Mikuni and Pazon questions

After two years of restoring my 72 Combat, including Pazon ignition and Mikuni VM34 I started it for the first time last night.
Two kicks with switch off, started on first kick with switch on. Better than I hoped.
However tonight a different story, lots of kicks, drying plugs, confirming spark ok, etc.
Lots of small coughs but finally fires up.
After a couple of minutes settling down nicely it cuts off. Won't restart.
Check for spark with plug on head, nothing! I will check all Pazon connections so hoping just a connection problem.
Does this problem sound familiar with anyone and should I be looking for something in particular?

The Mikuni question is that I notice when I depress the starter plunger lever the rod that goes down through the rubber seal tends to return down 1/16" - 1/8" after my thumb leaves the lever.
Is this normal, possibly the way the seal below reacts.
Or is it maybe not opening the passageway fully at the bottom of the plunger resulting in the more difficult starting today.
Can someone look at theirs and see what happens.

Thanks
Bob

Dont run the bike with the choke on, use to start and then switch off holding revs up manually, they foul the plugs very quickly on the choke

Dont run the bike with the choke on, use to start and then switch off holding revs up manually, they foul the plugs very quickly on the choke

splatt said:

Dont run the bike with the choke on, use to start and then switch off holding revs up manually, they foul the plugs very quickly on the choke

Click to expand...

Yes found the same thing with a VM36 plus fouled if starter circuit on for 30 secs switch it off right away.

First Buy new plugs, and a spare set. Second did you seal between the intake and manifold. I used ultra black between the two. It made a significant difference.

splatt said:

Dont run the bike with the choke on, use to start and then switch off holding revs up manually, they foul the plugs very quickly on the choke

Click to expand...

Initially I tried to turn off choke within 5-10 seconds but cut out. I probably didn't have enough throttle open.
I was leaving it on longer the next start to get some warmth built up in engine but I probably did leave it too long.
However the cut off was so abrupt it seemed more like a fuel or spark cut off. Since the Pazon spark was gone I'm guessing it was caused by loss of spark.
In the future I'll cut the choke as soon as it starts. I'm still feeling my way on this.

I used the gasket sealer that Old Britts recommends on the manifold to head gasket so I'm thinking there shouldn't be a leak there.
The cut off was abrupt so I doubt if a leak there would cause that.

I'll look at the electrical feeds to/from Pazon tonight.

I'm using .028" gap on plugs. With electronic ignition would a different one be advised?

Thanks for advice
Bob

Bob,
Sounds like an electric out problem. Did you put a new wiring harness on? If so, go and check the fuse terminals. I had 3 that dropped one of the terminals, flimsy little tin cap. Replaced with solid copper and tough solder.

Mick

rx7171 said:

The Mikuni question is that I notice when I depress the starter plunger lever the rod that goes down through the rubber seal tends to return down 1/16" - 1/8" after my thumb leaves the lever.
Is this normal, possibly the way the seal below reacts.
Or is it maybe not opening the passageway fully at the bottom of the plunger resulting in the more difficult starting today.
Can someone look at theirs and see what happens.

Click to expand...

I checked mine and the plunger does return about the same amount as yours when I let go of the lever. I don't think it has any effect. Mine's always done it. This is a great manual for the VM. It shows the plunger and it seems the circuit is not going to be sensitive to that last 1/8".
http://www.mikuni.com/pdf/vmmanual.pdf
So if that probably aint it and you said:

Check for spark with plug on head, nothing! I will check all Pazon connections so hoping just a connection problem.
Does this problem sound familiar with anyone and should I be looking for something in particular?

Click to expand...

then it does sound like maybe it's the ignition. I have a set of jumper wires with alligator clips for things just like this. Try bypassing everything in the harness, switches, connectors, fuse, the whole thing; and go right to the battery. I hate the 'authentic' wiring harness. Consider running a relayed ignition. Then, either the thing is totally and completely powered up or it's off.
P.S. Is the battery charged up?

Things are looking up.
I went through all the electrical connections to the Pazon ignition and although I didn't find an obvious problem I've got my spark back.
Started ok this evening so I had a chance to set the carburator. Idles nice and for now I've set it at 1100 rpm.
This Saturday I'll take her out to start the break in on the rings but right now there is no smoke, sounds great and no oil leaks.
I did put in that cv from Mikes so I'm hoping none will show up.
Thanks for the help.
When I've got the tank and side panels painted and she's looking pretty I'll post a picture. Big improvement after sitting for 30 years in a garage.

Bob

Funnily enough I was having some problems after my 750 top end rebuild, fitted a 34 Mikuni and it wouldn't fire up, it offered but wouldn't run on. Pretty pissed off at this point after all the TLC its been getting. Left it a couple of days then re assesed what was happening, found BOTH petrol taps were blocked and flowing hardly any fuel, changed them and then decided to fit the new Pazon I had in stock. What a difference! The bike runs better than it ever did. I'm considering junking the Boyers on the rest of my Commandos and switching to Pazon, a much better made bit of kit. Just back in from re torquing the head down. Pity Winters round the corner, don't want6 to get it dirty now so may put it in hibernation till next year!!
Short You tube vid of it firing up
http://www.youtube.com/watch?v=hdafOMxFurs