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john450f

throtle ssstop??

18 posts in this topic

got my bike today. my dealer removed the throttle stop completely and the bike seems extremely lean (glowing pipe and popping) Does the screw have to be in to prevent lean mix. Please respond - don"t want to run until I know. The mech. didn"t seem to know a lot about the bike

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First of all the bike runs hot to begin with. This is why they tell you not to let it idle for long periods of time. And yes the pipe will glow red after some time idling.

As far as the throttle stop is concerned, it should not affect the fuel mixture nor should it make the bike run lean. (I could be wrong on this, but I'm pretty sure). Maybe something to do with the "TPS" throttle position sensor. Perhaps you should try to adjust the air/fuel mixture screw. This will help the bike during idle (if the bike pops when idling). If not, I would take the bike back and have the dealer make it run properly.

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John, The throttle stop should be cut to length or replaced with the YZ screw p/n 5JG-14591-00. I bought the YZ screw and measured them both. The YZ screw is 11mm shorter. I was told by a reputable dealer that if you just remove it, the throttle position sensor (TPS) "may" have problems.

Good Luck!

Jeff

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Mine ran so hot with the baffle in after riding less than a mile that it freaked me out! I pulled the baffle. It runs better and stays cool but is still way lean. I am just waiting to see where the guys in warm weather go with the jetting. If you take the stop out the carb will actually open to far I would think, causing a bit of a stuble at WFO? Now, if the snow would lay off! Ahhh well. It will just let me get it all prepped without the distraction of riding it. Well at least not to much! ---Mike

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I've had two WRs, 400 and 250, both of which I removed the throttle stop. I have friends that cut the stop to speculated lengths. All the bikes, with thousands of miles, run well with no apparent problems. Is there any compelling evidence that would indicate which method works best? Or is it just a peace of mind thing?

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Adam,

Somewhere I read a tech article that said to cut the stop, and not to remove it. As I recall with it removed the Throttle Position Sensor can get confused. It should be ground or cut so the slide reaches the top of the carb throat, anything beyond this just pulls the slide up into the carb., with no benefit. I also like the feel of the stop, without it you just twist the grip farther and get your elbow pointed at the ground and its hard to ride that way. There also may be wear problems inside the carb when the slide rises farther than its designed to go. When I bought my 400 (used) the stop was removed, I put in the YZ stop and liked it much better.

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I'm not convinced there is a TPS confusion problem. But, in the name of reliability, I think the YZF throttle stop couldn't hurt. Anyone now how much it costs?

Thanks for the input TC :)

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MOmilkman , good link, thanks. :) I have never experienced the high RPM miss from a confused TPS. I think it's a good idea to install the YZF stop for reliabilty. It's only 10 bucks, better to error on the safe side.

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YZ 80 bars= same bend as stock but a little narrower. All the better to fly thru the trees.

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Adam,

The YZ 80 bars are approx. 2" narrower than stock. A lot of Enduro riders cut an inch off each end to improve clearance in the trees. With stock bars it is difficult to fit everything on the bars once they have been cut. With the YZ 80 bars the narrowness is in the middle, the cross brace and pad is narrower, but the ends have plenty of room to fit everything. I have a mirror and horn button on mine. They are also approx. 1/2 inch higher than stock. Dwight Rudder and several other endoro riders use the YZ 80 bars. I ride allmost exclusively single track and like the clearance. 1" on each side sounds small but seems like alot from the seat. In a previous post a TTer recommended this and offered to buy back the bars from anyone who didn't like them. A money back guarantee with no upside for him?, probably not the sharpest knife in the drawer. I spent $1,000 on mine, sure hope I like em.

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John, the trottle stop replacement would be a good idea if there is a sensor issue. In addition, the machine is jetted lean to address emmissions issues from the factory. Your dealer may have changed the jetting depending on altitude, but probably not the PJ. I found that going two jets richer than stock on the pilot jet made a world of difference in idle performance. At 52 degrees F my bike starts 1st kick no cold start knob and totally runs like a champ. It no longer glows the pipe as the exaust gas temp (EGT) is substantially lower w/ a richer idle mixture. In all of my 4 stroke experience, I have never seen a plug foul due to a too rich idle mixture. (2 stroke, different deal) The performance will go horrible long before you foul a plug. Give it a shot and good luck. :)

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I've always used the hacksaw method. I never thought about using "mini-bike" handlebars. The YZ80 bars sound perfect. You west coast guys know all the tricks. :)

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f6dood, that info is helpful. haven't gotten into the carb yet(a little more complicated than all my old bikes- one cable and a gas line- 2 strokes) but when I do disassemble I want to do all adjustments at once. I'm in N. AZ at about 5000 ft. Any advice about jet sizes appreciated. OH and it doesn,t pop idling, it pops after a rev on idle down. it definitely seems to run way hot. pipe will be too hot to touch after running for less than a min. It is fast as hell though. I love every thing about this bike except I'm worried I'm going to blow it up because of my lack of tuning knowlede. Also currently running no throttle stop, yz stop ordered

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