starter generator running at half power

[JUSS10 250]

well i started working on my 753 project again. last i left it i couldn't get it to start and the starter generator was bogging down. figured it was because it was an old battery. well we got a new battery for the 854 the other day so i hooked that up via HUGE jumper cables and still the generator seems to lope really bad. i had rebuilt it and put new bearings in, cleaned the commutator with a little emery cloth and cleaned the brushes with brake clean. at first it seemed fine then now it does that lope, almost like its at half power. i tore it apart again and it worked for a few turns of the key then loped again. any ideas? is it shot? did i do something wrong? later on i was able to start it with a rope on the pulley but that doesn't do me any good if the generator isn't there to charge it.

thanks

Justin

[WheelHorse_of_course 99]

Does the s/g charge the battery when the engine is running?

The engine probably does not have automatic compression release so it is not going to turn very rapidly.

Things to check that you have not mentioned:

Remove and wire brush both ends of both battery cables. Also the other cables to and from the ignition switch and regulator etc.

Best of luck :)

[JUSS10 250]

well it barely turns the engine. it lopes. it works up really hard and cranks it once, then work hard, and crank. i know it has a good ground as i cleaned off one of the bolt heads and put a test light on it and it lights up super bright. as for cables i got to the point where i just took a jumper cable and attached it to the terminal on the starter and still nothing changes.

can't tell if its charging when it runs because in order to start it with a rope, the belt for the starter can't be on the engine.

i am about to the point where i am going to pull the starter of my 854 and see if works i just don't feel like pulling the wiring and starter off my 854 haha.

Justin

[Kelly 1,028]

Have you trid junping power right to the starter? to take out the posible bad stsrter switch, may not let full current go through it, just a thought use a test meter to see what kind of amps it is pulling to crank it.

[JUSS10 250]

yeah i jumped the starter and bypassed the starter switch. i will check the amperage. i have a gut feeling its drawing really bad as i used jumper cable that probably around 2 to 4 gauge and it was getting warm through the insulation. if it is excessive amp draw any idea on a fix or count it as lost? do you have any sitting around kelly? thanks

Justin

[Kelly 1,028]

I might have one, is that the long or short one??

[Save Old Iron 1,563]

Justin,

http://www.wheelhorseforum.com/index.php?...30&hl=measuring

in case you need a way to check for excessive amps. The parts are available on ebay or you could use a 200 amp battery charger to read amps off the amps meter.

Having the amp shunt makes accurate measurements very easy to obtain on any circuit - starter, charger, SG or RR output.

If you have the time, I might be able to ship a flat rate box out to you this week for you to check out the SG.

You will probably find the wiring fried in the field coils.

:)

[W9JAB 156]

How to "flash" a generator when output is lost due to loss of excitation

Residual magnetism in the generator exciter field allows the generator to build up voltage during start-up. This magnetism is sometimes lost due to shelf time or improper operation, among other reasons. Restoring this residual magnetism is possible and is sometimes referred to as "flashing the exciter field".

To restore the small amount of residual magnetism necessary to begin voltage buildup, connect a 12 volt battery to the exciter field while the generator is at rest, as follows:

Remove exciter field leads F+ and F- from the voltage regulator. CAUTION: Failure to remove the field leads from the regulator during flashing procedures may destroy the regulator.

Measure the exciter field resistance from the F+ to the F- lead. You should be able to read some resistance as you are measuring a continuous winding. An infinite resistance reading would indicate an open in the exciter field. Also check to be sure there is no path to ground.

Connect F+ to the positive pole of the battery.

Hold the F- lead by the insulated portion of the lead wire, touch F- to the negative pole of the battery for about 5 to 10 seconds, then remove.

Reconnect F+ and F- to the regulator. Repeat the procedure if the generator fails to build voltage.

[JUSS10 250]

Kelly - i'n not sure how to tell short vs long but its the same starter generator thats on my 854. i can measure it later today.

SOI - im not sure what you mean by SG or RR? i read the post you linked and i that is a pretty trick rig. i have all the parts except that shunt. is that what you are talking about shipping? thanks for all the info

[Save Old Iron 1,563]

Justin,

SG = starter generator unit

RR = rectifier / regulator assembly

the shunt is available on ebay

http://cgi.ebay.com/100A-75mV-Current-Shun...=item564000cba3

for the 100 amp / 75 mv shunt - but you have to multiply the amps ready by a "factor" to get true amps thru the shunt

http://cgi.ebay.com/100-Amp-100-Mv-Shunt-A...=item2c57a776c2

gets you a 1 to 1 readout of amps to millivolts. more expense but a direct readout of amps from your multimeter.

I would offer to ship the meter out to you if there is an interest in actually measuring the amperage thru the SG unit.

The problem is within the SG unit - not the regulator. The regulator controls the charge to the battery - not the inrush amps to the SG.

[WheelHorse_of_course 99]

The amps on a stalled unit will be higher than a running unit, so you cannot directly compare.

However if they are the same or less that will say something.

The only SG engine I have always lopes, but it get at least a few revolutions which is enough to get it started.

Best of luck

PS: I don't know the reason but emery cloth is specifically NOT to be used on commutators. I have seen this warning more than once. It probably does not explain your problem though. :wh:

[Save Old Iron 1,563]

PS: I don't know the reason but emery cloth is specifically NOT to be used on commutators. I have seen this warning more than once. It probably does not explain your problem though.

The more contact you have between the brushes and the commutator, the more current will flow thru the brush into the commutator.

the more current flow, the stronger the motor will turn.

if the commutator surface is not flat and polished, poor brush contact and arcing results. a shiny commutator is not enough - it must be flat too to allow maximum contact with the face of the brushes.

arcing wastes power and further destroys the brush surface and commutator surface resulting in even further arcing and further power loss

viscous cycle until total failure happens along.

too rough an emery cloth could put striations in the commutator and result in poor brush contact - lathe work and a final polish may be the only way to restore a worn commutator.

http://www.martindaleco.com/html/electrici...saver_brush.htm

can be used to put a final polish on the commutator.

[jachady 130]

Justin, I've got my SG off if you'd still like to buy it. Your Inbox is full so I couldn't send you a message. This SG turned my motor ove no problem so hopefully it will solve your problem.

John