I thought that with a little TLC, new plugs and caps, and a bit of gentle encouragement the le Mans would be better, but I took her for a quick spin this morning, and she’s still not right. Uneven idle speed, and an occasional misfire. I just got the impression that there is something fundamentally wrong, so I checked the charge - I’ve only got an analogue voltmeter and it’s not very sensitive, but at idle it looks like 11 volts and the same at 3000 rpm.Should I be looking to put a new battery in? And at risk of starting another debate, what should I put in? The sky isn’t the limit for the budget…I’ve got a digital meter but it needs a new battery too - I’ll get one later
The weak battery will cause the poor running (the ECU is affected) but will be worth checking it is charging before splashing out.
I would think the battery is not charging if the alternator is only delivering 11 volts as this will be too low to push current back against the terminal PD of the battery which is probably nearer to 12 volts.
To put it another way, if the volts don’t rise as you rev the engine to something like 13.5 then you have a charging problem. Replacing the battery will not address this.Check the regulator is earthed properly, they often rely on being bolted to a painted or rusty bit of frame.
I checked and cleaned the earth yesterday, so it should be O. I’m going to borrow a decent meter to get a definitive reading.
iF YOU HAVE THE SAME REG AS ON MINE FITTED ABOVE THE ALTENATOR ANDABOUT WHERE ALL THE CRUD HITS IT FROM THE FRONT WHEEL? THEN THEY DIE LIKE THIS MATE, i HAVE PUT A SECOND EARTH TO MINE GOT A 2ND HAND WORKING REPLACEMENT FROM PETE AT REBOOT
OOPS CAPS LOK SORRY
Right, digital meter fired up.
Steady output of 13.54V across rev range. Any ideas?
def should not be stable
1- check battery at idle with ignition off as if fully charged it could be 13.5 volts
2 check at zero revs with ignition on
3 - then start it up and rev it slow and volt should increase
cut of point should be 14.5 volts max
Ex smokingbiker2013-11-30 19:41:10
I’m assuming that it is actually charging. Otherwise it would have expired once the battery was drained…
12.1V ignition off, 11.9V ignition on, but engine not running, and then 13.5V 1000 - 4000rpmHave I understood you correctly, Ray?
Yeh that is too low I believe. On these the reg IS weakened by the bad earth and the alloy does corrode badly. (If it is the same as mine) I found out after mine died.
I not only cleaned the org earth and then added vaseline BUT put another earth on the other bolt holding it.
The replacement reg is not too expensive as they are used on bikes other than Guzzi. The charge at 3000+ revs should be around 14 and a bit Volts mate and at least 13.8 once over 2000rpm, it is on my replacement one.
By the way also check, if you haven’t already done so the main 30a fuse and the holder IF it looks at all worn or the contacts are dirty it will cause a problem. When my reg went it melted the fuse contacts and the fuse plastic before it blew the fuse…scary as it could have caught alight under me bum…
Electro sport in the USA do them for $89 IF you can get them to post it as an “unsolicited gift” that would be about what Â£50 UK plus the courier cost (Parcel2go will get you a quote on that) even if you pay customs duties it will be less than a UK one. By the way DO NOT use ups otr the postal service they both charge just for it dealing with customs.guzzibear2013-11-30 21:33:02
Thanks Ken,I’ll check the earth again tomorrow - can’t find one for $89 though - best price appears to be $129 so far. I’ll try Reboot as well.The fuse appears to be fine.
I’ve now run an extra earth to the other bolt on the reg/rec. No change to meter readings, so I need to find a replacement.
I’m not sure what causes the problem with poor running, as there is obviously enough charge to keep the battery topped up, so why won’t the bike run properly? Someone out there knows more than I do…
Are your carbs balanced or have you one choke sticking on? Not sure if your carbs are similar to my T3 but I had one carb that was not working at all at low revs because of a combination of bad setting up of float level, mixture, throttle cable lengths, throttle stop screws…in fact everything was wrong.
All the best,
Was the headlight on when you did the readings with the engine running? This might bring the volts down a bit, but 13.5 is still a bit low.
It’s fuel injection! Got a soft spot for carbs though - you don’t need a laptop to set them up!
No, it was switched off David. Looks like a new reg is needed [:-(]
Found these mate
I’ve actually got an Electrex RR51 which I bought for the Bevel Ducati and never fitted. It’s single phase - any idea whether it could be adapted? Physically, it would sit nicely where the old one is located.