The 30 has 2 pickups, the 35 has 2 within 1 unit, so any slippage will alter all 4 sparks timing.
They feed ignition coils sparking the 2 rear [1 and 3] and 2 front plugs [2 and 4]
There is little common to diagonal or left or right hand side pairs of cylinders.

Do you have a spark at the failed cylinders?

I still find it odd that first the rear 2 fail, then the right hand pair, and now diagonal?

Dave.

Pickup resistance around 500ohms, if faulty then likely open circuit or short circuit.

arsey30 wrote:The 30 has 2 pickups, the 35 has 2 within 1 unit, so any slippage will alter all 4 sparks timing.
They feed ignition coils sparking the 2 rear [1 and 3] and 2 front plugs [2 and 4]
There is little common to diagonal or left or right hand side pairs of cylinders.

Do you have a spark at the failed cylinders?

I still find it odd that first the rear 2 fail, then the right hand pair, and now diagonal?

Dave.

Pickup resistance around 500ohms, if faulty then likely open circuit or short circuit.

I have this problem also found several problems with my carbs. emulsion tubes in wrong, dirt in float bowls, broken pilot jet. Mixture screws out 2 1/4 turns out manual says 1 5/8.

Man, this is doing my head in now. I'm getting good spark from all cylinders but only 2 will fire. It runs on full choke but when I push the choke in I have to hold the throttle full open to keep it running. I did manage to get the two rear and one front running for about a minute but then one of the rears stopped again. I'm going to wind the mixture screws out a 1/4 turn on the two cylinders to see if that will help tomorrow , failing that I thing I will have to take it.to a shop and pay them to fix it.

With all plugs firing and cylinders failing at random, it still points to carbs/fuel.
Opening the pilots may see an improvement, but will only mask the fault if weak.

Is the fuel supply OK, [float bowls full?] Does it pop or bang in exhaust, and won't pick up.

Carbs dirty, or wrong assembly Iis most common fault, only running on choke is a clue.

Dave.

I've had carbs in the past that were unable to be tuned out, usually affeting the fuelling at starting and idling.

I put it down to the choke enrichment circuit having blockages/restrictions from old fuel gum. The only way to fix this is by ultrasonically cleaning each carb assembly (you need a decent sized ultrasonic bath for this). Leaving fuel in the carbs during storage can cause this very easily.


Point is, you can't always adjust the carbs to sort out issues.

Cammo wrote:I've had carbs in the past that were unable to be tuned out, usually affeting the fuelling at starting and idling.

I put it down to the choke enrichment circuit having blockages/restrictions from old fuel gum. The only way to fix this is by ultrasonically cleaning each carb assembly (you need a decent sized ultrasonic bath for this). Leaving fuel in the carbs during storage can cause this very easily.


Point is, you can't always adjust the carbs to sort out issues.

I think you hit the nail on the head. This bike was laid up for 5 years. But I was told the cabrs were ultrasonically cleaned ? By the state of the carbs they did not take float bowls off. The choke made no difference at all if any thing it did not help bike to start I am still waiting for my new pilot jet. Is it worth dismantlining choke side as I have not touched it yet.

samace wrote:The choke made no difference at all if any thing it did not help bike to start I am still waiting for my new pilot jet. Is it worth dismantlining choke side as I have not touched it yet.

That's typical symptoms of the enrichening (choke) circuit not working corectly. Pulling each choke plunger out and spraying with carb cleaner will probably not solve the issue, at least it hasn't in the past for me.


Finding a cheap ultrasonic bath that's big enough for each carb is a task, but it's on my wanted list as carbs with these issues are probably salvageable. Buying a known good set of used carbs might be cheaper in the short term.

Talking to a few people on the estate were I work this morning and would you believe theres a guy on the estate that restores bikes and does sonic cleaning.Went to talk to him this morning and he said bring the carbs to him and he will sonic them for me for nothing.How cool is that.Nice to have a bit of luck for a change.

Sounds good.

Let us know how it goes.

TROUBLED OTTER wrote:Talking to a few people on the estate were I work this morning and would you believe theres a guy on the estate that restores bikes and does sonic cleaning.Went to talk to him this morning and he said bring the carbs to him and he will sonic them for me for nothing.How cool is that.Nice to have a bit of luck for a change.

We had a tank in work but its broken could have got all four carbs in at once !!