Sherpa 350cc 183 (1976) wiring problems / no spark

[Jcarteradams]

Hello all, 

I have a Sherpa 350cc 183 (1976) that is in need of some attention as she’s not starting. 

Ive cleaned the carb and jets and replaced the spark plug, but realised here isn’t any sparks coming through. 

Ive take some pictures for you guys as I think it is wire fault which I can’t seem to bend my head around! 

There seems to be a cut off switch installed but I’m just not certain about the actual wiring in general so thought I would ask the specialists on here. 

If you need any more pictures or info then please do ask. 

Thank you in advance. 

Regards 

james 

[lorenzo]

James - 

Welcome to the forum - nice to hear from a Bultaco owner from my neck of the woods.

Bike looks like it's been standing around for a while.

Re the lack of spark :

Where does the HT lead tail off to ?  (Can see it attached to the coil and the plug, but it seems to disappear off the pic.)

I think for starters (sorry for the pun) you should ditch, or at least disconnect the kill button, which looks so rusty it may be causing the problem.

Then check out/remake the connections and clean the contact-breaker points.

 

[lineaway]

Just looking at the condition of the bike, the condenser will need to be replaced or added at the coil wire.

[sherpa325]

Bultaco points ignitions are quite reliable  and easy to work on. The black wire goes to the coil and kill switch and the green is earthed as it appears on your bike, however the coil doesn't look like a Bultaco one but I could be wrong.You will need a flywheel puller to replace/clean the points and as has been suggested definitely replace the condenser. As you only have two wires coming from the flywheel it would appear the other ones have cut off or terminated in the flywheel area, so that would need to be checked also. First thing to do is remove the kill switch wire and clean the points, making sure they are opening and closing and go from there - make sure to run some clean paper through the points after you clean them to remove are residual dirt/grease.

Cheers Greg

[stevem75]

That wiring looks correct.  Green is grounded through the white wire to the ignition coil bracket.  Black comes from the points to the coil.   But that kill switch looks suspect.  I’d disconnect it and try again.  If still no spark then for the heck of it disconnect the white wire from the coil bracket.  If still no spark then reconnect the white to the bracket and carefully clean the points under the flywheel.  They may just be dirty and slightly corroded.  

Steve 

[Jcarteradams]

Thank you so much everyone. 

Yeah the bike has been standing around for a long time and needs a good refurb. It’s my first one and I’m loving the process so far. 

The HT cable really is that long and loops around back into the picture as you can see, it was coiled up and tied to the frame so it will probably benefit from shortening.

The kill button is most certainly coming off as everyone suggests and I think this will sort it, but shall I just disconnect and leave the wiring as it is or is there something else I will need to do?

I have ordered some bits from In motion, such as new condenser which I will relocate as suggested. I’ve also ordered the flywheel puller so we can get in and give the points a good clean up / tweak  as suggested. 

Once I have done all this I will report back with some news. Here is some more pictures just so you can all see the project in hand. 

[tony27]

From what I can see the connection for the killswitch is the type that can be opened & the wire removed without needing to cut anything, just remove the wire & clip the cover back together while you check for spark, you don't need a killswitch fitted until you try starting the bike

Another thing to check is that the crimped connections on the wires are actually working which will involve a multimeter when you have the flywheel off, it could be a good time to replace the wires while you're relocating the condenser which will make sure the connections are all good & there isn't a break in a wire

Shortening the plug wire isn't a silly idea, looks like you'll have enough left over to have a spare for the future, replace the cap while you're doing that

 

[lorenzo]

James - 

Already looks way better after a clean !

My intitial suggestions were based around the assumption that the bike was actually running before it was stood up, and doing the absolute minimum to get the igntion working and seeing if the engine can be persuaded to run. Wiring to kill switch looks like a piece of old rubber-covered mains cable.......bin it.

Does the engine have compression ? (A drop of oil down the plughole may assist what's already there)

Is the fuel tank alloy or fi-glass ?

 

[Jcarteradams]

Hi Lorenzo 

Yeah I’ve even had the wire wool out on it and it’s looking great, but still not starting! 

The bike hasn’t been going for a few years now but I have taken another look today and have replaced the spark plug and cap, air filter and removed the cut out button. I’ve also cleaned the points up and relocated the condenser, but still no spark! 

I havent adjusted the points or anything but they are closed when you look at them. 

There is plenty of compression and the tank is fibreglass. 

Bit confused over the electrics situation!? 

Please do take a look at the pictures of the points and the condenser I’ve relocated, I believe the condenser is wired correctly as it’s from the black wire. 

Also, before I go purchasing new points, HT and tension coils, re wire etc, I probably should understand a little more about it, and I just can’t see when exactly the points should ‘open’? I was trying to see exactly when I was looking for a spark on the plug - I was pushing the kicker down with my hand and looking right in but couldn’t see any movement. Am I correct in thinking that the points start closed and then open to a setting of roughly .4mm. Or do they start open at that setting and then close?

Any advice on setting the ignition timing too would be great as I should think that is off too. 

Furthermore, the kicker is really hard with the spark plug screwed in, but without it in it’s seems very easy. Is that normal?

Many thanks again

 

James 

Edited August 7, 2019 by Jcarteradams

[lorenzo]

James - 

Looks like you're on the right track.

The condenser needs to be earthed, i.e. the outer casing needs to make electrical contact with the frame.

Don't buy anything in the way of more parts just yet.

The two screws fixing contacts to stator plate enable the gap to be set at .016" (or .4mm)  fully open : slacken big screw, turn little screw either way (eccentric cam), tighten big screw. 

The cam that opens the contacts is formed around the centre boss of the flywheel - make sure that it's smooth and rustfree. The  "lift"  part of the cam is around the keyway  and you should refit the flywheel with this at the bottom to avoid damaging the points operating heel., making sure that you don't dislodge the key  (For the time being simply re-fit stator plate with screws in centre of slots). Once the flywheel is back on you should be able to adjust the gap as necessary through the two little access windows.

Here is a schematic of the ignition system, which you may find helpful :-

 

With the spark plug screwed in there will be considerably more resistance when kicking - for this reason DO NOT kick when magneto cover is removed, as this could bend the shaft......!

Don't leave fuel in the tank - the ethanol content will dissolve the resin, and you will add a leaking tank to a list of other things to be fixed....... 

[Jcarteradams]

Evening all, 

So I’ve had a bit of time today and managed to replace the HT Coil with a Buktaco one, replaced and repositioned the condenser and re crimped the wires and soldered the new connections. I’ve replaced the points, spark plug and the cap, yet still no spark! 

So I guess I’m left with a timing issue which I’m unsure how to do, I can find TDC on the piston but unsure what to do with the position of the points and magneto. The points are set to open just a bit. 

Or I guess I could be left with replacing the low tension coil!

I shall double check all the connections again tomorrow. 

Any other ideas?

i also think I’ve flooded it, will this make any difference to gaining a spark at all? 

Many thanks and hope we can get it fired up, not really up for the garage doing it after all this time and effort but perhaps that could be the best bet after the weekend! 

J 

[bullylover]

You will need a set of feeler gauges to set the points correctly. The gap should be .40mm. after that check the plug gap. It should also be .40mm. If you still have no spark then there must be a break in the wires somewhere. Use a multimeter to check the black and the green wires from the ignition up to the coil. Make sure the earth between the top coil and the frame is bare steel. To set the timing you will need a Dial gauge or something similar. Good luck. Graham.

[sherpa325]

The points have to be set with the flywheel on and are set through the right hand slot. As you rotate the flywheel counterclockwise the points will open when the second slot [right hand] passes over centre and exposes the points, it will be directly above the left hand slot.Remember even new points need a clean piece of paper pulled through them to remove any grease or residue.You should still get spark even if the timing is out provided the ignition system is all good. If you set the ignition backing plate in the centre of the three mounting slots and set the points as above you wont be too far out.

Cheers Greg