easy to adjust. I'm not familiar with it but does it adjust the gas flow?
With no pilot jetting its one screw that adjusts the gas flow for the whole range of the throttle?
So in the end were actually balancing the flow of gas to the diameter of the carb to the engines needs.

Can't we have the same performance by tuning the mikuni?
 
There werent any 390s in '81 or '82, the Autos were 420s and the big bikes were 430s. I have no doubt a 390 with a 40mm felt faster, I am sure it was more abrupt because it didnt make as much power down low, but it is very unlikely it actually produced more power.

A Lectron uses a metering rod (slide needle) to tune the entire circuit, the taper of the needle takes the place of all the jets in a standard carb. Most modern Lectrons also have a power jet circuit, which uses a standard Mikuni pilot jet. A Mikuni or standard carb can not be tuned to the precision of a Lectron.
 
Fact when we go from a 2 barrel carb to a four barrel carb on a v8 engine it produces more power?
 
yes, the lectron is a whole different animal..im a pretty die hard fan of the mikuni vm carb, but im starting to like them less...
 
Bigbill said:
Fact when we go from a 2 barrel carb to a four barrel carb on a v8 engine it produces more power?
Click to expand...


Yes, assuming the 4bb is larger than the 2bb, but that is not comparing apples to apples, since racing dirt bikes like a Husky already come with the largest size carb the engine can efficiently use, unlike a car V8. If you are talking about foo foo play bikes like a Yamaha RT180, sure, it could work better with a bigger carb. Heck, Husky even went too big on the 500, they first had a 44mm, and it was too big so they went down to a 40mm. Many owners of 500s have gone down another size to a 38mm and like it even better than the 40mm.
 
Using a simple cfm calculator app a 390 at 100% volumetric efficiency at 8000 rpm can use 60 cfm. According to a Mossbarger table an estimated flow for a mikuni 38 mm carb is 129 cfm. In comparison a 350 chevy spinning 5000 rpm only needs 550 cfm but we all want a dual quad tunnel ram. Once you get past the science it is whatever floats your boat.
 
simple fact with carbs is the bigger the throat the less torque you get. as the mix de atomizez partially at low velocity speeds and looses efficiency, only coming up to full efficiency as the revs build. a lot of people need a smaller carb.....but go for a big one!
 
Now, to bring this back to the original topic, 82+ 250s, they also came with a 38mm Mikuni. I am not happy with the way my '82 250XC runs so I am going to swap on a 36mm to see how it works. I'd bet money it runs better with the 36.
 
You must log in or register to reply here.
Back
Top