Topic: modified throttle, shorter travel way ?

[Viktor.J]

Have anyone modified the throttle ?

My throttles "travel way" is estimated (by me) 110+ degrees and its not comfortable to ride with the wrist twisted 90 deg.
Any one tried to modify the "throttle grip" so the travel way gets shorter ?

I will try to explain 

Alternative Original:
original throttle gripp (i dont really know the numbers) but lets say the throttle has a radius "R", thickness "t" and the throttle cable moves 1 mm / degree (twisted throttle) .



Alternative modified:
thicker "t" => bigger R , throttle radius so the throttle cable moves 2 mm/ degree hence total travel length is 80 degrees ?

The numbers fictional but the principle is the same.

Well, for every added 1mm to the throttle grips radius, the "mm throttle pull/degree twist" ratio increases with 0,017, the question then is, how much can you modify (increase the radius) before the throttle cable interfere with the "switch house"  ??

Any thoughts ? recommendations ?

[liPPy]

http://www.venhill.co.uk/Controls_and_Levers/MOTORCYCLE_CONTROLS/TWISTGRIPS/888_VENHILL_FAST_ACTION__PUSH-PULL_TWISTGRIP.html

[Viktor.J]

http://www.venhill.co.uk/Controls_and_Levers/MOTORCYCLE_CONTROLS/TWISTGRIPS/888_VENHILL_FAST_ACTION__PUSH-PULL_TWISTGRIP.html

Thanks, but the question wasnt really if i could find another throttle with shorter "pull"
I want to modify the one that i have, cheaper and stock look

[LesterPiglet]

If you could find something suitable to modify the diameter of the throttle tube where the cable wraps around that would work. I have a spare tube, I must look into this.

[RickB]

I have a similar problem with my CB400F. I changed from bulky cafe style grips to slim GP style grips. Now I have to 're-grip' if I'm at full throttle. I like the stock switch/throttle assembly and would love an ingenious way to make the twist quicker other than using a bulkier grip.

[Viktor.J]

I dont have my stuffs here.. anyone know how much space in the "switch house " => how much you can build up the throttle hence get a bigger lever arm, or any internal measurements  ?

worst case i guess you'll have to some turning in the switch house if there's enough material.

[lucky]

They have made 1/4 turn throttles since 1950's.
Just go to the dirt bike catalogues.

Street bikes have 1/2 turn throttles and racing motorcycles generally use 1/4 turn throttles.
And it all started with 7/8 diameter handlebars too so you are in luck.

One more thing. Almost all of those plastic throttle sleeves fit most switch housings.

End of problem.

[lucky]

I have a similar problem with my CB400F. I changed from bulky cafe style grips to slim GP style grips. Now I have to 're-grip' if I'm at full throttle. I like the stock switch/throttle assembly and would love an ingenious way to make the twist quicker other than using a bulkier grip.

Just buy a 1/4 turn throttle sleeve and put it in your switch housing.
Not a big deal.

[RickB]

I think Viktor wants to keep the stock switch/throttle assembly, so that would mean a modified tube, not the whole throttle assembly. I wasn't aware there were 1/4 tubes, so thanks for bringing that to my attention.

Something like this perhaps?

http://canyonchasers.net/shop/sv/R6-throttle.php

Rick.

[RickB]

There's some great pictures and walkthroughs here too Viktor, I think this will answer your question:

http://cbrforum.com/forum/f4i-main-forum-11/want-more-oomph-1-6-quick-throw-throttle-mod-must-see-****-132894/

If you try it, be sure to report back!

[Viktor.J]

I have a similar problem with my CB400F. I changed from bulky cafe style grips to slim GP style grips. Now I have to 're-grip' if I'm at full throttle. I like the stock switch/throttle assembly and would love an ingenious way to make the twist quicker other than using a bulkier grip.

Just buy a 1/4 turn throttle sleeve and put it in your switch housing.
Not a big deal.

The switch housing have this extra space ? i mean for a 1/4 throttle you would need a bigger "throttle radius"..
But if there place in the switch house, then everythings cool..

There's some great pictures and walkthroughs here too Viktor, I think this will answer your question:

http://cbrforum.com/forum/f4i-main-forum-11/want-more-oomph-1-6-quick-throw-throttle-mod-must-see-****-132894/



If you try it, be sure to report back!

Great thanks !

That was exactly what I thought of doing, the question now is then what the measurements are inside the switch house. As earlier mentioned i don't have the housing here, so if someone have easy access you are welcome to measure it for me

[bjbuchanan]

Increase the radius where the cables attach. Take thin wire and wrap it to increase the radius where the throttle cables ride. If you want you can hog the innards of the switch a little to make some clearance. It will reduce to an extent the needed "twist" due to a larger radius where you want it, not where you sometimes get stuck having to apply it(i.e. grips)

[RickB]

Did you have a chance to see how much room you had to play with inside the housing Viktor?

[bjbuchanan]

I'm a fan of epoxies so I would say jb weld and would build up the circumference of the throttle tube plenty oversized and the file and sand to take it down to how I would like. I don't mind hogging out a stock switch because mine were a little beat up anyway. It seems to me like a little 3 beer project to try it out

[HondaMan]

Also try a lighter return spring: this helps.

[MRieck]

I have used R1 sleeves in othe bikes.

[Viktor.J]

Did you have a chance to see how much room you had to play with inside the housing Viktor?

No, the bike is 200 km away, and i have a lot in school now so I can't find the time
But maybe next week.

Also try a lighter return spring: this helps.

In what way ?
At first thought i can't se how a lighter return spring (<Fs) would change the travel lenght of the throttle cable, in another way then that the weaker spring dont have the power to return the throttle gripp to start. pos.

[DJ_AX]

It's on my list to modify the tube. I'm going to try the wire (plus some JB weld maybe) method.

Also try a lighter return spring: this helps.

This makes sense... as the twist distance (twistance?) is reduced it'll require a little more wrist.

[lucky]

Its plastic it can be modified.

[lucky]

If you work on bikes long enough you will see good throttles with different "ramp" configurations for the throttle.

[DJ_AX]

If you work on bikes long enough you will see good throttles with different "ramp" configurations for the throttle.

I like it!
As a kid, I've built lots of ramps!

[BuffaloBill]

How about leaving the throttle tube stock, and using a smaller radius pulley on the carb shaft?
Bill

[Dimitri13]

When I had my Ninjette, a common mod would be to put a zip tie on the area where the cable lies on the throttle tube, making the diameter larger.

[bjbuchanan]

How about leaving the throttle tube stock, and using a smaller radius pulley on the carb shaft?
Bill

I think that would probably be the hardest way to go about it. Not knocking you but its prob true

[BuffaloBill]

How about leaving the throttle tube stock, and using a smaller radius pulley on the carb shaft?
Bill

I think that would probably be the hardest way to go about it. Not knocking you but its prob true

You're right, it would be more involved.  It'd be handy to have a lathe and milling machine for that project.  I'd think there'd be a market for an after market kit including a new pulley and cable mounting bracket.  What would be the optimum amount of ratio change be? 30% less rotation at the grip or so?

[bjbuchanan]

I would agree with the 30% bc IMO you dont want to little twist and thirty would probably kill the need to re-grip for full throttle

[MCRider]

Many threads on this subject. Not really much market for a quick throtle on an old street bike. IF you reduce the rotation you increase the effective return spring pressure and that's what most people complain about.

I think using a throttle tube from a different bike is the easiest route. Mike said he uses an R1. I've heard the the CBR900 and similar models will slip right in.

I have an Italian job on my project. It fits into the stock switch, adding about 1/2" to the stack of stuff on the right side.  Knowiing what i know now about the replacement pipe throttles, I would have gone that way and may still.

PS: They are often called "1/4 turn quick throttles" but in fact are something else, usually more than 1/4 turn as that would be very radical on a street bike. But appropriate perhaps for a dirt bike or a road racer.

[Viktor.J]

WIIIHHOOOO

I have now meassured the switchhouse... and there's plenty of space...
Some how the picture i took with meassure ments dissapered :S
I remember the total distance to be 10 mm - 1 cm... And my throttle grip with wire is about 4-5 mm.. så you should have a few mm to bouild up the throttle grip...

I figure im going to order a new plastic grip (mine was metal :S ) and modify that one (dont wanna destroy stock).... I guess the procedure would be building it up, sand it down to fitment..

Any one have any Ideas to what material (plastic) that could work ?




HAHA I Just figured, if you look at the first picture.. where the cable attaches that would be the max radius that fits in the switch housing, right ?

[MCRider]

If you're going to order a new pipe throttle, why not try the CBR900 or as Mike said an R1? The work's already been done for you.

[bollingball]

Mc How would I look up the part what year R1 or CBR900. They allways want the year and model
Ken

[MCRider]

Mc How would I look up the part what year R1 or CBR900. They allways want the year and model
Ken

Well that's the rub isn't it? For the R1 I'd PM MRieck for details. Mike said it worked.

As to the CBR900/929 etc., I've just read about this, here and elsewhere. I think Kit put one in her CB650, she hasn't been on line for a while that i've noticed. My guess is that if you check out several microfishies on the CBR, you'll find the part number is the same for multiple years. Sp pick one.

I'm guessing these are less than $10, so within my threshhold for speculation buying. You may be uncomfortable with such an approach.

If I were really interested, and i may be later, I'd go to a salvage yard like CycleRecycleII and dig thru their boxes of throttles.

[bollingball]

http://www.westernhillshondayamaha.com/fiche_section_detail.asp?section=2100127&category=Motorcycles&make=HONDA&year=2001&fveh=124413

#8 is the best I have found. I don't know if these bikes had 7/8ths bars.
Ken

[MCRider]

http://www.westernhillshondayamaha.com/fiche_section_detail.asp?section=2100127&category=Motorcycles&make=HONDA&year=2001&fveh=124413

#8 is the best I have found. I don't know if these bikes had 7/8ths bars.
Ken

Curious it seems they sell the pipe and grip together?
As to the bars, I would normally say all jap bikes are 7/8, but some of the newer Jap (Metric) cruisers may be 1". I don't know either for an absolute fact.

[bollingball]

I will pm Mike the only R1 I found was a single cable. I noticed that about the grip. Same for the C,F or RR. If it works I might get the grip for the other side . If I like how it feels. Thanks any way.
Ken

[MCRider]

I will pm Mike the only R1 I found was a single cable. I noticed that about the grip. Same for the C,F or RR. If it works I might get the grip for the other side . If I like how it feels. Thanks any way.
Ken

My R1 Fishy (Motogrid) for a 2008 R1 shows it as a 2 cable pipe throttle. What may have thrown you is that the cable itself is combined into 1 part number, rather than 2 separate cables. Still a 2 pull cable though.  Curious that they include the grip with the pipe, same as the honda.

[Viktor.J]

I found a CbR900  grip in Ebay.. asked the seller about the outher diameter, she answered 32 mm... Thats not so big, isn't that the exact size of the original ? 22 inner dia, and then around 5 mm per build up for throttel leverage = 32 mm...

[TwoTired]

Unless your bike has accelerator pump carbs, CV types, or fuel injection.  Moving the slides faster on throttle twist is a recipe for increased hesitation in acceleration.  imo
I suppose you could mediate this issue with making the carb set up very sloppy rich.

Cheers,

[MCRider]

Unless your bike has accelerator pump carbs, CV types, or fuel injection.  Moving the slides faster on throttle twist is a recipe for increased hesitation in acceleration.  imo
I suppose you could mediate this issue with making the carb set up very sloppy rich.

Cheers,

I understand your concerns. And certainly success may be on a model to model basis.

From personal experience: stock CB750K2 carbs (no pumps) and Mikuni VM29 (no pumps) are not overwhelmed by the increase rapidity of slide movement. For my purposes, it was a huge improvement. Reduces the peception of needing to grab 2 handfuls and it increases response. No special jetting wsa needed for the throttle itself.

Downside as i've mentioned is it increases the effort needed to turn the throttle. And it increases response (I said that already?) which has the downside of twitchiness.

A real man can handle the downsides. 

[TwoTired]

I did say you can overcome by making the carbs sloppy rich.  But, if you don't care what sort of fuel economy ($) you get, it will "run well (enough) 'til parked". 


These days, it seems a "real man" must act (react) before thinking about why, and what for, and then adapt to the outcome.

Reminds me of a Pee-Wee Herman quote.  "I meant to do that."

Pee Wee's Big Adventure - Bike Flip