Wassel with Mikuni with Lucas Coil

[FGF]

Hello ,
Now the running in is finished on the B50 , the clutch has stopped to slip : Full throttle !

And NO , It doesn't want to fire correctly , misfiring at high rev ....
It fires correctly on the idle and at mid-range .
The Mikuni 's main jet was 200 at the beginning as my seller told me , now 240 : same problem misfiring

I don't see any air leak with fuel on the inlet manifold , i 've tried a little fuel filter with short fuel hose , nothing.

I 'm going to try the 190 main jet but i shouln't want to be too lean , and next may be to change the igntion coil ( original Lucas now )

It 's really a B50 , I 'm sure
Francois

[beat]

hi Françoise,

what kind of air filter you are using ?
can you try ( run ) your bike with NO air filter in place and se what happened ?

beat

[FGF]

Hello Beat ,

I put a '' K&N RU1710 '' air filter , so a large one .
I shouldn't be very comfortable to ride without air filter...

I think too , I 've seen somebody writing that some ignition coil heated with the Wassel-Vape...

Francois

[Mark Cook]

It might make sense to change the coil to the Wassell recommended one.

https://pesltd.uk/?ptno=LU47276

[baz]

Not sure if this would apply to a mikuni but I had misfiring on my b50 at full throttle
It turned out to be the float needle jet was too small on the concentric float bowl I was using

[Armstrong Phil]

Just cured a misfire at high revs on my A65, it was the ignition switch, old age and vibration had got the better of it!

[FGF]

Thanks a lot ,

As Phil wrote , i read again some BBENXE 's old posts : he cured a similar problem by shaking electric connections ...
I think i 've put a kill switch on the handle bar which couldn't be suitable with the B50 vibrations ..

First , the kill switch and if not air filter , ignition coil ...
It takes time for me as my decompressor is really tired and the weather is cold now to start one kick
Francois

[beat]

And NO , It doesn't want to fire correctly , misfiring at high rev ....
It fires correctly on the idle and at mid-range .

this sounds for lean mixture for me, - so the cheapest test is to run it shortly with no air filter to be sure there is no kink rubber ore a to tight filter fitted.

beat

[FGF]

Thanks Beat ,
I wanted to try some solutions like it this afternoon and ....of course the B50 didn't agree with me !
two kicks , POUM POUM and return spring broken ....

Bye bye for two weeks
Francois

[beat]

.of course the B50 didn't agree with me !
two kicks , POUM POUM and return spring broken ....

Cheeeeeeeers

[Mark Cook]

This should help.

https://pesltd.uk/?product=57-4338

[beat]

This should help.

at least it helps perfect in my case...

beat

[FGF]

Already ordered Beat ,...
But waiting for parts , the winter will be back and my garage is very cold , not as yours i could see

[Mark Cook]

Thank you, Francois,

[FGF]

Hello ,
kick spring , PES kick lever replaced ...i try a longer ride...

Always misfiring at high revs without my kill switch BUT with hot engine , the engine stalls .
It starts easily , fires fairly at mid-range and stalls again .

It doesn't seem to be the Mikuni 's fault ...
The spark plug colour is right .
kind B50 ...

[beat]

hi Françoise

Always misfiring at high revs without my kill switch BUT with hot engine , the engine stalls .
It starts easily , fires fairly at mid-range and stalls again .

my guess is still the carby.
have you checked the plug in the center of the bowl, - is there shurely no water drops ore other bits in they can block partly the mayn jet
is enough fuel entering the carbs bowl

IMO, spak plug color is misleading in top revs.

beat

[baz]

Hello ,
kick spring , PES kick lever replaced ...i try a longer ride...

Always misfiring at high revs without my kill switch BUT with hot engine , the engine stalls .
It starts easily , fires fairly at mid-range and stalls again .

It doesn't seem to be the Mikuni 's fault ...
The spark plug colour is right .
kind B50 ...

I'm still thinking maybe fuel delivery
Does the misfire stop if you close the throttle a little?

[kommando]

Is it fuel or ignition ?

Fuel issues show at certain throttle openings, change the throttle opening and if the symptoms go away then its likely a fuelling issue.

Ignition issues show up at certain revs, change the revs and if the issues goes away then you likely have an ignition issue.

These are general rules which are guidelines not hard rules.

Other clues are time, if it happens after a certain time then a could be a component that is failing once warm eg a coil.

So mark your hand throttle and experiment.

[FGF]

Hello
Thanks for these advices.
My ignition switch was dieing slowly , so the engine stalled more often.
I ordered a Lucas replica for this week end ....

I 've changed many jets on the Mikuni and it 's a new carburator , 1000 kms

I 'd like to try an easy solution , some told me to ride without the DB killer on the megaphone '' Megaton ''.
I 've removed the DB killer and the counter cup .
It starts always first kick and the noise is better than with the counter cup , but the ignition switch stalled the engine.

I 'll try again after this week end with a new ignition switch...
Francois

[beat]

don't forget to switch it to " ON "

wishes you a good new year Francois

beat

[FGF]

Hello Beat ,
I can imagine you , jumping with your snowboard today with the sidecar sleeping in the warm garage !
The beginning of the Swiss Cross championship is not so far , best wishes too to start it with a reliable B68 engine

You 're right , i 'm diving myself in the nightmarish electric box this week end...
Francois

[FGF]

Hello ,
New ignition switch , DB killer removed .
I 've been very kind with the electric box :
It start first kick and no misfiring now , the engine breathes fairly , it would be possible to try a 260 main jet later ...
And a longer exhaust as a Dunstall , Vattier ...

[beat]

hi francoise

And NO , It doesn't want to fire correctly , misfiring at high rev ....

New ignition switch ,

It start first kick and no misfiring now

I have had twice problems with the main switch. when I was imagin what it could be, it was easy to find out finally: whilst running the bike, and listening to the misfiring, I was holding one hand on to the switch, pressing the key strongly to the left ore to the right.
pressing to one side - engine stopped, - pressing to the other, - engine was running fine. live the switch alone, - misfiring.

the all trouble was a result of the enormous vibrating this old english shaker is producing....

wishes you many nice and long rides with your B50 in 2023.

beat

[hhh]

I've had similar issues. I wonder if running a large capacitor after the switch would be a good idea? Of course it would mask a failing switch in the early stages, but they probably all have moments where they're intermittent that mess with electronic ignition timing. Normally capacitors (like on a Norton) are placed behind the switch where they wouldn't help this problem at all.

[minetymenace]

Sounds like a good idea hhh

[beat]

running a large capacitor after the switch

Sounds like a good idea

what size capacitor ?? - do's it needs a trailer on behind the bike for it

[hhh]

Something similar to the Norton stock item, around 10,000 uF@50V should do it.

[kommando]

Fix an original is the best option, the new ones are rubbish but the old ones suffer from a bad design that can be fixed.

https://www.nocnsw.org.au/technical/reb ... terthannew

[BSA_WM20]

under the axiom that nothing so simple works so well it can not be made to run better by making it more complicated.
fit an ignition relay
My OIF A65 used to eat switches
After fitting the relay, no more problems

[Ian Hingley]

under the axiom that nothing so simple works so well it can not be made to run better by making it more complicated.
fit an ignition relay
My OIF A65 used to eat switches
After fitting the relay, no more problems

Yep, agree with Trev. He's mentioned this before and I've done the mod on my Victor IHO. Instead of all the ignition current passing through a potentially dodgy ignition switch, it passes through the more robust relay.



Ian

[beat]

interesting.........

beat