Helping an old friend and his 125
 

I'm new to the forum, but only because I'm helping an old friend with his 125. After rewiring his burnt up harness, and doing a maintenance once-over(plug and wire, oil change, grease), the starter turns very weakly. I've gone through the faqs, cleaned all connections, checked voltage drop at each stage, and cranked w/two car batteries in parallel. Still slow cranking and 11.5 v at the starter. I've even jumped the battery directly to the starter.

I've opened the starter/gen, cleaned and undercut the commutator, checked the bearing/bushing(OK), and cleaned the post connections. I've checked continuity on the rotor. The brushes look ok, but the owner says he had it rebuilt last summer by an automotive alternator/starter shop.

Any ideas why it turns over slowly? I get about 6 slow revolutions, and the motor pops each time but not enough to kick it to life. Is it possible the wrong brush material(automotive vs tractor) could cause weak cranking?

Thank you-
Tom

I would try another starter/generator if you may have one. This would help you eliminate possible bad grounds (even though you checked them). Make sure you have good cables for ground and the soleniod as well.

It may be mechanical rather than electrical!!

There is an automatic (centrifugal) compression release that makes the engine spin faster.

Check out, "starter problems" in this forum.

Thanks for the replies. I've cleaned the ground connections, and even tried a separate cable from the ground post to the starter/gen. I'll check into the compression release after that. Maybe I'll try jumping the start interlock and release the brake, in case the fwd/rev lever is not properly centered and is dragging the motor down.

Unfortunately I don't have a spare starter.

:Welcome2:

Sounds like your heading in the right direction! I hope you get it figured out soon!

Same here.

I checked the valve clearances just in case they might be affecting my issue, and they were in range.
Does anyone in the NE CT area have a starter/gen that I could try out, to verify whether or not it's the starter? :bigthink:

I don't want to spring for another one if the problem lies elsewhere.

Thanks

Tom

Tom,
Do you have a starter generator repair shop in the area? We have a good shop that rebuilt My S/G in about 4 hours after I toasted it! And it saved me a lot of dollars too!
Regards,
Chris

Good idea; I just dropped the starter off at Woodstock Rebuilders- fingers crossed!

Did you put on a new coil or upgraded to an electronic ignition?
If so it may be on backwards. I replaced a EI on a simplicity a while back,
the motor would start on the bench but when I hooked it up the the drive line it wouldn't turn fast enough to hit.

I did put on a new coil, and was careful to hook it up as the old; power to +, points to -.

sounds good to me. Before I would get into a major overhaul, what would it hurt to switch the coil around? What faces back, try putting it forward. :beerchug:

Gotta wait till I get the starter back tomorrow-

He has it hooked up correctly...installing it backwards is not going to magically solve an unrelated problem. So, don't bother, TommmR.

Thank you for your input, sir. Although it is most likely unrelated, If you have eliminated all other possibilities it wouldn't hurt to try. Maybe that is the reason for slow turning, maybe it isn't. I'm just trying to help a guy out.

Understood, but there is no reason at all for that to even be possible. The only thing the ignition circuit shares with the starting circuit is the ignition switch, and even so, connecting the coil bassackwards is NOT going to magically fix an unrelated problem elsewhere. Period.

TommmR-

You say you tried a different negative battery cable...did you replace the two positive cables (battery to solenoid, solenoid to S/G) with new cables? Those can get corroded inside and not conduct well, and they weren't particularly large wire to begin with, IMO.

hi i,m new hear but not new to this problem .i went through with my 125 ,i though it was my hydro ,even pulled it apart ,repalced bearings ,,placed it back ,and still same thing ,rolled the engine over by hand and heard a sound coming from the cam cover ,pulled cover ,and seen weight move on c/r tied a thread on spring ,and removed spring ,replaced with new spring .besure you leave thread on spring ,didn,t need spring going down the pan ,i used a needed noise ,and put engine back in place ,and first try ,it was running ,so hope this helps .David

I just got the starter back, and determined I wasted money on the rebuild as it is no better.
I did replace the positive cable from the solenoid to the starter, soldering all terminal ends that were previously crimped on; am not getting any significant voltage drop on anything.

But to David's point, I'm suspicious of the compression release. Is the cam cover the one next to the points cover? It seems impossible to remove it with engine installed as the bottom bolts are bound by the frame.

You would be better off pulling the head and verify the exhaust valve lifts slightly during the compression stroke. Otherwise you will have to remove the bolts that holds the motor to the frame and lift the motor up to remove the cam cover.