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I know this might belong in wanted section but maybe I can get some advice before buying. Looking for decent oem trx thumb throttle assembly. Apparently I have a 400ex one and no matter what I can’t get slide open all the way(38mm as). Hangs about 4mm Down. I have new cable and another new cable and now there’s work. Here are a few pics of what I’m dealing with. I crudely moded for more throw but it’s not enough. I also don’t like having a huge throw. Any pointers towards a after market throttle or tips on this. Thanks in advance.
image.jpg image.jpg
 

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I don't really have any insight for you on an aftermarket thumb throttle. I do have experience with the 400EX throttle. I have had one on my R for 8 years. I never have noticed any issues with the amount the throttle travels or the slide not opening all the way. Possibly the previous owner modified it, or it could be that I have an adjustable Motion Pro throttle cable. You can adjust the cable to where the engine revs quite a bit.
Loren
 

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Thanks norm. I’m running the MP cable # 01-0604 adjusted all the way out. I don’t know maybe it’s fine opening that far. Gotta be 97% open.
 

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That is the same cable I have on all my R's. I have never looked inside the carb to see how far the slide opens. So mine could possibly be doing the same thing as yours.
 

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The 01-0604 is the same cable I use for the stock thumb throttle & pwk. Not trying to question your methods but are you looking inside the card throat to verify the slide's not opening all the way or are you going by feel? When I adjust mine I use an inspection mirror & adjust it until it just reaches wot but when it gets there it's not actually topped out so you wouldn't feel that in the throttle.
 

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I know this might belong in wanted section but maybe I can get some advice before buying. Looking for decent oem trx thumb throttle assembly. Apparently I have a 400ex one and no matter what I can’t get slide open all the way(38mm as). Hangs about 4mm Down. I have new cable and another new cable and now there’s work. Here are a few pics of what I’m dealing with. I crudely moded for more throw but it’s not enough. I also don’t like having a huge throw. Any pointers towards a after market throttle or tips on this. Thanks in advance.
View attachment 64493 View attachment 64494
I was looking in the carb and holding wide open.
View attachment 64499
Easy answer;

The 400ex, or even the 450R Thumb Throttle will not fully open a 38-41MM Kehein or Mikuni. It will either be a bit short at fully closing or a bit short at fully opening. Before someone jumps all over my statements; it is essential for Racers to be able to fully close or open a carburetor on the track, that is why I know a 400ex or 450R thumb throttle won't, been their many times. The issue is worse with 40-41.5MM Carb Bores. Even the Urmosi does not work.

Cable choice is correct, the problem is not enough movement in the 400ex or 450R Thumb Throttle to fully open the carburetor…this is the case for almost all thumb throttles except the OEM 250R or aftermarket Billet Thumb Throttles.

Get a real 250R OEM Thumb Throttle or an aftermarket Billet Throttle (like Terry Cable, not the poor-quality Chinese ones); problem solved.

PS: in the picture you posted your Carb is not fully opened, it is partially closed.

Carlos
 

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Discussion Starter #8
Thanks Carlos. Yea I posted that to show It will not open all the way. I had no idea I was not a stock throttle. The old carb whatever it was would open all the way. Let the hunt begin for an oem trx throttle!😬
 

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Discussion Starter #9
Update. I took the terry cable off my raptor, works great on 250r. Not sure if they all the same. Mine is fairly old. Raptor has super short throw due to throttle body and the adjuster had plenty of swing to open the 38. The 400ex works really well on the raptor. Will just need to ad a stop which looks likes it’s cast for one just needs taped and a new cover. Also tried a chariot off of banshee which also works just has a ton of travel. Least out of all this both quads are rideable. The raptor is comfortable with Honda throttle. OG terry cable is awesome on trx. 😁🍻🍻
 

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Easy answer;

The 400ex, or even the 450R Thumb Throttle will not fully open a 38-41MM Kehein or Mikuni. It will either be a bit short at fully closing or a bit short at fully opening. Before someone jumps all over my statements; it is essential for Racers to be able to fully close or open a carburetor on the track, that is why I know a 400ex or 450R thumb throttle won't, been their many times. The issue is worse with 40-41.5MM Carb Bores. Even the Urmosi does not work.

Cable choice is correct, the problem is not enough movement in the 400ex or 450R Thumb Throttle to fully open the carburetor…this is the case for almost all thumb throttles except the OEM 250R or aftermarket Billet Thumb Throttles.

Get a real 250R OEM Thumb Throttle or an aftermarket Billet Throttle (like Terry Cable, not the poor-quality Chinese ones); problem solved.

PS: in the picture you posted your Carb is not fully opened, it is partially closed.

Carlos
So an oem trx250r OEM throttle assembly will fit on a 38mm PWK a/s? I want to double check. Looking at a used PWK and want to get everything together at once. Thanks?
 

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Easy answer;

The 400ex, or even the 450R Thumb Throttle will not fully open a 38-41MM Kehein or Mikuni. It will either be a bit short at fully closing or a bit short at fully opening. Before someone jumps all over my statements; it is essential for Racers to be able to fully close or open a carburetor on the track, that is why I know a 400ex or 450R thumb throttle won't, been their many times. The issue is worse with 40-41.5MM Carb Bores. Even the Urmosi does not work.

Cable choice is correct, the problem is not enough movement in the 400ex or 450R Thumb Throttle to fully open the carburetor…this is the case for almost all thumb throttles except the OEM 250R or aftermarket Billet Thumb Throttles.

Get a real 250R OEM Thumb Throttle or an aftermarket Billet Throttle (like Terry Cable, not the poor-quality Chinese ones); problem solved.

PS: in the picture you posted your Carb is not fully opened, it is partially closed.

Carlos
"Get a real 250R OEM Thumb Throttle or an aftermarket Billet Throttle (like Terry Cable, not the poor-quality Chinese ones); problem solved" ...YES, TRX or ATC 250R 85-89

Carlos
 

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So an oem trx250r OEM throttle assembly will fit on a 38mm PWK a/s? I want to double check. Looking at a used PWK and want to get everything together at once. Thanks?
Correct. However, you will also need a Motion Pro cable, part # 01-0604.
 
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