carb question

[psychoracing]

Well I am hopeing the back fireing is because of the carb adjustment, I did some searching on here and bluetraxx and there was a thread about adjusting the jet and so fourth, the pictures were gone so it wasnt very detailed. something about 3 notches in or something, just curious if anyone has a diagrahm or something with the details of setting it up, I know it has a 150 jet and I put that spring in as someone else said out of an ink pen.

 

[1998yamahawarrior]

userfriendlys rejetting giude in tutorials at the 47 second of the video it starts to show how to get to the needle that would be the notches that they are talking about. heres the link to that thread.

http://www.trx450rforum.com/phpBB3/viewtopic.php?t=9672

 

[psychoracing]

hmm then I have a different problem then, mine back fires out the exhaust and has a hicup in the intake and wont stay running, before it would atleast stay running just wouldnt rev up, that I belive was my spring problem. It seems you and maybe 2 other people are the only ones that know anything about these quads. what gives ? I am sure I am wearing you out with this stuff, but atleast I am trying to learn. I really appriciate the help.

 

[1998yamahawarrior]

well im assuming you have cleanned the carb. did u check the carb boot that goes to the motor for crack. also how many turn is the feul screw out. i ll start with those questions.

 

[psychoracing]

brand new carb boot about a month old, and 2 1/2 out on the a/f screw. carb was cleaned out when the boot was replaced.

 

[DeadLastRacing]

DUDE....give it some time man. You just started this post today. Most of us have jobs or a life outside of this forum.....but there are plenty of members on here that know these machines in side and out all while being blindfolded. So to say the only three people know how to fix your problem (a problem that has been covered nearly 100 times now) is just your lack of patience man.

On to your problem.....backfireing is a carb (air) problem or a spark timing problem so your on part of the right track at least. Few questions for you. Has it ever ran right since you had it? What air performance mods have you done (exhaust, filter, airbox) Is the pilot jet stock? What position is your needle clip at. ect. All these are factors in figuring out your specific problem.

Often when you have a ATV that is backfiring you will find that your bike is having a problem with bad spark timing. Your CDI or coil could be going out but you said you fixed all that right?

Your valves could be outta whack too. Not set right or timed wrong? Your timing on? I just worked on a war dag that had its exhaust rocker arm seized up, no oil change is a bad way to trash an engine.

 

[bomber315]

it runs so rough that you havent even rode it around yet?

hmmm maybe check compression, sounds like maybe your valves arent closing tight.... i know you probably already thought of that but i just gotta rule it out...

also make sure your valves are set right... i dont know the numbers off hand but they are in the service manual...

it almost has to be something to do with the valves allowing the fire to get past them...

either the spark has to be coming at the wrong time or the valves have to be moving at the wrong time...

maybe you have a sheared flywheel key?
maybe try your stock CDI, i cant remember if it works or not (i might now that you have a new stator)

im delivering pizzas tonight so that involves alot of boring driving around, (providing im not super super busy) you can call me if you want 814-229-1544.. theres shitty signal around these parts but ill answer if it rings

not sure ill be able to tell you i know exactly whats wrong but i can atleast try...

dont go getting into your carb too much.. it should at least start and run enough to ride it wound the yard with the stock settings.. it might stammer here or there but it should at least start

 

[bomber315]

refresh me on what the guy said the symptoms were when you got it?

did you have the flywheel off? if so are you sure you tightened the piss outta it? (i thought mine was tight but it managed to shear a key on me)

 

[psychoracing]

DUDE....give it some time man. You just started this post today. Most of us have jobs or a life outside of this forum.....but there are plenty of members on here that know these machines in side and out all while being blindfolded. So to say the only three people know how to fix your problem (a problem that has been covered nearly 100 times now) is just your lack of patience man.

On to your problem.....backfireing is a carb (air) problem or a spark timing problem so your on part of the right track at least. Few questions for you. Has it ever ran right since you had it? What air performance mods have you done (exhaust, filter, airbox) Is the pilot jet stock? What position is your needle clip at. ect. All these are factors in figuring out your specific problem.

Often when you have a ATV that is backfiring you will find that your bike is having a problem with bad spark timing. Your CDI or coil could be going out but you said you fixed all that right?

Your valves could be outta whack too. Not set right or timed wrong? Your timing on? I just worked on a war dag that had its exhaust rocker arm seized up, no oil change is a bad way to trash an engine.

DUDE NOT SPEAKING OF THIS POST ! meaning any tread it seems like unless its "how do I change oil" or hwo much air pressure do I need" there is never any posts it seemed like. I am not the only one that said that, if you are taking that comment personal then sorry you feel that way, with the last subject I had there was only 2 or 3 different responses hence my comment in this thread. relax, take a breath its ok !

The air box is stock minus the k&n, it has a big gun exhaust and seems to be a full exhaust. jet is a 150 no clue of the position of the needle clip. I havnt tried the stock cdi box and will do that later, before the magneto went it would atleast idle and would give hell reving up, I just put the spring in the carb when I got it to fire yesterday. now it wont idle and runs like complete crap. it will idle for a min or so and shut off, starts only with the choke half out. before it would atleast sit there and idle. but the back fire out the exhaust would be on acceleration and de exeleration and pop thru the intake box alot. I checked the timing marks and they are dead on. that was my first though when all this no spark thing started.

 

[psychoracing]

havnt had the flywheel key problem as of yet, it seemed tight when I replaced the magneto, I havnt checked comression yet either, just before this magneto and cdi it would atleast make it up the street and back and now it wont leave its spot. I will swap the cdi alittle later and see if that helps.

 

[psychoracing]

just swapped the cdi real fast and it fires up and does pretty much the same thing as the rm stator cdi does. it hicups more thru the air box then it does the exhaust, when I go to push on the throttle its dead then will throttle up but back fires out the exhaust. maybe its valve adjust ment and carb issues. but like I said before it would atleast sit there and idle with an occastional hicup out the intake but I could get it out the garage, now it wont do anything but shut off.

 

[DeadLastRacing]

first off.....this forum has been around since 2005 and I have been a member since 2007, mod status this year. We have never deleted any or our old topics (occasional post, yes) Which the number of years and 100,000+ post, the issue of backfiring HAS been covered many times before. Take the time to use the search tool or to back track through old post to see if your problem has been covered, before asking again. That all I'm getting at. We answer the same basic carb/shock/electrical questions every couple of months just because new members are quick to ask and not research. Nothing personal here, just doing what I can to get repeat questions handled.

Sooo, moving on. Your running too lean. Try going up one on the pilot (45) and leave the main at 150 or even try it at 147.5. The needle clip should be in the middle setting. A/F screw should be sat at 2 1/2 or three turns out. RE-Check the carb boot for any tears. If you had a strong enough backfire, it could be torn again. With just your exhaust, that should be a good running setup. Try all that and if you still have problems we can diagnose it from there. We would then most likely have to move onto valve lash and valve seet.

 

[bomber315]

yeah i didnt really think it was CDI related but now we can rule that out.... check the service manual for valve adjustment settings.... shitty part with this is you have to take the gas tank off to really get at the intake good.... i think the spring you keep refering to is for the accelrator pump... it is only used whan you stab the throttle.... thats why sometimes you read where guys say if they ease into the throttle it goes but if they hammer on it, it falls on its face....

i still wanna blame crank to valve timing even tho you said you got it set perfect... so i won't...

its a major pain in the ass to do this but if adjusting the valves doesnt make somethnig happen then if afriad your going to have to inspect that flywheel key...(unless someone else has an idea).... if you do go to look at the flywheel key, just tip the fourwheeler on its side and be very very careful you dont drop anything in the motor... that way you dont have to mess around with draining oil and all that crap...

 

[psychoracing]

Well I am hopeing the back fireing is because of the carb adjustment, I did some searching on here and bluetraxx and there was a thread about adjusting the jet and so fourth, the pictures were gone so it wasnt very detailed. something about 3 notches in or something, just curious if anyone has a diagrahm or something with the details of setting it up, I know it has a 150 jet and I put that spring in as someone else said out of an ink pen.

If you check my original post I did search, came across a few answers I needed, one of them being the 2 1/2 and I had mine at 1 1/2 so in deed the search did do its duty, for the other parts the pictures were gone so I decided to ask the question again, I didnt see it anywhere else and everytime I click back to go to a different thread it would say time out or something, so I figured I could ask my own personal question so that it would be answered in detail for my benefit as well. I am not some 16 year old kid that has nothing else better to do and ask useless stuff. sorry you have the attitude you do in this matter, it seems the others dont have a problem with me asking again. not sure if you just having a bad day, you along with the other 2 I had in mind are the only ones that have helped me out on here and yes its been a battle and finally it starts. time to move onto the next battle. I dont have the right adapter for the compression checker so I gotta find that, I will pull the carb again and check the other jet, I forgot to write it down as it was stated in another search I did was a good idea to write this stuff down. I just remembered the 150 jet thing. also noticed there was no spring so I did that as well. not sure of what all a rebuild includes on these carbs but usually its just a gasket and needle and such, I will try taking apart the top end of the carb for I just sprayed the areas out I could get to without completely tearing it down. I have worked on carbs and such before, I have a bottom 11 second all motor mustang that I built myself, but when I get stumped I like to ask questions.

 

[bomber315]

deadleast, on the fuel screw... the further out the more gas at idle right? (my local friends are trying to tell me its in for more gas)

 

[DeadLastRacing]

Its cool man....I ain't into starting any battles. Nothing wrong with asking questions. Just some topics get played out over and over and over again. It gets under my skin from time to time.

You seem fairly knowledgeable in repairs and mechanical stuff so I'm sure we'll figure this out. Walk back though my "in general good running setup" and hopefully then you will be set.

 

[psychoracing]

What is that ? I am fixin to head out and pull the carb, my motorcycle shop said to bring it to them and they will set it up as well. they are cheap on the labor for me but I figured this is something stupid atleast..... I hope....

 

[psychoracing]

42.5 150 4th groove from the top is what I have so far.

 

[DeadLastRacing]

K ,so you have the stock pilot in now, the main is up two settings and the clip is down one. That's kinda weird though. with your current setting, you should be getting a bunch of fuel......HUH? ANYWAYS....Lets start from a in general slip on type setting. One up on pilot (45) one up on the main (147.5) and set the needle clip to the middle setting. Try that? or if someone else has a better idea?

You double check your carb boot?

 

[psychoracing]

I dont have any stock jets or anything to replace what I have. I watched that video posted above and he is just where I am except he said the 150 was to big for him. the carb boot is brand new but I did check around just to make sure. here are a couple of pics, I never did check the valve clearance as of yet, figured it was something in the carb. I am soaking the bowl and getting the rest of the trash out just to be safe. it is squirting from a little jet when I twist the throttle so I am taking it that the accelerator pump is working now. the valves didnt look the greatest though, looked kinda wet to me indicating maybe time for a upper end service. I am still working on getting the adapter to check the compression,if its low I might as well do it all in one shot. I did blow into the fuel line port and lifted slowly on the float and it shuts off just around level. just strange it idled and ran before but baby steps I suppose.