F1 Sport Running on One Rotor

[barney]

Hi All,

I have an F1 Sport that was rebuilt by Richard back in the NML days.

I've got a consistent problem with it running only on one rotor. The symptoms are,

Bike starts fine, runs on both rotors

Warms up a little, drops back to one rotor. (Before the ticker drops on the temperature sensor)

Occasionally after a bit of a run, the second rotor comes back to life. (This only happened once I think - I got stuck and had to come back 2 junctions on the M4)

Here are the things I have tried.....

Rebuilt the carbs, new jets, needles and float jets and needles. I even bought a dial gauge to set the jets correctly.

Replaced the plugs - it now has expensive iridium plugs (same result as standard cheaper plugs btw)

Replaced the coils - I noticed one coil was leaking oil, so replaced both coils.

Replaced the HT leads.

Still the problem persists. I've managed to identify it's always the brake side rotor that's the problem. With a little effort I can remove the HT lead to that rotor while the bike is running.

I've also started the bike with that plug removed and it's making a good spark. Only problem is I don't know if its making a spark because the bike would be in a mode of running on two rotors if the plug was connected!

I've put my inductive coupled strobe on the HT leads. The strobe fires on both HT leads, even when the bike is clearly only running on one rotor. However I'm not sure how good a test this is as the strobe also fires when coupled to the earth to the battery!! There obviously a big enough pulse flying around to trigger it even if their isn't a spark or a fire at the problem plug.

I'm desperate for some help and advice please!!!!.....

Questions I have are,

Does a rotary have a redundant spark? i.e. can I swap the plug leads to see if the problem rotor moves from brake side to clutch side? (I'm assuming they don't, as there is a yellow lead to the -ve on one coil and a white wire on the other coil - I assume this means the ECU is firing the coils separately and at different times)

My bike has the later type ECU fitted - is anybody aware of problems with these units? Can they fail or go intermittent?

Is there anything else anybody can suggest I try or check?

Thanks in advance everybody.

Barney.

[Joe]

Hello Barney,

First of all, good on you for being able to remove the plug lead all be it with a little effort, I can't even see mine.

I suspect the most likely cause of your problems are wiring, remember these bikes are over twenty years old now. Check the three pin plug and socket which feeds the coils, check carefully each individual terminal both male and female and the actual wires. Verdigris, green corrosion on the copper cable is a common problem. Also check the two pin connector at the pick up depending on what type of box (ECU) you have.
Tha later type ECU's are very good. I've had one for years covering over 150,000 miles without any problems despite problems with my voltage regulator once pushing I think from memory 35 volts through it, it still works fine.

Two types of ECU are available but both are made by Julian Kemp at Mini Mag. The Norton unit has two threaded plug and sockets with a 3 pin round multipin plug for the black car type pick up which is different from standard Norton where as the Startright unit has the same plug as original Boyer and is a direct replacment so uses the original two wire pick up.
If you have the latter type you can swap the H.T. leads around but you'll also have to exchange the polarity of the pick up plug at the socket. It's tight but the plug can be offered into the socket the wrong way round. Doing so should transfere the fault if any to the other side, gear side, confirming both rotor housing and fuel system including carbs are ok indicating a pick up fault.
I can't remeber if I have modified my F1 Sport wiring or not as I last used it in 2011 but it has two of each type of connector so yours may have too, check them all.

Cheers, Joe.

[barney]

Hi Joe - thanks for the reply.

I'll recheck all the connections, but I don't think is a copper corrosion problem. This bike was completely rebuilt by Richard in Rugeley in '05 and has only done 7k dry miles since then. The loom and connectors are all very clean and new.

I had an email from Richard overnight he thinks it might be sticking rotor seals. I'm just waiting to hear from him as to how these might be unstuck without a major strip down!!

If anybody has any other ideas I'd greatly appreciate them and I'll keep updating the board with any news!!

Thanks in advance,

Barney.

[fogrider]

My first thought was the bi-metallic strip on that side carb jet. Its' part of the cold enrichment, if it has gone duff, or failed somehow, maybe that could make the mixture far enough out to cause a misfire.
A mixture probe in each silencer end would give some idea of what's happening - rich or weak . Simple to do anyway.
Regards, Terry.

[wust588]

The only thing I can think of is that you might have a carb flooding problem.

Although the F1 and F1 Sport share the same fuel pump, as far as I can remember, the Sport has no way of controlling pump
pressure. The F1 has the fuel tank weir.

To see if this is the case, remove the tank and carb dashpots, switch on the ignition and see if fuel comes up the main jets.

[wust588]

When you rebuilt the carbs, did you change the choke O rings?

[steve traynor]

I believe my f1 played up on right rotor due to boyer ignition was replaced with startright ignition which richard had rechipped by mini mag maybe to alter timing or max revs ?

[barney]

Guys - sorry I just released as I reply to another thread, that I hadn't closed off this thread with the final answer.

It was the carbs! again!!! The cold start mechanism wasn't returning properly. Once I fixed that, we where on the road again!!

Thanks again for all the help.

Barney.