Possible coil problems

[hollywood]

Ok,

Here is my list

 

"04" stock motor

stock carbs 270 mains,25's pilots,1 1/2 turns out on the air screws.

tusk inline fuel filter

tr6's

tors removed for motion pro twist install

Pro design filter with 12 vents in the box.

Yamalube 2r at 36:1

ngk br8es

 

The thing has run great for over 2 1/2 years since I've had it and yesterday it started missing and running on one cylinder at times.So I put a new set of plugs in it and still the same thing.The old plugs still looked real good and clean.{determined that it was the left cylinder}

I thought maybe I had a reed problem so I pulled the carb and the reed cage and inspected.

Nothing wrong that I could visibly see and the reeds did not seem to be broke or damaged!

Put it back together and started it up.It ildled fine.Took it out and rode it and after it was warmed up it would not fire until I got half way into the throttle and then it would hit and pull like normal.

So I switched the plug wires,left to right and right to left,same thing as before!

So I then left the rightside plug wire on the left cylinder and tried to start it,but no go.

I then put the left plug wire on the rightside plug and it fired and ran on the right cylinder only.

I decided to pull the left carb and tear it down and clean all the passageways and everything looked good.I used carb cleaner and compress air.I also took off all the plastic and tank so that I could check all of the wiring harnesses and connectors and did not find any problems at all.

I have not run yet since I checked the carb as it was to late tonight without pissing off the wife and neighbors.The way it acts to me it's electrical and not a fuel delivery problem but I'm stumped!

Could it possibly be the coil starting to go bad.

 

Sorry for the long post ,but I wanted to give as much detail as possible.

[akita8]

I'm pretty sure that both of the wires fire at the same time no matter what. It's possible that you have a bad wire coming from the coil. How is the compression on the left side? Have you done any work on the egine before this started happening?

[dirtyernie52]

coil wires fire at the same time, try plug boot or wire. are plugs wet or dry? do you have spark on both plugs? check you compression that what i sounds like to me.

[jlsparky7]

Dirty reeds?

Edited September 5, 2006 by jlsparky7

[sheefreak]

Dirty reeds?

 

:baseball_bat:

 

That sounds exactly like what happens when you lose compression on a side for whatever reason be it sticky rings, leaned out condition at one time, or just plain wear. Need to do a compression test to see where you are at. If that is good, you can start concentrating on fuel delivery and elecrical.

[dirtyernie52]

it will be compression our fuel. if your coil works both plugs are firing. what do your plugs like?

[Bansheeman1121]

Mine did this when it was time for a rebuild, check your cylinders

[hollywood]

ok, thanks for all the replys.

Now just 3 more ?

What is the compression supposed to be for stock cylinders ?

I assume the motor should be cold and do I hold the throttle Wide open when testing?

How many times on the kickstarter to make sure it has built up the compression?

[addicted]

ok, thanks for all the replys.

Now just 3 more ?

What is the compression supposed to be for stock cylinders ?

I assume the motor should be cold and do I hold the throttle Wide open when testing?

How many times on the kickstarter to make sure it has built up the compression?

I'm not sure what the comppresion should be on your setuo, but the important thing is that both sides are within 10 % of each other. You also want the motor to be at opperating temp., hold it wide open and kick until it stops building preasure. If things check out, then I would do a leakdown test. Cracked intake boots, leaking base gasket, crank seal.

[dirtyernie52]

compression should be no less than about 110 lbs. 120 is pretty good for a stock head. kick until the guage doesnt go up anymore.

[hollywood]

I'm not sure what the comppresion should be on your setuo, but the important thing is that both sides are within 10 % of each other. You also want the motor to be at opperating temp., hold it wide open and kick until it stops building preasure. If things check out, then I would do a leakdown test. Cracked intake boots, leaking base gasket, crank seal.

 

Ok I did a compression check when the motor was cold and held the throttle wide open.

each cylinder was 90 psi

Took it out and rode it and it ran fine until it really got warmed up then the left side missing again,but not all the time.

Checked the compression again and the right was 90 and the left was 85.

Now my ? is how do you do a leak down test?

[hollywood]

Ok I did a compression check when the motor was cold and held the throttle wide open.

each cylinder was 90 psi

Took it out and rode it and it ran fine until it really got warmed up then the left side missing again,but not all the time.

Checked the compression again and the right was 90 and the left was 85.

Now my ? is how do you do a leak down test?

 

Ok I did a search and found out about the leakdown test and the tester that a guy sells.

After reading some info on the leakdown test I think the crank seals are fine.

I also used a craftsman compression gauge tonight to make sure that the other guage I used last night was ok and I got the same results as before.

So I tore it down and I was really suprised to see no broken rings or any scoring on the piston or cylinder! Everything just looked like normal wear.There was no carbon buildup on the head and very little on the top of both pistons.

So now my ? is should I go back with OEM or go with aftermarket such as Wiesco,etc etc,

Any feedback would be great, Oh I do want to keep the motor pretty much stock as it is my young son's quad and it runs very well for him !

[Handyman]

Boy oh boy. mine did this not too long ago, same side too. Pull your slide and needle and inspect everything really well. i was told that the needle immulsion tube in the slide was to blame. A new needle was installed and it ran fine. Try swapping your slides and needles to see if that affects anything. I had to redo my top end due to loss of compression when warm and the damnt hing started to act up. Almost a year later I gave up and took it to the stealership and they fixed what ever it was. I sayt his because I don't think they knew what they did to fix it.

[itsaripper]

Even though you are doing a rebuild, I would still check both sparkplug wires. Where the plug boot screws into the wire, mine ate out till the spark had to jump about a inch. It sounded just like what yours is doing. Ideled good then started missing as the rpms went up, then kicked in and ran hard right up to max. That is just something to check and eleminate.

[dirtyernie52]

Ok I did a compression check when the motor was cold and held the throttle wide open.

each cylinder was 90 psi

Took it out and rode it and it ran fine until it really got warmed up then the left side missing again,but not all the time.

Checked the compression again and the right was 90 and the left was 85.

Now my ? is how do you do a leak down test?

he needs a rebuild, asap