These damn karts will be the death of me...

I have a Motori Seven TAG motor(s) with electric start and I think I face 2 gremlins:

1. Starter cranks over too slow (if at all)
2. Stator and Coil/CDI combo fires off at too high an rpm (1200 RPM)

On a good day I can get the starter to spin the motor at 400-700 rpm. I've tried several starters, rebuilt one of the three starters (new brushes anyway), and direct connected the starter to HUGE, AGM batteries. No change. Presumably this isn't a current issue then...

What DID make a change was upping the voltage. I started with 24V (2 - 12V in series) and then went to the track with my Dewalt Li-ion battery from my impact gun strapped to the kart (20V). The starter JUMPS to life with that thing and all is well in the world.

But...

What on earth is wrong with the 12V starters? I have two motors and 3 starters. Any combo of starter, batter, engine, and any connection method all do the same thing. Can I have some sort of failure in all there starters that wouldn't show up in ohm tests and visual inspections that would require them to need more voltage?

Stupid question since you're looking at the starter but does this motor have some kind of low-rev decompression system to aid in starting which might not be working? Smaller 4-stroke bike motors have them and they don't always work well. Some guys I know run their bike starter motors at 24VDC to overcome the high compression.

These are 2 stroke, so no... Even with the plug out they still don't make a ton of RPM. It's like the starters all want more voltage suddenly.

Or, there is something binding internally to the motor??

Is there a bushing in the engine into which you insert the nose of the starter? Misaligned bushing, causing starter to drag - I have no real clue as I haven't seen the setup, but the common factor...is the engine. You've changed every thing else, so....Crap, just reread - 2 motors involved - Nevermind!!

Aaron,
Just curious if those are shifter karts? Sorry, I have no solution to your issue.
My only experience is with my Rotax Max 125cc with a centrifugal clutch on my Kart. I need to rebuild the motor before I get it going this year

Good luck with you karts, they are a ton of fun...when they work right

Cheers,
Dominic

The kart in question is not as shifter. It's more or less just like your Rotax (same class anyway - TAG).

I have an older, 125cc 6 speed shifter too nicknamed "Satan". It's fast...

I'm inclined to say no as it's on both motors (I have a spare).

I raced TaG for years. Starters always sucked and that is why IKF almost instantly allowed remote starters on the grid. As you stated the spin RPM was too low to excite the CDI Magneto and the bendix always jumping out early. The start motors were a cheap and poor design. When TaG was very new it was total panic on the grid. It REALY sucked when you qualified up front and could not start, especially on a cold day. If you aren't racing in a club, feel free to use whatever batteries work. If racing, the battery must be approved 12 volt unit per IKF rules.

I know people who made "stock legal appearing" 18 volt batteries. Using large gauge wire and good grounding helped a little.

I can't see how grounding would help if I'm directly (and I mean directly) connecting a HUGE AGM battery to the starters posts and it's still not enough.

Like I said they were never worth a damn even brand new and we never relied on them. Compare that crappy little motor with the one in a remote starter which spins your engine 2000 RPM. If you didn't start in few seconds you risked a fowled plug and again you just missed your race.