Quad quit running HELP PLEASE

[racer82]

i have a 2007 trx 450 electric start. i was riding at a friends house when i was going up a hill and it sounded like the choke was on sputtering. i took it to his field and let it idle and i tapped the gas amd it died. when i tried to start it back up it was shooting smoke alot of it too. but when i got home i tried to start it and it didnt smoke and it idled. it is when u tap the gas is when it dies. any advise on this issue. Thank you in advance.

[DnB_racing]

fresh gas and clean carb

[racer82]

thats what ive been told but how would it do that now all of a sudden

[DnB_racing]

pump gas mixed with ethanol softens plastic gas tanks, along with leaving deposits to plug jets,

remove carb from quad and take completely apart and spray ALL passages with compressed air

[racer82]

thank you so much!

[racer82]

well i finaly cleaned the carb. it will start and idle but when you touch the gas it dies. any help is greatly appreciated.

[racer82]

i looked closer at the carb today.im a 2 stroke guy and 4 stroke carbs are out of my league. haha but any ways i looked and it looks like the slide moves up and down and the needle stays the same. it doesnt move or anything. if anybody could tell me about my carb problem i would appreciate it.

[hrc450er]

Pull the top off the carb and there will be a hex screw that holds the needle in. Take that off and see if the clip is still on the needle

[racer82]

Ok i did that and the needle was on the third slot, ihave stock 2007 trx 450 with an hrc kit is this a good slot for it it has stock pipe, but anyways i put it back in and it was sliding with the slide, would it be one of my sensors went wrong

[hrc450er]

Could be, most likely the wire that goes in by the throttle cable. Its the wide open throttle sensor. You can cut those wires and and the ones coming out of the thumb throttle. I cant recall if u have to connect them or leave em unconnected. Try different combos of the two. This just gets rid of the sensor but if throttle ever gets stuck you better react fast cause quad wont shut itself down.

[racer82]

K thanks man ill try that

[DnB_racing]

Originally posted by hrc450er
Could be, most likely the wire that goes in by the throttle cable. Its the wide open throttle sensor. You can cut those wires and and the ones coming out of the thumb throttle. I cant recall if u have to connect them or leave em unconnected. Try different combos of the two. This just gets rid of the sensor but if throttle ever gets stuck you better react fast cause quad wont shut itself down. its actually not a wide open sensor..

its technically a "closed throttle position detection sensor"

meaning it does nothing to stop motor with stuck wide open throttle,(unless thumb lever is fully closed and carb open)
its for cables that have too little play with throttle closed,
if the cable slack is less then 5mm the quad wont run,

but yes it can be reliably bypassed by splicing the 2 wires together

[racer82]

so you cut both the wires coming out of the carb and the thumb throttle and it should work?

[DnB_racing]

Originally posted by racer82
so you cut both the wires coming out of the carb and the thumb throttle and it should work? yes you can cut both pairs, but one of the pairs needs to be spliced together, it doesnt matter which pair

[racer82]

well i did a compression test today and it was 35 psi. guess it time for a rebuild

[racer82]

UPDATE
i put a new set of rings in the quad and it still had 30 psi. i was talking to a local mechanic who said it could be a bent valve, a bad valve seal, or crank seals. when i pulled the cylinder off for the rings oil poured out. so i was thinking crank seals what do you guys think

[CJM]

Take the head and put oil on top of the valves. Let it sit awhile. A bent valve or bad seal will leak.

[racer82]

thats what geno said. hes my mechanic haha. im probably going to do that tonight if i have time

[racer82]

i tore it apart and the valves arent leaking. i think its the crank seals. anyone else have a thought?

[buddy willard]

decompression adjusted right? or is it stuck

[racer82]

how would i check that

[racer82]

ok a little bit of an update.
i tore it apart and put new seals in and still 30 lbs of compression. the book says they should have 50 but mine has new rings and they are in spec. im thinking it is the stator because it seems like when the motor needs more spark it just isnt getting it. so i think im gonna call ricky stator and get a new one ill see how it goes

[DnB_racing]

before you go spending more money...

I would try to find out why you only have 30 lbs starting compression.... the stator has nothing to do with this..

when you say 30lbs how are you testing it?
are you WOT?
and what is your decompression clearance?

try opening up your decompression mechanism more to see if compression will build up, and if it does build up measure the clearance at 55psi,


its time for you to do a leak down test and find were your loosing compression,
get a stethoscope and listen for were the air is leaking out,

I would do this before buying a stator, im not saying you do or dont need a stator but first things first

[gnccracer456]

These type of things wouldn't happen with a YAMAHA Jeremy....

[DnB_racing]

Originally posted by gnccracer456
These type of things wouldn't happen with a YAMAHA Jeremy.... thats because people that have yamahas ride like little girls:blah:

[racer82]

he cant talk much he has a raptor 125 haha :D but any ways the honda manual says that it should have about 50 lbs. my decompression is set at my mechanics setting at 24 thousandths.
how do i do a leak down test

[DnB_racing]

Originally posted by racer82
he cant talk much he has a raptor 125 haha :D but any ways the honda manual says that it should have about 50 lbs. my decompression is set at my mechanics setting at 24 thousandths.
how do i do a leak down test what is 24 thousanths?
is that the total of exhaust and decompression clearance???

the correct amount is

exh valve=.011 and
decomp clearance=.010


but put this out for a test... keep opening the decomp adjuster until you get 50-55 pis and see what you have for clearance


google leak down there are some u-tube vids that explain it much better then i can


I ask again...how did you do your compression test?was it WOT?? and are you sure your tester is accurate?

[racer82]

the tester is good, i tried it on another quad. i did wide ope throttle to test it. my mechanic geno told me to set the decompression at 24 thousandths where it hits the rocker arm.

[DnB_racing]

Originally posted by racer82
the tester is good, i tried it on another quad. i did wide ope throttle to test it. my mechanic geno told me to set the decompression at 24 thousandths where it hits the rocker arm. your mechanic Geno is wrong

first set your exhaust valve clearance from shim to rocker arm to .011, then set the adjuster screw from rocker arm to adjuster screw to .010 on the +06,
and .006 on the 04/05

then see what you have ...

[racer82]

more bad news.
i put new crank seals in, it starts and does the same thing. i was thinking it would be the stator becuase when the motor start trying to rev it dies? but that would not explain the blowby of oil in my airbox?
I NEED HELP!

[DnB_racing]

have you fixed the compression problem yet??

if not start there, dont worry about the stator, until you have the proper compression

[racer82]

when i put it back together it still had 30 lbs. but it still starts!? it still has blow by and i dont know why. i think im just going to drop it off at a shop and have them do it.

[d3ktrix]

The oil blowing to airbox and low compression are probably related.

The reason you are getting oil blowing into your air box is because your crank case pressure is too high.
Caused by some of cylinder gases escaping into your bottom end instead of out the exhaust valves.
...Also causing the low compression.

Do the leak down test like DnB said.
To me it sounds like a cracked head or cylinder.
Did you use new gaskets when you did the rebuild?

[racer82]

i always use new gaskets when tearing into a motor.
could some explain what i would need to do a leak down test and how to do it

[d3ktrix]

Originally posted by racer82
i always use new gaskets when tearing into a motor.
could some explain what i would need to do a leak down test and how to do it

This is for a car, but its all the same.
http://www.youtube.com/watch?v=ofSiTGeLXvc

Hold ur crank in place with a breaker bar to keep the piston at TDC when u pressurize ur cylinder. Just dont let it hit u in the face =)

[shadyRacing]

Check your coil wire behind the left fender(oil side) same thing happened to me in the woods mine the metal female end on the wire was loose and just about hanging on I plugged it back in squeezed it tight runs great ever since ..

[racer82]

which wire are you talking about, and havent done much to the quad yet, im thinking i need to adjust the decompression are though

[racer82]

i took off my stator and took it and put it on my friends quad(same quad and yea) and it did the same thing. i put his back on and his started right up and would rev up. so i ordered a new oem one and it should be here soon.

[racer82]

i put my new stator on and it fixed it. Thanks for all the information guys!!

[racer28]

I was under the impression it was your kanooder valve