Coils ???

[guyver1]

Hi guys

Took the bike out earlier, got about a mile from home and the bike started to feel really rough. I filled it with fresh fuel and it took ages to start. I've checked the exhaust and found number 1 is ambient temperature only so I've fitted new leads to the coil and tried again. Bike started a little better but still not firing on number 1 cylinder.

I've tried a known working spark plug and still nothing.

Can anyone that it's the coil that's packed up ?

There's a pair of coils on eBay from a breakers yard going for £50, or pattern parts brand new £25 each

I'm tempted to go for the genuine from the breakers yard.

[Burchy]

The coils both fire 2 plugs at the same time. Known as a "wasted spark" system. So, if only one pot is not firing, its not the coil. If its not coil, or plug or HT lead, them its looking like carburation. Might be a stuck float giving a very rich mixture. Will start from cold OK but as it gets progressively warmer it will start to stall on that pot.

What colour was the plug that you pulled?

Is the vacuum lead on OK?

[guyver1]

Plug was brand new before christmas and covered in petrol so it's definately not firing, the vacuum pipe looks fine and there vacuum there, when I tested the sparks after putting the cooling system back together latter part of last year, the sparks were VERY weak all round.

It struggles to start hot and cold and needs heavy revving to get any acceleration. Also the exhaust is wet and stinks of fuel at the end if the race can, also when stationary a strong smell of fuel is present.

[Burchy]

All points to a carburation fault, I reckon

[guyver1]

What's the best way to go about cleaning them?

Can the float bowl be removed while in situ?

[Burchy]

Don't think so, there's just not enough room underneath the bodies to do anything useful.

Try this: No guarantees but it did work on YBs 11..

Disconnect the vacuum pipe from the petrol tap and plug the pipe to stop air getting in. Practice turning onto "prime" so you can do it without looking. Turn the fuel tap to "on" and start the bike. Either go for a very short spin, or keep it to a fast tickover until it starts to run out of fuel. You will find the revs start to rise rapidly from tickover. Now turn onto "Prime" and see how it goes from there for a bit,

Logic behind it is that disconnecting and blocking the vacuum pipe will stop fresh petrol entering the carbs with the engine running. The engine will gradually use up all the fuel in the floatbowls causing the level to drop and the floats with it. This will allow the needle valve to fully open. When the engine stutters and you turn to prime you will get a rush of fuel that might, just might flush through the bit of dirt causing the flooding.

If it works (or even if it doesn't), put the vacuum pipe back on and turn the tap back to "On" when you've finished.

A lot easier than pulling the carbs off

[guyver1]

If I start the bike and disconnect the fuel line till it almost cuts out then reconnect the fuel line and switch to prime would that do the same sort of thing?

[phoenix]

Did it run OK before you took it all apart? If so just take time to retrace your steps. I recently took mine apart & it was running shite when put back together. All it turned out to be was part of the carb manifold rubbers missing.

[guyver1]

It was running sweet, low on fuel as I was on the way to the petrol station when it felt like it was mis-firing, I turned the tap onto reserve which made no difference, filled up with £20 of fuel and it struggled to start. Went for a blast but it sounded like a twin instead of a four cylinder bike.

When I checked the exhausts the first pipe wasn't even the least bit warm and there was tons of smoke coming out of the exhaust.

I fitted brand new HT leads to the one coil but nothing changed.

I'll double check I'm getting a spark at plug 1 in the morning then I'll drain the float bowl and see what comes out.

[lightspeed]

If the plug has been fuel fouled you may need a new one. For some reason I've found that a fouled REX plug can almost never be cleaned and re-used. Don't know what that is about, but a fresh plug will likely be needed.

[guyver1]

Coil is sparking fine

Can't remove the carbs for love nor money

Drain the float bowls on 2,3,4 cylinders but can't reach number 1

Number 4 spat green muck out, 3 was clean fuel, 2 was empty

Bike is starting fine and all pipes are getting hot, but after 5 mins number 1 is back to ambient temperature and the exhaust is blowing tons of white smoke.

If I use a fuel additive/cleaner, what chance is there that it will clean out the gunk that's causing the carb to flood???

[phoenix]

White smoke is usually water, are you losing any?

[guyver1]

Coolant level is fine

Fuel level is terrible, half a tank on 15 miles

Got a local mechanic removing and cleaning and balancing carbs next Sunday for £60

[brakeline]

did you check the plug caps, same sorta thing was happenin to me, was corrosion in the caps, replaced them, job done

[lightspeed]

If the carbs are still flowing some fuel, a cleaner in the gas might help, but if they are actually plugged up, the cleaner will not likely be able to do anything.