High Idle and Knock - Carb/Engine Problem

[flipp3r]

I'm a newbie, and recently picked up 2 blasters (89 and 92) from 2 different people. Here's the low down on each:

1989 Blaster - Has title issues, ran 3 years ago when parked. Reson for selling - "got a new quad". Was going to use this a donor, if needed. Stock engine, Oil Injection removed, FMF Fatty Gold head pipe w/ core 2 silencer. Cleaned the fuel tank and carb. Going to change the trans oil. Waiting on tht FMF spring kit to secure the head pipe. Haven't tried to start it yet.

1992 Blaster - Clean title, all stock engine, Oil Injection removed. Owner said it died after running through a puddle and it had never ran again. He thought it was electrical and never tried to track it down. Reason for sale - "they don't ride anymore".

I am trying to get the 1992 running and here's what I've done:
- Cleaned Fuel Tank
- Cleaned Carb
- Went through all wiring and cleaned connections
- Tested all electronics (all were good, except the Coil showed Ohms out of spec. The Orange to ground was at like 1.91 and the orange to tip was way off, I figured I wasn't doing this part right. )
- Removed TORS
- Changed sparkplug
- Changed the Trans oil (Yamalube 4 10w30)

I noticed that the sparkplug the guy had in there was the wrong one. It had a very small electrode, but looked like it had actually been running ok. I put the correct plug in, gapped at .30. I put everything back together and put a mix of 91 octane and Yamalube 2S in at a 32:1 ratio. I figured we'd see what happens when I kick it, expecting nothing since I thought the coil was bad. I kicked it twice with the choke on the first notch and it fired after 2 kicks.

So, here's the problem...

As soon as it starts, the thing starts to idle really high, like it's at 1/2 throttle. I could hear an occational knock in the 5-10 seconds that I'd let it run, before killing it. The knock wasn't constant, and I'm not sure if I should be concerned about it. I've never had a 2 stroke, so I'm not sure what's normal on a cold start, after changing all the fluids. My next move was to screw the pilot jet in and back it out 1.5 turns. I tried to start it again and the same thing happened. I then pulled the carb off the '89 and tried it on the '92. Same results. I looked into the intake side of the carb when I screwed on the throttle slide cap and it looked like the slide was going down as far as it was supposed to. There was maybe a 4-6mm gap where the slide was open, once the cap was screwed on all the way.

Any ideas? Thanks!

 

[MimsBlasterer]

when you take the seat off you will see a big silver "screw" that screws into the "thingy" screwed to the top of the carb where the throttle cable connects. this big silver screw is the idle speed adjustment. turn it to the left while running and your idle speed should drop. I had the same problem. Cheers

However I don't know about the knocking sound...

Ryan.

 

[01blaster_freak]

First of all you shouldnt let a 2 stroke run at half throttle when first starting.

air cooled 2 strokes have a knocking sound to them.

if the screw ontop the TORS don't work adjust it on the thumb throttle.

 

[01blaster_freak]

Ohh an run your premix at 40:1 instead of 32 or you can also go 50:1 I'm running mine at 50:1 because i race MX an at 50:1 it doesn't load up as much gets on the pipe alot faster.

 

[flipp3r]

I definately didn't throttle it up at all. I was just describing the how high the RPMs seemed at idle. There really isn't much to adjust at the thumb throttle end. It's pretty much all the way in. A few questions:

- Do I have to have it running for the counterclockwise turn to lower the idle, or can I back it out a 1/2 - 1 turn to start with, before I kick it over?

- Both of these carbs seem to be equally off. If the previous owners were running 40:1 or 50:1 and the carbs were tuned for that, would my running 32:1 be the thing making the idle so high?

- The guy at the shop was the one that suggested the 32:1. He said I'd be more likely to burn things up at 40:1 or 50:1. I just want it to be as dependable as possible, while getting a little more power from the K&N and FMF (which I haven't installed yet). I do have an UNI filter on now. Any input?

I will try the big idle adjust screw tomorrow morning and let you guys know what happens. Thanks for the input. I hate it when I feel like I got in over my head.

 

[01blaster_freak]

The carb isn't tuned depending on what you mix your oil at.

The air/fuel mixture screw, turn it 2 1/4 turns out from all the way in.

Your going to have to rejet once you add the filter an pipe.

 

[01blaster_freak]

Check your plug an see if your running lean or rich, after adding a air filter your letting more air in which means you need to let more gas in so it doesn't lean it out an seize the motor. I would turn the screw thats on top the tors like half a turn then fire it up an hit the throttle a few time really fast an see if it idles down if not turn the screw while it's running.

Your throttle cable also could be routed wrong, i did that once an when i fired it up it idle up very high. but try the screw on the tors before moving the cable.

 

[flipp3r]

I think I've got it. I looked at the thumb throttle adjustment first. It was about 1/4" out. I screwed it in all the way and backed out the TORS screw a 1/2 turn. Kicked it and it was good. Decent idle and no knocking. I definately still have some tuning to do, but at least I'm in the ball park now.

If I let it idle for a little, it starts to die. If I give it gas to keep it going, it starts to fall on it's face a little, before reving up. Is this an indication of fat or lean. I'm guessing fat. I saw conflicting info on which way to turn the air/fuel screw for rich/lean. Which way is which? I am trying to avoid having to remove the spark plug 20 times to figure it out Thanks for your help.

 

[MimsBlasterer]

lefty leaner, righty richer.

The screw is actually partially blocking a bypass "tunnel" for air to flow during idle. so when you back it out you let more air in leaning the fuel vice versa