XR600 Flat spot

[yzhilly]

Ok I need a few tips from the Honda gurus , My new  XR600 .1998  .Runs well ,starts ok but has a big flat spot from about 1/4 throttle ,if you wind it quick it will backfire and carry on if you ease through it runs ok and top end is good . It has a staintune exhaust ,valve clearances are on spec .Pulled carby and cleaned all seemed pretty good .

[80-85 husky]

they all do that....

[frostype400]

My mates does that too jetting changes might help search jd jetting they sell kits with info on how to setup your carb good if you are new to that sort of thing.

[matcho mick]

maybe with the staintoon,is lacking in backpressure??,try enrichening around the flatspot??,

[frostype400]

My mates also has a staintune exhaust on it but his you can easily get past the flat spot even if you wrap it on fast it is only at about 1/4 throttle never effects riding it because it gets on the power straight away it is only a slight hesitation.

Where my other mate has a ktm520 and that has a real flat spot from idle to 1/2 throttle going to play with the jetting on that one.

[80-85 husky]

I told ya...all the big 600's suffer from too much air if the throttle is suddenly pegged. you could try richening the pilot and needle to see if it can be reduced. most people ride around it. not often you want to peg a 600. that was one reason for the dual carb models to give a small primary to overcome the manifold "yawn".

the early single carb models (from g on I think) used to have an annoying "sticking" throttle at idle due to the inherent vacuum inside holding the slide against the carb until it got of idle.
just as you wanted a trickle of go to get through a tight bit, it would momentarily stick and down you went some used to drill a small hole in the slide to try and sort it but I don't know how this worked.

[crossedup2]

One of the fixes about 10 years ago was to find a WR400 yamaha carby. Hot start button on carby model (I guess any one of them would do the job). Has accelerator pump which helps with the flat spot.

Peter B

[Slakewell]

Roll the throttle on, dont just crack it like a two stroke or ring Ballard if anyone knows those big girls it's him.

[yzhilly]

Hmmm tried rolling it on fast or slow , this thing struggles lifting the front wheel .

[Ted]

Roll the throttle on, dont just crack it like a two stroke or ring Ballard if anyone knows those big girls it's him.

Why ring Ballard. Send it to the bloke that built Ballards and GHR Honda safari winning bikes.
Nick Dole. Teknik Racing. 0247322626.

[ghostrider]

Agree with Ted, I have had a few XR600s and Nick sorted any issues I had 

[Curtis]

Fairly comon on the old XRs. It can be jetted out to a certain degree and with the correct riding style, rolling on the throttle you can live with it. Otherwise a flat slide pumper will do wonders!

[TT5 Matt]

i went up 1 notch on the needle and 1 size up on the pilot jet with good results on my 1st model single carb xr600 which suited my riding style but not the chap who i sold it to so i put it back to std complete with the 45t rear spocket coz he didn't like to rev the motor too hard