Still have pilot jet problems.

tuffbuilt · Posted: May 13, 2009, 3:15 pm Post subject: Still have pilot jet problems.

OK While rebuilding the carbs a while back I had read about drilling the covers off of the pilot jet adjustments to correct some lower speed problems. While I had the carbs off I did this. I am now having problems at lower throttle running, sometimes I have to open the throttle up to get the bike to stop feeling like it is trying to bog down. At idle I seem to have a popping in my left exhaust pipe, and when I rev the motor it is slow to idle back down. Is there a way to adjust the pilot with the engine running? I have tried the 3 turn and 31/2 turn methods and it dosen't seem to be right. Any ideas? Thanks, 81 xs650 special II, stock all the way through.

woodman · Full Member Joined: Oct 12, 2008 Posts: 256

I have an old snowblower gas tank that I strap on the handlebars to run mine with the tank off so I can synch the carbs

Retiredgentleman · Posted: May 13, 2009, 9:00 pm Post subject: Re: Still have pilot jet problems.

You can adjust the air/fuel mixture screws with the engine running using the "dead cylinder method". Just be sure to always have both spark plug leads connected to a grounded plug.

xs650temp.proboards.co...read=10538

Click on the first link for BS carbs.

If you "sync" the carbs, it will help to bring the hovering idle down.

tuffbuilt · Posted: May 13, 2009, 10:47 pm Post subject: Re: Still have pilot jet problems.

I use gas out of the tractor we use to plant once a year. I went through the carbs again and found the small hole at the end of the pilot jet colgged on both cylinders. I have cleaned these out and set the pilot jet screws at 31/4 turns each. I am going to get the manometer from work tomorrow and fire the thing up and see what I can do. Thanks for the help guys. RG you always seem to be there when I have lost my way, Thanks. All of the guys on this web site have been great to help me keep this thing going and we are getting closer!!!!!!!!! Thanks Rob.

tuffbuilt · Posted: May 13, 2009, 10:49 pm Post subject: Re: Still have pilot jet problems.

The only thing that really bugs me is I can only find the pilot screws I uncovered to adjust! Is there something I am missing?

Retiredgentleman · Posted: May 13, 2009, 11:56 pm Post subject: Re: Still have pilot jet problems.

Its not good to use gas that has been sitting around in a tractor. Stale gas may make your engine run poorly or not at all! In line fuel filters will stop dirt before it gets to the pilot jets. 650central has some with the barbs at right angles, which I find work well.

tuffbuilt · Posted: May 14, 2009, 5:18 pm Post subject: Re: Still have pilot jet problems.

I was just joking about the tractor gas. Evidently the pilot screws are the only adjustment I have along with the carb. sync screw. I got a stone filter at the local bike shop, the element looks just like the one in your photo. I installed it in the line between the tank and the carbs. I only have one line. Whays your opinion on linking the vacuum ports together? I have read some of the post and some swear by it and some at it.

weekendrider · Posted: May 14, 2009, 11:04 pm Post subject: Re: Still have pilot jet problems.

tuffbuilt, have you checked for vacuum leaks? You're correct about the adjustment, you have the idle speed, mixture, and sync screws. The other adjustments being jet sizes. You may want to try going up one size on the pilots.

tuffbuilt · Posted: May 16, 2009, 4:37 pm Post subject: Re: Still have pilot jet problems.

Thanks for the response, I am still messing with syncs and pilot settings. I now have a problem with after a wide open throttle run it is slow to idle down. I can put the engine under load and it will idle right down, however if I just pull the clutch in it stays around 2500 to 3000 and comes down very slowly. May very well be a vacuum leak, sounds like time to dig out the propane torch and look.(finds the leak without the mess) Low speed running is much better and a lot less surging than I use to have though. I still have a oil leak some where around the base of the cylinders, maybe for the cam chain adjuster cover nut.If I don't find a vacuum leak where did you say to get those jets? Thanks Rob.

gordo · Posted: May 16, 2009, 7:42 pm Post subject: Re: Still have pilot jet problems.

Slow to return to idle is a symptom of lean/ vacuum leak. The 'carb holder's' are notorious for that. Very sparingly spray some carb cleaner around the holder's while running at idle, if it smooth's out ,they're leaking. Watch where you spray, because the throttle shaft's also are leaker's. So find the leak or at least you'll know if it is or not.When I install my carb set up, I use just a "film"of silicone sealer on the head side of the holder's for a little insurance against leakage. The pilot jet's are very lean, & weekend is correct on going up 1 size. Good luck, Gordo PS,,,, Mike's has the jet's your looking for,,,

tuffbuilt · Posted: May 17, 2009, 11:20 pm Post subject: Re: Still have pilot jet problems.

Borrowed a digital manometer from work and worked with the pilot jet screws and the carb sync to get it as close as I could. Bridged the vacuum ports together with a "T" and it doesn't run like the same bike. Smooth and very responsive. I read in one of the post about putting a 3/8 fuel line on the sync screw to turn it with the tank on, works great, made a screw driver to get to the pilot screws with the tank on and rode and worked with them. Used needle nose vise grips with fuel line hose on the jaws to close off the lines until I had a stable reading. Set up worked good. Can't wait to ride more. Thanks guy's for all the help and advice, Rob.

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