Need help on 2000 blaster - backfiring, high idle, choke required to run

[07TEAM]

I bought my son a used 2000 blaster for Christmas. It's now April and I still don't have this guy running right. Most of the delays have been to the tough winter here in NJ but anyway, here's the state of things:

With choke on and throttle open it starts right up but runs high idle and backfires. It won't idle unless you keep giving it gas. It will backfire. When you put it in gear it most often will stall when you release the clutch (possibly due to the need to constantly give it gas).

I poured through these forums and received a lot of great info. I started with cleaning and rebuilding the carb - replacing the jets. It seemed to run worse when I did this. Then I realized that I think the exhaust is not stock - neither are the reeds, so I put back the old jets but it still didn't run good.

I learned backfiring generally means there is an air leak somewhere, so I invested the time into the leak down test and found massive leaks around the reed cage. Those are now resolved but it runs no better. I also noticed one of the modded reeds (looks like a black carbon fiber) was slightly stuck open (about 1/8" inch) - so I replaced them with new stock reeds. No change.

Autolube is not used on this quad but it was only yesterday that I noticed it still has the black hose going from the pump into the carb. So I thought, problem solved right? Just cap off the inlet and this baby is going to run perfect. To my surprise, it will not even start when I cap off the oil inlet. I have to open the oil inlet for air in order to get it to start. Now I'm truly boggled.

FYI - my air/gas screw is set at factory default (1-1/2 turns out). I've been reading some stuff about the flywheel key but I haven't checked this yet.

Thanks in advance for your help on this.

 

[MURPH]

do you know if your tors is disconnected?

http://www.blasterforum.com/threads/how-to-remove-your-tors.655/

 

[07TEAM]

do you know if your tors is disconnected?

http://www.blasterforum.com/threads/how-to-remove-your-tors.655/

Not sure actually - I'll have to dig in and inspect that. Though I have read about this but I figured if I open the throttle and it runs then it's not the TORS. Is that an incorrect assumption?

 

[Blaaster]

Is the carb leaking fuel, have you checked the fuel level in the carb?

 

[speedyslyder]

compression test? stock is around 120 psi
ngk b8es or br8es
fresh gas bought like today/drain out old gas
gas cap is venting properly/unscrew it a lil to check it
free flowing gas from tank to carb
idle is under seat,under rubber flap on stock carb
could be electrical=timing of flywheel/stator
got any pics of this troubled blaster?
find out what pipe it is or take a pic we need to know

 

[tbrooks]

What jets do you have in it? Any other mods, lid on or off, air filter? Right bend or left bend pipe? Did you leaktest again after fixing the boot? Check floats/fuel level as blaaster mentioned

 

[bummer981]

Backfiring is a sign of timing being off or bad reeds which you have eliminated. I would check the flywheel to see if the woodruff key is sheared.
Air leaks cause high idling. if you are premixing the fuel keep the nipple on the carb blocked off. The air being sucked in will cause you to run dangerously lean.....boom

 

[07TEAM]

Is the carb leaking fuel, have you checked the fuel level in the carb?

No visible fuel leaking. I have checked the float height and it is at specification. As far as checking fuel level - I'm unsure how to do that.

 

[07TEAM]

compression test? stock is around 120 psi
ngk b8es or br8es
fresh gas bought like today/drain out old gas
gas cap is venting properly/unscrew it a lil to check it
free flowing gas from tank to carb
idle is under seat,under rubber flap on stock carb
could be electrical=timing of flywheel/stator
got any pics of this troubled blaster?
find out what pipe it is or take a pic we need to know

Thanks for the good questions. All I could address at the moment is that the gas is fresh (same day) and it is free flowing. I will post pics and a video tomorrow. I have adjusted the idle and I can get it to go from high to stall.

I will check the sparkplug number and woodroof key and post pics and video tomorrow.

 

[speedyslyder]

good idea
you need a flywheel puller to check the key 10bucks for puller 3-4 bucks for the woodruff key
but you can check plug and header exhaust
and post video/pics

 

[07TEAM]

Backfiring is a sign of timing being off or bad reeds which you have eliminated. I would check the flywheel to see if the woodruff key is sheared.
Air leaks cause high idling. if you are premixing the fuel keep the nipple on the carb blocked off. The air being sucked in will cause you to run dangerously lean.....boom

Thanks - I will check the flywheel tomorrow.

I am premix and I understand about putting a nipple on the carb at the oil inlet; however, as I mentioned in the original post, it won't even turn over when it's blocked off. That being the case, should I block it off and adjust the pilot air screw?

 

[07TEAM]

good idea
you need a flywheel puller to check the key 10bucks for puller 3-4 bucks for the woodruff key
but you can check plug and header exhaust
and post video/pics

• I forgot to mention that I measured 130 psi on the compression test.
• You said "...check plug and header exhaust". Can you elaborate on checking header exhaust? I can tell you that there is no gasket between the exhaust and the block.
• Lastly, can I get a puller at Autozone or similar? A link or specifics would be tremendous.

 

[speedyslyder]

take some pics both sides of carb/exhaust ect
read plug
comprssion is good then
if your chasing carb problems with no luck then
electrical might be the problem but toghther we will prevail
i will look for a link

https://www.rockymountainatvmc.com/p/925/17329/Tusk-Flywheel-Puller?term=flywheel puller

 

[tbrooks]

There should be a crush gasket in the cylinder, if not thats air freely entering your combustion chamber and screwing up the afr and causing a lean condition, and yes that nipple needs to be capped. The fuel level is controlled by the float. And also this:

What jets do you have in it? Any other mods, lid on or off, air filter? Right bend or left bend pipe? Did you leaktest again after fixing the boot?

 

[Blaaster]

Idle speed adjustment.

Set float level, make sure that all jets are clean and fuel flows freely from the float bowl drain when the screw is cracked open.

Start with air screw 1.5 turns out.

Set idle screw so that it has some sort of idle. With TORS it is the big screw under seat on top of unit. With no TORS is is the brass screw midway down carb body.

Warm up motor and then set idle screw for a faster idle, 2000rpm+

Adjust air screw either way to get the fastest idle.

Adjust air screw a little at a time leaving 10 secs or until the motor responds.

Re adjust idle screw for desired idle .

 

[tbrooks]

There should be a crush gasket in the cylinder

for the exhaust, I meant to say

 

[Larry's Shee]

Because it runs with the nipple cap off, it's telling you that it's getting to much fuel !!
You MUST tune with it capped off as it is allowing unfiltered air in=dirt=BOOM.
Cause could be too high float/fuel level, dirty needle/seat, leaking needle seat O-ring.
Start with air screw 1 1/2 turns out from lightly seated.

 

[07TEAM]

Thank you to everyone with the great info. I think I made some good progress yesterday but I'm not exactly out of the woods just yet. Listed below is the info I gathered (based on your questions), corrective steps I took and where things stand right now. I also took pictures and a video for which I have provided links to.

Findings:

• Confirmed new spark plug is NGK B8ES.
• Confirmed spark plug gap is correct.
• Confirmed main jet that was there when I bought it is a 230. New 230 is now in there.
• Realized I could remove the main nozzle (embarrassed) - I hadn't removed this during the clean/rebuild last month.
• Confirmed that the float was indeed out of spec. I was not previously measuring from the gasket surface (embarrassed again).
• There is no crush gasket (or any type for that matter) at the exhaust port. In the pictures you may see that the area is filthy - presumably because of leaks.
• Where the two sections of exhaust pipes meet, it's simply a loose-fitting slip joint.
• Air box is sealed, new filter (properly oiled).

Actions:

• Cleaned the main nozzle.
• Reset the float height using the correct reference points this time.
• Plugged the oil inlet port.
• Cracked open the drain screw (?? good/bad?)

Current status:

• Starts on first kick!!!
• No more backfiring!!!
• Won't idle without constant throttle lever action - it stalls otherwise. See video.
• Extremely fine line with throttle stop screw - goes from stall to extremely high idle. Pilot air screw is at 1-1/2 turn out. See video.

Questions:

1. I'm wondering if I'm dealing with an air issue still (perhaps at the exhaust port due to no gasket) or a mechanical (throttle cable) issue.
2. Is that a modded exhaust (see pictures) and if so, is 230 the wrong main jet?
3. What position should the drain screw be in?

pictures: https://drive.google.com/folderview...9BOEExaWF6SWp5Nl9tUXk1U25JQy15Z0k&usp=sharing
video:

Thanks again everyone!

Marc

 

[tbrooks]

Where the two sections of exhaust pipes meet, it's simply a loose-fitting slip joint.

There should be something over that joint. There is a member that sells rubber couplings or you can get a piece of properly sized radiator hose and a few hose clamps. That is not stock exhaust, that is a FMF, and calls for at least a 260, depending on other mods and where you are. As always a plug chop is necessary to confirm jetting. Now there is supposed to be a crush gasket between the exhaust flange and the block, but there isn't a gasket between the flange and the pipe, normally a good helping of some copper rtv will do the trick here.

Cracked open the drain screw (?? good/bad?)

The drain screw is really just there for checks and maintenance, it should normally be closed!

Extremely fine line with throttle stop screw - goes from stall to extremely high idle

I'm not sure on that guy, I would say throw that tors brick away and get a new cap and tap in a new idle screw

 

[bummer981]

Nice job on your homework, I would say best reporting back ever. Try adjusting the idle screw just a bit then blip the throttle to see how your adjustment has gone. give the engine time to come back down in rpms then adjust further. I think you are close to finding its sweet spot.