Getting the ht leads off the coils was a problem so I took the ht leads off of the rear plugs and started the engine, it ran exactly the same as with them connected so I guess I now have a twin not a v4!

I measured the resistance of the coil the secondary was as per haynes but the low voltage side seemed high but my multimeter isn't that accurate at low resistance.

I guess the coil may be shot, so is it a case of trying a new coil?

Also it is likely I have flooded the rear cylinders and buggered the rear plugs?

Why not just swap over the front and rear coils to check them out.

arsey30 wrote:Why not just swap over the front and rear coils to check them out.

Struggling to get the ht leads off the coils, or are the leads fixed to the coils?

Are the coils and leads compatible front to rear

Or is it a case of just brute force to get the leads off?

Coils are reliable, check the low tension wires/connector first
The leads push into the coil, I can't remember if the electrode centre pin is spiral or straight.
The hollow threaded plastic retainer grips them with a tapered ring, unscrew the retainer.

You could just fit the complete coil, leads, caps to the rear, if you can get to the front caps [behind top rad]

Dave.

Neosophist wrote:

oldgreyandslow wrote:Got more carb cleaner sprayed at front left carb rubbers and the revs rose to 2k fell back after a while so I sprayed some more but this time there was some cracking from the ht leads and the revs fell so is it an air leak or an ignition problem, or both?

sounds like the rear coil isnt working.

Swap the coils over and see if the pipes get hot in the reverse order

as i thought it's running on two.

Easy way.

Swap the fron and rear plugs.

If the sytomps are reversed its plugs.

If not its coil related.

Bolt the whole coil inc plug leads off and swap it with the front.

if its not the plugs then theres a problem feeding the coils so it's either a broken wire, bad connection or faulty pickup / ecu

Neosophist wrote:
as i thought it's running on two.

Easy way.

Swap the fron and rear plugs.

If the sytomps are reversed its plugs.

If not its coil related.

Bolt the whole coil inc plug leads off and swap it with the front.

if its not the plugs then theres a problem feeding the coils so it's either a broken wire, bad connection or faulty pickup / ecu

Plugs were new last month, however if they have had some time being flooded in petrol as they're not firing I suppose this may well have buggered them?

If it proves to be coil related the challenge then is to find out if its the coil itself or something feeding the coil on the low voltage side. Out with the Haynes.

This bike is a real bastard! It looks like I've moved on to electrics now, I wonder what'll happen when I try to fit the braided brake lines?!?

It's probaby becuase it's suffered many years of neglect at the hands of previous owners. A risk when buying any 'old' bike.

The problem is compounded on the 400's as there owned by many abusive young people who see them as a 'stepping stone' to larger bikes.

Plugs can be knackered right out of the box, i've brought plugs only to have an intermittent miss, spent hours chasing it only to find out it was the new plugs!

Flooding them will also kill them quickly.

Before you clean up the plugs (or try to) swap them over first and see if the sytems are switched, changing just one thing at a time is easier for diagnostics.

Its not plugs, swapped front to rears and the rear pipes still stay cool the front ones hot

I'll swap coils tomorrow when I get an 8mm socket

Its not the plugs, the coils, or the HT leads.

Swapped plugs, still front pipes hot, rear pipes cold

Swapped Coils, no change

Swaped HT leads, no change

So it must be either a wiring fault or pulse generator or ICU

Or?

Haynes says to check the wiring at the black 4 pin connector, it looks as if there are two 4 pin connectors and this is the top one, correct?

I am a little unsure as to how it disconnects? Haynes also says to measure the resistances, no problem. Is it possible to check the wiring? I assume the wires run from here to the LV side of the coils?

Is it common to get faulty pulse generators or ignition control units?

Bloody bilke'll be in the skip soon!

Its gota be carbs then, as ive said your problem sounds very similar to mine yet you've got it on 2 carbs where as mine was just the one. I stripped and cleaned mine within an inch of their life a number of times and everything looked spot on yet one of the float needle seats was dodgy, i only found this by accidently swapping them round front to back.

Replaced dodgy part and hey presto............it still didnt work lol. No seriously it did get a lot better but still not perfect so atleast i know im on the right track. Im putting it down to the carbs sitting with stale petrol in them for too long and messing the rubbers up