Lower temperature... "NO" power

[MtnEX]

I don't know... I guess something else is wrong.

It cranked right up today at about 50 degrees no problem.
It ran ok on the low end of the throttle range.

Then I got on it and it just absolutely fell flat on it's face.
No power at all when farther in the throttle.
I mean you can pin it and nothing...


The reality of it is backwards from what I am seeing.
Colder weather should make it go leaner.
But that's not what my plug says.

I gotta be lean and something else has to be causing the dry black plugs.

So what should be on the suspect list?

Ignition/Electrical
Float
Rings

[leasureryan]

did you let it warm up?

not rings, if your float was stuck, it would eventualy run out of fuel at idle....did yoour main jet come loose and fall to bottom of bowl?....lol...it has happened to alot of us. Check your diaphram?


sounds like carb issues or air leak some where...idk

[MtnEX]

Originally posted by leasureryan
did you let it warm up?

not rings, if your float was stuck, it would eventualy run out of fuel at idle....did yoour main jet come loose and fall to bottom of bowl?....lol...it has happened to alot of us. Check your diaphram?


sounds like carb issues or air leak some where...idk

Yeah, it was good and warm, plenty hot. I'd been riding around on it slow for a while. It was cold... and sometimes I enjoy it. But I hadn't noticed a thing was wrong until my daughter got bored with the casual ride. On request I thumbed it a little, but nothing really happened.

I would think rings would always cause a wet film.
Just wanted to make sure.

Float... well it has died on me at idle before after sitting a while.
I don't recall it happening since I went into the carb a while back.
Might not have let it sit at idle long enough.
I'll fire it and check that tomorrow.

I think I'll check for the main jet before I do that though.

Thanks for the input.

[leasureryan]

in other words....if the float was stuck.....it would only run until the fuel in the bowl was gone, then it would quit. And until the float was unstuck, no fuel would pass through the needle valve until the float drops. So that ain't your problem.

everyones quad dies every now and again

So...let me get this straight.....it won't run at ALL past half throttle?

Or does it choke out when you go from 1/4 throttle to full throttle in 0.0000048 seconds?....if so....this may be a needle position issue.

Can you get it to 8,000 rpms if you ease into the throttle slowly? Or does it just stop running at around 4-5,000 rpm?....if so, that sounds like what it would do if the main fell out


may be a pickup coil....don't know if these motors have crank sensors or not. It may be electrical.....but lets rule out the mechanical first....cuz eletrical is a biznithch~!

[brian76708]

did you leave the choke on

[MtnEX]

Well, I couldn't stand it... I took the cap off the bottom of the carb.
The main jet is where it's supposed to be... so it's not that.

As far as the problem, it runs. There is just no throttle response past the bottom. When I say no... I mean none. You can pin the throttle and it just accellerates a little... the rpms build extremely slow.

I don't think it really matters how fast you thumb it. The only thing different I noticed is if you go instant to WFO, there is a hiccup in there somewhere past half throttle... like maybe it cuts out a single time the instant it goes full on the main jet.

[BrandonR]

i had a problem similar to this where it just started popping past half throttle. a good idea i did was wait til it gets dark (i just turned the lights off in my shop with the doors closed) and start it up and rev it up and look for any spark jumping...... I found out that the male/female connector on the coil under the tank on the right side of the frame had come apart and was barely connecting until i put a load on them then spark would jump to the frame.. hope this helps.....

[MtnEX]

As much as I'd love to fire it up and piss-off several neighbors of mine... I still have some I respect more than that... LOL.

I'll be able to check it out just after dark, but not until Wednesday evening.

A weak spark may be cause for the black plugs instead of rich jetting.

[BrandonR]

lol true, but trust me you would be amazed at what you might see in the dark.... I know what ya mean about the neighbors, we used to have a bunch til we moved and built a little shop. just a 35x35, its plenty big enough for the race car and a few 4 wheelers.

[BrandonR]

also make sure that the air filter is clean. I know alot of people clean there filters regularly but I one bought a warrior that wouldnt run right and come to find out that i took the carb off,cleaned, and rejetted all because of a extremely dirty air filter...... :rolleyes: I hope that somethin works for you..... I hate it when i have problems with my quad that just seem to never end..... thats why i got a honda :D

[MtnEX]

My dad taught me that way back in the day when he was tuning big blocks.


I can see it going leaner on me in the colder weather, but I can't see having dry black plugs still like I had already before.

[BrandonR]

Originally posted by MtnEX
My dad taught me that way back in the day when he was tuning big blocks.


I can see it going leaner on me in the colder weather, but I can't see having dry black plugs still like I had already before.

I heard that, my dad taught me almost everything i know about cars, which is alot as im a mechanic now..... I learnt alot from building this...

[MtnEX]

NICE!

[MtnEX]

Well, I still have not had a chance to fire it up in the dark to look for apparent electrical issues.

I have not had the carb off and totally back apart yet either to rule out some sort of stray blockage of the main jet, etc. I figured I'd order a couple of kits and have them here first in case I found nothing.

I thought I would order a rebuild kit and a jetting kit with several different factory jets. Anyone have recommendations on where to get these two kits from?

Maybe it's just the jetting, but I swear it "looks" just opposite of that to me.


I want to rule out air leaks too. I doubt it, but I want to know for sure. What are the methods you guys use to find them?

i would suggest getting the rebuild and jet kits from:
http://www.jetsrus.com/main_page.htm

[MtnEX]

I actually had that in mind... only place I found them easily.

[Ruby Soho]

to find an intake leak, get some carb cleaner or brake cleaner, and spray areas around the intake, if it runs better when being sprayed (say theres a hole in the airboot) on the boot, it will prove theres a leak there. but i doubt there is one if it idles for alittle bit.

[MtnEX]

Originally posted by Ruby Soho
to find an intake leak, get some carb cleaner or brake cleaner, and spray areas around the intake, if it runs better when being sprayed (say theres a hole in the airboot) on the boot, it will prove theres a leak there. but i doubt there is one if it idles for alittle bit.

Yeah, it idles fine.
I doubt an air leak too, but it's worth eliminating.


The only thing logical I can come up with is this...
It's never been rich, but instead has had weak ignition, black plugs but running a little on the lean side... add temperature drop and it's so lean it has no ballz at all... but still black plugs.

Could be dead wrong, but not much else I can think of makes sense.

[78ta]

if your quad is burning some oil you are wasting your time trying to read plugs.

[MtnEX]

Originally posted by 78ta
if your quad is burning some oil you are wasting your time trying to read plugs.

The plugs aren't wet though... they are dry.




On a side note, I rode it around here just a few minutes ago... since it got up to 63 degrees.

It's pretty much the same, except the 'cut-out' is way more pronounced when I stab the throttle. There's almost a pop.

Wierd stuff.

[MtnEX]

Well, I took it for a drive in the dark tonight.
Stopped and inspected it cold and hot.

I didn't have the plastic stripped, but I couldn't see a spark arc anywhere.

Doesn't mean it's not electrical I guess, but it's not obviously electrical (visible).

[leasureryan]

have you changed anything since it was running fine? Anything at all? Sounds like it may be lean....but that couldn't be if you haven't changed anything. Did you check your diaphram? Or gone through the carb? Take the main out and make sure it isn't pluged. I can have a carb off, gone through and back on in less than 15 minutes....

New plug?

head gasket blown?

any funny internal motor noise?

Compression?

drain the gas, and use new?

[MtnEX]

Originally posted by leasureryan
have you changed anything since it was running fine? Anything at all? Sounds like it may be lean....but that couldn't be if you haven't changed anything. Did you check your diaphram? Or gone through the carb? Take the main out and make sure it isn't pluged. I can have a carb off, gone through and back on in less than 15 minutes....

New plug?

head gasket blown?

any funny internal motor noise?

Compression?

drain the gas, and use new?

No... nothing I could think of changed except the outside temperature.

I'm in line with you... all I know to do is pull and go through the carb. If I can't see anything I'll drop the clip on the needle and see if I can tell any change while waiting for parts.

[leasureryan]

it's deffinately not jetting, or needle position issuse. A 60 degree drop in temp STILL would NOT make a quad run as bad as you are making it sound


its gotta be blockage of fuel, other things wrong with carb, or not carb issues at all. This is kinda a mystery....hope it goes well

[maxfior]

Hey man, sorry about all your weirdness... You might want to check to see if your plug got cracked. I was doing a plug chop when I did jetting and must have pushed to hard on the side of the socket and it was enough to crack the white part of the plug a little bit. My EX ran like SH*T! When I took the plug out I could wiggle the white part side to side (like I was turning) just a little bit. Have you tried a new plug yet and have you completely ruled out a clogged jet or something? All it takes is one little nasty piece of dirt... Keep us posted... Nothing more frustrating then this kind of stuff!

M.

[rideracelivemx7]

I've been reading this for sdays and started to think. but by golley I think I might have it. can you check your decompression lever for me please? see if itssuck. I can almost guatentee your issue is compression. somewhere its leaking. your carb is flwing well and your not popping and you have spark and fuel. your set. pop out the 16 bolts and pop the cover. gasket is reusable. check your valvce clearance. im new to my crf4t50 and I messed with my decompression lever amd it was wayyyy to easy to kick over and didn't like to run. if you loosen it to much you can litterally stand on the kick stat and won't budge. decompression will make or break and engine. im almost positive I've got it. try that and tell me. if not ill keep thinking.

[Ruby Soho]

check your fuel petcock, may be clogged.

[rideracelivemx7]

if you can full bore hold it open and it doesn't pop. with that apump dontyou think he would run out of fuel? pet cock would never affect the acceleration.. it would choke and die when you run out of fuel. same thing as turning the fuel off. technically its clogged isn't it? you can rev to the moon and back but it will die soon. his issue isn't fuel..

[leasureryan]

I'm on the same page as this cat.....it's more than a fuel issue at this point

provided he gets back with us and says nothing was blocking the main jet


lol....did the clips fall off you needle....lol....this kid came into work the other day and was like....when I push the throttle, the needle just stays in the carb and doesn't move....I was like...did you put the clip back on the needle...he's like....what clip.....instantly.....I sent him packing....he called me later and was like.....got that dunce cap for me to wear????...lol

[rideracelivemx7]

lol that's awsome haha. but main jet is wot and rpm isn't it? and he can still hit high rpm wit out popping or anything so that eliminates any kind of blocking or anything

[MtnEX]

This is really getting helpful... thanks guys...


I'm on the weekend shift right now, so I'll have a look at it monday.
Lots of good stuff for me to check already.

[MtnEX]

This is really getting helpful... thanks guys...


I'm on the weekend shift right now, so I'll have a look at it monday.
Lots of good stuff for me to check already.

[MtnEX]

Originally posted by MtnEX
This is really getting helpful... thanks guys...


I'm on the weekend shift right now, so I'll have a look at it monday.
Lots of good stuff for me to check already.

Well, I tore it apart, took the carb off, and while I was checking the accelerator pump squirt... I saw the problem. The slide wasn't moving at all. I was afraid of 'why' but it turned out the screws had came out... the two that hold the link arm to the slide.

I'm not sure if they vibrated out or if I forgot to tighten them past the snug-up.

I took it all out, put it together again and re-gapped the gap for the slide/butterfly synchronozation. Seems you have to re-gap every time you loosen that set screw for the slide link arm.

I did a couple laps around the house right after dark and it seems OK.

[rideracelivemx7]

thats weird lol that happened when i got my crf450. it was all stripped down and had alot of parts missing but i jerryrigged a gatorade gastank and a susuki seat on tehre just to see if i could get it started. it would start but no mater how much throttle you gave it, it would still die. i took a closer look the slide wasnt opening! lol 800$ in the hole and its a gorgeous bike now lol

[leasureryan]

see I thought it was carb problems.....must suck to be so busy....took you forever to figure that one out....lol