vf1000 fe missfire

on starting my 84 vf1000 fe seems to only run on two or three cylinders then all four but has a constant miss fire popping in exhaust on tick over it takes a fair bit to start from cold when riding the bike gos ok untill revs are low then popping in exhaust could it be pick ups ?

Hi jayruss

Have to admit that I stand alongside you on this one, but can’t help. Possibly similar problem mysefl…? I have an '84 Vf1000f… starts from cold ok, runs - but with popping at low revs, occasional backfire and then complete and sudden engine shut down. Difficult to start when warm though. Under normal circumstances seems to be getting fuel ok. If you find a solution I’d be keen to explore… . I’ll try anything at this stage.

hi jayruss,
to me your problem sounds to be more like carbs than electrics, is your bike standard or do you have aftermarket cans and air filter…

when you say that you get complete engine failure… does it feel like you have run out of petrol… then does the bike start up again as normal when its cooled down ?

VF Pete … thanks for reply. Yep, that’s it. Wondered if it was CDI? Everything else has been examined but nothing odd found. Any advice would be great.



from my own experience i have never had an actual CDi go faulty, the only problem i have encountered with them is the wires breaking about an inch below them, this resulted in 2 cylinders dropping out then coming back in instantly as the wires contacted again, which lead to a few quite hairy moments especialy going around a roundabout in the rain…

i have encountered a few faulty pulse generators, the first one on my 1984 fe, symptons were… riding along as normal, partial loss of power as the 2 front cylinders dropped out, then bike eventuall lost all power as if it had run out of fuel,
This happened because the pulse generator that suplies the impulse to the 2.4 cdi failed, this inturn knocks your front 2 cylinders out and your fuel pump relay, which switches the fuel pump off, hense running out of fuel,
This was quite a tricky one to find as everytime i was recovered home i would check for sparks, ok, check pulse generators, ok… and anything else i could think of checking at the time, all ok… the bike would now have completely cooled down and would restart as normal again…
It turns out that fault on the pulse generator was intermittent, apparantly when the heat builds up inside the engine it causes them to loose all there risistance and fail, then as they cool they come back to life,
I changed them for a new set and the bike has never missed a beat…

If the pulse generator for 1.3 cylinders failed, you would probably be able to keep the bike running on 2 cylinders, the tacho would drop to zero or fluctuate as it is on the same circuit.


Thanks, that’s great… it definitely happens when warm and normally starts ok from cold.
It doesn’t, however, feel like fuel shortage rather than just immediate shutdown… Would that be the case from a pulse generator? I guess can but try… bike is rodgered with out it…
Any ideas where I could find one? Is it an idiot proof fit (it would need to be for me to try :confused: ), or best auto-electrician to fit it? Thanks a lot fo rthe advice.

electrical problems are dammed awkward things to sort, the same fault can throw up different symptom’s, and the same symptom’s can have different causes.
the pulse generators come as pairs and are wired together with the harness and block connector, they are an easy fit… last time I looked they were still available at cmsnl, quite pricy though at about £120 a set + postage so you need to be pretty sure you have checked and double checked everything else before going down this route.

Hi… I don’t think the pulse generator failing would feel sudden unless both failed at the same time… i know you say it dosent feel like the bike runs out of fuel. But one of the first things I would try is bypassing the fuel pump relay… I must have at least a 6 relay in the shed, all of which have intermittent faults on… (I have had that much trouble with them in the past that i don’t evan have a relay fitted to any of my vf 's)… depending on how you are riding it is pretty sudden power loss when the petrol pump stops running as no fuel can trickle through the pump…
And the best thing is it won’t cost a penny to try it…


Sorry about the delay. thanks a lot for advice, I will (once I figure out how to do it) try that.
Great fourm, very helpful.
Thanks a lot.