Wr430 1988 - Too Rich But... Why ??

Hello Everyone,
Maybe someone will have an idea to solve the problem I’m facing ;

The bike is a Husky WR430 bought new in 1988 (and still in very good condition

Had always perfect performances.
Since last year, engine is running perfectly from idle to ¾ throttle, beyond ¾ opening, I can ear that its running too rich and doesn’t rev as it should and this on all gears.
That engine have never been overhauled and, after 32 years, I changed, piston and crankshaft and all crank seals.

Still the same problem…

With such symptoms, the logic would be to decrease main jet size, but...this doesn’t make sense as this bike ran perfectly for 32 years with that jet.

The very last thing that comes to my mind are reed valves but they look good and the symptoms doesn’t call for a reed valve problem.

Any idea ??

Thkx a lot for your input

Tech Details:

Bike: Husqvarna WR430 1988
Carb: Mikuni 38- VM
Carb. Float: 18 m/m – Checked OK.
Carb : Cleaned (ultrasonic twice)
Carb. Needle : 6DH20 (new – same as original)
Needle Jet : 166-R0 (New – same as original )
Main Jet: 400
Air filter: Clean – Checked and changed OK
Mix ratio: 50:1 now with new engine for braking in. Used to be 57:1 good quality Synthetic (Motorex)

Plug: Dark but dry (NGK )
All factory original, no special engine parts, all jets factory standard.

Hello and what a great bike to have and keep all these years.

All those new goodies are great and at this point, perhaps try new reeds, old and stiff who knows.
Double check seals, gaskets with a leak test at 6 psi.
Put a new carb in, but that's not really my style

I would try some new main jets still, give her what it wants. Because if it improves with a main jet main, go to what you feel is needed and makes it happy.

Staying with stock jets may work, but many have to sort it out some more for the elevation needs.
It a fine tuning process and maybe its been over looked for some time, but any motor needs a little correction.
To be safe and really if you are thinking its rich, go richer and see for sure, yes its rich and the move was the WRONG way.
Buy an assortment of main jets and some more plugs. Don't go by the what goes on with only the same or plug color a 100%. Sure the signs of extreme of rich or lean will be show but we are talking tiny changes. The small change from 390 to 400 is minor and wont be a real easy thing to read from the plug. But It will be something you feel and notice only at wide open.

Try to go for the same gear and speed, spot and to hit it once through the RPM spot and change away to find a way it will responds too best.

Steve

Thkx for your input Steve.
Your comment make sense and I will probably go along that road...and I will be careful, I don't want to seize a brand new engine
I read somewhere that oil ratio could be an issue also, again, doesn't make sense as the same symptoms appeared with a lower oil mix with the "old" engine.
Reading your post, another thing come to my mind: the needle valve could be culprit (strange to me was changed 2 years ago and I didn't rode that much). But worth a try to put a new one before starting to play with main jet.

You are right, this is a fantastic bike and I wouldn't trade it for a new husky or any orange one

I will revert with results (be patient, we are under total lock down here due to the coronas**t and getting anything is a nightmare).

Did

Needle and main do rub and contact all the time, from vibration and sliding and do wear a little
I have seen it on the 510s, the most. When they just change the 2 out, again new stock sizes it clears up many of the rich conditions.

I have 2 88 WRs, they are great.

Good luck and i'm sure you will get some more replies to test with from some other left kick riders.

Cheers.

Steve

Your comment make sense, vibration and sliding can change the jet diameter, good point !
I just ordered a new needle valve and jet(s), we will see what I will get from those, at least I will be 100% sure that I start from a clean point.

Thkx again for your feedback and enjoy your WR's !

Cheers,

Did

ps: Next step, restore the WR250 1988 stored in boxes for the time being

Silencer good ? Check spark arrester if equipped . How are all grounding points from stator to coil ?

Could be tons of issues.....

Lots of good input above.

Here are few that relate to richness.

Crank seal on tranny side might be sucking oil.

Blockage in pipe or silencer.

Weak ignition.

Didn’t accidentally use a resistor plug versus non resistor plug?

Reeds in good condition?

Make sure choke plunger is not open slightly.

Carb vent hose not plugged?

Make sure you don’t have broken piston ring.

Make sure float isn’t letting excess fuel into intake.

Forgot to take paper towel out back of carb when cleaning filter.

How fresh is your fuel? Didn’t make a mistake without knowing on premix ratio?

If water cooled? Sure you don’t have small amount of antifreeze leaking into cylinder?

Classic plugged spark arrestor.

Yup, go through that silencer. I once had the perforated core break and "displace" so that only about 1/4 of the area was flowing from one piece to the next. Had exact same problem.

And the Band is Back together!!

+1 on the blocked exhaust.

Hello Everyone,

Feedback about my problem which is now SOLVED !
This could maybe help others;

Changing the needle valve and putting a new jet (same value) solved my problem !

Things to remember:
When getting suddenly too rich at WOT, change needle, needle jet, needle valve and a new main jet (same value) before starting playing with different main jet.

Thkx to everyone involved and enjoy your day (probably home as everyone on this side of the pond...)