pitbike
 

Yea, mostly complete bike for 100 bucks. I ordered all the parts I needed from Amazon and T-bolt. They should be in today. Now i'm just waiting on a bit warmer weather. lol

A buddy got a couple of those coleman pitbikes as well. They're surely chinese made, so should be able to get what you need fairly easily. I'm learning about these little bikes as I go.

Damn carb
 

Soooo I installed the new carb a few weeks ago. I thought I had it dialed in decently. I think i'm using the 125 main jet and the pilot jet that comes in the Sigma kit, with all the mods they recommend in the walkthrough, i opened up the airbox with a couple holes and opened the exhaust up as well. Do both of the vacuum ports need to be blocked off if the air injection and all that is removed? One is blocked but the other is routed to one of the hoses that is on there. I couldn't find a vacuum diagram anywhere. Can both ports on the side of the carb just be blocked? It felt like it ran good under power, but when i decel it will kinda sputter and just die. I have to wait a like 10 seconds and i'll restart. I'll get it running fine at idle, but then after i ride it a bit, i'll have to adjust it again. So it's acting like a vacuum leak to me. I'll block that other port off if i can, but wanted to check with you guys. Just trying to get it to run normally so i can enjoy it. Any of you guys run a pod filter on your bikes or should i stick with the airbox? I put a pod filter on my XR70.

Glad to hear you had some warmer riding weather!

I doubt the 125 main jet is your problem. I can run a 132.5 on my bike without to much trouble. Did you put in a larger pilot jet as well? I think a vacuum leak might not be out of the question. The only time I have had issues on deceleration was when I overdid it with the main jet AND too many shims under the needle.

As far as vacuum lines go I have only removed the line between the air box and the exhaust header; be sure to cap off the hole under the air injection pump somehow. Did you block something else off? Hole drill mod? use any shims under the needle?

First I would check the idle mixture screw and make sure it hasn't backed itself out or fallen out. Consider popping the cap off the carb and making sure the black rubber membrane is seated properly all the way around, and also make sure the needle and spring are seated properly. Good luck and I hope you get it going.

it just kinda feels all over the place when i ride it - it'll idle fine, then i rev it and it idles fast. Then I full throttle it and after i let off it bogs and dies, like it has too much fuel and won't restart. It feels pretty decent while in the power. When it starts to die, i try to give it gas and it just dies even faster. It has the two ports on the right side of the carb. That stupid air injection, i cut off the flange on the exhaust header and welded it closed. There wasn't anything that ran to the head at all for that. Just like a charcoal canister thing and some hoses, but I was stupid and can't remember what goes to what. So I'm just trying to figure out what needs to go to the carb and what needs to be blocked off, or if they both can be. just one shim under the needle. The replacement carb i got actually had a needle that spots to adjust it! So i put it on the 3rd notch down i think and one shim on it. The idle mixture screw is there for sure, i screwed it in all the way and backed it out 2. And yes, i've done the hole drill mod - i've put two big holes in the top of the airbox. I don't have the rubber boot on the carb to the airbox because i wanted to try and get it running decently before i put it back on. I thought about the pod filter as well.

Can I see what both your lines are connected to on that side of the carb?

This sounds like two distinctly different symptoms.

Steady idle, rev, fast idle - classic symptom of a lean idle mixture. So is the tendancy to die on decel. Is your bike hard to get started when cold, even with the choke fully engaged?

As far as full throttle and bogging. Does it have any symptoms while at full throttle? Does it feel like it loses power or surges?

The biggest bit of advice I can make is, one thing at a time. I would sort out the idle first. Make sure the engine is fully up to temp, and then use the idle drop method to help set the idle. If you end up past 2.5 turns out to get a good idle, then you need to up the slow/pilot jet a step and try again.

Obviously, before any of this, make sure you know for sure that all of your vacuum issues are resolved, otherwise you will be chasing your tail lol

It starts fine with the choke, seems to take awhile to get it to idle with the choke off. Full open seems time, but dies after you let off. I'm just trying to figure out where the lines are supposed to run.

Here is a photo of the lines attached at the carburetor. One should be going to the charcoal canister and another just runs to the underside of the seat where it ends randomly, I think it acts as a fuel tank vent.

Since it runs better with the choke on, I wonder if you have tried running the bike with the air filter attached? I am also going to be trying a pod filter but I'm unsure what to do with the crankcase ventilation hose that runs to the stock airbox. I suppose I could just pop a mini filter or pcv valve on the end of it.

From the Haynes Manual

I've attached the pic I removed the charcoal canister and assorted crap, but I'm not sure if that hose on there is supposed to run to that, reference vacuum, atmosphere, or plug it since I took that stuff off. Not sure about the capped line. If you attached a pic, I can't see it.

Oops, pics loaded now. So I'd assume the left one goes to charcoal canister. I should be able to plug that. I'd think the right one is manifold vacuum and that go to the gas tank to pull fuel? Obviously should have paid more attention when I took it apart.

It looks like the capped one is vac for either the charcoal can or the air pump. On my QLink, it split out to both, I believe.
I'd say the other may possibly be a bowl vent. I wouldn't cap it.

Your symptoms sound like a clogged pilot, if it runs better on choke. I know the carb is new but have you cleaned the tank or put in an inline filter? You may have sucked something up.

new carb, new jets. I've barely put 2 tanks of fuel through it. It doesn't cut out in full throttle, it dies after you let off full throttle. Probably supposed to run one from the tank to the capped one I'd guess. I'm just not sure what the one that was supposed to go to the charcoal canister should go to now?

I will try and get under my seat tomorrow morning and find out where each of these lines go.

I appreciate it. It's my own dumbass fault for not paying better attention when I took it apart.