I'm stumped.

I<3Dirt · Feb 16, 2007

I'm Confused

I've been having some problems lately with the bike,(http://dirtrider.net/forums3/showthread.php?t=146565) thought I'd fixed them, but now it won't start at all.

This morning I drained the old gas and mixed it 32:1 hoping that would help. I also found a manual online and set the carb. back to spec and the air/fuel screw to normal. It started up on the first kick but the revs shot up, then straight down and died.It hasn't started since.

I checked the plug and it was soaked with gas. So I cleaned it off and tried again and it sounded like it wanted to start for the first two kicks, but then went back to normal and the
plug was soaked again. I've ripped apart the carb. several times, checking the float needle/seat, adjusting the float height to stock then back to where it was before that, cleaned out all the jets, put fresh gas in and adjusted the pilot screw to many different settings. The only thing I haven't changed is plug, but it's clean and has plenty of blue spark.

The manual says the float heigh should be 29mm, which I thought was a little high. I've tried it at 29mm and 16mm which is what it was before I messed with it. Neither of them seem to be working.

I really don't see it being the jetting, as I haven't changed anything to cause the jetting to be out of whack. Should I lean out needle clip?, or is there any other suggestions?

CaptainObvious · Feb 16, 2007

Assuming that the airfilter is clean, the silencer is freash and the plug is good...

1) Clean the jets, in fact clean the whole carb,
2) Check Compression,
3) Check condition of reeds,
4) Check for cracks in boot between carb and cylinder.

I<3Dirt · Feb 16, 2007

CaptainObvious said:
Assuming that the airfilter is clean, the silencer is freash and the plug is good...

1) Clean the jets, in fact clean the whole carb,
2) Check Compression,
3) Check condition of reeds,
4) Check for cracks in boot between carb and cylinder.

As I said in the origional post, the plug has lots of spark, and I've cleaned the jets and carb. numerous times. I did however, forget to mention that both the filters have been replaced.
The boot is good and has no cracks.
I don't have a guage to check compression but since it has minimal hours on the rebuilt engine, I assume it's good.
I haven't checked the reeds yet though.
Thanks for the reply.

whenfoxforks-ruled · Feb 16, 2007

If your engine is running rich then the compression is out of speck or the crank is bad. If your carb is rich then the float adjustment or valve seat, a clogged passage will throw you off too! Stock jetting and being cold that bike should be lean. If the bowl has a drain then put a hose on it and pull it up along side the carb and see what the fuel level is doing, or leave the bowl off and move the float up and down.

I<3Dirt · Feb 16, 2007

I think I may have figured out whats going on. It seems the throttle had been sticking open a bit and flooding it. The cable was frayed and wasn't letting the slide close all the way. The cable snapped a few minutes while I was trying to get it unstuck, so I'll try to go see if I can get a new one tomorrow and see if it'll start up.

rmc_olderthandirt · Feb 20, 2007

A stuck throttle cable should cause flooding.

If you have a jetting issue, and the bike has a general "bog" issue at a specific throttle setting then perhaps if the throttle stuck in the bog region it would make life difficult. You certainly want to fix the cable, but I doubt that will be the end of your problems.

Rod

actual mechanic · Feb 20, 2007

rmc_olderthandirt said:
A stuck throttle cable should cause flooding.
:bang: A stuck throttle cable DOES NOT cause flooding. It causes a partially open throttle. Too high a float height, sticky needle, leaking seat o ring etc will.

rmc_olderthandirt · Feb 21, 2007

Oops, yeah, I left out the "not". A stuck cable should NOT cause flooding

sorry about that!

Rod

Oldman125 · Feb 21, 2007

actual mechanic[/QUOTE said:
Love the screen name. I use OldMechanik other places.

:cool:

I<3Dirt · Feb 21, 2007

Well, I haven't gotten a throttle cable yet, been tied up with working on the... dare I say... quad.
I'll get back to it this weekend though, hopefully with a new cable. As for the float being too high, the manual says 29mm... is it just me, or does that seem high? I've set it at that, 23mm, and if I remember correctly, before I adjusted it, it was at 16mm.
None of those settings seemed to work when I tried it last weekend. The plug always came out clean, but wet with gas.

The needle and seat are good shape. The needle has a good point, and no deformations and the seat looks fine.
Is there a way to check if it's leaking?

TimberPig · Feb 22, 2007

I<3Dirt said:
The needle and seat are good shape. The needle has a good point, and no deformations and the seat looks fine.
Is there a way to check if it's leaking?

The only way is to pressure test it. Hold it upside down and apply pressure through the fuel inlet, If it doesn't hold, your needle and seat are shot. They often look good but fail to seal, so appearances aren't everything here.

I<3Dirt · Feb 23, 2007

TimberPig said:
The only way is to pressure test it. Hold it upside down and apply pressure through the fuel inlet, If it doesn't hold, your needle and seat are shot. They often look good but fail to seal, so appearances aren't everything here.

Okay, that makes sense.
I'll try that today, or this weekend.
Thanks.

JasonJ · Feb 26, 2007

If gas leaked down into the motor is likes to pool up in the case. Pull your plug, open your throttle wide open (or prop it) with the gas off and kick the bike for a few minutes. If there is gas down there you will see it splashing up out of the plut hole. You may have to dump your exhaust out too, fuel can get in there like a sink trap and prevent exh flow. Sounds like your float was mis adjusted. Cloged tank vent tubes can case the tank to "pump" fuel past even a good float seat as temp changes create pressure in the tank.
good luck.

I<3Dirt · Mar 2, 2007

Well, I tried pressure testing the needle/seat and it sealed perfectly.
I put it back together at the stock float height (29mm) and it's pouring gas out of the middle vent hole, not the bottom.
I'm getting really sick of this carb., if no one else has any input, I'll probably just bring it in to get rebuilt and rejetted.
Just to refresh everyone as to what I've done.
Adjusted float height to stock (29mm)
Set air/fuel screw to stock
Put a new plug in
New filter
The carb. itself is spotless, no clogged lines, no dirt, seat/needle are good, seal properly and the needle isn't sticky or deformed.
The gas cap vent line is clear
Gas is mixed properly
Petcock is clean

whenfoxforks-ruled · Mar 2, 2007

Middle vent hole? You mean like the choke circuit? Do not know how else fuel can by-pass the seat!

adam728 · Mar 2, 2007

When you pressure tested, you didn't hold the needle down, did you? Just the weight of the float is all that should be used.

Speaking of float weight, are you sure the float is not leaking? A float with a crack or pinhole can fill with fuel and then sink, causing a fuel leak.

I<3Dirt · Mar 4, 2007

Well, yes, actually, I did hold it down, but I tried it again, using the just weight of the float and it sealed fine.
I don't know what I did differently this time, but when I put it back together again, it's not leaking anymore.
But now it won't start at all. It used to pop/backfire once in a while when kicking it over, but it won't even do that now.
I'm going to try use the quad and pull start it today, to see if that works.

I<3Dirt · Mar 27, 2007

UPDATE:

I lowered the float heigh a bit and it helped. I can get it to run now for a minute or two within the first couple kicks but when I shut the choke off it eventually bogs down and dies. It'll sound like its going to start after that, but never does. I have to let it sit for a while to get it to start again, or clean the plug off. I'm thinking it's still a bit rich, but would that cause it to bog down and die like that?
Should I try going up a clip on the needle to lean it out a bit?
Or does this still sound like a float problem?

whenfoxforks-ruled · Mar 28, 2007

Just replace the float valve,its cheap and old. Can you put your carb together and rig a vent on your overflow or drain,pick it up next to your carb,that is the same level that is inside your carb,too high or low is a problem. Either the float or valve.

I'm stumped.

I<3Dirt

CaptainObvious

Formally known as RV6Junkie

I<3Dirt

whenfoxforks-ruled

Old MX Racer

I<3Dirt

rmc_olderthandirt

actual mechanic

rmc_olderthandirt

Oldman125

I<3Dirt

TimberPig

I<3Dirt

JasonJ

I<3Dirt

whenfoxforks-ruled

Old MX Racer

adam728

I<3Dirt

I<3Dirt

whenfoxforks-ruled

Old MX Racer

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