1972 Kawasaki 500 H1B

[Taipan]

I stuck in fresh fuel today and took the bike for a short run. Same issue.

It pulls cleanly for the first couple of miles,then begins to misfire badly. Turning on the indicators makes the misfire much more violent.

The header of the middle cylinder is noticeably cooler to the touch,so this is the one being affected. How this ties in with the indicators beats me!

Still,at least I now know it wasn't bad fuel. That's got to be some kind of progress,right?

Have you pulled the plugs to see if the middle plug is more sooty/oily than the others? At least you'll know if its a misfire that way, as if the plug is dry we can assume its fuel related?

[Skub]

Have you pulled the plugs to see if the middle plug is more sooty/oily than the others? At least you'll know if its a misfire that way, as if the plug is dry we can assume its fuel related?

I put new plugs in as one of the elimination points,so there's not much colour to any of them yet,as it never runs long enough to tell! None of them look out of the ordinary at the moment.

[Yorick]

Have you pulled the plugs to see if the middle plug is more sooty/oily than the others? At least you'll know if its a misfire that way, as if the plug is dry we can assume its fuel related?

I put new plugs in as one of the elimination points,so there's not much colour to any of them yet,as it never runs long enough to tell! None of them look out of the ordinary at the moment.

When we were racing we all did plug chops. Flat out in high gear, then hit kill switch. Then check plugs

[Skub]

When we were racing we all did plug chops. Flat out in high gear, then hit kill switch. Then check plugs

Don't forget to pull the clutch in too.

[Taipan]

Have you pulled the plugs to see if the middle plug is more sooty/oily than the others? At least you'll know if its a misfire that way, as if the plug is dry we can assume its fuel related?

I put new plugs in as one of the elimination points,so there's not much colour to any of them yet,as it never runs long enough to tell! None of them look out of the ordinary at the moment.

Did you, or can you, swap teh coils around to see if the misfire follows the coil to another cylinder? The indicator thing makes me think its an earth issue. As you know, bikes of this era had crappy electrical and charging systems on...

[Skub]

Did you, or can you, swap teh coils around to see if the misfire follows the coil to another cylinder? The indicator thing makes me think its an earth issue. As you know, bikes of this era had crappy electrical and charging systems on...

I have an old strobe in the garage somewhere,lying unused for the last 100 years,so the plan is to use it as a spark tester to give a pointer.

The bike is really clean and I've been over all the earthing points and connections,everything rings like a bell. The indicator thing does suggest an earth fault,but I'm buggered if I can find anything.

I've actually stopped being annoyed and I'm now mostly curious to see what the resolution will be. If there ever is one.

[Taipan]

I cant get my brain to work but i know I had similar on an old bike, indicator dimmed the headlight and the bike would splutter etc. Cant for the bastard life of me remember what bike it was, or how I , or soemone else, fixed it!

We used to make up little additional earth leads and hook them up between whatever it was that was suspect and a chassis point or neg battery terminal. Just a length of wire with ring connectors at each end.

[Eclipse]

I know you checked the earths but it might be worth isolating them to the 3 coils and running them straight to the neg on the battery
and see if the problem disappears or is still effected by the indicators

[Skub]

I know you checked the earths but it might be worth isolating them to the 3 coils and running them straight to the neg on the battery
and see if the problem disappears or is still effected by the indicators

Good point,cheers man.

Update. I ran a ground wire from a casing screw to the main earth point. Issue remains.

The bike is getting more difficult to start from cold,it dealt a couple of decent backfires from the middle pot before it decided to run.

I took it out for a couple miles and it's still got the indicator misfire and the intermittent miss on a steady throttle.

I found my strobe and connected it up. On the left and right pots,there's a nice steady pulse showing on idle and when revving. On the middle pot the light pulses when the revs are up and nothing at all on idle. I can hear the centre cylinder picking up when the revs hit around 3k.

So,breaking down coil is likely.

For the sake of £30 at this stage of the game I'm willing to take a punt.

[mangocrazy]

Reading back through the thread I noticed that you'd checked the resistance of the plug caps but not replaced them. Ever thought of swapping the middle plug cap with one of the plug caps from the outer cylinders and see if the fault follows the plug cap?

[Eclipse]

Did you try swapping two coils to see if the problem moved to another cylinder ?

It would be interesting to see if the indicator problem effected all cylinders or just the middle one
I tried to find a wiring diagram for it online but only found low res crappy ones.

[mangocrazy]

Having a triple means you have three of everything to use for substitution testing

[Skub]

Having a triple means you have three of everything to use for substitution testing

And two H1s for some parts too.

[Ian]

Maybe check for pitting on the distributor too - does yours have a flat disc with metal strips on the end of the alternator rotor? Brushes got plenty of life in them?

[Skub]

Maybe check for pitting on the distributor too - does yours have a flat disc with metal strips on the end of the alternator rotor? Brushes got plenty of life in them?

Distributor on the H1a Ian. The B came with points,mine has Accent ignition.

[Ian]

Ah! Mines such a bitsa it's had all sorts on there

Sadly I don't have any spare coils.

Have you unscrewed the end of the coil, pull the HT lead out and cut 1/4 inch off? There a spike in the end sometimes it doesn't make great contact, same with the plug end.

Maybe the condenser if it's points - try riding with the points cover off so the condenser doesn't get so hot. Not permanent, just to see if it makes a change

[Skub]

Ah! Mines such a bitsa it's had all sorts on there

Sadly I don't have any spare coils.

Have you unscrewed the end of the coil, pull the HT lead out and cut 1/4 inch off? There a spike in the end sometimes it doesn't make great contact, same with the plug end.

Maybe the condenser if it's points - try riding with the points cover off so the condenser doesn't get so hot. Not permanent, just to see if it makes a change

Yeah,I replaced all the HT leads earlier. The bike is a points model,but they've been changed to Accent ignition.

A new coil arrived today,so when the spirit moves me I shall fit it and hope for a result.

[Ian]

Sorry I wasn't familiar with accent. It really does look like the coil is the only thing left

[Taipan]

[Taipan]