Modern Vespa

Hello,

After installing Koso heated grips on my wife's '20 Primavera 150, the throttle is now very sticky (it basically doesn't return at all) - I fear I may have over-torqued it when putting the grips on, as they were verrrry tight.

In retrospect I should have trimmed the inside of the grips/sanded the throttle tube a lot more, but I do not know how to determine where exactly the issue is

I removed the right grip in a bit of a panic before the superglue set, and it's still sticking badly

I'd like to at least figure out what I broke before taking it to the shop (although I'd much prefer fixing it myself for reasons of cost and most importantly, pride).

Guessing the throttle tube got squished, or the return spring un-sprung, or possibly the cable really stretched (this latter seems unlikely)?

Also, where do folks tap into switched power for heated grips? Scooter West's video said "orange wire at the fuse box" but there are a bunch of those, and the one I more-or-less randomly chose did not work (grips didn't turn on).

Thanks!
Adam

Is the grip pushed too far on the bar? Have you got some pics?

There is no grip on the throttle side presently, and the throttle body seems not-overly-pushed-in.

Here are two videos showing the issue:

https://youtu.be/E8eQsTXyRbQ

https://youtu.be/Wg3_6AmePAw

And two photos below.

Thanks,
Adam

From the bar end photo it looks like the plastic on the throttle tube at the 2 o'clock position is cracked and bent inwards? It may have deformed the plastic throttle tube during assembly and is now dragging on the handlebar.

I'm assuming it worked fine before the grip install attempt. Backtrack to last know good position! The throttle side grip has a slightly larger inner diameter to compensate for the throttle tube diameter. Any chance you accidently tried installing the left grip on it?

Try spraying some brake clean or similar between the throttle tube and the bar. Flush it as good as you can. You may have some gunge in there that's causing it to drag. Even WD40 will work at least to see if that helps improve it. You may have to remove the tube and see what's going on in there. It wouldn't hurt to lube the push-pull cables also.

I did this once. If it's a really tight fit the glue gets squished out and runs back into the gap between plastic throttle tube and the handlebar. Go to town with some wd40 and dissolve the glue. Since it is such a tight fit use the smallest amount of glue possible when refitting. Can help to shave the ridges off the throttle tube.

Don't use the superglue provided - use a 'strong hold' hair spray instead.

I use a high temp 2 part epoxy and have installed 10+ sets for my self and others over the years, never an issue.

on to the op's problem I suspect excess glue between the throttle tube and the handle bar and possibly into the throttle tube cable housing.

Having had to remove worn out heated grips a few times, I would avoid using any 'permanent' glue.

When I worked as a bicycle mechanic in my younger years, Aqua Net was the go-to hairspray for grips. My buddy owns a shop and I believe I saw a can on his workbench the last time I visited.

100%
Hairspray sticks great and the grips go on easy and come off easy.

Never spun or lost a grip on any of my motorcycles or mountain bikes using Aqua Net or similar product.

Also works great for Ricky Ricardo hair.

Y'all are awesome - some WD40/Triflow did the trick!

Next up, where does one tap into switched power for heated grips? They need a >= 5A line.

Best is direct to battery with an inline 10A fuse. Tapping into anything else while taking that sort of current draw and you run the risk of blowing fuses with all the consequences that could involve.

direct yes but ideally with a relay in case you forget to turn them off (although with my oxfords they can detect this themselves)

Makes sense - what's the right relay for this? I've used them before installing accessories on my motorcycles, but they've always been included with the accessory, and McMaster-Carr as usual has a bewildering array of them.

And what would I tap into as the trigger for the relay (guessing something non-critical like turn signals)? Is a wiring diagram available for these scooters? I've had no luck searching for a service manual (which I'm happy to pay for).

recent thread with using a relay to power some extra horns
Tapping power from relays

service manual
https://file.dogantrend.com/dogantrend/dtonline/Dogan_Trend_Servis_Manuelleri/2022/Vespa/

Standard 4 or 5-pin 30/40A automotive relay from any FLAPS (Favourite Local Auto Parts Supplier).

Use Aqua Net. I think this is best for you.