Hawk carb tuning help

Suppress · 06-29-2021, 08:40 PM

So, few weeks ago I bought a Vitacci Raven 250, by all means it is Identical to the Hawk 250 just with some factory upgrades. (mine came with 17/45 sprockets) doing top speed runs I managed consistently to get 62mph stock (GPS)

Recently I ordered a mikuni clone carb and went about modding my bike.

I cut a into the side of the cat and managed to pull the honeycomb out and weld up the cover again, didnt do anything to the muffler though. I removed the baffles on the airbox and cut another hole on the front of the airbox cover and replaced the filter with a cutout of UNI foam (maybe oiled too heavily). Removed all the EGR and plugged the holes.

Initially, per forum advice I installed a 25 pilot and 115 main. The bike was more torquey on the low end but I felt I lost alot of power on the high end and it wouldnt rev very high, (top speed 58, GPS) so convinced that the low end was running well and unsure as too whether the main jet was lean or rich I decided to switch to a 120 main. High end is better, 4th gear revving higher than with 115 main, but top speed is only 63mph GPS, just like it was at stock.

To me it feels like 5th gear doesn't have the power to rev higher, even though 4th gear will make it ~ 8,000 rpm and 55mph. So I am stuck, I did all this modding to end up with the same top speed as stock.

is the 17/45 limiting me?
am I running too rich?
is it possible its still too lean?
What I really want from this bike is to be able to get on the Freeway for an exit or two just to cross the river, so ideally top speed 70-ish.

location - Portland OR (its been really hot recently and the stock bike was test in cooler weather idk how much of an impact this can have?)
I am already using the NGK spark plug.

any advice?

Megadan · 06-29-2021, 09:28 PM

How many miles on the bike? Until they get a few hundred miles on them the rings aren't fully sealing yet so they will be anemic at higher rpm. Also, just to cover the bases, did you set the valve lash?

Suppress · 06-29-2021, 10:14 PM

ahh I see, it is at 900km on the odometer, perhaps that is the case. I did set the valve lash albeit slightly tight at 0.004" exhaust and 0.003" intake

06-29-2021, 08:40 PM	#1
Suppress Join Date: Jun 2021 Posts: 3	Hawk carb tuning help So, few weeks ago I bought a Vitacci Raven 250, by all means it is Identical to the Hawk 250 just with some factory upgrades. (mine came with 17/45 sprockets) doing top speed runs I managed consistently to get 62mph stock (GPS) Recently I ordered a mikuni clone carb and went about modding my bike. I cut a into the side of the cat and managed to pull the honeycomb out and weld up the cover again, didnt do anything to the muffler though. I removed the baffles on the airbox and cut another hole on the front of the airbox cover and replaced the filter with a cutout of UNI foam (maybe oiled too heavily). Removed all the EGR and plugged the holes. Initially, per forum advice I installed a 25 pilot and 115 main. The bike was more torquey on the low end but I felt I lost alot of power on the high end and it wouldnt rev very high, (top speed 58, GPS) so convinced that the low end was running well and unsure as too whether the main jet was lean or rich I decided to switch to a 120 main. High end is better, 4th gear revving higher than with 115 main, but top speed is only 63mph GPS, just like it was at stock. To me it feels like 5th gear doesn't have the power to rev higher, even though 4th gear will make it ~ 8,000 rpm and 55mph. So I am stuck, I did all this modding to end up with the same top speed as stock. is the 17/45 limiting me? am I running too rich? is it possible its still too lean? What I really want from this bike is to be able to get on the Freeway for an exit or two just to cross the river, so ideally top speed 70-ish. location - Portland OR (its been really hot recently and the stock bike was test in cooler weather idk how much of an impact this can have?) I am already using the NGK spark plug. any advice?
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06-29-2021, 09:28 PM	#2
Megadan Join Date: Apr 2017 Location: Omaha, NE Posts: 7,976	How many miles on the bike? Until they get a few hundred miles on them the rings aren't fully sealing yet so they will be anemic at higher rpm. Also, just to cover the bases, did you set the valve lash? __________________ Hawk Information and Resource guide: http://www.chinariders.net/showthread.php?t=20331 2018 Hawk 250 - Full Mod list here. http://www.chinariders.net/showpost....62&postcount=1 2024 Royal Enfield Shotgun 650 https://chinariders.net/showthread.php?t=34124
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06-29-2021, 10:14 PM	#3
Suppress Join Date: Jun 2021 Posts: 3	ahh I see, it is at 900km on the odometer, perhaps that is the case. I did set the valve lash albeit slightly tight at 0.004" exhaust and 0.003" intake
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