I think this has already been done in this case bypass the ignition switch and put the fused +ve straight to the start relay.
Thanks for the replies. I now I understand the operation of the starter circuit better, but I’m not sure if I’m any closer to a solution. Is the solenoid a possible cause and if so are there any worthwhile electrical checks I can do with a meter? If I changed the fuse from 15 to 20 Amps is it likely to cause any damage?
Fuse rating normally chosen as depending on the current rating of the wire. On the old Tontis it would be 16 Amp, so they (the designers) are not expecting it to be higher than that. Bear in mind that’s the max. continuous current, typically the melting current is double what its rating says.
I agree this isn’t getting us anywhere as far as what’s actually going on.
It’s feasible I suppose that the solenoid might actually have a fault, such as shorted turns, that would raise the current beyond the designed expectation. Clutching at straws really.
It did occur to me try another starter motor, but didn’t want to mention it
And depending on where you live I can lend you one.
Thanks for offer. I’ll continue to monitor the situation and may take you up on your offer by sending you a PM. I’m hopefully off to the summer camp near Norwich tomorrow - I have a supply of spare fuses packed!
Any more news on this?
The intermittent problem is still happening. I’m not keeping an exact record but I guess it starts fine perhaps 70-80 % of the time. The problem happens a similar amount on cold engine starting and hot engine starting. So far it has always restarted immediately after replacing the fuse.
The bike has not had a great deal of use in the last few weeks due to a family holiday and work.
At the moment I’m living with the inconvenience of changing fuses but would prefer a solution as I’m concerned the intermittent problem might suddenly turn into a permanent problem at an inconvenient moment !
Mine seems to have settled down now with the 15a fuse back in. I didn’t find anything loose.
One thing I did find is that you only have to touch the starter and it keeps churning . I didn’t realise this. I wonder if you keep it pressed it makes the problem worse.
I hadnt touched mine for a couple of weeks but it started first time after about 2 secs churning yesterday.
Is this a Valeo? I’m wondering if it’s simply a case of underestimating how much power the solenoid needs on these to engage. As compared to the old Bosch type say.