XR600R stiff throttle fix??

Holy crap the throttle is stiff on this thing!!

Especialy the initial opening...makes for abrupt throttle use!

Is there a aftermarket spring and or mod?

Might help if you specify year, if it,s new could be normal. If it's a couple yrs old cable might be rusted up inside or the sheathing is breaking down.Also check for routing, most cables hate sharp bends or turns.


Double check and make sure your grips are not hanging up on your handlebars and or wrap around hand guard.

Try cutting yoiur grips off and see what it does, probably ready for a new pair anyways.

Try lubing those cables. When everything is right, it's not stiff at all.

I've had two stock XR600s and an HRC628. These engines have so much manifold vacuum when the throttle slide (stock carb) is closed that the slide is sucked up against the front side of the slide bore and when you hit the throttle, the slide jumps open suddenly causing control problems. I have had decent results by adding an ounce or so of two-stroke oil to each gallon of gas, this provides some lubrication on the slide. The best cure that I have found is to go with an Edelbrock carb, easier starting, no flooding when you crash, excellent throttle response.

Thanks for the tips fella's....cable routing/lubing/grips etc.....already covered the basics though.

I was suspecting the vacuum issue too...that's prolly what it is alright.

Feels exactly like that as it is resisting opening from closed and then once it's open it is smooth. I don't suppose there is much to do about it?

The bike is a 90, maybe there is some play in the slide exsagerating the problem too?

I thought I had read somewhere about a lighter throttle spring for these carbs?

Anybody try modding the stock spring?

since its a 90 model, could be your linkage shaft on the carb, either worn or some crud built up around it, and theres probably some build up of gasoline/ carbon deposits on the slide itself especially on the engine side, pull the slide and clean it carefully making sure not to damage the membrane on top, while you have it apart try daves mods, drilling the slide vacuum ports is supposed to make it open easier. Although the throttle is not directly connected to the slide, its not gonna hurt to make sure its clean. But more than likely it is probably in the throttle assembly, when cables are near failure they tend to be frayed at the end where they are required to flex the most, the fraying causes excess friction at first movement. Just some ideas, sorry not more specific.

I have the same issue with my bike (93 XR). As creeky posted, adding a small amount of two stroke oil to the slide cures the problem. While you have it apart, lube the linkage as well.

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