Boyesen reeds will undoubtably be better anyway.

But it ran fine before you rebuilt the bike...............so its not the reeds, too much of a coincidence.

I agree with Mark, but replace the reeds anyway.

Just to get it straight - 'Is the PV servo still messing around?'

helisupp wrote:But it ran fine before you rebuilt the bike...............so its not the reeds, too much of a coincidence.

There were signs of a bit of a problem before the rebuild but nothing like it is now

knackeredMk1 wrote:I agree with Mark, but replace the reeds anyway.

Just to get it straight - 'Is the PV servo still messing around?'

Not now.

Mike thinks similar to you and the dredded ECU is a possible. I spoke to my engine guy today, told him what I had changed and apart from reeds he said the generator or pick up could be on the way out but said if it was the generator it would be more likely a mis fire at high revs. He then suggested if not that, the ECU. ECU off to Mike tomorrow so should hopefully confirm if the ECU is the offending item

Some very swift analysis of my ECU by Mike (MTFB) and the ECU is OK (phew, that has saved me a few £££).

It's this midrange misfire that's the odd conundrum.
Unlikely to be fuel related as the main jet was altered and no discernible difference was apparent.
So, it's more than likely one of the following, coil, lead, HT cap, field coils, or pick up coils.
The magneto's not been disturbed of late has it?
Idiot question, you have tried alternative plugs?, sorry.
Bad earth, unlikely.
No chance the needle has got bent whilst out of the carb?
Mike

fallenmikethebike wrote:It's this midrange misfire that's the odd conundrum.
Unlikely to be fuel related as the main jet was altered and no discernible difference was apparent.
So, it's more than likely one of the following, coil, lead, HT cap, field coils, or pick up coils.
The magneto's not been disturbed of late has it?
Idiot question, you have tried alternative plugs?, sorry.
Bad earth, unlikely.
No chance the needle has got bent whilst out of the carb?
Mike

So, it's more than likely one of the following, coil, lead, HT cap, field coils, or pick up coils.
- will change the coil, lead and HT cap this weekend
The magneto's not been disturbed of late has it? - engine got rebuilt over the winter so possible
Idiot question, you have tried alternative plugs?, sorry. - 3 different one's all the same type
Bad earth, unlikely.
No chance the needle has got bent whilst out of the carb? - posible, will change it form a spare Mk2 carb I have

So MFT, in nine days and 2 pages of posts all that has been checked is the ECU.

If the ecu is fine and the servo motor is acting up something does not add up at all.

I would set the servo at halfway and unplug it from loom, run bike and see what is happening. If you are getting a misfire something is wrong with ignition (one thing at a time, easiest first) or an electrical connection, as you have just assembled the bike its probably something you have done to it, it normally is.

If it was ok before, and not now, what have you done.

If it misfires start a list so tail is not being chased, and good for future engine problems for everyone:

1.ECU...is fine and tested
2.Regulator...
3.Plug lead and cap...
4.Coil...
5.Generator....
6.
7.
8.

ECU back on, - same problem
HT lead off, cut a bit off the end and changed the plug cap - same problem
Checked the earth on the coil to frame - good but same running problem
Video of the sero running http://www.youtube.com/watch?v=0MGL1woq ... e=youtu.be

video of servo disconneted at half setting

The mis fire can be heard http://www.youtube.com/watch?v=shBM8NEq ... e=youtu.be

I can't change the coil as the spare I have is a mk2 and they are different.

I can send you a coil to check if you return it.

I have not seen you post that the voltage regulator is working correctly. Third time asking.......

helisupp wrote:I have not seen you post that the voltage regulator is working correctly. Third time asking.......

Can't see this a being problem, then again, eletrics are not my strong point

knackeredMk1 wrote:I can send you a coil to check if you return it.

PM sent

The expansion pipe hasn't acquired a new dent lately has it? Or the exhaust system altered in some manner?
Mike