Hawk Talk - Page 8

Ariel Red Hunter · 10-09-2016, 04:50 PM

Air boxes seem to fall into three classes. As a still air box, with an airfilter in it, a schnorkal that allows you to operate in streams so deep the water is higher that the engine cylinder head, as a still airbox cum intake sound muffler and air filter. Oh yeah, as an ornament on certain China bikes intended for dual sport use because one is supposed to be on there. The schnorkal type is almost always used only on military motorcycles. Now, inn the days of my youth, these were metal boxes that held a round paper element filter in the best examples, or had woven wire air filters that were aptly described as only for keeping gravel and small, low flying birds from being ingested into the engine. Oh, and I forgot the ones which had no filter of any kind, and were only supposed to keep mud and rocks out, while insuring that the engine got still air. Still air is more important than you might at first think. All kinds of carburetion problems occured with airflow coming over the cylinder head, around various frame rails, and other items hung wherever convenient during assembly at the factory. We used to coat the interior of those airboxes with grease in order to trap some of the dust coming in, and overloading the air filter.

Ariel Red Hunter · 10-09-2016, 10:44 PM

The Hawk air box is designed to quieten intake noise, and hold an air filter. Unfortunately, the air is pretty restricted getting into the air box. Motocheez has a video on modifying the intake of the box by opening up the area so that the air can get in easier and faster. I think it would be educational to watch that video. I wouldn't put the hardware cloth in the box unless you have a real bad mouse problem. With the intakes opened up, you now have what is called a still air box. Next decision is the air cleaner. It doesn't really matter if you choose a K&N tapered round filter with a sponge around it, or put in some good quality square filter where the stock one resides. But if you ride where it's wet, I would not reccomend a paper filter. And I would move the crankcase breather line out of the air box, and put a PCV valve in the line, installed so that air can get out of the crankcase, but cannot get back in. This has a couple of benefits besides keeping the filter clean. It reduces crankcase pressure, which is beneficial to keeping the seals from leaking, and it reduces air pumping losses. It also reduces oil misting, resulting in less power loss. Don't forget to plug the hole where the crankcase vent line used to go in the air box.

hertz9753 · 10-10-2016, 05:17 AM

I'm pretty sure the Hawk doesn't use a crankcase vent to the air box.

Ariel Red Hunter · 10-10-2016, 03:42 PM

I have seen many pictures of Hawks with a kink in the pipe/hose that goes between the air box and the carburetor. A kink disrupts the air flow, so try to get rid of it. I would try undoing the clamps on both ends of the pipe/hose, and see if you can get the kink out, if you have one. Next is checking how well the carburetor matches up to the cylinder head. It is important to have them both in line, and with no step going from one to the other. Do not polish the head's inlet tract. You actually get a better flow if you leave it alone. Now about carburetors. The one that comes with the bike works OK, it is just hard to get jets for it. That's why many have gone to the Mikuni VM-26. But if you want to stick with the Keihan that came with the machine, you should check out Motocheez's video on how to modify the carburetor so you can change jets. If you choose to go for a Mikuni VM-26, there are two different kinds (at least). The easy ones to find on e-bay, and elsewhere have butterfly chokes for cold starting. The hard ones to find have no butterfly choke, but use an enriching circuit for cold starting. Because there is no butterfly choke, there is less airflow disturbance in the carb. This is better. Potentially, a little more horsepower, assuming it is jetted correctly. A little more horsepower, gained here and there can add up to a difference. In other words, cleaning up the intake tract all the way from where it begins to the head is the trick. Not just one thing, but all of them working in harmony in order to get a greater weight of fuel/air mixture into the engine is the answer.

hertz9753 · 10-10-2016, 07:33 PM

It's plastic and that is how it is molded. It doesn't look so bad from the top.

pete · 10-11-2016, 01:02 AM

Quote:

Originally Posted by Ariel Red Hunter

Do not polish the head's inlet tract. You actually get a better flow if you leave it alone.

In other words, cleaning up the intake tract all the way from where it begins to the head is the trick.

glad yer cleared that up....

.

Ariel Red Hunter · 10-11-2016, 09:57 AM

Quote:

Originally Posted by hertz9753

It's plastic and that is how it is molded. It doesn't look so bad from the top.

Yours doesn't look all that bad. I've seen a lot worse on this forum.

Ariel Red Hunter · 10-11-2016, 10:00 AM

Quote:

Originally Posted by pete

glad yer cleared that up....

.

I try to write stuff that everybody can understand. That's why I used two sentences to say the same thing in two different ways.

hertz9753 · 10-11-2016, 10:06 PM

The Hawk also doesn't have a clamp to the air box, it is glued to it.

pete · 10-12-2016, 12:58 AM

Quote:

Originally Posted by Ariel Red Hunter

I try to write stuff that everybody can understand. That's why I used two sentences to say the same thing in two different ways.

one says Don't do it.... the other says Do it...

...

Bruce's · 10-12-2016, 08:35 AM

It is confusing to me too Pete .

pistolclass · 10-12-2016, 11:49 AM

Must be a yank thing. I got it.

Ariel Red Hunter · 10-12-2016, 04:06 PM

Quote:

Originally Posted by Bruce's

It is confusing to me too Pete .

Did you really read it, or did you skim read it. Maybe it's my fault. One sentence means leave the cylinder head porting alone. The other sentence means work on smoothing the airflow from where it begins to the carburetor. And check the carb to head fit, no steps is what you want. Does that help?

Bruce's · 10-12-2016, 06:25 PM

I have read it ,and you clearly state do not polish the heads intake tract ,and near the bottom of the paragraph you clearly state the exact opposite to me ,cleaning up the intake tract all the way from where it begins to the head is the trick .In one sentence you say to clean it up is the trick ,the other sentence says don't polish it ,which at least to me ,is exactly how you clean up something like that .What is the difference between polishing an intake ,or cleaning one up to you ? to me ,it's the same thing ,but it appears you might have a different idea about it .Have you got any data from the Hawks you either did or didn't clean up the intake on for a comparison ?

Jmcgee · 10-12-2016, 07:08 PM

Quote:

Originally Posted by Bruce's

I have read it ,and you clearly state do not polish the heads intake tract ,and near the bottom of the paragraph you clearly state the exact opposite to me ,cleaning up the intake tract all the way from where it begins to the head is the trick .In one sentence you say to clean it up is the trick ,the other sentence says don't polish it ,which at least to me ,is exactly how you clean up something like that .What is the difference between polishing an intake ,or cleaning one up to you ? to me ,it's the same thing ,but it appears you might have a different idea about it .Have you got any data from the Hawks you either did or didn't clean up the intake on for a comparison ?

I have worked on heads a bit, NOT hawk heads but drag bike heads, and race car heads. with heads you look at the angles and flaws in the flow track. usually where the track turns down near the valve is the most restriction. you "massage" them and get rid of hard angles and open the flow up. Polishing to a mirror finish is what some consider polishing and it is a waste on the intake, most say you need a little turbulence so the gas and air stays mixed. Ive tried both ways and see no difference at all with the polish so why waste the time....

10-09-2016, 04:50 PM	#106
Ariel Red Hunter Join Date: Jun 2016 Location: akwesasne, NY-13655 Posts: 2,220	A few thoughts on air boxes. Air boxes seem to fall into three classes. As a still air box, with an airfilter in it, a schnorkal that allows you to operate in streams so deep the water is higher that the engine cylinder head, as a still airbox cum intake sound muffler and air filter. Oh yeah, as an ornament on certain China bikes intended for dual sport use because one is supposed to be on there. The schnorkal type is almost always used only on military motorcycles. Now, inn the days of my youth, these were metal boxes that held a round paper element filter in the best examples, or had woven wire air filters that were aptly described as only for keeping gravel and small, low flying birds from being ingested into the engine. Oh, and I forgot the ones which had no filter of any kind, and were only supposed to keep mud and rocks out, while insuring that the engine got still air. Still air is more important than you might at first think. All kinds of carburetion problems occured with airflow coming over the cylinder head, around various frame rails, and other items hung wherever convenient during assembly at the factory. We used to coat the interior of those airboxes with grease in order to trap some of the dust coming in, and overloading the air filter.
	1

10-09-2016, 10:44 PM	#107
Ariel Red Hunter Join Date: Jun 2016 Location: akwesasne, NY-13655 Posts: 2,220	Why modify the box. The Hawk air box is designed to quieten intake noise, and hold an air filter. Unfortunately, the air is pretty restricted getting into the air box. Motocheez has a video on modifying the intake of the box by opening up the area so that the air can get in easier and faster. I think it would be educational to watch that video. I wouldn't put the hardware cloth in the box unless you have a real bad mouse problem. With the intakes opened up, you now have what is called a still air box. Next decision is the air cleaner. It doesn't really matter if you choose a K&N tapered round filter with a sponge around it, or put in some good quality square filter where the stock one resides. But if you ride where it's wet, I would not reccomend a paper filter. And I would move the crankcase breather line out of the air box, and put a PCV valve in the line, installed so that air can get out of the crankcase, but cannot get back in. This has a couple of benefits besides keeping the filter clean. It reduces crankcase pressure, which is beneficial to keeping the seals from leaking, and it reduces air pumping losses. It also reduces oil misting, resulting in less power loss. Don't forget to plug the hole where the crankcase vent line used to go in the air box.
	0

10-10-2016, 05:17 AM	#108
hertz9753 Join Date: May 2016 Location: Bismarck, ND Posts: 868	I'm pretty sure the Hawk doesn't use a crankcase vent to the air box. __________________ 2015 and 3/4 RPS Hawk 250. Most people would call it a 2016 but the MCO didn't.
	0

10-10-2016, 03:42 PM	#109
Ariel Red Hunter Join Date: Jun 2016 Location: akwesasne, NY-13655 Posts: 2,220	Other induction factors I have seen many pictures of Hawks with a kink in the pipe/hose that goes between the air box and the carburetor. A kink disrupts the air flow, so try to get rid of it. I would try undoing the clamps on both ends of the pipe/hose, and see if you can get the kink out, if you have one. Next is checking how well the carburetor matches up to the cylinder head. It is important to have them both in line, and with no step going from one to the other. Do not polish the head's inlet tract. You actually get a better flow if you leave it alone. Now about carburetors. The one that comes with the bike works OK, it is just hard to get jets for it. That's why many have gone to the Mikuni VM-26. But if you want to stick with the Keihan that came with the machine, you should check out Motocheez's video on how to modify the carburetor so you can change jets. If you choose to go for a Mikuni VM-26, there are two different kinds (at least). The easy ones to find on e-bay, and elsewhere have butterfly chokes for cold starting. The hard ones to find have no butterfly choke, but use an enriching circuit for cold starting. Because there is no butterfly choke, there is less airflow disturbance in the carb. This is better. Potentially, a little more horsepower, assuming it is jetted correctly. A little more horsepower, gained here and there can add up to a difference. In other words, cleaning up the intake tract all the way from where it begins to the head is the trick. Not just one thing, but all of them working in harmony in order to get a greater weight of fuel/air mixture into the engine is the answer.
	1

10-12-2016, 08:35 AM	#116
Bruce's Join Date: Apr 2015 Location: Sudbury ,Ontario Posts: 855	It is confusing to me too Pete .
	0

10-12-2016, 11:49 AM	#117
pistolclass Join Date: Oct 2015 Location: connecticut Posts: 980	Must be a yank thing. I got it.
	0

10-12-2016, 06:25 PM	#119
Bruce's Join Date: Apr 2015 Location: Sudbury ,Ontario Posts: 855	I have read it ,and you clearly state do not polish the heads intake tract ,and near the bottom of the paragraph you clearly state the exact opposite to me ,cleaning up the intake tract all the way from where it begins to the head is the trick .In one sentence you say to clean it up is the trick ,the other sentence says don't polish it ,which at least to me ,is exactly how you clean up something like that .What is the difference between polishing an intake ,or cleaning one up to you ? to me ,it's the same thing ,but it appears you might have a different idea about it .Have you got any data from the Hawks you either did or didn't clean up the intake on for a comparison ?
	0