Easier Thumb Throttle?

[Waynes400ex]

My wife rides the bike and her thumb gets sore after about 30 minutes, it is pretty tough!

Bike has a 39mm FCR carb from a crf450 on it. when I bought it used it came with the cable, I want to say it was from a Honda Rancher. Anyways is there anyway of making it easier? The cable has been lubed and that is not the problem.

someone suggested using a 2009 yfz450 thumb throttle? Has anyone done this does it help? Thanks for the help!

[slightlybent47]

I have my throttle just lose enough so that if I take both hands I can rotate it just a little bit. If my thumb starts to get tired I just rotate it down a little bit and it helps a lot.
Also you should do that to all the leavers so if you turn it over they can rotate on the bars and in most cases it will keep from breaking the leaver. Those things can get expensive, bars and lever can set you back as much as 500 bucks depending on what you have.

They also make an extension for the thumb throttle but I road one with it on there and I didn’t like it. You can take the cover off the throttle and take the spring out, that will take some of the tension off.

[JOHNDOE83]

They sell a palm pad that bolts on to the thumb throttle, it makes it so you can use the palm of your hand instead of the tip of your thumb.... or do like me and get a twist throttle, i bought my palm pad then went to the twist for the same reason.

[KISSmyACE]

They make a dual gasser that allows you to twist or use the thumb throttle, and it locks one or the other out at a time. I'd check it out.

Really the only thing that will change her soreness is just more use of it. It's a muscle.



And Slightly Bent... buy ASVs and aftermarket pars. you'll rarely bend aftermarkets, and the ASVs are virtually bulletproof. if they do break, they're under warranty. it's dangerous to have your stuff movin around on you while you're riding.

[Miami_Vice454]

^^ Agreed, after a while of riding, her thumb muscle will build up and it wont hurt anymore. same thing happened to me when i first started riding, but i was only 8 hahha

[3400ben]

I have the same carb. I just let the spring that is closes to the cable unwind one around. It cut the tension by about half.

[lester985]

i have a 39mm sparks fcr and its very light on the thumb

[3400ben]

Originally posted by lester985
i have a 39mm sparks fcr and its very light on the thumb

Does your carb have the stock springs? They do make a spring kit for them that reduces pull by 30%

[slightlybent47]

Originally posted by KISSmyACE
They make a dual gasser that allows you to twist or use the thumb throttle, and it locks one or the other out at a time. I'd check it out.

Really the only thing that will change her soreness is just more use of it. It's a muscle.



And Slightly Bent... buy ASVs and aftermarket pars. you'll rarely bend aftermarkets, and the ASVs are virtually bulletproof. if they do break, they're under warranty. it's dangerous to have your stuff movin around on you while you're riding.


There not loose enough that they move around. You have to take both hands to move them and then just barley. I have ASV on the clutch side and it came with a plastic sleeve that allows it to rotate, I just use the same technique on the break and throttle side.

[lester985]

no i dont think its a stock spring i was looking on ebay xbobs has the lighter springs for 30$

[NacsMXer]

Originally posted by 3400ben
I have the same carb. I just let the spring that is closes to the cable unwind one around. It cut the tension by about half.

Can you please share how you did this? I looked at my Sparks FCR 39 today and i'm not sure how to let it unwind around. I don't want the spring to get away from me and fully unravel. Thanks.

[3400ben]

I will post some pics tonight.

[NacsMXer]

Originally posted by 3400ben
I will post some pics tonight.

Awesome, thanks a lot :)

I think I see how to do it, unhooking the end of the spring near the "cable wheel" and letting it turn around. The pics and explanation of how you did it would be great though.

About how much easier is the pull now? 30,40%? It's not too easy now is it?

[3400ben]

Push down and over with the srewdriver. That will let that spring come out of the notch and spin around. On mine it reduce it by 30% if not more.

[coryatver]

Don't Get a yfz thumb throttle! Everyone I know with yfz runs honda throttles becuase the yfz one is horrible.

Best thing to do is get a Honda trx90 thumb lever. they are longer and are easier to push

[NacsMXer]

Originally posted by 3400ben
Push down and over with the srewdriver. That will let that spring come out of the notch and spin around. On mine it reduce it by 30% if not more.

Sweet, that's exactly what I was referring to. 30% sounds real nice, I don't want it to be too easy ya know? Thanks a lot man.

[3400ben]

I hope it works for yours. Every spring is a little diff. Good luck

[NacsMXer]

Originally posted by 3400ben
I hope it works for yours. Every spring is a little diff. Good luck

It looks like we have the exact same carb, I got mine from Sparks too. Gonna try it out tomorrow thanks again!

Oh and do you have a pic of the side of the carb by chance showing how far it goes into the airboot in the motor? My airboot on the airbox side has always seemed bunched up like it wants the carb to go towards the motor more. Since you have the same carb i'm wondering if mine can go in further.

[3400ben]

Here you go hope this helps

[togup]

http://www.exriders.com/vbb/showthread.php?s=&threadid=426914

[3400ben]

Originally posted by togup
http://www.exriders.com/vbb/showthread.php?s=&threadid=426914

Whats your point????

[NacsMXer]

Originally posted by 3400ben
Here you go hope this helps

Thanks a lot man I appreciate it ;)

[togup]

Originally posted by 3400ben
Whats your point????

sorry sent the wrong link
http://www.exriders.com/vbb/showthread.php?s=&threadid=370765&highlight=thumb+throttle

[3400ben]

Good link thanks

[tri5ron]

I did the same thing to my daughters trx90, and she has no more complaints of sore thumbs or hand cramps.

Last time we went riding, it was only her third time out on her quad, (she is 8 years old), and she did a 20+ mile loop ride. sure we took a few rest stops, but she did very well, and her throttle hand did not hurt after modifying the lever.

I'm glad I did it to both of their bikes, and they are both much happier.

[NacsMXer]

Originally posted by 3400ben
Push down and over with the srewdriver. That will let that spring come out of the notch and spin around. On mine it reduce it by 30% if not more.

I tried this once and failed, I tried again today and failed once again. I must have slipped off that spring 30 times lol :scary:

I can't for the life of me get the spring to slide over to the left to let it out and unwind. I'm trying my best to pull the spring over with one hand while pushing down with the screwdriver with the other. Any special trick to it or just brute force? :chinese:

[clemsonteg]

Originally posted by 3400ben
Push down and over with the srewdriver. That will let that spring come out of the notch and spin around. On mine it reduce it by 30% if not more.

Did you have to actually force it around 1 turn or did it come on around on its own like it was already pre-wound?

[3400ben]

Originally posted by clemsonteg
Did you have to actually force it around 1 turn or did it come on around on its own like it was already pre-wound?


It came around on its own (Pre wound)

[3400ben]

Originally posted by NacsMXer
I tried this once and failed, I tried again today and failed once again. I must have slipped off that spring 30 times lol :scary:

I can't for the life of me get the spring to slide over to the left to let it out and unwind. I'm trying my best to pull the spring over with one hand while pushing down with the screwdriver with the other. Any special trick to it or just brute force? :chinese:

Alot of brute force. Try using a needle nose pliers to help out.

[NacsMXer]

Originally posted by 3400ben
Alot of brute force. Try using a needle nose pliers to help out.

Gotcha, thanks. It is misleading because just pushing the spring off its "tang" it is easy to push. But getting it to actually slide over is a mother :mad:

I'll give it a go again.

[clemsonteg]

Originally posted by 3400ben
It came around on its own (Pre wound)

Last one from me, did it want to go around more than once? That way I know what to expect when I do it. Im sure it still has to be pre-wound some in order to keep its tension, unwinding it once just takes off some of the pre-load I am guessing.

[3400ben]

Originally posted by clemsonteg
Last one from me, did it want to go around more than once? That way I know what to expect when I do it. Im sure it still has to be pre-wound some in order to keep its tension, unwinding it once just takes off some of the pre-load I am guessing.

Yes it takes some of the tension off. One round worked good for mine. Every spring is a little different ( weaker stronger with age) You just have to make sure there is enough tension to close the slide. Good luck

[clemsonteg]

Originally posted by 3400ben
Yes it takes some of the tension off. One round worked good for mine. Every spring is a little different ( weaker stronger with age) You just have to make sure there is enough tension to close the slide. Good luck

Thanks for the info, I will make sure to hold onto it with something so it doesn't make it around more than I intend it to.

[NacsMXer]

I finally was able to wrestle the little spring over using small needle nose pliers. I let it unwind once around but I quickly noticed that there was no more preload on the spring like originally.

The slide snapped shut if I went WOT with it and let go real quick. But if I opened it something small like 1/8" throttle and let it go, it just sort of hung open. This was just opening the slide by hand with the carb off the quad.

I wanted this mod to work but ultimately I didn't like how the slide had become so "lazy" to close itself. Luckily I was able to reverse the mod by winding the spring back up to its original tension (was a little more difficult :o )

No free lunch for me on this one I guess :ermm:

[3400ben]

Originally posted by clemsonteg
Thanks for the info, I will make sure to hold onto it with something so it doesn't make it around more than I intend it to.

Did the mod work for you? Just wondering.

[clemsonteg]

Originally posted by 3400ben
Did the mod work for you? Just wondering.

I wouldn't know yet. I have been in Mexico working for 3 weeks, still have 3 more weeks to go. I plan to rejet in the spring so I figured while I had the carb out I would do it then.