Another Hawk Tuning Question

[Newwood]

Not another tuning question!!!

Anyway, here is the rundown on my Hawk:

600 miles on the bike, valves have been adjusted. NGK plug, airbox mod,17/45 sprocket, stock carb and until today a 115 main with a stock exhaust, save for a couple holes poked in the rear baffle. The bike was running great.

Today I cut the cat out of the stock exhaust and thinking it would be running lean switched to a 125 main.

The bike ran great all the way up to full throttle/60mph when it started hesitating/hicupping slightly. Do you think I'm still lean? If so does anybody know where a 130+ main can be found?

[rwl6935]

I'd try going back to the 115 jet. Did you look at the plug afterwards to see how it's burning? Should be dark to medium tan. If it's lean it will be a light tan color, and too rich it will be almost black.

[2LZ]

Like rwl says, go back to the 115. If that still doesn't work, then try moving the needle clip to the fourth notch down. If it's not notched, put a small washer under the clip.
Set your idle mixture at 2 turns out, then adjust in and out from there.

[JerryHawk250]

Ditto

[chuck]

Originally Posted by Newwood

Not another tuning question!!!

Anyway, here is the rundown on my Hawk:

600 miles on the bike, valves have been adjusted. NGK plug, airbox mod,17/45 sprocket, stock carb and until today a 115 main with a stock exhaust, save for a couple holes poked in the rear baffle. The bike was running great.

Today I cut the cat out of the stock exhaust and thinking it would be running lean switched to a 125 main.

The bike ran great all the way up to full throttle/60mph when it started hesitating/hicupping slightly. Do you think I'm still lean? If so does anybody know where a 130+ main can be found?

Raising the needle (one clip down) should do it with the 115 or 117.5,it solved the back firing on my Hawk.

[Newwood]

Thanks guys, I will do some puttering around on it, needle is already shimmed with 2 washers.

[Ariel Red Hunter]

Originally Posted by Newwood

Thanks guys, I will do some puttering around on it, needle is already shimmed with 2 washers.

I would think that a 125 main should be plenty enuff. If you can find slow jets for that carb, go up on that. The slow jet feeds fuel all the way up. It can't pass a lot of fuel, but it still effects top end. The slow jet problem is why a lot of people have switched to a Mikuni carb. It is much easier to get really good carburation if you can change both jets. Mikuni calls the slow jet a pilot jet....ARH

[Newwood]

Thanks ARH, Mine seems to be liking a 120 main with the stock slow jet. Plug seems to tell me it's not running fat, but I'm getting that slight "burble" when I chop the throttle, always thought that meant it was NOT too lean.

Took it up to full throttle several times, got only one tiny hiccup the first time then it ran fine.

I'm going out on an overnite adventure this coming week, we will see how it runs. If nothing else 30-40 bucks for a Mikuni will be probably be in my future.

[Ariel Red Hunter]

Originally Posted by Newwood

Thanks ARH, Mine seems to be liking a 120 main with the stock slow jet. Plug seems to tell me it's not running fat, but I'm getting that slight "burble" when I chop the throttle, always thought that meant it was NOT too lean.

Took it up to full throttle several times, got only one tiny hiccup the first time then it ran fine.

I'm going out on an overnite adventure this coming week, we will see how it runs. If nothing else 30-40 bucks for a Mikuni will be probably be in my future.

Well, only one hiccup in several runs is statiscally not enough to go on a carb re-tuning frenzy. I'm not sure what a "burble" is. An oddity of this style carb is that, after running a well warmed up engine at full throttle, but still accelerating, rolling the throttle off 1/8th or a little more causes a temporary richening of the mixture. If you roll off, and the bike seems to pull hard for an instant, it means the main jet is too lean. On the other hand, if you roll off like stated above, and the engine hesitates, or sounds woolie, main jet is too rich....ARH

[Newwood]

ARH,

I'm thinking my "burble" is your "woolie"! I'm not too concerned about it at this point and am feeling better after getting your input.

Thanks!

[Ariel Red Hunter]

Originally Posted by Newwood

ARH,

I'm thinking my "burble" is your "woolie"! I'm not too concerned about it at this point and am feeling better after getting your input.

Thanks!

Woolie is the quality of sound in the exhaust. It is a dead certainty indicator of an over-rich mixture. BUT, a momentary, one time only over rich condition can be caused by a lot of things, like crossing a bump in the road while doing the test. In other words, it can be caused by a momentary surge in the float bowl. That's why you need to repeat the test four or five times to
get repeatable results....ARH

[enforcer89]

Ok I have a high idle issue I've tried adjusting screw on carb and throttle cable with no luck I put the vm26 with 115 jet on the hawk the idle screw turned all the way in and out has no effect constant high idle . Any ideas ?

[Ariel Red Hunter]

Originally Posted by enforcer89

Ok I have a high idle issue I've tried adjusting screw on carb and throttle cable with no luck I put the vm26 with 115 jet on the hawk the idle screw turned all the way in and out has no effect constant high idle . Any ideas ?

On a VM-26 there are two idle adjusting screws, one an idle mixture screw, the other an idle speed screw. How high (fast) is the idle?...ARH

[enforcer89]

Ok I think it was cable binding I played with it again and got it idled down . I didn't know there was more than the screw on the side to make adjustments with . Thank you for you quick responses arh

[Ariel Red Hunter]

Originally Posted by enforcer89

Ok I think it was cable binding I played with it again and got it idled down . I didn't know there was more than the screw on the side to make adjustments with . Thank you for you quick responses arh

It will pay you dividends to route the throttle and clutch cables to where you have nice, easy curves in the cable. These bikes are kind of thrown together at the factory, as are most other bikes. When I worked at a dealership we spent whatever time was necessary to get cable runs smooth and in gentle curves....ARH