Just took my 749R trackbike out to get a daylight MOT and then to get fuel. Everything was running fine on way to MOT (2 miles in town), at MOT (which it passed with one comment: "exhaust noisy"...ahem!), then rode approx 3 miles to fuel station. Put fuel in and the went to start it and it just went "click" and the EOBD orange light illuminated. Voltage was reading approx 12.0V. Couldn't bump start it with help of passing Vauxhall Corsa geezers ("cor mate, look at that tyre on yer bike...did you do that on the roundabout??") so I had to push it home in the baking sun. Now at home - charged battery for 30 mins. Starts fine again. No orange light. Revved it to 5000rpm and voltage output was about 14.5V so the charging circuit seems fine. Idle voltage (doesn't idle below 2500rpm due to Supersport cams etc) was around 13.5V. Let it warm up until the fans came on to see if it was something getting hot and breaking down - water temp got up to 102degC with both fans kicking in at about 100 and all was fine. Turned it off, started it up again - all fine. Voltages still good. Any ideas???? Got a Trackday on Monday so we'll see how it goes there. Gotta LOVE these fickle Italian machines eh? R X
Could be the regulator/rectifier beginning to fry.....they do start to break down rather than fail instantly, watch out or it may boil your battery.....I'd also check the earth connections.....maybe you need a new thicker earth lead from the battery or new leads from the battery to the starter solenoid and from the solenoid to the starter motor.....
Which earth connections? I have the LH fairing off at the moment so will check them if you can point me in the right direction. Cheers.
I had exactly this problem. Was fixed by a better earth strap available from halfords. Googling it seems to throw up suggestions of it attatching to the starter etc but im sure mine runs from the - to the frame or engine (not at home so cant check).
There is an earth strap that goes from the battery -ve terminal to the engine......that usually is the culprit.....its apig to get to as its in the rats nest behind the battery tray....
as Dave has said, sounds like a heavy duty lead has gone open circuit somewhere momentarily. Have experienced it and witnessed it a few times and it is 'a phenomenon'. No telling when it might happen but usually in the summer and at a dry, not necessarily corroded (but likely) joint.
Took battery out - didn't like the look of removing rats nest and replacing earth leads. Cleaned battery connections with emery. Removed engine earth on vertical cylinder and cleaned connector, washer etc with emery. Removed starter earth - nasty corroded yuck. Put on a new washer and nut, cleaned thread with emery and put it all back together. All started fine once again. Hopefully that will do it and it was the starter connection that was corroded. Thanks for the advice from all. R X
Yes, you are probably right. Looks like I will be popping down to Halfords tomorrow just to be on the safe side.
Been thinking about the replies: I had exactly this problem. Was fixed by a better earth strap available from halfords. and Its still worth putting a new earth strap on while you are down there....... Couple of questions: I assume that Halfords don't do an off the shelf 749 earth cable so I will need to make one up "to pattern" from Halfords cable and fittings. What exactly is a "better earth strap": do I use the same gauge wires as original or do I go up a size? Do I need to solder the fittings onto the cable or just crimp them dry? The 749 arrangement has two cables: one thick one to the starter and a thinner one to the engine earth. Both cables join at the battery -ve connector. I was planning to remove the original one and take it along with me to Halfords to make sure I get the same sized cable. Does this sound reasonable or should I go up a size on both cables? Appreciate a speedy response as I need to get this sorted tomorrow due to Trackday on Monday. Cheers, R
you definitely need to solder - I use :- 1m METRE RED WELDING OR EARTH 25mm CABLE FLEXIBLE ARC MIG TIG 170A 170 Amps | eBay and :- 10 COPPER TUBE 25mm x 6mm LUG BATTERY STARTER CABLE WELDING CRIMP TERMINAL RING | eBay but most people use 20mm (squared) which is perfectly adequate. I would strongly advise that you don't replace same for same as this is the opportunity to make a definite improvement in cranking speed by upping the starter/earth lead cross sectional area.
In other words a thicker cable? I thought when I checked before there were some decent ones on evilbay but I just re-checked and found f-all. If you can wait (your bike works now so you could) then ebay has plenty. Worth checking your local bike shop too. +1 for a good oportunity to upgrade. I read something a while ago which was discussing how the loom was basically under-rated so its always going to fail. I guess the more you know, the less you wish you did.
Halfords sell a range or ready made up leads......thats what I use....just work out how long a lead you need and go get it...between £2 and £5, in fact, I replaced the +ve lead from the battery to the solenoid too....
Thanks to all for the excellent advice it seems that this is a fairly common defect on 749/999 (there's another post "999s randomly won't start" that sound like the same issue to me) It appears that the long term solution is going to be making some proper new earth leads that may be a complete pain to stuff into the battery box... This is patently not going to happen today due to other stuff going on in my household! I am going to base my temporary fix on what JC749 said: "If you can wait (your bike works now so you could....." and do it later when I have more time rather than rush into it and end up with a gash job on the cables! I will take my battery charger to Brands tomorrow and hope it doesn't conk out mid session! Cheers for all the help! R
The newer 999/749 have multiple earth and positive leads all going into the one terminal that goes to the battery . Not just one cable but 5 or 6 that go into the wiring loom . How else are you going to get all these small cables into your halfords lead.
My 04 749R has at least two cables going into the -ve terminal at the battery - that's why I am doubtful that there will be an off the shelf replacement at Halfords which will mean I will have to fabricate my own from component parts. This is why I'm not going to attempt to do it today as I may end up with a worse performing earth if I rush into it.
