Getting a Hawk Running Properly

[Torgo]

The stock carb is a little clunky, but it should run OK after it warms up. First of all, what exactly are you doing with the choke? How are you setting it?

There are three positions for the butterfly valve: open (bottom), half (middle), and closed (up).

When it's cold out, I have to close it (up) to start. I let it warm up before I drop it down to half, and then fully open it. You only want to operate it when it's at temperature at the open setting (bottom). So hopefully you're stepping through that similarly.

Also, it will not idle by itself as it warms up. After it starts, I have to hold the throttle open a bit. After it warms up a bit, about the same time I start to open the carb, I can then tighten up the idle screw and it'll start idling. Once it's fully warmed up, I'll back the idle off until it idles at what I think is a good RPM. If you turn it too low, it'll kill it, but it doesn't have to be that accurate - you just want a reasonable idle that keeps the engine spinning when you have to stop.

The one nice thing about the stock carb is that the idle adjustment screw is easy to adjust by hand. So you'll figure out how to add and back off the idle after a little bit.

Hope that's a little bit of help - you may not be maximizing the performance with the stock carb, but I've found it to be OK once I got a better feel for its quirks.

[Sport Rider]

Originally Posted by Torgo

The stock carb is a little clunky, but it should run OK after it warms up. First of all, what exactly are you doing with the choke? How are you setting it?

There are three positions for the butterfly valve: open (bottom), half (middle), and closed (up).

When it's cold out, I have to close it (up) to start. I let it warm up before I drop it down to half, and then fully open it. You only want to operate it when it's at temperature at the open setting (bottom). So hopefully you're stepping through that similarly.

Also, it will not idle by itself as it warms up. After it starts, I have to hold the throttle open a bit. After it warms up a bit, about the same time I start to open the carb, I can then tighten up the idle screw and it'll start idling. Once it's fully warmed up, I'll back the idle off until it idles at what I think is a good RPM. If you turn it too low, it'll kill it, but it doesn't have to be that accurate - you just want a reasonable idle that keeps the engine spinning when you have to stop.

The one nice thing about the stock carb is that the idle adjustment screw is easy to adjust by hand. So you'll figure out how to add and back off the idle after a little bit.

Hope that's a little bit of help - you may not be maximizing the performance with the stock carb, but I've found it to be OK once I got a better feel for its quirks.

pretty much followed what you said. I was able to get it off choke once it warmed up some and tinkered with the idle screw to keep it running. once warm and off idle it is losing power in higher rpms, but not through what I think is the mid range. I've seen comments about it being too lean at higher rpms, so this might be that condition being referenced.

the other thing I am noticing is how it comes off idle. it seems to be lagging at the rpms coming back down. I'm familiar with that as perhaps an air leak, so perhaps I'll check the boots to be sure they are good and tight.

open to other thoughts/ideas though! thanks!!!

[jbfla]

Originally Posted by Sport Rider

...
open to other thoughts/ideas though! thanks!!!

Have you checked the valve clearances?

jb

[wilserchinarider]

Originally Posted by Torgo

The stock carb is a little clunky,
.

This was my experience as well!!! I installed an ebay mikuni, replaced the jets along with a 17T front sprocket and it is a totally different machine. I suspect that the stock carb is jetted very lean to meet emissions.

The stock carb could likely be rejetted as well, but will require drilling out the tamper resistant screws that hold on the carb bottom bowl., but would be $40 cheaper than the mikuni.