Bad Running Zilla still

Bad Running Zilla still
Posted by CrustyOreo on 07 Sep, 2013 13:15
So I fixed the engine vacuum leak from the left side flywheel cover.
Changed the mixture to 21:1.
I can only get it start if I have the choke lever in the down position (which I think is choke on?) It will idle for a few seconds then die. If I push the choke lever up the bike will just rev up so I kill it.

ALso, the air box is off. How the heck do I get it to fit in the frame?

Thanks

#1 Reply
Posted by LT250RWV on 07 Sep, 2013 13:43
Is your slide height right. Go with a fatter piolt till it idles with out running away. Have you done a leak down test.

#2 Reply
Posted by Frank on 07 Sep, 2013 13:59
So if I understand it correctly the engine is running short with drawn cold start ?
have you cleaned the carburetor ?
let the air filter box from now.
or build it into what you want.
you need to tighten the swingarm side somehow .
I know not remember exactly 's been two years .
but your engine is running too rich anyway !

#3 Reply
Posted by CrustyOreo on 07 Sep, 2013 14:05
Quote from: LT250RWV on 07 Sep, 2013 13:43
Is your slide height right. Go with a fatter piolt till it idles with out running away. Have you done a leak down test.

What's the correst slide and mixture setting?

#4 Reply
Posted by CrustyOreo on 07 Sep, 2013 14:17
I fetled with air box and got it on. bike started and did the same thing. Now it won't start. Every couple of kicks it will "sneeze" and a puff of smoke will come out.

#5 Reply
Posted by CrustyOreo on 07 Sep, 2013 14:38
I got it to start then it ran away again so I killed it. Now it does nothing but backfire. Made one so bad it blew the expansion chamber off the head. I wonder if it's timed wrong?

#6 Reply
Posted by Frank on 07 Sep, 2013 16:21
Check your Flywheel and the seat of the screw in it.
and ignition coil to have good ground
Check your spark and the flash
Check your carb and all your jets clean it out
Check the petcock
Is there a mass dirt in the tank
When this is all ok
Than take a look behind the head
I think the top end is good when you have compression.
Is bad when entering water in it is the same f..... starting procedur
I wish you a lot ..... Frank

#7 Reply
Posted by CrustyOreo on 07 Sep, 2013 16:56
Carb is clean. I checked spark, all was good. I drained the bad fuel out, petcock flowed fine.

#8 Reply
Posted by LT250RWV on 07 Sep, 2013 19:35
Read carls tech section about jetting

#9 Reply
Posted by Frank on 08 Sep, 2013 01:39
Your motor runs ?
You have a oem engine or is he ported ?
What is with your reeds?
What brand of carb dou you have ?
Yerry give me a good startpoint for the mc cooney TM38 ;-) for the OEM Engine

When you have worked all points out.

An this zilla do not work
And you have compression
The leak down is positive
Switch the cdi and the complete Stator when you can ?

When you say the motor is all good
Then must be a lonely thing : Ignition

And put out your Killswitch . but make it good dou you can install it again when its isn't

#10 Reply
Posted by WRDturbos on 08 Sep, 2013 09:11
Did you buy it not running, or has it ran excellent and just started running poorly?

#11 Reply
Posted by Dezsled on 08 Sep, 2013 09:30
If you reinstall the air box lid you can test if its lean or what.

Reinstalling the airbox lid will richen up the jetting, which may help your situation.

Avoid a costly siezure, go bigger on the pilot jet one size

#12 Reply
Posted by Q2W on 09 Sep, 2013 07:46
If your carb has the lever style choke, up is off. If its the plunger, up is on.

Pulling the choke bypasses the pilot circuit. When you said you flipped the choke up and the motor ran away makes me think you have a lever style. If so, you either have an incredibility lean pilot jet in, incorrect throttle cable, or air leak.

First, set your slide height to about 3mm. Remove the boot connecting to the airbox. Make sure the slide is all the way down in the carb. You can let it out with the adjustment on the handle bars. Using the thumb screw - big screw with the big spring on it - turn it in until the slide raises about 3mm. Never touch that screw again as long as you own the bike.

Second, adjust the throttle cable. Adjust the cable out until you feel the slide bottom out in the carb. From there, adjust it until all the slack is out and your slide moves as soon as you touch the throttle. All the adjustments can be made at the handle bars. Also, make sure it's not in a bind.

third, adjust the air/fuel mixture screw. Where is it set? a good starting place is about 1 1/2 turn out. If you have to adjust it more 3/4 of a turn either way, you need to change jets up or down accordingly. If the idle doesnt change either way, you're not even in the ball park on your pilot jet or you still have an air leak.

#13 Reply
Posted by Frank on 09 Sep, 2013 11:17
he said ... while the engine died after some time.
since there are only two things for me ...
Water in engine and ignition problems

#14 Reply
Posted by CrustyOreo on 09 Sep, 2013 13:05
Quote from: wrdturbos on 08 Sep, 2013 09:11
Did you buy it not running, or has it ran excellent and just started running poorly?

The PO claimed it ran but the fuel was old.

#15 Reply
Posted by CrustyOreo on 09 Sep, 2013 13:06
Quote from: Q2W on 09 Sep, 2013 07:46
If your carb has the lever style choke, up is off. If its the plunger, up is on.

Pulling the choke bypasses the pilot circuit. When you said you flipped the choke up and the motor ran away makes me think you have a lever style. If so, you either have an incredibility lean pilot jet in, incorrect throttle cable, or air leak.

First, set your slide height to about 3mm. Remove the boot connecting to the airbox. Make sure the slide is all the way down in the carb. You can let it out with the adjustment on the handle bars. Using the thumb screw - big screw with the big spring on it - turn it in until the slide raises about 3mm. Never touch that screw again as long as you own the bike.

Second, adjust the throttle cable. Adjust the cable out until you feel the slide bottom out in the carb. From there, adjust it until all the slack is out and your slide moves as soon as you touch the throttle. All the adjustments can be made at the handle bars. Also, make sure it's not in a bind.

third, adjust the air/fuel mixture screw. Where is it set? a good starting place is about 1 1/2 turn out. If you have to adjust it more 3/4 of a turn either way, you need to change jets up or down accordingly. If the idle doesnt change either way, you're not even in the ball park on your pilot jet or you still have an air leak.

I will do this when I get home. Thanks

#16 Reply
Posted by CrustyOreo on 09 Sep, 2013 18:27
So I figured it out.
The base gasket is leaking air. See attached images. The bike will run okay with the choke on because it's getting enough fuel to compensate for the air it's sucking in. But once you turn the choke off, it gets too much and and just revs to high heaven. I'm uploading some vids now.

#17 Reply
Posted by Rider414 on 09 Sep, 2013 20:13
That's good that you found it. Now its time to fix it.

#18 Reply
Posted by LT250RWV on 09 Sep, 2013 20:22
Good old leak down tester is a must with these 2 strokes.

#19 Reply
Posted by CrustyOreo on 10 Sep, 2013 06:01
Is there anything I should buy besides a gasket kit?

#20 Reply
Posted by Hotbutta on 10 Sep, 2013 20:35
Get the fuzzy one.

#21 Reply
Posted by CrustyOreo on 11 Sep, 2013 11:41
Que?

#22 Reply
Posted by James Dandy on 11 Sep, 2013 14:49
If it's the stock Mikuni flat slide, I think it's a 38mm, and with the lever up, it's on. Man I wish I could post pics. I have that carb on my bench right now. If it's that carb, take it off, put it on the bench, leave it there and go get a big keihin PWK and a 180 main jet and about a 62 slow jet. Set the needle at the middle position and then tune from there as needed. Check the Salvage yards, craigslist, old motocross guys have them laying around. They are much easier to tune IMO than the flat slide Miks.
The excessive backfiring sounds like a plug that's way too hot, or timing is off. Buy a flywheel puller. They are like $15. Make sure the flywheel didn't spin out of time. Then make sure the timing marks are lined up with the center of the screw holes where the stator mounts.