Bike bogs stalls and looses power when hot

[dezmitchell]

Let me just start off by sayin i love my xs its a mean fast and powerful bike i am having some problems with it tho.

Bike starts awesome......Bike runs awesome when cold has lots of crisp throttle responce and power. Once the bike heats up it runs like crap .....Bogging when i stop at a light and eventually it will just get worse and worse WHATS GOIN ON HERE i have cleaned the carbs and adjusted them to manual spec and not a difference.

My question is it electrical ?? Coil heating up perhaps the stator heats up and has a crack in it??

So breaking it down
Cold = GREAT
Hot = Running very rich (spark plugs are just BLACK and sooty)/they are new and gapped right/Bikebogs and eventually stalls/ all power is lost.

Can you help me out here boys ......

[BigRed]

Welcome to the Forum!

Sounds like something in your ignition system. Could be the plugs sooting up and misfiring, or a coil that heats up and misfires. Do you have a timing light? You can hook that up and find out which cylinder(s) are the problem.

[randy]

Sounds to me like you've got the mixture set too rich.

How did it run before you messed with the carbs?

Are you using the right 'manual spec'? there are different specs for different years.

[CatatonicBug]

Sounds to me like you've got the mixture set too rich.

How did it run before you messed with the carbs?

Are you using the right 'manual spec'? there are different specs for different years.

+1 to that. What "spec" did you use? Did you use a colortune to adjust the fuel/air muixture screws, or did you adjust them by ear? What kind of sync gauge did you use?

[yamtom]

so what happened just prior to this

Hi Dez,

What happened just prior to this starting to happen. Something must have changed. Is it possible that youre choke is on, could the control for it be off location?

[slow mo]

just a guess

hi all i,m not a mechanic and i don,t play one on tv but it sounds to me that you need to check your coil wires ,,there is a section on the site about how to do it and its easy ,,good luck,,ride safe ,,slow mo!

[petejw]

sounds rich to me also,
are you using a clean air filter,
make sure there are no blockages in the snorkel,
what have you set your mixture screws and floats at?

also the engine wont self clean fouled plugs, youll need to clean
or replace them after making changes.

[dezmitchell]

Its had this problem since i bought the bike......But here is my thing about it not being the carbs .....If it was the carbs it would run like junk all the time would it not??? And this thing rocks and rolls when its cold (i can ride it fine around town problem free for about half an hour 25min).

How do i do a stator test?
How can i test my coils?

Im just thinking im not getting enough spark to fully egnite the fuel in the cylinders thus its electrical ?? right??

[cywelchjr]

Its had this problem since i bought the bike......But here is my thing about it not being the carbs .....If it was the carbs it would run like junk all the time would it not??? And this thing rocks and rolls when its cold (i can ride it fine around town problem free for about half an hour 25min).

How do i do a stator test?
How can i test my coils?

Im just thinking im not getting enough spark to fully egnite the fuel in the cylinders thus its electrical ?? right??

The symptoms you describe sound like overly rich carbs. That's exactly what will happen if the carbs are too rich, it will run well when cold and then poor when hot, as the bike wants a richer mix when cold (which is why there is a choke/enricher) and leaner when hot, if it's right when cold, it's gonna be too rich when hot.

[petejw]

cy has it right about a rich fuel mixture,
check your plugs for colour.

might be as simple as adj the mixture screws in
quarter of a turn or 2.

[dezmitchell]

Leaned carbs right out last night and NOTHIN .....did not change a dam thing now im really confused.....Perhaps valve anjustment?? somethings not closing all the way once it heats up or something? Weak spark thats not igniting all the fuel thus building up carbon??

[CatatonicBug]

Leaned carbs right out last night

What did you do to accomplish this? Have you pulled the fuel/air mixture screws out and looked at the tips? If turning them all the way in doesn't change anything, there is a chance that the tips are broken off in the hole.

Again, what process are you using to tune? What kind of sync gauge are you using? Are you tuning with a colortune plug, or are you tuning by ear?

[dezmitchell]

I am trying to tune by the plug (i ride and build sleds and on all my machines i tune by the plug) As far as for leaning it out i dropped the needle by upping the clip. when you say air/fuel screw what one are you talking about .....

there is no airfuel screw in the manual all i have in the book is
pilot screw- Isint this not just for idle mixture
main screw-witch the jet slides into (is this the one)
idle adjustment screw- adjusts idle.

and for main screw can some one tell me what it has to be at 2 and a half turns from all the way in or something??

thanks

[CatatonicBug]

You have the following things to adjust on these carbs:

1. Sync - This is adjusted with the synch screws between 1/2, 2/3, and 3/4 carbs. This must be done every time you do ANYTHING to the carbs, including cleaning them.
2. Air/fuel mixture screw - accessed from the outside of the carb, located in the top of the carb body, just before the engine intake boots. This and the sync work together, and must be adjusted individually, per carb, every time you change ANYTHING in the carb/intake/exhaust. It is adjusted at idle (actually at low idle, about 800rpm), but affects the whole range. There is no defined setting (i.e., 2.5 turns out from seated) that works for every bike. Mine are over 4 turns out, but none of the 4 carbs are exactly the same. 1/16 of a turn makes a difference.
3. Float height - To properly measure, the fuel level must be viewed from the outside of the carb while the engine is running. This will affect how rich/lean each cylinder is running at higher RPM.
4. Needle position - looks like you're familiar with this one.
5. Main Jet size - the big one down in the float bowl
6. Pilot Jet size - the tiny one up in the tube, just forward of the main jet.

There are a few other things that can be done to fine-tune, but this is the basic stuff that should take care of just about any setup. Tuning by looking at the plugs? It may work, but you're not going to get a very precise adjustment that way IMHO.

[dezmitchell]

so what way would i turn the air fuel screw to lean it ?? clockwise ??