YZ 1/4 turn race throttle mod

Ok, I've been waiting to do this mod on my 02 YZ426 for some time now and haven't really seen anyone post on this board on how to make a 1/4 turn throttle.

This is a very popular mod on sportbikes and it's a must have on my trackbikes. I've done a 02 R6 and a 01 R1 and it makes a world of difference in how quick you can turn the throttle and doesn't put you arm in a strange position when going full throttle.

If you have a spare throttle tube I would suggest giving it a try and let us know how you like the mod, you will be amazed at how much difference the bike will feel after you do the mod.

You may notice on a stock throttle to get every bit of full throttle you end up with your wrist in a strange position unless you start with your elbow sky high. Now that I have done the mod on my track bikes I've had a real tough time finding the stock YZ throttle acceptable.

Here's what you have to do

1. Take off throttle tube assembly, duh.

2. Here is a pic of the stock diameter tube.


3. What you need to accomplish is increase the diameter so when you twist the throttle it is actually pulling the cable further since the tube has a larger diameter.

4. To increase the diameter of the tube go to home depot and purchase a PVC coupler (I believe 1 1/4"). approximately $0.37

5. Measure the width of your cable guide. see pic.


6. Cut the PVC coupler a few mm larger than the width of the guide.


7. Use 100 grit sandpaper and smooth the edges of the PVC piece and make sure to get approximate width correct.


8. Once you get close to the approximate width you need to test fit the PVC piece on the throttle tube making sure to cut the approximate amount to allow the PVC coupler to fit flush with the tube.


9. If you are satisfied with the fit, I would sand a nice transition on the throttle pull side so the throttle will have a nice smooth throttle reaction, this will very depending upon how much you smooth the PVC. Take a look on the really expensive custon aluminum throttles and you get the idea. Alsocut a slight slot in the return side so the cable fits nicely, you'll understand when you put teh cable back on what I'm talking about.

Take a look at how the PVC rolls into the throttle tube on the lower right.


10. Now it's time to cut the internal tabs off of the throttle housing with a dremel. With the larger diameter throttle tube the PVC WILL HIT the tabs on the throttle housing and bind the throttle action, not good. Cut these small tabs off.

With tabs...


Without tabs...


11. Before you glue the PVC to the throttle tube be sure to test fit the throttle assembled to ensure the throttle doesn't bind.

12. Now you are ready to use 5 min epoxy to glue the PVC to the throttle tube. make sure to leave a little extra on the cable side so when the glue hardens you can sand the edges perfectly smooth.

13. After everything is dry I would adjust the cable tension to the loosest setting on the carb. Note if you don't do this before you install the assemble you will have a really difficult time adjusting the throttle play.

14. Assemble the throttle tube with the cables and install on bike....

15. Adjust throttle cables and make sure you have enough free play and go out and enjoy a faster, more responsive throttle, without the extra wrist twist...

Total cost of mod

1. PVC coupler $0.37

2. 5 min epoxy $3.00

One of this best mods you can do for under $5. Heck if you don't like the mod go to ebay and buy a stock tube for $10 and you're back to stock.

Do this mod at your own risk. :applause:

So your saying you can't twist the throttle fast enough? lol yah right. I can understand on a street bike where the power would be smooth but this would jerk your arms out of their sockets or possibly cause it to stall because 4-stroke like the throttle to be rolled on.

You can still roll the throttle as slow or as fast as you want, this just allows you to have less twist to go wide open.

Think off this as if you are looking at the end of the throttle tube and it takes say 60 degrees to go full throttle, this mod will have you at full throttle in 50 degrees. These are just approximate numbers but I hope you get the idea.

And trust me on a liter street bike throttle control is much more touchy than a dirt bike.

Here is a link to the expensive aluminum throttle tubes I mentioned http://www.pwccost.com/shopping/g2/g2_ergo.htm, they explain how the throttle will work with the various curves. I'm doing the same thing just for $.37. You can customize how quick the throttle will roll on just by the curve of the tube. As you can see with my mod I have the throttle be sensitive at first and then roll on heavier with mid to full throttle.

Like I said you could go to ebay and find an extra throttle tube to do this mod if you are riding in and area you need a lot of throttle fast( like the dunes) If you are riding in the woods etc. you can swap it back to stock in a matter of minutes and your good to go.

Personally I think alot of people on this board would really love this mod, I sure do and heck it cost me less than two gallons of gas here in So Cal. :applause:

I find this hard to believe that nobody is even interested in this mod???? Once you try it you'll never go back to a stock throttle.


That is a great detailed post.

Thank You :applause:

I was thinking for something similar often, because i have really a problem with angle of my arm through the throttle positions. I tried to change my inital grip position to ride more comfortable with half throttle but the i got more armpump. I was concerned about this integratet stop in the throttle unit and was afraid to grind it out. When you use the g2 quick throttle do you have to grind it out also?


I think i will give it a try over text weeks.

I am gonna do it, I will post results! I need something to do in the garage today, raining today...

Is that straight off of #22?

Things happen fast enough on a 450 the way it is.....


I did the same thing on my bikes, all of them. I just did it a little differently. I took two part epoxy and built up the throttle tube then sanded and shaped it how I wanted. It does the same thing but does take more work.

Anyway, what bit did you use on your Dremel?

i love it on road race/track days, not sure about it on my 450...props on the detail and time you spent making this post either way!

MJ, yes it will help tremendously about having to twist your wrist, that's really why I do it to all my bikes. Once you try the mod you will be hooked and never go back to riding a motorcycle that can't be wide open with a single twist.

Not sure about the G2 throttle, my guess is yes, if you increase the diameter of teh throttle tube it should hit which is why your remove the tabs. The G2 kit looks great, it just cost $60 and my mod is $0.32 and you get to pick your throttle curve yourself.

Baron, thanks , you have seen the light as well, I will never go back to stock throttles...... ever.

And yes, your way would work perfectly, it is just MUCH harder, I'm lazy.

The reason I spent time photographing each step is I knew so many people would love to have this mod on their bike, I learned this trick on the R1 and R6 forums why not share with my dirtbike friends. :applause:

So has anyone tried this yet???

I did it 2 nights ago and was very easy to do. I have not ridden it yet, going to try and get out and ride tomorrow...:bonk:

I'm so trying this.

Mbiker, where were you a year ago when I bought the expensive version. I am going to use my original throttle from my 450 and make one. I will swap it out with my aftermarket throttle and give it a shot. Very creative mod.Thanks

A friend of mine bought the alum tubes in a 3 part set for his RM 250 and loves it. but i like this cheap mod.

once i get the balls to ride my bike the way it should be ridden, ill have to try that mod. my forearms are always killing me from wrenching my arm all the way to get WOT.

I installed the mod last night and we are going to try it today....I hope it will

give me better lap times...Do you have any cures for my brake master cylinder

hitting the ground? I can't go fast around left turns...


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