Triumph Forum: Triumph Rat Motorcycle Forums

Triumph Forum: Triumph Rat Motorcycle Forums (
-   Air Cooled Twins Technical Talk (
-   -   Safety Circuit Simplification (

H3CT1C 04-06-2019 06:28 AM

Safety Circuit Simplification
Since my m-unit re-wire a few years ago I've been running no safety circuit - I earthed the clutch/sidestand switch circuit pin 9 & neutral switch pin 10 on the igniter - so the bike WILL start in gear on the sidestand - it's not been a problem yet, but one day ... dot ... dot ... dot ...

I'd be entirely satisfied to reduce the safety circuit to "only starts in neutral". Well, I'd have to be - I have no clutch or sidestand switch...

Wouldn't the simplest way to achieve this be to earth the starter solenoid through the neutral switch? Couldn't I just splice the -12V into the wire from neutral switch to idiot light? i.e. circuit completes to earth when in neutral allowing the solenoid to operate, but in gear the solenoid can't earth so the bike won't start?

1) Is the neutral switch (and wiring) man enough for the job

2) Will I need a diode in there somewhere?


RichBinAZ 04-06-2019 11:26 AM

I think you are better off with the system eliminated as you have it... Why?
If you stall at a traffic light, pulling away in first, you can just hit the start button.
If you make the mod, you would need to shift to neutral before the starter would turn.

Ripper 04-06-2019 12:08 PM


Originally Posted by H3CT1C (Post 2003908470)
1) Is the neutral switch (and wiring) man enough for the job



2) Will I need a diode in there somewhere?
No, it should work as is.

Personally I'm not in agreeance with Rich about this - disabling the clutch switch was one of the first things I did when I bought the bike. I thought it was a nuisance (still do) to have to engage the clutch in order to start the bike. It worked well for years until one day I hit the starter, forgetting the bike was in gear. It almost left me sitting on the road side.

I don't happen to think that making the traffic wait for a few seconds while you select neutral outweighs the risk of personal accident. Besides, a motorcycle is narrow enough to pull into the side to let traffic past while you get it restarted. The solenoid disabling is definitely worth doing, I think the only danger left is riding away with the stand down. Kawasaki had a good solution for that, they fitted a split clutch cable that pulled the stand up when you pulled in the clutch.

Psycrow 04-06-2019 06:08 PM

Im of the oposite mind... Push that starter once with the bike in gear and dump it... Youll never do it again. Good lesson learned the hard way are the best instead of having a system that complicates thinks and creates a fail point.. But Im still not a traction control or ABS fan so my opinion is probably worth even less than 2 cents...but there it is anyways.

Sent from my LG-H873 using Tapatalk

TTRIgnitionSystems 04-07-2019 01:36 AM

I'm a fan of the safety circuits, having been stood-up through a left-hander by the side-stand, and having watched another guy's race bike go for a stroll through the paddock. They were put in for a reason, and should only be removed for a better reason.

Babaganoush 04-07-2019 04:58 AM

Ripper is on the money here - your plan should be OK. FYI, I recall measuring 3,9ohms through the starter solenoid control circuit, which gives a 3-amp load on the wires. Something to think about in case you have very thin wiring for the idiot light. The 0,5mm2 wires that go into the switch itself should handle it, though.

Having done the m-Unit works with full safety circuit, I completely understand why so many want to skip it. The safety features probably double the amount of wire and adds an extra relay. However, with everything in place, I’m really happy to have it. I think the simple splice you’re doing here is a mod with one of the best safety/hassle ratios.

H3CT1C 04-16-2019 02:09 PM

Finally got round to trying this out - and can confirm it works.

Those of us who have done wiring chops can regain some basic functionality of the safety circuit by earthing the starter solenoid through the neutral switch - when holding the solenoid so both threaded posts are at the front, run a wire from the right rear tab and splice it into the wire from the neutral switch. Now the starter motor can ONLY turn over with the bike in neutral.


Dazzzz88 04-17-2019 05:03 AM

Nice win and a simple rearrangement.

All times are GMT -4. The time now is 12:59 PM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.

For the best viewing experience please update your browser to Google Chrome