engine will not turn over

hi all, how can i tell what is the reason for reluctance to turn over,torque figure to turn engine at a particular point. any info appreciated… ta mick

hi mick, i have a well worn spares engine and a recently rebuilt engine, without the plugs in the spares engine takes 17 newtons to turn it over from the altinator, the rebuilt engine takes 21 newtons (sounds alot but the engine runs perfect)

things to check would be, battery earth, starter solanoid (arc it across the terminals) battery then starter motor, these engines do need a good battery to turn them over… if its a original starter motor it could be getting a bit lazy, but check other stuff before changing that.

pete

thanks for that, i am picking up my overhauled starter motor tomorrow,but great to have the figures as a reference.

Pete, I noticed my starter motor was very reluctant to turn the engine over whilst hot ( stalled the bloody thing in traffic ) Apart from being embarrassing, could it be a “coffin dodger” starter ? It works great when the engine is cold.

Martin

hi martin, yes it could be, im no expert on electrical stuff but my starter got so it would only just turn the engine over whilst hot, but would seem ok when cold, then after a few months of this it wouldnt even start it from cold…tried all the things i mentioned above to no avail… then tried to revive starter with new brushes and springs with no success, so bought a second hand one from a VFR750 FN (1992) which was a direct fit, spins the the engine over easily hot or cold now,(or it did before i dismantled bike for restoration this winter)

pete

Yeah, sounds like the armature in the starter is toast, they tend to build up resistance as they get hotter, instead of converting voltage into rotating force they send it to ground, causing the lack of starting grunt when hot.
Can you borrow a “known good” starter to test it? Have you tested for resistance in the positive and negative leads to the starter? Battery voltage when hot?

Thanks guys, I,ll pull it off the bike and have a peer inside. If its nothing obvious I think I`ll take the VFR route like Pete did.

Cheers

Martin

quote:
Originally posted by vf pete

hi mick, i have a well worn spares engine and a recently rebuilt engine, without the plugs in the spares engine takes 17 newtons to turn it over from the altinator, the rebuilt engine takes 21 newtons (sounds alot but the engine runs perfect)

things to check would be, battery earth, starter solanoid (arc it across the terminals) battery then starter motor, these engines do need a good battery to turn them over… if its a original starter motor it could be getting a bit lazy, but check other stuff before changing that.

pete


Turns out I have exactly the same issue, but I have not yet tested the battery charge, charge rate, voltage to the starter or from the starter solenoid.
Most likely a job for this coming weekend.
Tony

hi sorry slow to respond but my problem was my battery charger, all though it gave the right volt readings not strong enough to spin the motor,used an optimiser charger and after three failed charges on the battery it brought it back up to spec so old charger now in bin and i have a spare battery,deep joy.

Glad to hear that you sorted it out, and not too expensive either.
Unfortunately once mine cools down it spins the starter, but not when hot. I think I may have diagnosed my own problem that I didn’t know I had when I posted further up the page, irony huh? My bike did come with a spare stator and starter motor among other parts, so maybe the previous owner was trying to figure it out as well, just failed to mention it when he sold it.

Hi guys will all model VFR750 starter motors work on the VF1000? Cheers Wayne

hi wayne, im not too sure about all the other vfr starters, i seem to think i read somewhere on here that some of them were permanent magnet and possibly spun the other way. best to check before buying.