missfire till warm

well its getting warmer up here in canada so it seams to be running better now that i ride it everyday.
readjusted valves,
cleaned carbs,
new park plugs
adjusted air to fuel

still burns and leaks a little oil but im still goin to ride it

[KEITH KRAUSE]

Your symptoms sound a lot like a leaking valve seal. Cold/hardened seals allow oil to drip through.
Just a little oil coats the plug at cold start up and it won't fire. As things warm up the oil film wears off from raw fuel washing it and as heat increases it helps basic combustion. It starts firing. The pops you hear are from accumulation of unburned fuel in the header and at some point it combusts. Once fully warm things clear up.
I would guess the longer the bike sits the worse the problem? Generally, the cylinder on the sidestand side is effected first, or at least noticed first, simply because of gravity allowing the leak to enter the combustion chamber. Depending on the position of the valve at turn off, the volume of the leak can change. In a worst case scenario, a lot of oil can enter over several days and you'll get a lot of smoke at start up. Other times you may see no smoke at all but the plug can still foul.
If the above is the case here, you can clean off the plug well and cold start up may yield a pretty good firing plug. Eventually, you'll have to replace the seals. Parking on the centerstand can help temporarily. Riding the bike more often can help too.
Could be other things too as others have said.

[49er]

bike fired right up after i put the carbs back on but the left side is still dead till warm then she pops like a gun till it kicks in ,,
spark plugs right side looks good left black but not oily
after work tomorrow i will be looking at the valve clearance any one else have an idea ? workings of a dieing coil ?

Electrical faults usually get worse when heat builds up. I doubt that you have a dud coil of lead. Re-check the carbs and their mounts. Also thoroughly check the condition of the airbox seals and mounts.

Tight valves could also be an issue.

Because it runs better after it warms up, my bet is a partially plugged pilot circuit on the left carb.

bike fired right up after i put the carbs back on but the left side is still dead till warm then she pops like a gun till it kicks in ,,
spark plugs right side looks good left black but not oily
after work tomorrow i will be looking at the valve clearance any one else have an idea ? workings of a dieing coil ?

Seriously. I'm not sure if it was the 400, but I remember seeing somebody post some time back that one model engine had to be removed from the frame to gain access to the airbox for removal.

I believe there was a thread concerning the 1983 750E that required tipping the engine forward to remove the airbox. I've never personally seen the airbox on the 83, I figured it was the same as the 80-82 16 valve airbox. I've had the airbox out of mine and it did require removing the battery box and a bunch of other stuff but not the engine.

[Steve]

Hopefully somebody will speak up and edumacate me ...

was it the 400 or some other bike that required engine removal to take out the airbox?

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[49er]

Please don't think I'm just pulling your leg here, but was it the 400 that you had to pull the engine to remove the airbox?

Seriously. I'm not sure if it was the 400, but I remember seeing somebody post some time back that one model engine had to be removed from the frame to gain access to the airbox for removal.

.

Steve, this sounds like an advert we had running over here last year where the customer leaves his auto with a mechanic for a tune up. When he returns to pick up the car the mechanic says, "Well, we had to drop the sump so that we could disconnect the the con rods and draw the pistons to check the spark plugs. And sure enough, they needed changing". The look of dismay on the customers face had to be seen.

well that dont sound like fun i think im just goin to give it the old one two and see where it gets me

[Steve]

.... also does anyone know how to get the air box out with out bending every mounting tab on the frame?

Please don't think I'm just pulling your leg here, but was it the 400 that you had to pull the engine to remove the airbox?

Seriously. I'm not sure if it was the 400, but I remember seeing somebody post some time back that one model engine had to be removed from the frame to gain access to the airbox for removal.

.

ok carbs pulled, still looks as good as 2 years ago when i rebuilt them,

would the valves (I/Ex) give me this effect, weak coil or ....

also does anyone know how to get the air box out with out bending every mounting tab on the frame?

I would check the ignitor. If yours can be taken? apart do so and check the solder connections on the circuit board...
make sure you have 12 volts at the coil

[Johno]

Electronic ignition and battery

Does your bike have electronic ignition?

You should have a good fat blue spark on both plugs.

Make sure your battery is fully charged or you may get a weak spark on one or both cylinders.

Don't ask me how I know! It took me nearly two years to get mine right and the difference is amazing. I hardly need any choke now and warm up is a breeze in comparison to what I was putting up with.

[1948man]

I'd love to watch and help out what little I can I but can't make it Saturday.

[Steve]

In Steve's case, I think he's just lucky. He also gets "free" motorcycles, how often does that happen to the rest of us?

Yeah, I'm always "lucky", but sometimes it's bad luck.

As far as getting a "free" bike, sure, there was no money that changed hands at the time, but so far, the tab is at about $675 to get "Freebie" back on the road (not counting registration and insurance).

I am going to be changing clutch springs on him tomorrow, anyone want to tag along?
Sunny central Florida (at least until it starts raining in the afternoon), temps are finally back up where they belong, should be a decent day.

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[Steve]

OK, sounds somewhat reasonable. The way it appeared when I first read your statement, it sounded like you had done each set several times. Now I see that you have also done several other sets, too.

It's just that I rebuilt the carbs in my wife's bike almost 5 years ago and they have not been apart since then. Since we live in oHIo, we have several gasoline-powered engines that only see seasonal use. Besides the bikes, this includes mowers, snowblowers, weed whackers, etc., so you can see that several of these engines are idle for months at a time. By using either Stabil or Seafoam in the fuel system before parking them, I have never had any problems with "dirty carbs" when it's time to use that device again. Chances are, if you use some sort of fuel stabilizer before you leave for your month or so, things should be just fine when you return.

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