hi guys,

i've been reading that our bikes can be picky about battery.
what are some issues that can arise from running on weak/not fully charged battery? (aside from having a hard time to start the bike)

is it possible a weak battery can cause surging/loss of power etc...
and why if you know!

thanks!

I don't really know if you can cause any damage when trying to run an mc21 with a dead battery, so I wouldn't recommend it. On the other hand, and you shouldn't do this until one of the pro's give some advice, but I had a totally flat battery and the only difference it made was that the lights flickered at night. It still started on the first kick every time. The battery was that flat that the oil light wouldn't glow at all and obviously no rc valve movement.

I don't know if my bike is good, bad or just a little strange like it's owner. All I know is that a flat battery had basically no effect on it.

Andy

Bandit7

I remember Watfordhorn rode his MC28 a fair way back from Beaulieu a few years ago. Might need a bump start. I guess the weakest link could be the rectifier
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Why do things simply when you can complicate them

Main problem I had was getting it to start...mainly because the MC28 needs some power so it could read the card to actually turn the ignition on. The MC21 has a mechanical iginition so I presume this wouldnt be an issue.

On another note, I remember Tom not being able to get a certain race MC21 to start at all with a flat battery, as soon as fontyyy robbed a battery from his spare bike it started up.

Not sure where the conclusion is in that, but I really dont think it will cause any damage as its usually a too high current that breaks things, flat batteries would be too low and a quick run around the block usually gives enough power to get things running properly again.

Faulty recifiers have been known to destroy batteries though by over charging them, then they dont hold any power at all.

ya...not worried about the starting issues, more interested about performance related issues.

I think bandit_7 made a good point:

and obviously no rc valve movement

would it be possible that a weak battery could cause issuess with rc valve movement in turn creating surges/loss of power? ie. not opening completely when they should be?

also, would a weak battery have any impact on spark? eg. bad spark

thanks!

If the battery is really shot (i.e. won't hold charge at all) an mc21 will struggle to run (splutter at low revs, won't idle) and won't run at all with it's lights on, it'll just splutter and die.

An mc18(PGM-II) will lose a couple of bhp in the same situation.

And as mentioned you'll be lucky to even get a '28 started at all with a dead battery, if the steering lock is on you're shot.
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Please do not PM me technical questions, if you can't find it on the Forum start a thread

And as mentioned you'll be lucky to even get a '28 started at all with a dead battery, if the steering lock is on you're shot.

Or get very giddy trying to bump it

bandit_7 wrote: The battery was that flat that the oil light wouldn't glow at all and obviously no rc valve movement.

The comment above refers to the bike not running. That was with the key turned and the run switch flicked to on. While running there was no noticeable difference at all.

Andy

Bandit7

Listen to none of what I said!!!

I just found out I have a faulty reg/rec and is putting out 18-19v while running, which would explain why my bike ran well with a dead battery.

Sorry all.

Andy

Bandit7