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Discussion Starter #1
SO here's the problem. a couple of weeks was out riding. was ridiing on and off for about 3 hrs. No problems with engine performace at all. On the way back to camp, i was going over some whoops. as I cleared the last one i accelerated and about 3/4 throttle it started cutting out. anything below this is runs fine. Idles ok, starts fine.

Here's what I've done so far.

1. removed carb, cleaned it all out. found nothing. used compressed air to blow through all ports.

2. checked valve clearance and cam timing., intakes were about .004 and exhausts were around .009. only .001 off on each on the tight side. timing ok. re-shimed valves to spec. even used micromiter to get right size shims. valves right on now.

3. checked spark plug condition and for spark. gap ok good spark. even put new plug in.

4. Checked TPS, oil primary peak voltage,Alternator exciter coil peak voltage,Ingnition pulse generator peak voltage. all checked good.

5. took know good coil from 05. no change.

6. Checked complete wiring for shorts, open circuits. none found.

7. Bought a new pro comp cdi, but it was bad out of the box. when I installed it, got no spark to plug. installed stock cdi got spark.

8. Adjusted f/a screw while running from closed to al the way out. 1/4 turn at a time. no change at high rpm, still cuts out.

9. checked all vent lines, all clear, no blockage.

10. checked rubber sleeves that connect air box to carb and carb to head. no splits or cracks. cleaned air filter and checked intake tube for cracks or splits.

Have I missed anything?

If you reply with a suggestion, please state the reason for what i need to do. I've been messing with this for about 8 hrs total, ( i'm bald now,) and i don't need replies because you read it on this or some other web site. I need some good advice.
 

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Discussion Starter #3
Did you check the needle clip in the carb? My buddys' snapped last night and did the same thing.[/b]
Yes, when i cleaned the carb, i removed the needle. clip was on 4th groove.
thanks for reply.
 

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I noticed you never mentioned checking the air filter.If your air filter is really clogged up with dirt it will cause your machine to run rich which can cause a stumble on the top end.
You probably already checked it but I figured I would point that out just in case.
Sometimes it's the simple things that can get overlooked....good luck.
 

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Discussion Starter #5
I noticed you never mentioned checking the air filter.If your air filter is really clogged up with dirt it will cause your machine to run rich which can cause a stumble on the top end.
You probably already checked it but I figured I would point that out just in case.
Sometimes it's the simple things that can get overlooked....good luck.[/b]
Good thought, but it was cleaned the morning of the trip and cleaned during this troubleshooting process.i even checked the intake tube for crakes and spilts i'll edit post to add this.

Thanks for reply
 

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umm all that really awsome diag. and i didnt see where it said you checked if you had gas..??

but also the breather for the gas tank possibly clogged or pinched could do this loosen the cap and take it for a ride... causes vaccume to build and not let gas get into the carb fast enough..

now does it missfire or kinda just go booooooooooooooooooooooggggggggggg and then when you let off alittle it catches back up?? pin it again and boooooooooooooooooooooogggggggggg ..?
 

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Discussion Starter #7
umm all that really awsome diag. and i didnt see where it said you checked if you had gas..??

but also the breather for the gas tank possibly clogged or pinched could do this loosen the cap and take it for a ride... causes vaccume to build and not let gas get into the carb fast enough..

now does it missfire or kinda just go booooooooooooooooooooooggggggggggg and then when you let off alittle it catches back up?? pin it again and boooooooooooooooooooooogggggggggg ..?[/b]

Yep it has gas. I've checked vent for gas cap. not clogged. It doesn't bog, it's misfiring.

I put aspark tester on it yesterday. The kind that goes between the plug wire and plug. It has two probes that spark archs across. at idle, blue, steady arch. as u open throttle, spark remains the same till you get to the spot were it starts misfiring. the the spark breaks up and is white. Talked to a couple of mechanics, they seem to think it's with the ignition system.

Good thoughts, thanks for ur reply
 

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Discussion Starter #9
have you removed the main jet and shoot carb cleaner through it ?[/b]
I've cleaned the carb a couple of times, i hold a clean white rag around carb, jets, when i blow compressed air through all the ports. never find any debris on rag.

I did notice yesterday though that when I drained the carb into a clear container, i found some black specs in it, there so small, i can't tell what they r. like plastice from tank, dirt,sand whatever.

I pulled off tank, removed petcock, and flushed it out. should've let it drain into something but didn't just let water run down driveway, (Yes i drained the gas first so i didn't pollute). When i drained the fuel out, did see a couple more of those black specs. I didn't notice anything on screen for the petcock. Might even buy an inline filter for it also.

I'm getting ready to install tank with some fresh gas this morn. will clean carb out first though.
 

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well sicne it seems you have a bike to take parts of of jkust start trying everything

you said you already tryed the coil.. try the plug wire too...

and the spark would get alittle messy at higher rpm and not as strong do to the fact that the coil doesnt have much time to "sachurate" in between sparks... but obviously if its doing it too much it will missfire.. this could be a problem with the power to the coil or the ground/triggar for the coil

umm hmmmmmmmmmmmmmmmmmm

maybe its detonating? bad gas possibly, water in gas i know you said you were going to try some new gas after you just cleaned out the tank so.. lets see what happneds but i would possibly expect the plug wire..

Good luck

JOSH
 

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Discussion Starter #11
well sicne it seems you have a bike to take parts of of jkust start trying everything

you said you already tryed the coil.. try the plug wire too...

and the spark would get alittle messy at higher rpm and not as strong do to the fact that the coil doesnt have much time to "sachurate" in between sparks... but obviously if its doing it too much it will missfire.. this could be a problem with the power to the coil or the ground/triggar for the coil

umm hmmmmmmmmmmmmmmmmmm

maybe its detonating? bad gas possibly, water in gas i know you said you were going to try some new gas after you just cleaned out the tank so.. lets see what happneds but i would possibly expect the plug wire..

Good luck

JOSH[/b]
my other quad is an 05 so not much can be swapped out. When i swapped out coil off from the 05, swapped whole unit which included plug wire.

Got new fuel, 91 octane.Put gas tank back on, installed clear in-line filter, cleaned out carb again. put in a 160 m/j. fired it up. still misfiring at high rpm. i tried adjusting a/f screw 1/4 turn at a time no change. whent up in jet sizes 165,170,175,& 180. did the samething with each jet. no change. I really didn't think it was jetting, but since i have to wait a couple of days for a new cdi, figured what the heck, can't hurt trying.

Thanks for suggestion
 

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i see you have a hot cam stage 2, which revs higher then the stock cam. could it be possibly hitting the rev-limiter?

just a thought,
steve
 

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Discussion Starter #13
i see you have a hot cam stage 2, which revs higher then the stock cam. could it be possibly hitting the rev-limiter?

The cams been in there for over a year, and never had this happen before. It just started all of a sudden when ridiing.

Well, quad's been at the dealer now for a few days. The only thing i can say for sure, it isn't the cdi. They pulled one from a new quad, installed it on mine, and it does the same thing. Now they're in the process of checking out the wire harness. will post when i hear more.
 

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I had this same issue with my 05! My problem was that I was using the wrong style jet, there are several different types. Make sure the one you are using is tapered and clear of any objects, if you are using the wrong style jet the needle will never seat properly. Make sure you also check your float level; if it's too low you will run out of fuel fast. One more thing, check the needle and seat for the float bowl and make sure you don't have any small fibers from a rag stuck in there.

I hope this helps, if not please let us know what it was when you fix it.
 

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Discussion Starter #16
I had this same issue with my 05! My problem was that I was using the wrong style jet, there are several different types. Make sure the one you are using is tapered and clear of any objects, if you are using the wrong style jet the needle will never seat properly. Make sure you also check your float level; if it's too low you will run out of fuel fast. One more thing, check the needle and seat for the float bowl and make sure you don't have any small fibers from a rag stuck in there.

I hope this helps, if not please let us know what it was when you fix it.[/b]
Once again, I don't believe it's the jetting. I've had the same set up, jet, needle ect for over a year. so imo this isn't a problem. i've cleaned the carb out numerous times. the dealer also took the carb apart and checked flost level, ect. all ok.

I just asked my son if they hooked up a tach while they were checking out new cdi, to see what rpms it' starts acting up. He didn't know, but will ask when he goes into work today.
 

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Discussion Starter #17
Metal shavings on stator or spark plug wire where it goes into boot.[/b]

I swapped out ciol and spark plug wire from 05, no change. 05 runs ok with ciol and plug wire from 06. So that ain't it.

I haven't pulled side case to check stator for shavings. good thought.
 

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Discussion Starter #18
Latest update: Dealer mechanics went through the entire electrical system. found nothing wrong. took a carb off a new quad (showroom model) no fix. now there taking the head off to check valves and springs. hope to hear something from them today
 

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What did you find out with this as mine is doing the same thing it sounds like when under load just before the Rev limiter. Gone through everything as well mine is stock except a k and n filter and a two brothers slip on.
 

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What did you find out with this as mine is doing the same thing it sounds like when under load just before the Rev limiter. Gone through everything as well mine is stock except a k and n filter and a two brothers slip on.
For what it seems, after they worked on his valves it fixed the problem, as he never updated the post, however, intake valves are titanium and they do get cupped over time, it could be valves, I'm in the prosses of buying new ones as mine were a little cupped when I built the quad about a year ago, and make sure you stay on top of the maintenance, especially the air filter
 
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