Lights dim when I give it revs

[crumbobly]

Hi Guys,

New to KiwiBiker and actually just bought my first road bike tonight, 1992 Suzuki Bandit GSF 250, and pretty happy with it so far, however noticed that the lights seemed very dim whilst riding (even on high beam).
And stationary at idle they seem fine, but give it a rev and the lights dim.
Also if im riding along and pull in the clutch (to let revs fall to idle) the lights go from dim to normal and then dim again. odd!!!
Any ideas as to what this could be? Regulator rectifier?
Im a bit stumped,
Havent really had a chance to properly look at it yet, but any insight you guys can provide would be helpful.

Cheers in advance

[LBD]

Your not...um....you know....squinting your eyes when you ride?

Battery connections tight? electrolyte the correct level? Do the lights dim much when starting?

Other than that it has me stumped...very curious if anyone has an answer....

[BiK3RChiK]

I recently had the same problem. I've replaced the regulator/rectifier and the battery. I haven't been for a ride since replacing the battery, so can't tell you if it's solved the problem or not, but I suspect it will have. The battery was stuffed. Wouldn't even start the bike after a 3 hour ride and rest for 30 minutes!

[crumbobly]

Haha maybe ive developed some weird condition where everytime i grip the throttle i go all squinty eyed.
But ill have a look at all the connections and levels when i get a chance tonight.
Could quite possibly be a stuffed battery as the guy hasnt been using it much since upgrading to a bigger bike.

[notme]

You need a multimeter and a copy of the charging system troubleshooting chart that is all over the net and KB. Use the chart to narrow down the issue, it could be as cheap as cleaning up your earth connections and tightening and cleaning connectors, especially given the age of the bike.

[CeeBee]

Definitley need to check charge rate with multimeter against manufacturers specs. A way to eliminate the battery as being faulty is to bypass it withh another say out of the boat / car and if all ok has high resistance fault in the battery. To conduct an accurate charge rate test you must have a fully charged / good battery or you will get false readings.

[wysper]

Hi Guys,

New to KiwiBiker and actually just bought my first road bike tonight, 1992 Suzuki Bandit GSF 250, and pretty happy with it so far, however noticed that the lights seemed very dim whilst riding (even on high beam).
And stationary at idle they seem fine, but give it a rev and the lights dim.
Also if im riding along and pull in the clutch (to let revs fall to idle) the lights go from dim to normal and then dim again. odd!!!
Any ideas as to what this could be? Regulator rectifier?
Im a bit stumped,
Havent really had a chance to properly look at it yet, but any insight you guys can provide would be helpful.

Cheers in advance

keep an eye on this thread too - Charging

[neels]

If you can get your hands on a multimeter it might be worth checking if there is any AC on the output of the rec/reg or at the battery. If there is it could cause the light to dim as the revs increase, as the negative half of the AC gets bigger than the 12VDC that the battery is supplying at idle. Worth a quick check before you start buying bits.

[crumbobly]

keep an eye on this thread too - Charging

yes his problem does indeed seem similar to mine. I have done a bit of fault finding and with engine at idle (with high beams on) the voltage accross the terminals was about 12.5 and at 5000rpm dropped to 10 - 11volts.... with the lights off the figures are even worse.

Used a good battery from my van to do the tests

Worked my way through one of the trouble shooting charts i found.

And i think its pointing to the reg/rec as i am getting a strange reading between the black and red wire on the unit.

Have bought another used reg/rec for 30 bux so thought it was cheap enough to give it a go. Heres hoping ....

[crumbobly]

If you can get your hands on a multimeter it might be worth checking if there is any AC on the output of the rec/reg or at the battery. If there is it could cause the light to dim as the revs increase, as the negative half of the AC gets bigger than the 12VDC that the battery is supplying at idle. Worth a quick check before you start buying bits.

I should really be checking up on this thread more often haha (or at least before i go buying stuff) . I have a multimeter so will give it a check. If that were the case would that point to a reg/rectifier also?

[neels]

I should really be checking up on this thread more often haha (or at least before i go buying stuff) . I have a multimeter so will give it a check. If that were the case would that point to a reg/rectifier also?

Yep, if you have a sorted diode in the rectifier you will get some AC out the other side at the battery, if it's all DC at the battery then the rectifier is OK. The next thing after that is the regulator, which is in the same box anyway.

[greenman]

it's the regulator dude. and you will probably find that the battery is on the way out as well.

[crumbobly]

Ok well just an update on my situation. I have attached a new reg/rec and i am now getting some decent volts at idle about 14 volts. However i still have the problem where my lights dim when i rev it up. I think what im going to do is run new cables from the RR to the battery and see if that helps me at all.

[CookMySock]

Measure the battery and stator volts and see if they drop when you rev it.

Steve

[notme]

You need a multimeter and a copy of the charging system troubleshooting chart that is all over the net and KB. Use the chart to narrow down the issue, it could be as cheap as cleaning up your earth connections and tightening and cleaning connectors, especially given the age of the bike.

If you have worked through the troubleshooting chart (like this one http://www.electrosport.com/technica...ng-diagram.pdf) it should have pointed you to a definitive problem.....each section of the chart ends in a "your problem is this item" type of thing so there should be no question what the issue is if you follow the chart.

If you follow the chart and fix the defective item or find no problems and your lights still dim, the problem is with the lighting circuit.

Try not to get caught up in finding a complicated solution, that's an easy trap to fall into. It really is as simple as this: The lights will only dim if the voltage across them drops. The voltage can only drop if the charging system is faulty, in which case the chart is your friend, or if the lighting circuit is faulty, in which case the chart is still your friend because it will tell you that the charging system is not faulty, thus it must be the lighting circuit.

If you are still stuck i.e. the chart points to no problems and you look at all of the lighting circuit and find no bad connections, try running 2 wires from the battery to the light (with a fuse in the positive at the battery end). The lights will either STILL dim (charging system problem) or they won't (lighting circuit problem).