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basslips

'10 YZ fouled plugs?

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Went to start my bike the other day and that dang thing wouldn't fire. Just a couple of backfires. Pulled the plug out and cleaned it off several times but nothing. Got a new plug and the bike fired second kick and seemed to run great.

So fast forward to yesterday. Go to start bike to rip around the place a bit and again fire and die, then backfire and kinda want to start but then nothing. Pulled plug out a few times to clean it up. Pulled the tank and drained fuel and added fresh gas. Was able to get it running shortly after that. Ran up and down the road and had her purring. Started and rode it along with my other bikes several times on a little woods loop I have and ran like a champ.

Low and behold I go out to load it this morning to ride some arenacross. Decide to start if first to make sure. Wouldn't you know it. Damn thing won't start again!!!

Bought the bike it late August and have only ridden it twice on practice days. What the hell could be fouling these plugs?

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Oil.

Leaky valve seals would allow oil to crawl in there when the bike sits and foul the combustion chamber.

Any blue smoke coming out of the tail pipe?

A really clogged air filter will cause the bike the foul when trying to start, I know from first hand experience.

The other day I brought my bike out and couldn't start it for the life of me.. my brother was with me and pointed to my silencer and I realized that I still had the plug on it...

Pulled it out and kicked it over but the bike was so fouled it just would not start...

Remembered that if you hold the throttle at 100% open it turns off the injector for flooding situations, so I did exactly this and kicked it over 3 more times. Closed the throttle, choke on and one kick it started up, it worked.

If your bike is flooded for any reason, hold the throttle open fully and kick it over a few times to clear the chamber out of fuel.

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Went to start my bike the other day and that dang thing wouldn't fire. Just a couple of backfires. Pulled the plug out and cleaned it off several times but nothing. Got a new plug and the bike fired second kick and seemed to run great.

So fast forward to yesterday. Go to start bike to rip around the place a bit and again fire and die, then backfire and kinda want to start but then nothing. Pulled plug out a few times to clean it up. Pulled the tank and drained fuel and added fresh gas. Was able to get it running shortly after that. Ran up and down the road and had her purring. Started and rode it along with my other bikes several times on a little woods loop I have and ran like a champ.

Low and behold I go out to load it this morning to ride some arenacross. Decide to start if first to make sure. Wouldn't you know it. Damn thing won't start again!!!

Bought the bike it late August and have only ridden it twice on practice days. What the hell could be fouling these plugs?

How cold was it when you were riding?

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I really doubt its leaky valve seals or something like that. Anything is possible I guess but I really don't even think the bike has 5 hours on it yet. Air filter is clean. The temps have been in the mid-forties the last week or so with one cold snap to around freezing.

Could it be a sensor or something that is causing it to run rich?

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its possible something is wrong but I would be suprised. Do you have a tuner? If your coolant temps aren't getting up the engine will run very very rich which some people seem to not have any problems with. For me I get a lot of soot in exhaust , poping and backfiring and 1 stall due to plug foul. Holding throttle open and slowing kicking for 10 kicks or so cleared it right up. If cold is the problem which I'm betting it is you can cover radiators or install a thermostat which I am in the process of and will have it done soon. EFI really needs normal operating temps to work properly.

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Fuel injector leaking and filling cylinder with fuel, thus "drowning" the plug ?

I'd be draining the oil and measuring how much came out and smelling it for a fuel odor first thing. Just a thought.

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Hmmm, never thought about a leaky injector. I will drop the oil tonight.

I not sure if it might be a operating temperature issue. When starting it in the shop I can feel heat off the radiators in just a few moments of it running.

Is there an air/fuel sensor or something that may be gunked up?

All this efi b.s. may not be all its cracked up to be.

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Hmmm, never thought about a leaky injector. I will drop the oil tonight.

I not sure if it might be a operating temperature issue. When starting it in the shop I can feel heat off the radiators in just a few moments of it running.

Is there an air/fuel sensor or something that may be gunked up?

All this efi b.s. may not be all its cracked up to be.

I seem to think there was an injector issue with some of the earlier '10s.

Operating temp SHOULD be a non-issue assuming the efi system is operating properly. If it were an issue that would mean some component of the efi system is not operating properly to deal with with temp wheter it be coolant/operating temp or ambient air temp.

There are multiple sensors on the bike that can cause a "mis-management" issue of the efi.

EFI is nice, but a well tuned carb is just fine.:excuseme:

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All the 10's have a fuel smell in the oil, this will not prove if he has a leaky injector.

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Operating temp SHOULD be a non-issue assuming the efi system is operating properly. :excuseme:

it would not be an issue if there was a thermostat! Riding in low temps and not allowing coolant temp to reach lets say above 110-120 degrees the EFI is going to add unecessary fuel to a warm engine and without an a/f ratio or oxygen sensor it doesn't know the difference. Believe me its an issue. I've had mine out in 30 degree temps at moderate speed and its runs extremely rich almost to the point of stalling on decel from a flood condition.

However I haven't had any issue when starting from a fouled plug. I haven't looked at it but I can almost guarantee its black as coal. I'm not 100% convinced that operating temp is the problem but it would be easy to figure it out by taping off one of the radiators and see if you still have a problem.

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All the 10's have a fuel smell in the oil, this will not prove if he has a leaky injector.

Really ? Why is that ?

I did fail to remember that they do not have any A/F monitoring.:excuseme:

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It's a common issue, searching will reveal this.

I wasn't trying to shoot down your idea, in fact it sounds like the problem. Was hoping that there was some other way to test the injector for leaks...

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I'd imagine some fuel smell is normal being high performace engine and low oil volume. I was concerned about my oil just from running so rich but I didn't really smell any fuel, maybe a hint of it and that was it.

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Looks like my spark arrestor is in so I'll pick up a couple of plugs too and work on the bike tonight. I'm still trying to figure out how to tell if the injector is leaking down when sitting. Put a dry plug in and then kick it over on or two times without starting to see if the plug gets wet?

Why do they have to make bikes so complex we will be forced to take them to a dealer??? Two strokes really weren't all that bad were they.......

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Looks like my spark arrestor is in so I'll pick up a couple of plugs too and work on the bike tonight. I'm still trying to figure out how to tell if the injector is leaking down when sitting. Put a dry plug in and then kick it over on or two times without starting to see if the plug gets wet?

Why do they have to make bikes so complex we will be forced to take them to a dealer??? Two strokes really weren't all that bad were they.......

the best way would be an inline fuel pressure guage and watch for the pressure to drop. Kicking it over even if you do it slowly might squirt a small a mount of fuel. I'd think you'd get a strong fuel smell in your oil if it was leaking but a little bit of smell might be normal.

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I was just thinking, maybe there really isn't anything wrong. It may just be flooding due to incorrect starting proceedure and/or idle speed too low. These bikes flood very easy and are sensitive to idle adjustment especially for colder wheather starting.

Idle speed should be 2000 mine is 2100 rpm actually. If you have the tuner this is easy but it almost sounds too high if doing it by ear.

Just in case your not doing it this way: (after bike has been sitting and capacitor has drained)

Pull out cold start knob

Kick over slow and steady 3-5 kicks when first starting (this charges capacitor to operate FI system)

Then bring on compression stroke where you feel resistance and kick normally and it should fire in a couple kicks

If you think you flooded it which is easy to do (believe me), hold the throttle completely open which puts ecu in clear flood mode and kick slowly about 10 times (this shuts of injector and allows you to clear the cylinder of raw fuel) and repeat normal kicking. This always works for me if engine gets flooded.

dont forget idle speed very very important with this efi system crank it up!

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I'm trying to start it like any other time I have. I start it pretty much as you describe. It will sometimes backfire through the exhaust and sometimes pop through the throttle body.

I picked up two new plugs so will be working on it within the hour.

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I'm trying to start it like any other time I have. I start it pretty much as you describe. It will sometimes backfire through the exhaust and sometimes pop through the throttle body.

I picked up two new plugs so will be working on it within the hour.

Are you using EIX plugs....

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it may just be because it isn't broke in enough yet, mine was a PITA to start until it got about 7 or 8 hours on it. before that it could be real inconsistent on starting whether the engine was cold or warm, I got pretty wore out just trying to start it sometimes..

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Plug is a CR8E. Put new plug in and it fired in two kicks. Ran it up and down the driveway and it ran great. Just for kicks I tried the previous two plugs and nothing. In the garbage they went.

Probably won't get to really ride it for at least two weeks but I do plan on going out and starting it a few times each day.

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