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2000 Tourist Throttle Twist Grip Question


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#1 Snakeoil

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Posted 20 April 2015 - 09:24 AM

The twistgrip on my bike appears to have no internal stop. The barrel is a piece of steel tubing with a mount spot welded on that holds a small chain. The other end of the chain is attached to a square slug that has the slotted holes for the cable ends. There is also a small piece with two opposing slots that appears to be a cable retainer and goes into the bottom of the square passage where the slug travels up and down.

With tension the cable so that the slug is all the way to the bottom, the barrel will still rotate further closed. It makes for a very sloppy throttle. Is this just a poor design? It appears that there are too many links in the chain. Nothing appears to be broken or missing inside. Is there a missing part.

Thanks,
Rob

#2 teg

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Posted 20 April 2015 - 04:28 PM

I replaced the throttle tube and chain a while back with one from Russia.  I seem to remember having to remove a link from the chain to make it work right.  They may be 'calibrated' for Pekar carbs when new.
Terry
2011 Retro

#3 Snakeoil

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Posted 20 April 2015 - 05:29 PM

Thanks for the reply. But I would not expect the type of carburetor to influence this problem. It is a throttle closed problem so it is when the carbs are closed and the cables have pulled the twist grip to full off. At this point the slug at the end of the chain hits the bottom of the passage in the grip so it can go no further. At that point the chain now can do slack and fold up on itself, providing more off-direction twist movement. Hence the slop. Only thing I can see to fix this is either add a mechanical stop to the twist grip so it will not continue to turn and fold up the chain, or shorten the chain.

I just want to make sure nothing is missing before I start to cut pins.

regards,
Rob

#4 racepres

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Posted 20 April 2015 - 05:56 PM

View PostSnakeoil, on 20 April 2015 - 05:29 PM, said:

Thanks for the reply. But I would not expect the type of carburetor to influence this problem. It is a throttle closed problem so it is when the carbs are closed and the cables have pulled the twist grip to full off. At this point the slug at the end of the chain hits the bottom of the passage in the grip so it can go no further. At that point the chain now can do slack and fold up on itself, providing more off-direction twist movement. Hence the slop. Only thing I can see to fix this is either add a mechanical stop to the twist grip so it will not continue to turn and fold up the chain, or shorten the chain.

I just want to make sure nothing is missing before I start to cut pins.

regards,
Rob

I would not doubt if this is related to the carb differences...a butterfly carb requires less free cable than a Slide type...by enough to make a Difference.

#5 Snakeoil

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Posted 20 April 2015 - 08:35 PM

Okay, I'm obviously not explaining this well. Let me start again.

Basically I need to know what should be inside in case I am missing something. Parts drawings for these bike suck. No detail.

So, I have two questions.

First, should there be a small loose block with two opposing slots in the vertical cable chase inside the housing. I'm talking about the straight section where the cable ends go up and down. Mine is at the bottom and restricts the slug from going to the bottom by the thickness of the block.

Second, are there any other loose parts inside the housing other than the tube, chain and slug, that I might be missing?

This has nothing to do with cable free travel, guys. When the throttle is closed and the slug bottoms out. The tube should stop. When the slug hits bottom no further cable travel is possible. So, if the cables stop and the tube can still move, that creates throttle slop. I actually have the carbs removed. I am pulling on the cable cores by hand.

Thanks,
Rob

#6 teg

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Posted 20 April 2015 - 08:35 PM

View PostSnakeoil, on 20 April 2015 - 05:29 PM, said:


I just want to make sure nothing is missing before I start to cut pins.


Going from a failing memory here, but I believe it is possible to shorten the chain without destroying the ability to return it to original length.  Also, as racepres says, it could be that someone got some new cables from Russia where they don't use CV carbs.  I do know that the cables for Pekar, Mikuni, and Kehin CVs all have different length inner cables.
Terry
2011 Retro

#7 Snakeoil

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Posted 26 April 2015 - 05:48 PM

I took one link out of the chain and the grip is now perfect. I also removed that annoying little loose block that goes beneath the slug. When I started statically sync the carbs, I did notice that I had a bit too much free length in the cables. So, I made a pair of ferruls that took up 1/8" of slack and put the adjuster screws in the middle of their travel.

regards,
Rob




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