• 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.

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    Thanks for your patience and support!

1987 430CR 4-stroking

Grunbay

Grunbay

Husqvarna
AA Class
I have a 1987 430CR. The carb is clean, the timing is proper, there is no intake leakage at the carb, the silencers is newly re-packed.

The bike is 4-stroking under load. Any ideas on what could be causing this?

This is my first reed valve engine, so I can only lay blame on the part that I'm not familiar with - the reed?
 
Could be the ignition breaking down under load. Can you borrow a system from someone else - to illiminate this possibility?

I take it you have checked the main jet is somewhere near correct?

try a fresh B8ES plug.

Andy.
 
Yes, fresh plug. I'm using a B8EVX plug, but I'll try a standard plug.

The main jet is a 430. I don't know the standard size.

I have an ignition system from an OSSA. That fits older Huskys like my WR450, but I don't know about this one.

Can bad crank seals cause 4-stroking?
 
B8EVX is a fine wire plug and will spark easier than the stock B8ES.
4-stroking can be a rich condition in the carb.
At what throttle position does it start 4-stroking?
Does it smoke excessively?
Is the plug wet and oily?
Weak motoplats usually cause hard starting or no spark at all.
 
Yes, I have had good luck with the B8EVX in a variety of 2-strokes. It seems to run cleaner than the S-type NGKs. This bike is a bit unusual in that it's a CR, but has the external rotor Motoplat with lighting coils and a headlight, like a WR. The spark appears fine, for what that's worth. It fires up pretty well - 2 or three kicks.

4-stroking starts pretty much as soon as you crack the throttle, probably from 1/8th. It cleans up higher in the rev range and digs a trench like an excavator! I thought that my needle jet might be worn, but it looks perfect!

The plug is not oily, but is black, not brown.

It doesn't seem to smoke worse than my other 2-strokes (OSSA, Sachs, KTM), but the bike is new to me (for better or worse) so I don't really know what is normal yet.

One other thing, I put a new air filter on it - is it possible that excessive oiling of the filter can cause this? I've never had that problem, but I thought I'd float the idea!
 
If it that the stock main, it's too rich, Husky, as did all manufactures always went way too rich on there jetting.
 
Rich in the lower range could be an over oiled air filter but this normally occurs when it has half an inch of dust on it.:eek:
430 main shouldn't be cause of poor low end running. it more like the needle is rich or the pilot.

digging a trench suggests its ok up top.

So....Check the filter is located properly and not dripping with oil.

how many turns out is the airscrew? it should be out ~1.5 turns and turning it either way in a half turn range should fine tune the smoothest idle point. takes some listening but if you fool around for a bit you should hear it change from rough to smooth. (always hard with a big bore a/c "biding biding binging" in your ear as you chase it across the garage floor) ear muffs help!

screw it right in or out and it should nearly or completely stop the motor. if the airscrew is ineffective and nothing happens when you screw it in or out, there is a leak or a bigger issue for you to find.

find out what number the pilot jet is and make sure it hasn't fallen out

check the float level and the needle and seat are ok as it could be flooding slightly as soon as you start moving.

If nothing has changed and the airscrew is working, I would lift the needle clip 1 notch and test it in the first half of the throttle range. .. carefully.

if the needle is rich, leaning it off should smooth the needle to main transition.

good luck sorting that
 
I do not know if the CR430 jetting is the same as the 430 auto (or even close) but here goes anyway - it should be fairly close.
Try the following:
main jet 410
pilot jet 40
needle jet Q8
needle 6 DH 20 - 3rd clip from the top
air jet 2.0
throttle slide 2.5

These are what I run in my auto and it runs fine.
 
the air is heavier in nu zuland...:D . I have a 420 in my 400 and its a tad rich but not that you really notice.
 
I would have expected a lean out if a cranker had failed but it could suck a heap of oil in as well.... im intrigued to see if we can solve it...
 
Work plan for Sunday:
  1. Run bike with air filter removed to check for possible over-oiled filter.
  2. Try lowering the needle one notch
  3. Leak down test (um, how do I do that?)
  4. try smaller pilot jet
 
Will do...

Wouldn't "wound out too far" make it lean on a Mikuni? My assumption is that 4-stroking is a product of excess fuel. However, this is the first time I've run into this issue, so I don't know!
 
Ok,

Squeezed the begeejum out of my oily air filter. No improvement with or without the filter.
Moved needle around to several positions. No improvement.
Decided to clean carb - again. Although clean before, the pilot jet was plugged! I put in a new pilot and gave the bike a mighty kick.

Argh! The starter shaft broke clean off! Back to the drawing board!

I will treat you helpful readers with more exciting adventures from the state of Maine when I find a new starter shaft!
 
Argh! The starter shaft broke clean off! Back to the drawing board!

Not that uncommon, the one on my old 84 400 snapped off clean too

Husky John
 
Well, after a couple of weeks and a hundred bucks, I now have a new starter shaft.

My problem remains: breaking up a nd 4-stroking. I now believe that the condition is present at all throttle positions.

I have cleaned the carb four times
I have tried all of the positions on the needle
I replaced the needle valve and seat
I reset the float height
I replaced the pilot jet - #40
I have cleaned and adjusted the enrichment circuit to ensure that it's closing properly
I have run with and without the air filter - no difference
I have changed the plug

I'm starting to think that my problem is not with the carburetor!

Can a Motoplat ( external rotor with lighting coils) cause this proplem?

How do I check a Motoplat?

Any other thoughts?
 
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