1979 390 OR cold start problem

[Odin]

Does anybody have any suggestions for cold start problems on '79 390 OR. The spark plug seems to quickly foul up with fuel and I have to take out and clean. Most times I have to push start the bike and that doesn't always work. Also, fuel/oil mixture seems to leak out from exhaust port (I'm not sure as I need to clean it first and then look) but still have hard time starting bike. It has good spark and seems to run fine when it is running. Has anybody had similar problems. Is this a problem with this model bike and/or does anybody have any suggestions. Thanks, Dave

 

[390Dave]

Odin,sounds like the carb is flooding over and filling the engine with fuel.Take the carb apart,make sure the floats move freely on the pins,remove and clean the needle and seat,then reinstall them,making sure the wire clip that keeps the needle from dropping is installed,facing front-to-back.Check the float height by turning the carb upside down,the float arm that shuts the needle should be parallel with the bowl mounting surface.Kick the engine over with the spark plug out several times to clear some of the fuel out.Reinstall the carb and spark plug.If you kick it over and it just pops or backfires once or twice but doesnt start,its probably still flooded,repeat taking the plug out,kick it through again,sometimes you need to let the bike sit for awhile with the piston at bdc to air it out.Some Husqvarnas,390's especially,do not have 360 degree round crankwheels to displace some of the crankcase volume,which equals a lower primary compression ratio.This primary compression is what pushes the air/fuel mixture up the transfer ports and into the cylinder.That combined with slow cranking speed makes them sometimes difficult to start under less than ideal conditions.Changing the slide to a 2.5 will make the bike easier to start also.

 

[Mike-AK]

I remember my 1979 250OR being a hard starter when cold. I just figured it was that way and never worried about it much. You just kicked it until it kicked back hard enough to break your foot, then kicked it one more time and it would fire.

 

[Odin]

Odin,sounds like the carb is flooding over and filling the engine with fuel.Take the carb apart,make sure the floats move freely on the pins,remove and clean the needle and seat,then reinstall them,making sure the wire clip that keeps the needle from dropping is installed,facing front-to-back.Check the float height by turning the carb upside down,the float arm that shuts the needle should be parallel with the bowl mounting surface.Kick the engine over with the spark plug out several times to clear some of the fuel out.Reinstall the carb and spark plug.If you kick it over and it just pops or backfires once or twice but doesnt start,its probably still flooded,repeat taking the plug out,kick it through again,sometimes you need to let the bike sit for awhile with the piston at bdc to air it out.Some Husqvarnas,390's especially,do not have 360 degree round crankwheels to displace some of the crankcase volume,which equals a lower primary compression ratio.This primary compression is what pushes the air/fuel mixture up the transfer ports and into the cylinder.That combined with slow cranking speed makes them sometimes difficult to start under less than ideal conditions.Changing the slide to a 2.5 will make the bike easier to start also.

Thanks for the information. I will try your suggestion when I get back into town. You talk about changing the slide to 2.5, what is the slide? I know, probably a dumb question but I'm just getting back into dirt bikes after about a 25 year hiatus. Thanks for any and all information. Dave

 

[390Dave]

Odin,the slide is the round piece that slides up and down vertically in the carburetor,the throttle cable is hooked to it,it also holds the needle.You unscrew the round cap on top of the carburetor where the cable goes in and lift it out.Its easier to do this with the carburetor off the bike.Handle with care,be careful not to bend or damage the needle.Note when the slide is out of the carburetor main body,one lower edge on the slide will appear have some metal machined away,that is the slide cutaway.The bottom of the slide where the needle is protruding from will have a square symbol with a number stamped next to it,your bike came from the factory with a model 2.0,unless it has been changed already.When you re-assemble the carburetor,it is usually easier to get the slide and needle back in,holding the carburetor vertical,with the carburetor off the bike,cutaway goes toward the airbox.You will notice the slide has a groove cut up one side of it,that a pin inside the carburetor body fits into,it keeps the slide from rotating.Coat the outside of the slide with oil,line the needle up with the orifice of brass needle jet in the floor of the carburetor,align the groove on the side with its pin,drop it in and screw the carb top back on.Make certain when you are done that the twist throttle opens smoothly with no binding and snaps shut,and that the throttle cable is not touching the exhaust system,your original cable has a spring guard over it in that area.

 

[stormer254]

A typical 2 stroke problem, your fuel tap is probably letting fuel by even when closed, exacerbated by leaky float needle and down draught carb, when you finish riding run the carb dry pull the fuel pipe of the carb and put a bung in the pipe till you next use it. Older 2 strokes such as villiers had a crankcase drain plug so you could clear the excess fuel

 

[Old Geezer]

I'm starting to get a bad taste about Huskys as being the hardest starting SOB's of any bike I've ever owned. But then, I'm dealing with the most notoriously hard stating Huskies as well (the big lung'ers) so I guess I get what I deserve.

Just this weekend I 'attempted' to start the 500CR....no dice, when just the weekend prior it lit on kick #3. Go figure. Brand new float valve and seat too, and the petcock does not leak I'm certain....but then things do change and it probably was drooling gas down into the crank anyway, all week long. Spark was good, but plug was wet. So, pull the plug, kick it over a few times and let it sit for a week. Will attempt to start again next weekend and if it fires, then from now on I disconnect the fuel line from the carb when done riding. Ya gotta do what ya gotta do, even if it's BS....but part of the Sweedish ritual.

 

[Mike-AK]

I'd love to have my hard starting 250OR back. Should have never sold it but I was young and stupid and wanted the money for a car.

 

[Ron]

It took a long time to get this bike to start like a normal bike. I finally figured out the floats were set to high causing the carb to have a continuous drip of gas into the crankcase, whenever the fuel valve was left on.
The carb sits on an angle when mounted on the bike, so float height is very critical as is a good seal on the float needle and seat and the petcock.
A Stanley knife blade is very easy to use, for setting the correct float height.
Remove the gasket from the carb body and lay the blade across the body. The float arms should be parallel with the blade.
You may have to bend the tang between the floats where it sets on the float needle and straighten the float arms individually, to get them level with the blade. It's not un-common to find the arms all bent out of shape by previous owners.
I also find a 3.0 slide with a 45 pilot, makes the 390 start a little better and run cleaner.
It still takes a serious 3 - 4 kicks to start it cold, 1 or 2 when warm.
I usually hold the throttle open a 1/4 turn hot or cold and choke on when cold. I have never been able to get it to start with just the choke, throttle closed.
I realize opening the throttle cancels the choke, but it works. It does however need the choke on to stay running when cold, until it warms up.

I ride at 1500 to 4000 ft elevation;

79 Husky 390CR - 38mm Mikuni:

2.2 timing BTDC
480 main jet
R4 needle jet
6DH3 needle (clip in the middle)
45 pilot jet
3.0 Slide
air screw 2 turns out

 

[firecrackerkid]

It took a long time to get this bike to start like a normal bike. I finally figured out the floats were set to high causing the carb to have a continuous drip of gas into the crankcase, whenever the fuel valve was left on.
The carb sits on an angle when mounted on the bike, so float height is very critical as is a good seal on the float needle and seat and the petcock.
A Stanley knife blade is very easy to use, for setting the correct float height.
Remove the gasket from the carb body and lay the blade across the body. The float arms should be parallel with the blade.
You may have to bend the tang between the floats where it sets on the float needle and straighten the float arms individually, to get them level with the blade. It's not un-common to find the arms all bent out of shape by previous owners.
I also find a 3.0 slide with a 45 pilot, makes the 390 start a little better and run cleaner.
It still takes a serious 3 - 4 kicks to start it cold, 1 or 2 when warm.
I usually hold the throttle open a 1/4 turn hot or cold and choke on when cold. I have never been able to get it to start with just the choke, throttle closed.
I realize opening the throttle cancels the choke, but it works. It does however need the choke on to stay running when cold, until it warms up.

I ride at 1500 to 4000 ft elevation;

79 Husky 390CR - 38mm Mikuni:

2.2 timing BTDC
480 main jet
R4 needle jet
6DH3 needle (clip in the middle)
45 pilot jet
3.0 Slide
air screw 2 turns out

Ron, what oil do you use and at what ratio?

 

[ruwfo]

All good info, next time you get it started (jumping,towing or whatever), after it clears out & the engine
is warm, shut it off & pull the plug, is it nice & tan or black? Tan is normal , black is too rich, white/light gray
is too lean. Adjust the carb til the plug is tan, you didn't mention does it start when it's warm? I'd bet it does.

My 80 390CR, was hard starter cold, til i learned, how to start it. Gas & choke on.. put it in 3rd gear rock it
back & forth ..count to 30.. Gas & choke off.. get kicker to top of the stroke..kick it like you mean it..
mine starts on the 1st to 2nd kick..then turn gas on.. ride .. always turn gas off when it's shut off...

I've bought a bunch of Husky, sold because they were hard starters , owners said they couldn't ever, get
them going. Then they stood in amazement, when i started them with ease using that method.

Husky John

 

[Ron]

Ron, what oil do you use and at what ratio?

YamaLube 2R 32:1 100 octane Shell race gas. We only ride once or twice a month so good gas is cheap insurance.

 

[Kartwheel68]

With modern formulas in pump gas, plug color is no longer an accurate measure of jetting. The stuff they put in it makes plug colors look much lighter than it used to so a correctly jetted bike can have plug color that LOOKS dangerously lean, when it is not. Unless you are using race fuel, or AV gas, or a mix of those with some pump gas, and what ever you use you never use anything else, DO NOT use plug color.

As for leaky petcocks, Maicos and Pentons use the same size spigot on the tanks, and I never use the old petcocks on those bike, I use new modern replacements like these:

I actually get mine from a Ducati place called Bevel Heaven.

https://store.bevelheaven.com/

 

[Old Geezer]

Unless you are using race fuel, or AV gas, or a mix of those with some pump gas, and what ever you use you never use anything else, DO NOT use plug color.

So, although you are probably correct, if you're going to make that statement then it deserves an alternative approach for gauging proper air-to-fuel ratio. Personally, over time we can train ourselves on what plugs should look like with today's crap gas (which is what I've subconsciously done over the years). But trial and error can end quickly in catastrophic results.

 

[suprize]

watch out for that running out of fuel sensation... its a dead giveaway all is not well!
The 400 starts hot or cold 2 kicks, even with the fuel tap on and flooded, just hold it wide open and she fires .. lucky me

 

[V.R]

This is quite obvious but can easily be overlooked, just check the needle retaining plate in the slide is on top of the needle clip. I have seen it when the plate is put in first, and then the needle slid down the hole in the center. If you have a good spark, your timing and carb are setup right, it may just be excessive fuel caused by the reasons listed so you aint too far off.

 

[Kartwheel68]

I use the same method thats in the Husky owners manuals. On the main, I dont want fine line jetting, I want it as rich as I can get it without blubbering. I go rich until it blubbers, then lean it out one size. That might cost a bit of power compared to really crisp jetting, but I never have to worry about seizing it, and you dont even look at the plug because you are basing the jetting on how the bike behaves. Only time I look at a plug is to take it out and replace it with a new one.

 

[Old Geezer]

I use the same method thats in the Husky owners manuals. On the main, I dont want fine line jetting, I want it as rich as I can get it without blubbering. I go rich until it blubbers, then lean it out one size. That might cost a bit of power compared to really crisp jetting, but I never have to worry about seizing it, and you dont even look at the plug because you are basing the jetting on how the bike behaves. Only time I look at a plug is to take it out and replace it with a new one.

And that's good advice. Plug checks are fine for what they are, but a person should know by "feel" how their bike is running. Your approach is right-on, kinda like the old carburetted cars where you set the mixture to lean-best-idle, but in this instance it's the reverse....rich best idle for safety sake.

 

[Kartwheel68]

And even though I carry a box of jets, needle jets, and needles with me, I try to get the needle jet right with the clip in the middle so I have some leeway if the bike needs to go one way or the other. I'm sure I could gain some top end power if I leaned out the mains a bit, but I'd rather have it on the safe rich side.

 

[Ron]

I check my needle jet/needle combo without the main jet. It should run fine up to about 3/4 throttle and blubber past that.
If that combo is to small, it won't matter how big the main jet is.
It was an expensive education to learn that trick.