Author Topic: Throttle twistgrip doesn't snap back  (Read 664 times)

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JulianS

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Re: Throttle twistgrip doesn't snap back
« Reply #15 on: 08 January, 2019, 19:20:52 »
Spacer to head just a gasket.

Carb to spacer no gasket just the O ring, I suggest a new O ring.

The gasket and O ring will not seal if carb flange is bowed.

No jointing compound needed.

Bees

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Re: Throttle twistgrip doesn't snap back
« Reply #16 on: 08 January, 2019, 20:09:16 »
Does the slide move freely in the bore?
« Last Edit: 08 January, 2019, 20:37:29 by Bees »

Phil C

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Re: Throttle twistgrip doesn't snap back
« Reply #17 on: 08 January, 2019, 20:41:28 »
Mmm, Julian you say carb to spacer no gasket, but there is one there at present  (see photo), and I ask myself why. I guess it might be there for a reason? Difficult to decide whether to keep (renew) it, or get rid of it.
I'll renew the O ring in the carb.
Forgot to check the carb flange for bowing, and have left it with the bloke who is making up  the cable. Will check it when I get it back (actually he might well have checked it anyway.)
Bees, the slide didn't move completely freely round its circumference - when the slide was rotated it was loose in some places, tight in others - my local expert reckons it's been knocked at some stage.  Anyway, apparently it's fixable.
Just checked the battery, which has been on charge since this morning: it's now full, so that's good. I can investigate my no-headlight-or-tail-light issue. (Stand by for more stupid questions!)

Phil.

PS shed not very inviting just now. A bit cold. Next time I move house there'll be a nice garage.

Phil C

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Re: Throttle twistgrip doesn't snap back
« Reply #18 on: 08 January, 2019, 20:44:50 »
Here's the photo.

Phil C

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Re: Throttle twistgrip doesn't snap back
« Reply #19 on: 08 January, 2019, 20:58:53 »
I see the drawing on the Draganfly website appears to show it as Julian says regarding spacer and gasket. I guess I'll try that: so, a gasket on the barrel side of the spacer but not on the carb side. And no jointing compound. A light smear of oil, I guess.   Phil.

JulianS

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Re: Throttle twistgrip doesn't snap back
« Reply #20 on: 08 January, 2019, 22:01:42 »
There is a lot of good information on the Concentric on the Amal site. It is worth reading.

http://amalcarb.co.uk/rebuilding-mark-1-concentric-carburetter

AdrianS

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Re: Throttle twistgrip doesn't snap back
« Reply #21 on: 09 January, 2019, 09:05:28 »
I have never used any jointing compound between any of these joints. It should not be necessary.
Just make sure the carburettor flange if flat -they do become distorted through overtightening. Check it with a straight edge and if necessary flatten it. I used a piece of thick glass with some valve grinding paste on it as an abrasive. Make sure you clean it of well!
When refitting, do not overtighten the carb nuts. Just nip them up so they are secure.

Phil C

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Re: Throttle twistgrip doesn't snap back
« Reply #22 on: 19 January, 2019, 10:57:27 »
Took a few phone calls before I could find a heat spacer 1/4" thick. Most places only had thinner ones, but eventually I found one at Surrey Cycles - great service, arrived by post next day.

My local motorcycle repair shop made a new throttle cable up for me, and the  twistgrip now snaps back fine. The old cable had on it a ferrule which appeared to be not right. The bloke who made up the new cable  (hugely experienced) discarded that, didn't have the right ferrule, and said it would be fine without (see photo). As I say, the twistgrip appears to work absolutely fine.  It begs the question: what does the top hat ferrule actually do? Any comments please?

Phil.

JulianS

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Re: Throttle twistgrip doesn't snap back
« Reply #23 on: 19 January, 2019, 11:49:31 »
Most throttles need the ferrule to locate the cable and stop the end from disappearing into the body.

Your twist grip is a different pattern and does not need one.

« Last Edit: 19 January, 2019, 11:51:19 by JulianS »

MICKREEVES

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Re: Throttle twistgrip doesn't snap back
« Reply #24 on: 28 January, 2019, 09:17:16 »
I would not want my throttle to snap back when released.
Every time you want to hand signal, operate switches, adjust your goggles, scratch your nose etc, you would be slowing down
and holding up the traffic.
Mick

Phil C

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Re: Throttle twistgrip doesn't snap back
« Reply #25 on: 28 January, 2019, 13:48:25 »
I've  heard different opinions on this, and I expect it's been much discussed over the years without total agreement. I can see, of course, your points, Mick. What are the points in favour of snap-back? Is it a safety thing?   Phil.

Mark B

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Re: Throttle twistgrip doesn't snap back
« Reply #26 on: 28 January, 2019, 14:11:11 »
If the throttle does not snap back cleanly, the MOT man will not pass the bike.  It's just one of the amusing things about making a right-hand turn when you haven't got indicators.

Phil C

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Re: Throttle twistgrip doesn't snap back
« Reply #27 on: 28 January, 2019, 15:06:17 »
I don't know how many car drivers would understand the motorcyclist's right turn signal executed with the left hand.

AdrianS

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Re: Throttle twistgrip doesn't snap back
« Reply #28 on: 28 January, 2019, 16:09:59 »
A lot of the twistgrips have got a friction screw on them to adjust the "stiffness" of the twistgrip so it can be adjusted to stay open if not released so that right hand turn signals can be made.
It is OK to set the twistgrip accordingly but it is not good practice if the throttle wont snap back if the twistgrip is set loose. There is a chance the carb could stick open at high speed causing embarrassment to the rider and also a lot of grief for the engine!