Getting a Hawk Running Properly

[Weldangrind]

Sounds like a vacuum leak.


To be sure, disconnect the throttle from the throttle tube, and ensure that the cable is routed smoothly to the carb. Start the bike, and blip the throttle by pulling the cable while holding the cable housing. Does it still hang before settling back to idle? If so, a vacuum leak is most likely.


You have a few ways available to you to find the leak. One popular way is an unlit propane torch. Start the bike, open the propane valve and aim it around the carb and intake tube. When the idle picks up speed, the propane is being drawn in at the leak. Please be careful.

[Sport Rider]

thank you! no propane tank at the house, so that's probably good for saving me from burning down the place. I'll try the carb spray route.

any idea on the idle adjustment? is it possibly air leak as well?

[fitze]

I use starting fluid

[Weldangrind]

Originally Posted by Sport Rider

thank you! no propane tank at the house, so that's probably good for saving me from burning down the place. I'll try the carb spray route.

any idea on the idle adjustment? is it possibly air leak as well?

Could be. I'd search for the vacuum leak first, and then reassess.

[fishtime9]

Sports rider, did the aftermarket carburetor increase the speed by any chance? I really would like to know if it did because I have the same carburetor and my jets should be coming in the mail within the next days.

[Sport Rider]

ok....I'm frustrated and demoralized. this thing is really getting to be an emotional issue.

cranked and cranked last night and could barely get the thing to catch and run. I did get it to run on choke giving it a lot of throttle, but would not run on its own.

I'm at a loss as to how to move forward on it. you guys know how little I know about carbs.

I'm going to check the valves just for peace of mind, but could use some suggestions if anyone has some ideas to troubleshoot.

Fishtime9....when I DID get it running the other day on choke, I could immediately tell that it was going to be better. the fuel delivery had it revving all the way to redline. I have no doubt it will get better speeds. of course, the gearing is the real solution there.

[Adjuster]

Do you have your air filter connected? Try upping the idle speed screw a little at a time.


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[2LZ]

If it's only running on choke, and the carb is set up correctly, you have a fuel delivery problem.
Look to see if there's a bunch of crap in the bottom of your tank with a flashlight and that the fuel line's not kinked or plugged at a filter to the carb.
If it's unimpeded (disconnect the line from the carb and open petcock) and it still only runs on choke, something not right in the carb like plugged jets or something. It can be confusing but it's as basic as a tiny toilet.

[Weldangrind]

Originally Posted by Adjuster

Do you have your air filter connected? Try upping the idle speed screw a little at a time.


/

Originally Posted by 2LZ

If it's only running on choke, and the carb is set up correctly, you have a fuel delivery problem.
Look to see if there's a bunch of crap in the bottom of your tank with a flashlight and that the fuel line's not kinked or plugged at a filter to the carb.
If it's unimpeded (disconnect the line from the carb and open petcock) and it still only runs on choke, something not right in the carb like plugged jets or something. It can be confusing but it's as basic as a tiny toilet.

X2 on both posts.

The air filter is required so that excess air flow does not alter the correct air/fuel ratio.

Are you using a new fuel filter? New fuel lines? I've found that some of the black rubber China fuel lines can deteriorate and send bits of rubber into the carb. I use snowmobile fuel line, because it's typically clear or blue, and I can see fuel flowing in it, and because it remains flexible in cold weather.

I'm betting that there is crud in the slow jet, which is super easy to remove and clean. This is a good time to remove the carb and familiarize yourself. Take lots of pics and show us; several of us are ready to help.

[Sport Rider]

Originally Posted by Adjuster

Do you have your air filter connected? Try upping the idle speed screw a little at a time.


/

my initial time of having it running on choke, it was with the air box disconnected from the carb.

[Sport Rider]

Originally Posted by 2LZ

If it's only running on choke, and the carb is set up correctly, you have a fuel delivery problem.
Look to see if there's a bunch of crap in the bottom of your tank with a flashlight and that the fuel line's not kinked or plugged at a filter to the carb.
If it's unimpeded (disconnect the line from the carb and open petcock) and it still only runs on choke, something not right in the carb like plugged jets or something. It can be confusing but it's as basic as a tiny toilet.

I did not have a fuel delivery problem with the original carb still on it. I only connected the same fuel line to the new carb.

the jets etc were new. I didn't really check to see if they were blocked for any reason. is it worth taking apart to double check?

[Weldangrind]

Sport Rider, it looks like you and I posted seconds apart!

[Sport Rider]

Originally Posted by Weldangrind

X2 on both posts.

The air filter is required so that excess air flow does not alter the correct air/fuel ratio.

Are you using a new fuel filter? New fuel lines? I've found that some of the black rubber China fuel lines can deteriorate and send bits of rubber into the carb. I use snowmobile fuel line, because it's typically clear or blue, and I can see fuel flowing in it, and because it remains flexible in cold weather.

I'm betting that there is crud in the slow jet, which is super easy to remove and clean. This is a good time to remove the carb and familiarize yourself. Take lots of pics and show us; several of us are ready to help.

Weld, this is my new Mikuni that I just ordered along with new 115/30 jets I installed. fuel and operation was working with the original carb, but of course it was obvious it was running extremely lean, especially at higher RPMs. the guts of the carb was pretty simple, so I'm reasonably sure I installed both of the jets correctly. hard not to be able to screw them in, right?

as for the needle, I removed the clip and adjusted the e-clip to the second notch. then dropped it back into the slide and installed the pressure clip holding it in.

I used the original cap from the other carb rather than taking the cable out of it and installing in the cap that came with the new carb. it was easy to figure out how to attach the throttle to the new slide.

Oh...I set the pilot screw at 1 2/3 turns after screwing it in to a stop (lightly).

I KNOW this has to be a setup problem. I just don't have experience with them to troubleshoot. Plus I'm impatient, so I hopefully didn't start twisting the idle screw around too much and have it all out of whack.

[fishtime9]

I suppose you could follow welds process. However, would you really want risk of burning down your house? I suppose that the safest method would be to buy a new carburetor for 30-40$.

[Weldangrind]

Ok, let's make one change at a time, but that's after eliminating fuel delivery. Are you using a fuel filter?


I'd start with the pilot mixture screw backed out 1.5 turns.