82 kz550 ltd

Hey guys I have a 82 kz550 ltd all stock. I have an issue on the highway when I get up to speed at 65 mph, if I accelerate too much I hear the bike sputtering. Any ideas what it is and how to fix it.
Thanks

Do a plug chop at that speed when it does it.
Steve

What is that

Go out to a empty stretch of road, get up to that speed and make it do that. Pull in the clutch at the same time killing the engine with the switch. Coast to a stop and check a plug.That will tell you what is happening.
Steve

swest wrote: Go out to a empty stretch of road, get up to that speed and make it do that. Pull in the clutch at the same time killing the engine with the switch. Coast to a stop and check a plug.That will tell you what is happening.
Steve

Greene 1993 - download a picture guide from the 'net - in color - on how to diagnose spark plugs. That will be a good guide for what is happening. Here is one I found that is pretty good for diagnostics forcarb tuning....

To clarify the "plug chop".... for your specific application:

Take the fully warmed up bike out on an open stretch of road (no traffic or other dangers). In as high a gear as possible (top gear is best), get to the engine speed and load you are starting to have trouble at, and accelerate with the steady throttle setting that causes the worst performance. After 4 or more seconds, quickly pull in the clutch and kill the engine at the same exact time. Coast to a stop with the clutch in (o.k. to use the brakes, just don't let the engine turn over), and immediately pull one (or more) of the plugs and compare them to the color chart. Determine what problem you are having by the condition of the spark plug(s) and compensate accordingly. Most likely your bike is experiencing a fuel (carburetor) issue.

The "classic" plug chop you might read about elsewhere is to go out on an open road, uphill, in fourth or higher gear at sixty or more mph and open the throttle fully for 5 to ten seconds before pulling in the clutch + shutting the engine off. This is quite dangerous on a high powered bike, as you could be exceeding 80 - 90 mph, and it only tells you about the air - fuel mixture at wide open throttle - in other words mostly the main jet size. Steve's (swest) recommended way is much better to diagnose the problem, and safer, too....

I would say no need for high gear and high speed to plug chop. The throttle needs to be in be in wide open position when you "chop" . This could be done in any gear. I would sugest 2nd and chop when it is at 7000-8000 rpm. Be sure to hit the kill switch when the throttle is open or u won't have an assessment at WOT. This will tell u some about WOT or main jet selection. then if the plugs are white u r lean, black or wet rich and brown just right. If u have a cruise control you can pin the throttle openin fifth at 50 for a few seconds before it gets to 100. R

I suspect the plug/s will be wet.
Steve

I agree, no need to do a plug chop yet. First, just take the plugs out and see if one is different from the others.

How about some basic bike info?
Compression test results?
Valves adjusted recently?
Ignition timing checked (and advancer inspected/cleaned/lubed)?
Coils good condition?
Stock jetting confirmed?
Airbox is stock.
Stock exhaust.


Do you have the manuals?
You can get several manuals from the links in my signature, and read the valve train warning before removing the valve cover.