Help! Hawk 250 after gear change.

[zach3697]

Hello all!

I recently changed the gear ratio on my hawk to 17/45 and noticed that I don't have enough torque for wheelies, and my top speed is only about 58 with the change. Others I have said they are seeing speeds of 65 after the change which leads me to believe that my hawk is low on power. It is using the stock carb with a 110 jet and about 1 and a half turns on the mixture screw.

I'm wondering if that could be the issue and where I should go from here?

Thanks!

[Ariel Red Hunter]

Originally Posted by zach3697

Hello all!

I recently changed the gear ratio on my hawk to 17/45 and noticed that I don't have enough torque for wheelies, and my top speed is only about 58 with the change. Others I have said they are seeing speeds of 65 after the change which leads me to believe that my hawk is low on power. It is using the stock carb with a 110 jet and about 1 and a half turns on the mixture screw.

I'm wondering if that could be the issue and where I should go from here?

Thanks!

Exhaust may be strangling it. Did you shim the needle up?...ARH

[zach3697]

That's a possibility. It's still the stock exhaust, so I guess I'll have to look into taking the cat out or a new exhaust.

Also no I haven't. What does shimming the needle do? From my understanding of how carbs work that will allow more fuel flow correct?

Thanks again!

[Megadan]

Originally Posted by Ariel Red Hunter

Exhaust may be strangling it. Did you shim the needle up?...ARH

Even with the stock exhaust and air box I was seeing 62mph with the 17/45.

Anything beyond that and it definitely needs an exhaust. It also really needs to pass the break in point (500 miles-ish) before it really loosens up.

ZACH - there are a lot of factors at play that will potentially hold you back.

A big one that many people overlook is the valves need to be adjusted. If you haven't done this yet, do it ASAP.

After that, actually making sure your jetting is appropriate for the bike, the air temp, and your elevation. I found the 110 main jet to be too rich on my bike completely stock, and I am only at 1000ft elevation.

Too tight of a chain adjustment or a dry chain can create a lot of drag that will slow the bike down.

Lower tire pressures can create enough drag to slow the bike down a little too.

In the end the more info we have on your setup, the more we can help.

[zach3697]

Gotcha! I did do a top end rebuild on this approximately 200 miles ago so it's still not fully broken in. I did adjust the valves after I got the bike running after the rebuild but I'll take another look tonight after work. Maybe the gap has changed since then?

Also I live in Orlando Florida so I'm pretty close to sea level. I'm assuming I can reduce the jet size since the air density is higher at sea level?

I'll give an update tonight after I look at the bike!

[Mudflap]

The lower the elevation the richer the jetting needs to be.

[Megadan]

Originally Posted by Mudflap

The lower the elevation the richer the jetting needs to be.

True, and the hotter the air temps, the leaner it needs to be. The higher the humidity, the leaner it needs to be.

There is no magical easy formula for carb setupa.

For all we know the jetting is perfect, I was just giving a list of potential causes.

Heck, the stock catalyat in the exhaust may be clogged up or melted/broken. It wouldnt take much with the cat they used on these bikes.

[zach3697]

I'll take a look at those things and report my findings!

Thanks all!

[Ariel Red Hunter]

Originally Posted by zach3697

That's a possibility. It's still the stock exhaust, so I guess I'll have to look into taking the cat out or a new exhaust.

Also no I haven't. What does shimming the needle do? From my understanding of how carbs work that will allow more fuel flow correct?

Thanks again!

Yes, from 1/4 throttle to 3/4 throttle.