DAMN Riders - No rules, Just ride!

Hold the plug wire and unthread the cap from it.
Should be a little rubber boot that extends over the wire to keep the nasty stuff out.
It should be that easy.
Of all the cycles I have owned, none ever had the cap as part of the wire.

Roger all! And I inserted a picture of my set-up so you can see what I'm refering to.

I see the problem..
It is a KTM....should say Gas Gas then you would have no problems (JK)

I hate seeing people chase their tails with poor diagnostic work. Rule one is to check engine condition. That means a compression test and depending on the 2 strokes engine layout a leak down test to insure proper sealing of the crank seals. I don't care if the engine was rebuilt 2 weeks ago you have to test it to be sure it's not the problem.

I see way too many people just assume it's fuel related and chase their tails with jetting changes. If the bike ran fine with the jetting set like it was and then just started running rough out of the blue how could jetting be the culprit? Unless it sat for a long period of time and the pilot jet passage became restricted or you are riding at/In a different elevation/weather conditions.

Next you rule out ignition issues. A good rule of thumb is if you're bike can produce a spark across an 8mm+ gap (hold plug 8mm from grounding point and look for the spark to jump the gap) then the spark is strong enough to overcome any pressures of the combustion process. Once the bike passes those test then and only then should you go after a fueling issue.

Totally agree with you Redlevel....but how does one go about performing a compression/leak test without the proper tools? Or should I invest in a leak tester, assuming it isn't too expensive?

And one more piece of info - in case I hadn't stated this before - a fresh plug works great for about 3-5 hours, and then fouls.

Doesn't that point to too rich, too cold of a plug, or too high of an oil-fuel ratio?


~Patrick

You can borrow a compression tester from advance auto on their tool loaner program. The new plug will be clean of carbon and oil buildup which adds resistance to the ignition process. The fact that the plug begins to foul in 3-5 hours could be caused by a couple things. A leaky crank seal on the clutch side would allow trans fluid to be pulled into the crank area and mixed with the air/fuel mixture which would make the carb apear to be rich or oil fouling the plug. Low compression can cause the same problem because it doesn't allow the mixture to completely burn due to low combustion pressure. Again most would assume it's poor jetting. But if at one time the bike ran well with your current jetting and there hasn't been any major weather or elevation changes then someting else most likely is causing your issues.

Redline has got it dead on. Always compression test, you can waste a lot of energy and money, its an invaluable tool. if you know your bike you should have a feel for it but as it slowly loses compression it may be hard to notice

Only thing i would add is to look at the engine as a large air pump, most important thing is to get air in and get air out. A restriction any where along the air path will cause problems, a blocked or gummed up pipe or silencer, a rag in the intake or exhaust, a broken or stuck power valve, over oiled air filter and so on.

pulling the pipe is a real easy 5 minute way to take a quick look at the rings and piston and power valve function.

plus not all plugs are made alike, the ecm series, i think it is, last much longer than a regular BR8ES, especially in very rich conditions but boy you sure do pay for it, get them at Advance Auto, cant beat the price. Plug heat ranges have very little noticable effect on plug readings/fouling.

I never was a fan of PJ1 oil but its should not cause a dramatic change

ALCON,

So I'm going to take the sage advice of checking the compression and leak rate. I'm not able to perform the test myself due to family/work commitments over the next few days so I'm hiring a local shop for an hour to run the diagnostics. I'll reply back once I learn what's happening. And based on the results, I'll be racing till the end of the season and either spending the winter refurbishing the bike or spend the winter setting-up my new bike ;-)

Thank you all for the input! More to follow.
Tom

62Tom wrote:ALCON,

So I'm going to take the sage advice of checking the compression and leak rate. I'm not able to perform the test myself due to family/work commitments over the next few days so I'm hiring a local shop for an hour to run the diagnostics. I'll reply back once I learn what's happening. And based on the results, I'll be racing till the end of the season and either spending the winter refurbishing the bike or spend the winter setting-up my new bike ;-)

Thank you all for the input! More to follow.
Tom

Setting up a new bike is always more fun than refurbishing an old one