Hawk Mikuni Tuning advise

pistolclass · 06-04-2016, 06:50 PM

Hello everyone. I just put a Mikuni VM26 on my hawk today and I need some tuning advise. I put a 110 jet with the stock 20 pilot in it and I can barely take it off choke. The bike was very warm, I ran it for 15 minutes on half choke. When I move it to no choke and give it throttle it bogs and dies. This is the only change I made today. I had it running pretty good with the stock carb prior to putting this one on. The Valves are adjusted. I have the needle thingy set to the second from the top and screw thingy out one and a half turns. I made sure the carb was buttoned down good and no air leaks. It idles like a champ with the choke on full.

Thanks for any advise.

Azhule · 06-04-2016, 09:48 PM

Might try and drop a 25 or larger Pilot Jet in that Carb. My 197cc did something similar on the 20 pilot jet... and I'm just over 6,000 feet high

w0ss · 06-04-2016, 10:01 PM

mine is doing the same thing! I am going to swap in the stock pilot jet assuming it fits but I wont be able to do that till tomorrow afternoon. My main is a 115 right now.

pistolclass · 06-05-2016, 01:05 AM

can someone explain to me the difference between a Needle Jet and a Jet Needle?

w0ss · 06-05-2016, 08:47 PM

The stock pilot jet doesn't seem to fit. I fixed my issue by turning the screw in I think mine is at one turn out.

Ariel Red Hunter · 06-17-2016, 08:04 PM

Quote:

Originally Posted by pistolclass

can someone explain to me the difference between a Needle Jet and a Jet Needle?

Sure. The Jet Needle is a tapered pin that is attached to the throttle valve. Jet needles normally have five recessed rings at the top and this is where the needle clip goes. The Needle Jet is the jet the tapered needle goes through and is located in the floor of the carburetor throat, usually. As you turn the twistgrip, the cable it is attached to lifts the throttle valve with the needle attached. The throttle valve controls the air going in the engine while the needle controls the amount of fuel being admitted. The needle controls carburation from 1/4 to 3/4 of throttle opening. The main jet controls the fuel mixture from 3/4 to wide open. You should be able to leave the needle clip in the center groove normally. Moving the needle up or down is usually only needed on engines suffering from "Megaphonitis". This is very unlikely with an engine that has a muffler in the system.

pistolclass · 06-17-2016, 09:05 PM

Thank you for the explanation. My jet needle is set to lowest (nearest the pointy part) groove. I'm pretty sure my pilot is to small at 20 so this groove setting and being 2 turns out on the mixture screw make up for it. Currently it is running great. I will probably try a 25 with 1 1/2 turns on mixture screw and in the middle on the jet needle groove eventually but for now I'm just enjoying the bike.

Sport Rider · 06-17-2016, 09:30 PM

I'd suggest you try raising your needle to the 3rd clip. that raises up the needle from the needle jet and starts you with more fuel to begin with.

fwiw, my vm26 has a 117.5 main and 30 pilot jets. my pilot screw is 1.33 turns out. my needle is on the 2nd clip. while it's a great learning experience to work your way to the setting that works best for you, you might want to start with the 115/30/1.5 turn/2nd clip settings. I would suspect that will get you running well enough. from there you can start changing one thing at a time to see how the settings work for you.

I plan to drop my main to a 112.5 and my pilot to 27.5, going back to 1.5 turns and maybe 3rd needle clip. I beleive my setting with the larger main and pilot are running a bit rich.

Ariel Red Hunter · 06-18-2016, 03:00 PM

Quote:

Originally Posted by pistolclass

Thank you for the explanation. My jet needle is set to lowest (nearest the pointy part) groove. I'm pretty sure my pilot is to small at 20 so this groove setting and being 2 turns out on the mixture screw make up for it. Currently it is running great. I will probably try a 25 with 1 1/2 turns on mixture screw and in the middle on the jet needle groove eventually but for now I'm just enjoying the bike.

Interesting. I did that about 62 years ago on my Ariel Red Hunter after I put a megaphone exhaust on it. It resulted in flat spots in various spots in the power curve. Didn't matter to me at first, as I rode like a lot of guys on the Hawk videos. Idle or wide open. But the first time I went cow-trailing on it, I learned why you want absolutley clean carburation from idle right on up. There were baseball sized rocks on part of that trail. They immediatly taught me why one needed clean carburation right from a walking speed to wide open. Those rocks HURT when you get bucked off your steed of iron!

06-04-2016, 06:50 PM	#1
pistolclass Join Date: Oct 2015 Location: connecticut Posts: 978	Hawk Mikuni Tuning advise Hello everyone. I just put a Mikuni VM26 on my hawk today and I need some tuning advise. I put a 110 jet with the stock 20 pilot in it and I can barely take it off choke. The bike was very warm, I ran it for 15 minutes on half choke. When I move it to no choke and give it throttle it bogs and dies. This is the only change I made today. I had it running pretty good with the stock carb prior to putting this one on. The Valves are adjusted. I have the needle thingy set to the second from the top and screw thingy out one and a half turns. I made sure the carb was buttoned down good and no air leaks. It idles like a champ with the choke on full. Thanks for any advise.
	0

06-04-2016, 09:48 PM	#2
Azhule Join Date: Dec 2015 Location: CO Posts: 1,525	Might try and drop a 25 or larger Pilot Jet in that Carb. My 197cc did something similar on the 20 pilot jet... and I'm just over 6,000 feet high __________________ "Think as you like... but this self proclaimed Professor is always right" - Buckshot "You never know what someone is hiding beneath their smile..." - NinjaTom - R.I.P.
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06-04-2016, 10:01 PM	#3
w0ss Join Date: May 2016 Posts: 231	mine is doing the same thing! I am going to swap in the stock pilot jet assuming it fits but I wont be able to do that till tomorrow afternoon. My main is a 115 right now.
	0

06-05-2016, 08:47 PM	#5
w0ss Join Date: May 2016 Posts: 231	The stock pilot jet doesn't seem to fit. I fixed my issue by turning the screw in I think mine is at one turn out.
	1

06-17-2016, 09:05 PM	#7
pistolclass Join Date: Oct 2015 Location: connecticut Posts: 978	Thank you for the explanation. My jet needle is set to lowest (nearest the pointy part) groove. I'm pretty sure my pilot is to small at 20 so this groove setting and being 2 turns out on the mixture screw make up for it. Currently it is running great. I will probably try a 25 with 1 1/2 turns on mixture screw and in the middle on the jet needle groove eventually but for now I'm just enjoying the bike.
	0

06-17-2016, 09:30 PM	#8
Sport Rider Join Date: Jan 2016 Location: Mooresville NC Posts: 2,044	I'd suggest you try raising your needle to the 3rd clip. that raises up the needle from the needle jet and starts you with more fuel to begin with. fwiw, my vm26 has a 117.5 main and 30 pilot jets. my pilot screw is 1.33 turns out. my needle is on the 2nd clip. while it's a great learning experience to work your way to the setting that works best for you, you might want to start with the 115/30/1.5 turn/2nd clip settings. I would suspect that will get you running well enough. from there you can start changing one thing at a time to see how the settings work for you. I plan to drop my main to a 112.5 and my pilot to 27.5, going back to 1.5 turns and maybe 3rd needle clip. I beleive my setting with the larger main and pilot are running a bit rich.
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