1999 XR 600, help needed....

My Dad has an 1999 XR 600 that he has given to me to fix up. He does not ride as much as he used too, because I live a few hundred miles from him now. Last weekend while I was on vacation out in California, we went riding, and I noticed that his bike will not run unless the choke is on. The bike is next to impossible to start when cold, but it will start fine when warm.

When I rode the bike, the power it used to have was not there at all. It seemed to be way down.....

He told me that he just put in over $500 worth of work getting new valves and top end in it, but it seems to me that it is running worse now than it did before!!!!

I will be bringing this bike back from California to help him fix it, but I need help in diagnosing the problem. I tend to think that it may be an air or gas flow problem. The bike has plenty of compression and all, but just will not run right......

Any help any of you can share will be greatly appreciated.......

Thank you for looking......

Give it a good carb cleaning. If you have to run with the choke on it is not getting enough gas so you probably have a clogged jet.

Make sure that the carb is jetted properly, 152-158 main jet, 60 or 62 pilot jet, fuel screw 2-3 turns out. Make sure the jets are not clogged, especially the pilot, it clogs easily. Check the valve clearance.

Clogged pilot circuit.

I thought that it might need a good carb cleaning, and carb adjustment.

I just talked to him on the phone and he said that the carb has not been cleaned since the last time I did it.....over 4 years ago!!!!!

I think we have found our problem.....

But even more interesting is that he spent more than 500 bucks getting the valves and top end done, and the shop didnt even bother to look at the carb!!!!!

talk about taking short cuts......

Plus what is the stock jetting for this bike?

it has no modifications done to it, just a silencer and intake baffles ground out of it.....

Factory jetting is 152 main, 62 pilot. I have found that most 600s do better with at least a 155 main, sometimes the 62 pilot is OK, on others up to a 68 might be needed.

I have a 1998 XR 600R, I currently have a 160 main,65 pilot.Sea level.Starts cold on 4 - 5 kicks after the usual 5 slow decomp kicks and when a little warm,first time every time. Can you post your final choice for your pilot jet ?

Thank you

thank you for all your help.......

when I get it tore down, I will post results of what it was and everything like that.....

68 pilot and 158 main seems to work very good from sea level to 3500 ft.


Check the right exhaust valve. I spent all day re-adjusting mine. There is a special technique to do it. Just have patients, clean your piolet too.

I agree that the pilot circuit is clogged and mostly like the jet itself. The hole is tiny and easily clogged if not run often.

OK, what altitude do you live at? He lives at like 0 and if you live even 1500ft above sea level you need to rejet it. Having to run it on the choke and it not starting when cold means it is lean, VERY lean. go up on both the pilot and main one step and get back to us.

Hey guys ! I live at sea level " 0 " I will get another main today. I have a 68 pilot jet I will put in. The carb is clean,I have cleaned it 5X from when I bought it 3 mos. ago. I also installed a inline filter. I will check it out again this weekend and let you know. Thanks for all youre help ! Danny :cool:

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