Hawk Talk

[pete]

Just as a matter of intrest... power wise..
The Honda CRF150f... with a 175 bore kit,
cam , HD valve springs gives another 3.5hp..

the standard Honda sleeve is just bored for
the 175cc piston... So if these chinese motor
use the same thickness sleeve as Honda being a copy
it may well be just a bore job..
after all the crf150 is a 26cc increass & the Chinese bike
is less at 21cc..

http://www.mx-performance.com/id40.html






..

[Ariel Red Hunter]

Originally Posted by pete

Just as a matter of intrest... power wise..
The Honda CRF150f... with a 175 bore kit,
cam , HD valve springs gives another 3.5hp..

the standard Honda sleeve is just bored for
the 175cc piston... So if these chinese motor
use the same thickness sleeve as Honda being a copy
it may well be just a bore job..
after all the crf150 is a 26cc increass & the Chinese bike
is less at 21cc..

http://www.mx-performance.com/id40.html






..

Yes, that's right. The 250cc bore is only 3mm bigger. 1/8th of an inch....ARH

[mypd1991]

So first off sorry to hijack the thread, but i was needing some help with a hawk i recently picked up. It needed a little tlc but i got it running and driving, i know there are a lot of little mods that are recommended for this bike and i plan to do almost all of them in time.

But the main issue I'm having right now is that I've never had a carbureted bike before and think I'm mixing up a few terms. So the main issue i have is that when its running (since i don't really understand where the choke is on this particular bike) I've been adjusting the idle screw to keep it running when i first start it then turn it back down once its warm, which i understand is supposed to be the function of the choke. so i guess I'm wondering where exactly it is on this bike ( if someone has a link to a manual that would be great) and what positions are what on it and used for what.

Second issue i have which is actually a bigger issue is that when its in neutral and i rev it it seems to rev fine and not have any issues, but once I'm on the bike riding and i get like halfway up the rev range in gear the bike doesn't want to push it just seems to bog down and almost want to die. Now if i shift and stay real low in the rev range its fine and i can ride it but once i try to accelerate while in gear it bogs. Ive read and tried to do as much research on this issue as i can, and maybe I'm just not describing it the best so nothing comes up when i search. Has anyone had this issue or knows whats going on. I hope this isn't a super simple thing because then I'm just gana look stupid, but at the same time i hope it is.

Also i didn't really see a recommended place to buy parts from, where does everyone recommend? Thanks

[oldscooter]

Get down and look at the carb from the left side of the bike. There is a black lever on it. All the way up is full choke. Middle is half choke. All the way down, choke is off. I'll let the carb guru's tell you about jetting the carb. I get parts from Ebay and Amazon mostly. RPS has factory replacement parts. http://therps.net/DB-Hawk.html

[mypd1991]

Originally Posted by oldscooter

Get down and look at the carb from the left side of the bike. There is a black lever on it. All the way up is full choke. Middle is half choke. All the way down, choke is off. I'll let the carb guru's tell you about jetting the carb. I get parts from Ebay and Amazon mostly. RPS has factory replacement parts. http://therps.net/DB-Hawk.html

Awesome, ive seen that lever, just never knew what it was. so what is the small lever under the fuel tank on the left side of the bike?

Also to add to my previous issues, the airbox on the bike seems to have warped somehow and doesn't actually connect to the carb its lined up but there's maybe half a millimeter between it and the card intake. Could that be why its bogging, too much air?

[Bruce's]

The little lever under the tank is the fuel shut off ,I don't have a hawk so don't know it's positions ,but that lever could be in the wrong position and causing all of your troubles .Fix the air box to carb issue before riding it ,but no problems with too much air .

[JerryHawk250]

Originally Posted by Bruce's

The little lever under the tank is the fuel shut off ,I don't have a hawk so don't know it's positions ,but that lever could be in the wrong position and causing all of your troubles .Fix the air box to carb issue before riding it ,but no problems with too much air .

Gas lever all the way down is on, halfway is off and all the way up is reserve.

[mypd1991]

Originally Posted by JerryHawk250

Gas lever all the way down is on, halfway is off and all the way up is reserve.

Thanks

[Ariel Red Hunter]

Originally Posted by mypd1991

So first off sorry to hijack the thread, but i was needing some help with a hawk i recently picked up. It needed a little tlc but i got it running and driving, i know there are a lot of little mods that are recommended for this bike and i plan to do almost all of them in time.

But the main issue I'm having right now is that I've never had a carbureted bike before and think I'm mixing up a few terms. So the main issue i have is that when its running (since i don't really understand where the choke is on this particular bike) I've been adjusting the idle screw to keep it running when i first start it then turn it back down once its warm, which i understand is supposed to be the function of the choke. so i guess I'm wondering where exactly it is on this bike ( if someone has a link to a manual that would be great) and what positions are what on it and used for what.

Second issue i have which is actually a bigger issue is that when its in neutral and i rev it it seems to rev fine and not have any issues, but once I'm on the bike riding and i get like halfway up the rev range in gear the bike doesn't want to push it just seems to bog down and almost want to die. Now if i shift and stay real low in the rev range its fine and i can ride it but once i try to accelerate while in gear it bogs. Ive read and tried to do as much research on this issue as i can, and maybe I'm just not describing it the best so nothing comes up when i search. Has anyone had this issue or knows whats going on. I hope this isn't a super simple thing because then I'm just gana look stupid, but at the same time i hope it is.

Also i didn't really see a recommended place to buy parts from, where does everyone recommend? Thanks

Sounds like the main jet is too lean (the hole isn't big enough). Luckily for you, a Mikuni main jet will screw in even though the thread pitch is different. If it has the original exhaust system a 110 or 115 main jet should do the trick...ARH

[mypd1991]

Originally Posted by Ariel Red Hunter

Sounds like the main jet is too lean (the hole isn't big enough). Luckily for you, a Mikuni main jet will screw in even though the thread pitch is different. If it has the original exhaust system a 110 or 115 main jet should do the trick...ARH

Yep stock exhaust, awesome. Thanks everyone for the info and suggestions. Will be trying to get it running good by this Sunday, there's a big ride coming up in Dallas this weekend and I'm trying to ride on "supermoto Sunday" with the big boys. I'll let you guys know if I get her running right and if any other issues arise.

[Ariel Red Hunter]

It looks like it's time for another Mikuni tutorial. The Mikuni could be described as a very simple variable venturi carburetor. It has a simple cold start device (on the cheaper ones a butterfly choke, on the more expensive ones a cold start circuit.) It does not have a fast idle cam in the throttle control. So you start it cold with the throttle open about an eighth of a turn, and keep the throttle opened that much until the engine warms enough to keep running when you let go of the throttle. Now to tune it for your individual bike. I start by setting my idle mixture screw 1 1/2 turns out from the seated position. I have the needle in the middle position of the available slots in the needle. Then, after the engine is well warmed up I do a plug chop to check the fuel mixture at wide open throttle. About a half mile down the road at wide open throttle, I leave the throttle wide open as I cut off the ignition and whip out the clutch at the same instant. I cut off the ignition with the red button on the right handlebar. Let the bike coast to a stop and put the trans mission in neutral. Let go of the throttle, and pull out the spark plug to check the mixture. If the plug firing area looks all white, or very clear - the main jet is too small. If the plug has black in the firing area, the main jet is too rich. If the plug is tan, mixture is about right. Now check the idle. If you have to richen the idle screw to get a good idle, you need a bigger pilot jet. When you have the right pilot jet in there, the engine will immediatly respond smoothly from a slow idle on up to a quarter throttle, not just sitting, but under load. For off road use the range between slow idle to 1/4 throttle must be smooth or off road riding will be difficult and tiring. You should lead the engine with the twist-grip. In other words, open the throttle an 1/8th of a turn as you feed in the clutch, then smoothly open up through 1/4 turn on you way up. If there is a little hesitation at a quarter turn throttle, raise the needle one notch. You should now have very smooth power flow right from a slow idle all the way up to wide open. A word of warning; any thing you do to the air intake or exhaust after you set up the carburetor means you have to do it all over again....ARH

[Ariel Red Hunter]

The main advantages of a Mikuni carburetor are (1) easier to find jets. (2) easy to adjust mid-range mixture due to 5 slot needle. (3) Different throttle slide cut aways available. On the jet issue, luckily the Mikuni main jet will screw in to the jet block of the stock carburetor even though the thread pitch is different. Unfortunatly this is not true of the pilot jet. Since the pilot jet 100% controls the fuel mixture from idle to 1/4 throttle, it is important on a dual-sport or enduro to have total control of this part of the power band. Throttle cut away acts like an accelerator pump. The less the cut away, the bigger shot of fuel to get everything going from an idle up to 1/8th throttle. When I crack the throttle, I want a healthy "thump" right from the get go. Makes lifting the front wheel over a log, or whatever, much easier. Now there are places out west where you spend almost no time below 1/4 throttle. But in the rest of the country, life is much better when the carb is set up right...ARH

[kirbo7106]

Ok, this is something for the more technical crowd. I saw this article a few months ago about Drum Chargers.
Here's the link:

http://newatlas.com/drum-charger-che...e-turbo/46648/

Hope this link works. Any chance this could help our little Hawks out?

[Ariel Red Hunter]

Originally Posted by kirbo7106

Ok, this is something for the more technical crowd. I saw this article a few months ago about Drum Chargers.
Here's the link:

http://newatlas.com/drum-charger-che...e-turbo/46648/

Hope this link works. Any chance this could help our little Hawks out?

This would be an interesting idea to try. In theory, it should work. The devil is going to be working out the details (at the carb end)...ARH

[BlackBike]

And of course the latest thing , but skinny on the cost details