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View Full Version : Help FAST! 450 is cutting out!!



Narly R
04-22-2004, 10:55 PM
Well we have tried everything from a 160-172 main jet, tried 42,45, and 50 pilot, and the needle was at 5th and 3rd clip it keeps cutting out. It might not even be the jetting. It seems to cut out about 1/2 throttle. Sometime its runs fine, other times not....


:mad: It is very frustrating! Any ideas?

Quad18star
04-22-2004, 11:08 PM
Sounds electrical !! Maybe?? I aint a mechanic but I'm having electrical probs with mine right now . And yes , it's very frustrating !!! :@

Baley69
04-23-2004, 02:47 AM
Dirty carb?

jlhughes750
04-23-2004, 08:44 AM
I'm finding mine to be VERY picky about filter cleanliness!!!!!!!

make sure the filter is spotless!!!

SRH
04-24-2004, 12:22 PM
yeah most motors like that are, i remember i had a rm 125 that wouldnt run right and wouldnt start i guess the filter was too dirty but my 400ex would run fine

Splatter Matter
04-24-2004, 01:40 PM
it might be your flywheel. i got a bad +4 from trailtec.it did the same thing you are saying. they sent me a new one so for so good. check your plug to. or the tps. on side of the carb the thin wires some times break .

dwf126
04-24-2004, 05:06 PM
When you got your flywheel, did it happen right away, or over time? I have a +4 from trailtech ( the first one they shipped out). I run the GNCC series and I noticed at the first round, I would start to cut out on top end.

I thought I might be rich, because my buddy and I have the exact same setup, and he runs a 178 main, and I was running a 180. I dropped down to a 175.

It was still happening. Finally at Lorreta, I couldn't get much over half throttle with out it popping and cutting out.

I have spent the last 3 days trying everything. We went from a 42 pilot to a 48, and have tried every jet from a 158 to a 180. With the YZ needle in spots 3 and 4 and the stock needle in spots 5 and 6.

We started checking all the electrical today and came up with nothing.

For sh-ts and giggles we went and got some bigger mains. I started with 188 and it almost ran decent, so I went up to a 190 and it runs pretty good, with a slight hesitation about 1/3.

I can't explain why all of sudden it needs more fuel. I ran fine for 6 months with this setup

HMF Full system
K&N setup
Stock Needle 5th from top
45 Pilot
180 main


Now I am running this setup

HMF Full System
K&N
Stock Needle 5th Position
48 pilot
190 main



I am still getting hesitation, so I am going to try to mess with the YZ needle and some pilots between 48 and 52 and some mains between 190 and 195.

It just seems super rich too me and I can't explain why the old setup just quit working.

I thought for sure it was electrical. But the big jets seemed to cure it.

Let me know if you come up with anything good.


Derek

Splatter Matter
04-25-2004, 06:50 AM
[QUOTE]Originally posted by dwf126
[B]When you got your flywheel, did it happen right away, or over time? I have a +4 from trailtech ( the first one they shipped out). I run the GNCC series and I noticed at the first round, I would start to cut out on top end.

I thought I might be rich, because my buddy and I have the exact same setup, and he runs a 178 main, and I was running a 180. I dropped down to a 175.

It was still happening. Finally at Lorreta, I couldn't get much over half throttle with out it popping and cutting out.

I have spent the last 3 days trying everything. We went from a 42 pilot to a 48, and have tried every jet from a 158 to a 180. With the YZ needle in spots 3 and 4 and the stock needle in spots 5 and 6.

We started checking all the electrical today and came up with nothing.

For sh-ts and giggles we went and got some bigger mains. I started with 188 and it almost ran decent, so I went up to a 190 and it runs pretty good, with a slight hesitation about 1/3.

I can't explain why all of sudden it needs more fuel. I ran fine for 6 months with this setup

HMF Full system
K&N setup
Stock Needle 5th from top
45 Pilot
180 main


Now I am running this setup

HMF Full System
K&N
Stock Needle 5th Position
48 pilot
190 main



I am still getting hesitation, so I am going to try to mess with the YZ needle and some pilots between 48 and 52 and some mains between 190 and 195.

It just seems super rich too me and I can't explain why the old setup just quit working.

I thought for sure it was electrical. But the big jets seemed to cure it.

Let me know if you come up with anything good.



no it happen over time just like you stated. it just keep running worse.I did the same thing jetted the crud out of it and still did not run .put the stock flywheel in and had to go back to my 168 /45 2 turn setting on the carb

running this set up
modded stock pipe
K&N /outerwear
nvcq 4th pos
168 main
45 pilot
2 turns

dwf126
04-26-2004, 07:51 AM
Did trailtech replace the flywheel? Did they say what the problem was?

dwf126
04-26-2004, 03:19 PM
I just wanted to say what a great company trail tech is. They are sending me a return label for the old flywheel, and a new flywheel 3-day air, so I will have it in time for Sparta. I recommend them to anyone.


Derek

Splatter Matter
04-26-2004, 06:26 PM
Originally posted by dwf126
I just wanted to say what a great company trail tech is. They are sending me a return label for the old flywheel, and a new flywheel 3-day air, so I will have it in time for Sparta. I recommend them to anyone.


Derek

they did the same for me just did not respond quick.to your post.
did you find it to be your flywheel.

MXchamp82
05-06-2004, 09:21 PM
I am having the exact same problem with my yfz. It runs fine some rimes, then it will start to cut out and sputter. I ran into a similar problem before and it ended up being the TORS on the carb. I eliminated that along with the swithch on the clutch perch which also was causing it to cut out. It was fine for a while, but now I am having problems again. It doesn't do it all the time, and when it does, it is only at 1/2 to full throttle. I messed with jetting, but it doesn't help the problem at all. I am pretty sure it is electrical, but can't seem to pinpoint the problem.

If you guy come up with any answers or a surefire fix, let me know, this is getting really frustrating.

dwf126
05-07-2004, 06:18 AM
Mine was the trailtech flywheel. The guy from trail tech said they had seen issues with the magnet slipping on some of the early flywheels. I put my stock flywheel back on and it runs fine now.

Trailtech sent me a new flywheel and I plan to put it back on this weekend. Raced without it and it seems to stall a lot more without the +4oz.

Narly R
05-10-2004, 09:29 PM
Well it seems to be the same as dwr126, it just need more gas, we finally got it to run good with a 180main, and a 50 pilot, but then we went from about 600 ft. altitute, to about 1700. We put a smaller jet in it, and it was cuttin out again. We will see how its runnin again, and maybe mess with it more, if it runs bad we will send it to a local guy who can get it running amazingly!:)

Thanks for the info guys!

Bill Fuller
05-10-2004, 09:39 PM
Well I'm having problems myself.I put the full HMF on air box lid on and no cam mod and have been playing with the jets still can't get it just right.My problem now is I can't seem to find any jets.I am looking for a 168,172,178,180.I have the NQVC? needle and have tried all different combos.I have tried a 48 pilot but it still stutters 1/3 to 1/2 throttle.Just got the ziptye adjuster today so that helps.Somebody tell me where I can get some jets:mad: :cuss: I have had the YFZ for 2 weeks now and still haven't really rode it.

Splatter Matter
05-11-2004, 05:38 PM
try Bob he is very good when it comes to yfz parts
http://www.magnoliatractorinc.com/

Narly R
05-11-2004, 06:39 PM
Ok, thanks.

Bill, you can get jets at your local bike shop. Just need them for a Kehien.;)

Bill Fuller
05-12-2004, 06:04 PM
I have tried my local shops and Jeff@Quadshop,everyone says they are on backorder.I finally think I have found a supplier though,I'll tell everybody thier name if they come in by Friday as promised.:rolleyes: Keep us informed on what you find out about yours.I've asked for help at YFZcentral but the responces are very slow.

snox31
05-12-2005, 05:54 PM
my has been doing the same thing lately ,thought jetting because it is colder now,but not the problem now the other day at the track it was running bad so i pulled into the pits and pulled my tether and stayed running so I took it apart to clean it (a pro design) and it ran great.Just a coincedence? not sure, i will find out tomorrow going to race it so she better run good. if i can find anything else i will let ya know,oh i am kinda thinking about the charging issue ,will that cause the same symptoms? I will order a resistor kit next week but will put the lights on just to rule that out

sampleez
05-12-2005, 07:34 PM
holy crap!!, your post is almost exactly a year ago from bill's post. that's crazy. sorry can't help ya tho

snox31
05-12-2005, 07:59 PM
huh i never looked at when it was started either ,i wonder if he got it fixed

parks9
05-13-2005, 07:13 AM
you might check the little blue wire at the bottom of the motor on the left side...

Bill Fuller
05-13-2005, 07:45 AM
I did get mine fixed.It took me over a month to get the jetting right.Everyone was telling me to go richer when infact I was to rich.I tried every combo imaginable until I finally got to the right setup.45 pilot,162 main,NCVQ needle on the 3rd clip,fuel screw at 1 1/2 to 2 turns out.I thought I was having rectifier problems and all sorts of crap.Once I got the jetting right it has ran like a champ!!

jshtex
05-13-2005, 06:51 PM
Bill, I went thru the same crap when we first started "upgrading" our yfz. I read all the post about the big jets and how much the yfz craved fuel. Ended up tuning ours on a Dynojet and we have basicaly the same setup (jetting wise) as you. Two other yfz's that race with us locally are both in the same ballpark. One is running a 165mj and the other ended up with a 168mj.

Don't ask me why but since we run XC we need to conserve all the fuel we can so i don't have a problem running a smaller mj, as long as I am not running lean.