Forum

[Dennis C]

OK guys, a magnet when heated has it's magnetic strength reduced, and recovers when it cools, while riding the bike the airflow helps the cooling, and an immediate restart can be quite easy however when stopped the engine heat rapidly conducts along the armature on the SR series mag's and heats the magnets giving a weak spark. It took me four years to find the cause first time, since then I go straight to the cure. 😁😁😁. Your choice whether you believe me or not but I am sure that is the problem as I have cured three bikes with this.

[Mark M]

I don't absolutely disagree with Dennis, (sorry if I gave that impression,) I'm just saying check the carb first because a) it's easier than dismantling the mag and b) I have had similar problems with new Monobloc carbs before. I gave several suggestions, all of which have led to problems for me in the past, rather than give ideas one at a time. On the subject of plug colour, modern fuel leaves virtually no colour on the ceramic of the plug when mixture is ok so the colour could indicate rich running? Of course, it could also indicate a failing mag.... And remember the words of the wise man: "99% of carb problems are in the magneto and 99% of magneto problems are in the carb" !

[Rattlebattle]

To me it has all the signs of a failing mag; poor hot starting is nearly always the first sign. Most likely cause here IMHO. That said another possibility is fuel evaporation caused by the lack of heat insulation between the carb and the head. Because our host's carb conversion kit for the EFI model lacks any heat insulation (no room to fit a spacer) my C5 usually needs the carb tickling if left for a few minutes. I doubt that's the issue here, but if it were the engine would, like mine, start fine after tickling the carb. I still think it's the mag though.

[Tim NZ]

IF it is the mag, then resetting the plug gap smaller (0.015" or less) will effect an immediate short term cure...

[Chris Tindal]

Thank you all for your input, it's been a great help. I looked at the plug again today and it does look sooty, so I looked at the needle position, which was on the bottom notch. I moved it up one and reset the pilot screw and tickover until it was nice and steady. A three mile ride around the block and back and the tickover was still nice and steady. Then for the moment of truth....decompressor on, engine off, fuel left on, tick, instant start., but then it did that before. Then I waited 5 minutes and tried again, with the fuel left on and it started. Then I waited 20 minutes and it started again with the fuel left on, although a little harder this time. Fingers crossed it might be the needle position and I still need to see what jets are in there. Trouble is, when bikes run fine at home, they always play up at the bottom of a hill somewhere so it's yet to be tried and tested. I'm hoping it's not the SR1 because I like the separate system, I'll keep you posted.

[Dennis C]

Hi Chris, yes please keep us informed, if you still have the problem it's only an hour's job at most to temporarily rig a coil in circuit, if this effects a cure you can then get the SR1 remagnetised it isn't an expensive job.

[Adrian]

"Then I waited 5 minutes and tried again, with the fuel left on and it started."



It wouldn't do that before, sounds like you're on the right lines, I think you'll want to keep the mag. If the problem Dennis had with his SR1 is what you have been experiencing, it would still be worth going down the re-magnetizing route, though your success thus far with carb settings suggests that might not be necessary. SO, may I suggest you go out for a blat out on the Bullet somewhere, stop for a bacon butty and a cuppa or two at a cafe at the foot of a hill, THEN see if the Bullet will start...



A.

[Dennis C]

I think I would look for a cafe with a nice view, from the hill top

[Chris Tindal]

Well I've done just that Adrian. Been on a ten mile trip up hill and down dale this afternoon and the bike ran very well. Stopped for some petrol, left the fuel on, and it started again first kick. Got home and left it ten minutes with the fuel still on, and it started first kick again. I then went to Tesco and did some shopping for about an hour, got back, tried again and it started second kick. It seems to have been the carb needle position making it too rich, so the mag seems ok which I'm delighted about. I'm still not 100% confident about the mag, but I'll leave it and see how it goes. Thanks again to everyone for all your valid suggestions. Final job now is to try and tackle some of the oil leaks.

[Dennis C]

I hope you are right Chris and you have it sorted, however I can't see any way that the needle position can have any affect on the way the bike starts hot or cold, it only comes in to use above around a quarter throttle, below that the fuel is controlled by the pilot jet and the slide cut away.