• 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 The previous version was outdated and no longer supported.

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    Thanks for your patience and support!

390 Auto - Ignition Options

M

msmith345

Husqvarna
AA Class
I was looking into the 1980 390 ACC project last night. I'm still trying to evaluate where it all stands before I invest too much time and money into it. Anyway, I ran into a gotcha, that I need some advice on.

The guy I bought the bike from had bought it minus an ignition. It was said to be running fine before that went bad/missing/whatever. He had picked up an ignition off ebay for it, but he had not been able to identify that it was in fact a 1980 390 ACC.

I was pulling the stator and flywheel out of the baggy last night and fitting it up when I noticed the flywheel fits the crank taper perfectly, but the stator seems too be too tall for the flywheel to seat correctly. It's a motoplat ignition, and I can pull the numbers off it tonight, I just forgot to bring them with me to work when I wrote them down.

Looking through the parts list, the 1980 390 ACC had a unique part number for the flywheel/stator (16 14 751-02). The other 1980 390's had a different number and the '78/'79 autos did as well (16 14 714-01). Further, the right side crankshaft is a different part number for the auto compared to the other 390s of 1980, but it matches the part number for the 76/77/78/79 auto (16 10 851-01).

So, since I know the one with the bike was incorrect, and finding that exact original part might be a bit of a challenge, I was wondering if anyone knew the compatibility details of this.

It seems like the taper could very well differ between the auto and the other 390s, based on the right side crankshaft. However, the 76-80 would all have the same taper. So, they I would think they should fit.


I'm still trying to assess this all. But if my options are maybe finding a stator/flywheel on ebay, or having to buy one that costs more than the bike did, just to see if it will run then I might be looking to part with it and start looking for a new project. Everything on the bike will need to be gone through, but so far from what I've checked everything else seems to be in surprisingly good condition, despite the rough appearance.
 
The part numbers may be different, but I am not aware of different physical dimensions for any of those years, they should all be the same Auto or not. It is much more likely the ignition he got on eBay was not the correct one for any year or model 390, not just the '80 ACC.
 
From looking in the parts manual,Automatics use a Motoplat Mini-6 type,smaller diameter,shorter height stator and flywheel,along with a spacer plate and an adapter on the case,topped off with the small square 125cc type mag cover.
 
Yes, after reading that I went and had a look at mine. The 390 6 speed has a bigger set-up than the 390 AMX. Also the R/H crank stub is smaller on the Auto as Dave points out. I will need to look at buying an ignition for the Auto as all I have is the flywheel and innards. No coil unit. I am tempted to go for the MZB unit as it looks like good value for money with a decent lighting output.
 
Power Dynamo is the new MZB. They are very costly but good. Electrex World also make ignitions that are less costly.
 
Well, I had another thought...Sent an email to Penton Racing to check the feasibility of it.

I've got a PVL sitting in a box for my 2012 that I ended up not using, but also can't return. The setups are pretty simple, and I'm thinking without comparing them yet, that at most I would need to swap out the mounting plate, rotor, and the coil (from the 4000 to 5000 coil), and I'd still be able to use the cdi and stator. If I can get the other parts needed individually, that is.

If that works out, it wouldn't make me feel so bad about (a) having a $500 unused ignition sitting in a box, and (b) spending another $500 for an ignition, for a $500 bike that I don't know if it will run. I'd be out a headlight, but that's not a deal breaker for me.
 
i have a 79 wr250 motoplat i would let go of pretty reasonably...would that work on the auto? the system has been in dry storage but hasnt been used for 10 years...worked great when i had the 79 in action
 
I was wrong, I forgot the regular 390 used that gigantic ignition, I guess the Auto doesnt need all that flywheel so it uses the regular Mini 6 Motoplat. It should be the same as any '75-'80 250 Motoplat ignition.
 
I thought all 390s came with the big one, but apparently some Autos had the small one like on the 250 and later open bikes.
 
Kartwheel68 said:
I thought all 390s came with the big one, but apparently some Autos had the small one like on the 250 and later open bikes.
Click to expand...


From what I can tell, there was a 13mm, 15mm and 20mm crank end. All the autos seems to use 13mm (pre-82), like the 125s. 250s seem to split between 13mm and 20mm, then for 82 everything standardized on the 15mm.


-- This has me thinking, maybe the flywheel I have is correct, as it does fit the crank, but the stator itself is just incorrect. Going to take a closer look tonight and take some measurements and jot down some part numbers. Try to give myself something to reference while I scour the internet for information.
 
There are three crank snouts, the Femsa points (20mm) the pre-'82 (15mm) and the 13mm. All 250s '74-'81 had the 15mm except for some WRs with the Femsa. All the 390s should have the same snout, and with the correct stator/flywheel combo you should be able to swap the Mini 6 and the big one.
 
Alright, I've been emailing back and forth with B.J. Penton this morning. Man he's on top of things. He was also pretty interested in what parts I had, so we'll see if he has any input as to what those were originally for and if I can make them replace one of the two and make it all work.

So, if you have an auto and are looking for the MZB/PowerDynamo it's #40351. The PVL is #70054. I can reuse all except the stator and flywheel for the PVL I have, and he can sell those individually, so that puts it pretty reasonable.

The Motoplat setup that came with the bike is:
Stator part no. 48986
Flywheel part no. 98868

I'm not matching those to anything on ebay right now, so my method for identification isn't working out so hot.
 
grouty said:
Be careful if you are thinking of changing the R/H crank stub !
The parts books are wrong regarding the part number for this part.

See here ...... http://www.cafehusky.com/threads/motoplat-390-timing-issue.20363/#post-177895
Click to expand...


Thanks. I'm hoping to not have to split the cases yet. So, changing out the stub isn't on my list of things. much rather find a solution to what's there. I appreciate that post though, I'd not come across it yet, and that provides some really good info regarding the crank stubs.
 
I wouldn't use a PVL on the auto. PVL uses an internal rotor with very little flywheel effect. Autos use the external flywheel as far as I am aware. My 78 390 AMX ( mini 6) does and so does my 84 500 AE (SEM).
 
PEZBerq said:
I wouldn't use a PVL on the auto. PVL uses an internal rotor with very little flywheel effect. Autos use the external flywheel as far as I am aware. My 78 390 AMX ( mini 6) does and so does my 84 500 AE (SEM).
Click to expand...

Yep, I was wondering about that. It is for sure internal on a PVL, with a lot less mass. The MZB would be much closer to stock.

With how the automatic engages, would the flywheel mass have much of an impact? The engine isn't going to stall, so I would think that less flywheel would cause it to engage and disengage sooner. Not sure if the engagement would be harsher on parts, but yeah...it's had me thinking a bit. You can get a FWW that bolts to the PVL rotor. So, that's possible. Still holding onto the possibility of figuring out a stock one. If not the PVL has the appeal because I already have several of the components, so it's not such an investment. The MZB/PowerDynamo would be the best for this application, I'm thinking.
 
The flywheel mass helps keeps the engine from stalling. Autos idle into corners and you do not want them to stall as you can't bump start them. A small flywheel would make the bike a little snappier I agree but that is not necessary for an open class bike. Also a PVL with small flywheel does not produce as good a spark as an external flywheel modern ignition as I understand it.

Autos need to be nailed....not chugged along at slow speeds. This reduces slippage of the clutches and keeps operating temperatures down. The effect of the flywheel is not significant compared to how you ride it. However perversely autos are famous for snotty enduros because clutch slippage helps with traction....but at the expense of running the transmission very hot. Several mods for oil coolers were tried over the years but these days we don't tend to use these vintage bikes for hard core enduros any more....luckily! The refined gentlemen prefers short 3 lap motos and short enduro loops with a big rest after each!
 
PEZBerq said:
The flywheel mass helps keeps the engine from stalling. Autos idle into corners and you do not want them to stall as you can't bump start them. A small flywheel would make the bike a little snappier I agree but that is not necessary for an open class bike. Also a PVL with small flywheel does not produce as good a spark as an external flywheel modern ignition as I understand it.

Autos need to be nailed....not chugged along at slow speeds. This reduces slippage of the clutches and keeps operating temperatures down. The effect of the flywheel is not significant compared to how you ride it. However perversely autos are famous for snotty enduros because clutch slippage helps with traction....but at the expense of running the transmission very hot. Several mods for oil coolers were tried over the years but these days we don't tend to use these vintage bikes for hard core enduros any more....luckily! The refined gentlemen prefers short 3 lap motos and short enduro loops with a big rest after each!
Click to expand...


I am after all a rather refined gentleman as her indoors will tell you:lol:
 
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