HI i have been chasing a miss slowly in my engine, its a 1776, twin 40mm dells, slightly higher compression, and worked standard heads. So far for the miss i have replaced the following
-coil
-cap
-rotor
-leads
-plugs are iridium and should last 20k plus and have only 5k and look a little black but ok.
-all conections are good.

now i was talking to someone last night, and he suggested it could be a burnt out valve?

it seems to run on three and backfire and pop alot. its its idling, and i remove each lead in turn, number one doesn't efffect idle. It doesn't back fire much at idle.

I have a guage to compression check the engine, but forget what pressure it should be? 110 to 130 PSI?

can somebody confirm what pressure it should be and also any other ideas to check.

its been a few really bad months, with a broken gearbox (reverse completely gone), broken starter solenoid, burnt out ignition swtch, fuel pump breaking...... and all in the last 4 weeks plus the miss!!

Hi,
I did a compression check on my 1835 the other day and it was 140 psi in each pot. Doesn't mean yours will be the same, but just look for a large difference, like 3 will be 110psi and one will be 75psi etc. How's the fuel? No water in the tank?

had the tank out and cleaned out, so fuel is good, if it was water i would assume it would effect all cylinders?

Condensor & points?
Unless you have electronic pick up?
A good stock motor should have over 130psi, so high compression I would expect to be higher again. All depends on state of wear of course, As Sandy said, having them all close to the same is most important.

Also worth checking, but not likely your problem is does the dissy advance smoothly (vac & mech. depending on your dissy)?

Yeh, but I sort of had the same problem, I'd take off no.3 lead and the idle would stay the same. Turned out I had water in the fuel, so I can't explain it. Just thought it may be an idea.
Cheers.

thansk for the idea sandly, its better to check than not to and find out that was the problem. yet new points and tried another condenser.

its just getting annoying. i will check the compression tonite, and see if its all the same. i think the compression is about 8.9:1

the engine is under 25k old, but has been abused on the track, so extra wear and tear is expected

Could be a dud spark plug. It doesn't matter how good they look, it still could be.

Blocked idle jet.

well the plug is fine, i pulled it out and earthed it against the block, and it sparks nicely.

Good idea dave, but even under power it still misses, so assume the idle jet won't effect this?

It sure will.

check the earth lead inside the dizzy

check for airleaks in the intake side

check exhaust for leaks

are all the valves adjusted?

Is the timing spot on?

how is the mixture, rich can kill plugs

check compression on all four and see if there is one dropping

you can check the valve by taking the carby off, looking in with an extension light to see a bit of the valve, a mate then turns the tip of the valve with vicegrips, this is a real butcher way of doing it, dropping the engine to look at the head is the best option.