1978 390 CR Will not Fire Up

[Mangosteen]

Dear Husqvarna Gerus
I am new to this site and would very much appreciate any guidance or advice on getting my 1978 390 CR which has been sitting indoors since 1982 up and running. I found it in April and have been going through it all.

I just finished installing a Power Dynamo ignition system set up with a nice blue spark at 2.5 to 3 mm prior to top dead centre and the nut torqued to 50 ft lbs.

The reeds looked good and were intact and not seized in place.

New fuel of 94 octane mixed at forty to one with Castor 927

Carb is a 38 mm Mikuni with a 2.0 slide, 430 main, 45 pilot, 6DH3 needle, clip in middle position, screw turned out exactly 1.5 turns. Bike is in Western Canada in the Okanagan valley sitting at 340 meters above sea level with ambient temp of around 30 to 32 deg C.

Petcock just rebuilt last night with correct kit and holds fine.

Yesterday no sign of floats in carb flooding as no gas came out of the overflow tubes.

After many repeated attempts with choke on it would not even fire. No snort no hiccup and no kickback or any noise to indicate ignition. Compression measured at 90 psi yesterday.

Opened throttle to full with choke off to clear any gas. No life while kicking.

Tilted bike on left side to drain carb and gas came out.

If I put my finger half covering the spark plug hole if barely gets damp. There is a subtle mist coming out of the spark plug hole but not sure if mixture is rich enough. Pulled spark plug barely has noticeable gas on it.
Poured a half tablespoon of gas in cylinder through spark plug hole on two occasions and zero life.

My kick is aggressive after the compression build. I have a 1976 Husky 360 WR that I use full choke to get running. I also have a 1977 Maico AW 400 that I use the tickler quite a bit to get running.
Are there any starting idioscyncracies that need to be tried with this black beauty?

How do I know if there is enough atomized gas running into the combustion chamber. Other than when I poured the primer into the cylinder have not been satisfied there is enough fuel going into it from the looks of the plug.

What can I adjust or check. Maybe the carb floats are not allowing to fuel in the bowl high enough? But yet there was plenty of gas in the bowl when I turned the bike on its side to drain the bowl.

The bike now has sat overnight with plug removed on the theory that the crank case has been flooded with too much gas as the primer technique did not show any sign of life.

Your kind advice or starting technique would be most welcome.

 

[Mangosteen]

 

[justintendo]

90 psi with the throttle held open, kicking until the needle wont climb anymore?? are you able to get a good kick on it? sounds awfully low to me. should be 150-165 psi or so.. most of my rebuilds have been 80s models but my 79wr250 was 165 psi with fresh topend.
if you install the plug, kick kick kick and remove the plug and its pretty dry, i doubt you are flooded.

probably obvious, but are you sure the bike is set before tdc and not after?

bike looks great otherwise. i would think the bike should at least start and run "decent" with the book spec jetting you are running. if you are positive everything is right and the plug is pretty dry when you remove it, ive had good luck on a new start holding wot and kicking till it runs. careful tho as this can flood it after awhile. ive had to do this before on a new assy that needed "primed".

be sure the kill works and kills spark in case it does start and revs up or wont shut off.

 

[troy deck]

r u SURE the pilot jet is clean that hole is tiny i would think 90psi should be enough to do something DOUBLE CHECK that timing i kinda screwed up with my electrix when i installed it dont remember what i did to many years messin with motoplates

 

[silverstreakNZ]

have you tried crash starting it ? everything has to be perfect for them to kickstart .

 

[troy deck]

crash starting sucks LOL seen there anybody know how to get blood stains off white plastic

 

[grouty]

Double check the timing. When timing from TDC make sure you go back anti-clockwise on the flywheel to get your measurement. Been there done that !
If the timing was correct, it should have at least tried to fire when fuel was poured in the top.

If it has been sat since 82, I would have suspected the crank seals would have gone west ! That may explain the low compression reading.

Cracking looking bike :-)

 

[Mangosteen]

Ok just redid the compression readings this time holding full throttle and kicking hard for a longer time.
Got readings up to 132 psi now.

Next I will double check the timing going backwards as suggested and making sure I am 2.5 to 3 mm prior to Top Dead Center with my gauge that screws into the spark plug hole.
What is crash starting. Riding down a hill in second gear?

 

[Mangosteen]

Dear All

Just rechecked the ignition timing very carefully and indeed it's exactly 2.5 mm prior to top dead Center. Spun the flywheel backwards and had repeatability of the reading at top dead Center so I feel very confident the timing is spot on.
Did this twice. Just rocking the flywheel between 2.5 mm prior to TDC and TDC and double checking the gauge in the spark plug hole reading.

 

[troy deck]

grouty the expression is [gone south]

 

[silverstreakNZ]

south is degraded. west is gone burger

 

[grouty]

Gone south is where relaxed riding muscle goes ! Gone west is (as Silverstreaknz says) burgered !

 

[Mangosteen]

Dear All

Got it firing and running for only about six or eight seconds. I ended up pushing it and bump starting it down hill and it started quite fast but would not sustain running. Tried it without choke and then later with choke but would not sustain. It revved up to half throttle no problem but shortly thereafter died.
Petcock on and gas supply to carb good.
Thought the float was stuck closed but when I layed the bike on its side gas came out of the overflow.
Does anyone have any suggestions on what to check or try. All three times when the motor died I was revving about one third to two thirds throttle trying to get some motor momentum and continuous running.

 

[suprize]

check float level isn't too low as this will prevent starting. although it should have fired with the primer....

 

[Mangosteen]

Bike works perfect now. Problem was some dropped out castor oil in the bowl.
On top of that went through the Mikuni in fine detail including using a drill and a Qtip along with Brasso to ream and clean and polish the needle valve port. Tested the holding of the port needle assembly when on bike and held perfect.
Initially had to start it on a steep hill but once it ran it was really good. Idles perfect. Takes two kicks to start it. Thanks for the kind help. Still have no clue on the British or Down under terms used in some of the responses but thanks to all.

 

[84scrambler]

The low compression would be common on new top end that has not seated yet. Other wise if it has not been replaced its probable leaking out the crank seal. Or in one of my bikes cases one of the previous owners installed the wrong con. rod and it was to short to make compression. You said the rings looked good ? what does this mean , did you base this just by looking ? or did you measure end gap and check the clearance in the cyl.
Try adding some oil in the cyl. and then do a compression check. If this is not a new top end it must have more than 90 psi. to run properly.
If you ever get decent compression make certain that the bott. end is dry by letting it sit with plug out for 3 or 4 days then use a blow nozzle to air it out even.
Here is a starting procedure that is weird but works,
turn fuel petcock on
apply choke
put bike in 3rd gear
rock back and fourth more forward than back and count to 30
turn fuel off
put bike in neutral
choke off
now kick start
should start on 3 or 4 kicks.
then don't forget to turn fuel back on.
Good luck.

 

[Mangosteen]

Thanks 84 Scrambler. Actually the motor is virgin. Never been apart. Never raced. It was casually driven by the original owner from 1978 and finally parked in his basement since 1982. Seat is original. Compression after lots of kicking and open throttle did reach 132.
The bike now starts good with a kickstart. Problem was castor oil drop out in the bowl. Now I mix at 40 to one instead of 24 to 1. Was following the owners manual on mineral oil at 24 to 1 hence the problem.

Was surprised the castor oil did not stay in solution but maybe it was oil that was stored over winter and for some reason did not mix properly this summer. On the other hand I was mixing with the portable tank nearly full. Now I have learned to only use half tank to allow VIGOROUS mixing and mixing by shaking hard.

 

[84scrambler]

Good to hear that it runs, would love to see the bikes..

 

[justintendo]

Thanks 84 Scrambler. Actually the motor is virgin. Never been apart. Never raced. It was casually driven by the original owner from 1978 and finally parked in his basement since 1982. Seat is original. Compression after lots of kicking and open throttle did reach 132.
The bike now starts good with a kickstart. Problem was castor oil drop out in the bowl. Now I mix at 40 to one instead of 24 to 1. Was following the owners manual on mineral oil at 24 to 1 hence the problem.

Was surprised the castor oil did not stay in solution but maybe it was oil that was stored over winter and for some reason did not mix properly this summer. On the other hand I was mixing with the portable tank nearly full. Now I have learned to only use half tank to allow VIGOROUS mixing and mixing by shaking hard.

yes, the old ratios no longer apply. 40:1 will serve you well. i try to put the oil in can first, then fuel as this really mixes it up. perhaps i use a different brand of oil than you but i have never had castor oil separate, even in the winter months when i put the studs on or let a bike sit for a month.

 

[Mangosteen]

Very strange how the 927 separated and I have been mixing two stroke fuel since the 70's. Maybe it was a bad litre of castor oil from the get go.
Even in the gas tank I watched how globs of castor oil seeped down the transparent fuel line. That was at the 24 to 1 ratio.
Now at 40 to 1 no issues. Bike starts on second kick without choke after an overnight cool off.
Funny because the Husky 360 WR needs full choke to get going in the summer months. Photo attached as requested. It has been restored to museum quality.