slight hesitation (blip) coming off of idle

[beechfront]

it has been like this ever since i've owned the bike, and it has just not bothered me enough to tear into the carbs again.

but for some reason it has been bugging me lately and i would like to fix the problem.

coming off of idle, if i give it gas it hesitates just a moment then takes off.

also, if i am cruising down the road, hit the gas for a bit and let off just enough to maintain this new (higher) speed - it cuts out briefly when i back off on the throttle.

i don't know if the two are related... anyone have any ideas?

[DiverRay]

You know it's fuel or spark.
1. Put a timming light on #1, hold the trigger and blip the throttle. If the light fails for a split second, try it again at higher RPM. If it still failes when you go from idle to about 2,000RPM and hold, you may have the pickup coil wire problem.
Yamaha put the wire for 1&4 in a crimp, and that is the common break point. Check the teck tips to find the best repair, and ask if you don't understand something.
2. The timming was good, now you will be back into the carbs, maybe. I would do a valve check, timming chain adjust, timming check, and then carb sync. Of course, the easy way is just do the carb sync, to see if they "drifted" out of adjustment. If they are good, then it probably is something inside the carbs. You may be running a little lean or rich at the low RPM range. If you have had the carbs apart once, you probably know the drill. Just remember, it gets easier and faster the more you work on the
Ray

[beechfront]

well over the last 30,000 miles or so i've done the pickup coil, valves, timing, carb synch at least once each for unrelated reasons. this behavior has never changed.

i also don't recall 1&4 being in a crimp, but i could be wrong. i would think if it were electrical, it would have gotten worse with time.

i'm 99% sure it's in the carbs somewhere. idle mixture screws maybe? i'm sure i have those set to factory specs. i'm thinking that something is just gummed up somewhere but i have no idea where to start.

i've lived with it this long, and don't reallywant to dig in unless i have a good idea what might be causing the problem.

[DiverRay]

Then you are into a "total clean" carb time. Pull the rack, and pull all of the jets. Use a can of spray carb cleaner(I like Berrymans) with the supplied tube, to verify that ALL the passages are clean. Also, inspect the needles for wear, and the diaphrams for pin holes. There are threads that tell what and how to fix them.
I'm thinking you have two carbs that are just a little off. One probably would not be that noticable.
Good luck, and just take you time. Do plan on some parts, a "rebuild kit" at minimum. Just DON'T replace stock jets with ANY that are in the kit. Too many K&L problems out there already. Once you are done, play with the float hight a little. One MM up or down can make quite a difference.
Ray

[pggg]

Unscrew each idle mixture jet out another one or two turns and see what happens then.

[beechfront]

pggg - thanks i'll try that.

i've already done a massive cleaning/rebuild some time ago.

[RiskyBusiness]

Beech, glad to see you are alive and still fighting your old beast.

I have not had this issue with my XS but it reminds me of an issue I was exposed to in a car. In that case it was a timing issue and it was solved by advancing the timing because the timing was retarded. I'm not saying your bike is retarded... but it might be. *grin*

Good idea to adjust the idle as mentioned above. Always try the easy stuff first. My next check would be vacuum check. Then timing check... then rip into the carbs. Mine are on my workbench right now looking at me every time I walk through the garage.

Watch out for combines up there in corn land. I bet they would not even notice that you hit them!

-RB