My Hawk GT carb tuning. Any Hawk guys advise?

[Degsy]

Been waiting for a week to post this on Hawk GT Forums but they are down for a while.

I have a Hawk GT track bike I bought a couple of months ago. I love it. It handles well, runs well for the most part and I have a blast riding it.

However, it has a very annoying stumble at 6.5k rpms. It recovers but really falls flat for about 250 rpms at 6.5k.

I tore tha carbs apart already and cleaned them and that didnt fix it.

I checked the jets out and the needles and I'll post the sizes here in the hopes I can get some advice.

Stock Motor, full M4 system and pod filters.

Both carbs have the same jets and needles.

Pilots - 45
Mains - 144

Needles come down to a 1.25mm tip in 2 steps and the clips are on the middle one of 5 positions (position 3).

help!!!!

Gino? Doc? Bueller? Anyone?

Want to get it squared away for the Bomo trackday on 27th.

derek

[Degsy]

I see Mr. Kurlon perusing this thread. Nice! Just what i wanted to see. Help me out on this one. I'm not a small V-twin carb guy at all.

[Kurlon]

I'm not sure what to suggest, when I ran into this with my GS it was broken slide springs but you've been into your carbs so that's not it. Have your slides been drilled, might be opening too fast or bouncing at that RPM?

[gamorg02]

could the springs be cut/shortened?

[Degsy]

I'm not sure what to suggest, when I ran into this with my GS it was broken slide springs but you've been into your carbs so that's not it. Have your slides been drilled, might be opening too fast or bouncing at that RPM?

I'll put it all back together tonight and see if I'm getting flutter at 6500. Thanks

[Doc]

I am in no way a Hawk carb expert and all I have learned is from Gino, Matt Stone and a few others on the hawk forum...

IMHO the Mains are too small and the rear needs to be smaller than the front... (IIRC)

Give me a minute to find the right specs...

I think the needles sound like "factory pro" needles and they are in the right position. Are your mixture screws 2.5 turns out?

[Doc]

Try this.
Pilot at 42
Mains at 162 rear and a 165 front
Floats at 9.1mm

Other tips:
Stretch the springs to 42 inches and bake them at 325 for 2 hours. To make them be about 8 inches (gonna stink up your kitchen)

[neuthunder]

kinda sounds like an issue I had and I think after the tear down of the carbs a little adjusting of the fuel/air seemed to have fixed it

[Degsy]

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Try this.
Pilot at 42
Mains at 162 rear and a 165 front
Floats at 9.1mm

Other tips:
Stretch the springs to 42 inches and bake them at 325 for 2 hours. To make them be about 8 inches (gonna stink up your kitchen)

Ok. Got the 165. Anyone got a 162 they can bring to the track Sunday night? I'll bake my springs tonight. Screws are 2.5 turns out.

[Doc]

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Ok. Got the 165. Anyone got a 162 they can bring to the track Sunday night? I'll bake my springs tonight. Screws are 2.5 turns out.

I will look.

[gt_pedaler]

I had a hawk years ago and spoke with Erion racing about it. he told me that the boot from the stock air box acted as an air horn and the way the pod fit over the end of the carb didn't allow for the use of that horn. The pressure pulses hit just the right frequency at that RPM to mess up the vacuum to the slides. I messed with mine forever and never dot it to go away completely.
As a thought all these years later... what if you took the stock boots and cut out the pod boots and glued it together?

[nt650hawk]

My stock motor was Dyno with Dynojet 150 mains and 45 Pilot on the middle clip.
I streached the spring to 8" and baked them in the toaster 350 for 3 hours

My 700 has 165 45 middle clip with x8 cams and falls on its face and can not get out of its own way. I think I need some bigger mains.