Plug reading? Not a saw but 50cc quad

[tla100]

Hey just pulled plug on new to me kids Kawasaki KFX50 quad. Had trouble initially, guy said old gas. Flushed it, cleaned carb. Still didn't start. Ended up turning idle screw, i think, in about 3 turns and runs good now. Plug was a very wet and bit carboned up. I took wire brush to it. Been running good a week for him but thought I'd throw a new plug in. Has a bit more snap. This is old plug. Any suggestions? I know saw site but wondered if anyone would know be saw guys!

 

[tla100]

Will add it had zero oil in oil tank. Oil injected. Running synthetic 2 stroke oil, universal stuff that says marine outboard motor approved. Smokes a few puffs at idle, not much under load. Adjustable Throttle is not all the way open, maybe 3/4. Just a limiter on handlebar Throttle.

 

[J D]

Marine 2 stroke oil isn't designed to handle the temps that air cooled stuff gets up to.
There's a process to get a meaningful reading of the plug in a 2 stroke... I believe you need to kill the ignition while under load at open throttle. Then you want to be inspecting around the base of the insulator. Hopefully someone else will be along to provide further details

 

[tla100]

It is Quicksilver brand. Says it good for air cooled also.

This not a high rev engine. It runs great. I may add a better air filter later. I did find some plug pics online and it looks ok. Just didn't want to run lean...thanks for reply!

 

[Chevboy0167]

 

[bwalker]

View attachment 924620

Looks like these are from a four stroke.

 

[bwalker]

The original posters plug looks fine for a well used plug.

 

[dando127]

what kind of carb on it, and what does it have for adjustment screws or jets?

 

[iowagold]

use a better name branded quality oil if it is a 2 stroke.
and use e0 fuel

 

[Huskybill]

The balance screw should be between 1/2 to 2 turns out from bottom. It could be a clogged pilot jet

 

[tla100]

Not sure what brand carb. Pretty sure it has jet. No ethanol fuel.

The screw I turned is brass one in center, right of main fuel supply. It runs good like I said. Thanks for replies

 

[Chevboy0167]

Carb should be Mikuni VM12SC. Tuning done by pilot and main jet changes.

A lot of info here to take in.
http://www.mikuni.com/pdf/vmmanual.pdf

 

[Huskybill]

#29 is the idle speed screw, #32 is air balance screw, #36 main jet.

 

[holeycow]

The carb says Mikuni right on it. Yes, you turned the idle screw. The plug color is perfect. Just a hair rich.

not sure what the problem is, as you said it's running well.

 

[Huskybill]

Here’s how to jet a two stroke. I been doing bikes for a while.

https://motocrosshideout.com/dirt-bike-jetting-101/

 

[holeycow]

Me too. Your link does not describe the best way to find a correct main jet, for one thing.

and the explanation of spooge due mostly to rich jetting is somewhat misleading, as the mix oil used has a large effect on spooge, rather than simply jetting.

for power in a two stroke, the more fuel mix you can put through it the better. Period. Different mix oils and experimentation with them will allow this while keeping spooge to a minimum. With experience, jetting "by feel" becomes reliable and correct. As long as the pilot is close, air screw adjustments will clean up off-idle crispness and you can go straight to the main jet, imo. Your link's description of pilot jet selection is accurate, but not main jet selection, imo.

at some point you realize that reading the tailpipe (silencer) will tell you nearly what the plug will tell you.

imo, anyway.

 

[bwalker]

Me too. Your link does not describe the best way to find a correct main jet, for one thing.

and the explanation of spooge due mostly to rich jetting is somewhat misleading, as the mix oil used has a large effect on spooge, rather than simply jetting.

for power in a two stroke, the more fuel mix you can put through it the better. Period. Different mix oils and experimentation with them will allow this while keeping spooge to a minimum. With experience, jetting "by feel" becomes reliable and correct. As long as the pilot is close, air screw adjustments will clean up off-idle crispness and you can go straight to the main jet, imo. Your link's description of pilot jet selection is accurate, but not main jet selection, imo.

at some point you realize that reading the tailpipe (silencer) will tell you nearly what the plug will tell you.

imo,

Me too. Your link does not describe the best way to find a correct main jet, for one thing.

and the explanation of spooge due mostly to rich jetting is somewhat misleading, as the mix oil used has a large effect on spooge, rather than simply jetting.

for power in a two stroke, the more fuel mix you can put through it the better. Period. Different mix oils and experimentation with them will allow this while keeping spooge to a minimum. With experience, jetting "by feel" becomes reliable and correct. As long as the pilot is close, air screw adjustments will clean up off-idle crispness and you can go straight to the main jet, imo. Your link's description of pilot jet selection is accurate, but not main jet selection, imo.

at some point you realize that reading the tailpipe (silencer) will tell you nearly what the plug will tell you.

imo, anyway.

I've been riding and racing dirt bikes since the late 80's. Spooge is almost always caused by poor low speed jetting assuming your running any kind of load.
Ride and feel for the low speed circuits and a plug chop for the main has always been the best way to tune for me.
And simply throwing more fuel at a two stroke will not let it make more power, period.

 

[holeycow]

I'm talking about finding optimum fuel for optimum top end power while maintaining durability.
putting as much fuel as possible through while maintaining a clean burn is what I'm talking about. Some oils spooge before you get to that point. And I agree that it is usually the low speed that usually creates spooge Issues. Lots of times needle end-taper is the problem. Or slide cutaway...

sounds like I've been playing around almost 20 years longer than you..lol.

At some point in experience you just jet by feel with plug checks, tail pipe looks, and your ears. It's really not complicated. You just have to do the right steps. I always try to get the biggest main in as possible by finding too big and dropping one or two sizes down.

For me, experimenting with different oils found me the way.

anyway, we are all talking the same language here.

 

[tla100]

Ok, if it looks good I am leaving it. thanks for replies!