Why a Mikuni Carb for Hawk?

[JerryHawk250]

Here's a side by side comparison by TheGageinator http://chinariders.net/showpost.php?...20&postcount=1 Looks like the inlet and outlet are slightly larger. I'm just curious if anyone has done a comparison between the two. How much more power?

[pistolclass]

Notice the bandage on the guys finger in the video. Exactly why I spent the $30 .

[Ariel Red Hunter]

Originally Posted by JerryHawk250

Here's a side by side comparison by TheGageinator http://chinariders.net/showpost.php?...20&postcount=1 Looks like the inlet and outlet are slightly larger. I'm just curious if anyone has done a comparison between the two. How much more power?

I don't think that whether the float bowl has three screws or four screws matters even 1 iota. The guy found metal shavings inside the PZ carburetor. Even that's not a big deal to me. I can clean out a carburetor. Now the fact is that the easily found Mikuni main jet will work in a Keihin, even though the screw pitch is a little different. But the pilot jet will not - the threads are too dis-similar. As far as throttle slides are concerned, I don't know where to find any for a Keihin, but I know just where to go to buy one for a Mikuni. I could never find the right jets for the Keihin carb on my Honda Benly 125 cc twin 55 years ago, and nothing has changed. Still can't get all the jets I would want to have. There is nothing wrong with the basic design of the Keihin. The devil is in the details. Both of these carbs are bottom feeders. I wouldn't use either one. I'd spend 80 bucks to get the Mikuni with the start enrichment jet, which gets rid of the choke shaft and the butterfly. The choke shaft and butterfly cause air turbulance and restriction. Look at the pictures of both of these carbs. Notice that big shaft going across the mouth of it. Think about getting around that shaft and butterfly, if you were an air molecule. The 80 buck Mikuni will whup up on either of these lawn mower carbs. Especially on top end. So you pays your money and takes your choice. Sincerely, ARH

[Bill1]

The reason I bought a Mikuni for my Hawk was simple: it was an easy swap that has been tested and documented. I picked up the $35 carb from Amazon. Then I found someone on the forum that had the same mods and was at the same elevation as me. They used 115 main, 30 slow and had the mixture screw two turns out. I ordered the jets, put them in, and installed the carb. It fired right up and was nearly dead-on!
I'm interested in an easy swap so I can enjoy the bike, and I have no problems piggybacking off the victories of others.

[2LZ]

Originally Posted by Bill1

I'm interested in an easy swap so I can enjoy the bike, and I have no problems piggybacking off the victories of others.

...and that's what China Riders is all about (besides being cheap ;-))! For the last bunch of years, it's about carving paths and finding parts so others don't have to go through the same ordeal. Find something accessible and readily available that works, and spread the word. After all, there will be yet another handful of newbies tomorrow with many of the same questions.

[Customx253]

Originally Posted by Bill1

The reason I bought a Mikuni for my Hawk was simple: it was an easy swap that has been tested and documented. I picked up the $35 carb from Amazon. Then I found someone on the forum that had the same mods and was at the same elevation as me. They used 115 main, 30 slow and had the mixture screw two turns out. I ordered the jets, put them in, and installed the carb. It fired right up and was nearly dead-on!
I'm interested in an easy swap so I can enjoy the bike, and I have no problems piggybacking off the victories of others.

Bill - Did you just scour the forum for peoples settings? It would be cool if there was a common thread with location and carb setting for folks who aren't carb tuning experts.

[pistolclass]

Hey ARH you start spending $80 on a carb around here and you might get tossed from the forum. Those are for them 1 percenters 😁

Just kidding, had I known about them I might have gotten one before the $30 one.

[pete]

Originally Posted by Ariel Red Hunter

I don't think that whether the float bowl has three screws or four screws matters even 1 iota. The guy found metal shavings inside the PZ carburetor. Even that's not a big deal to me. I can clean out a carburetor. Now the fact is that the easily found Mikuni main jet will work in a Keihin, even though the screw pitch is a little different. But the pilot jet will not - the threads are too dis-similar. As far as throttle slides are concerned, I don't know where to find any for a Keihin, but I know just where to go to buy one for a Mikuni. I could never find the right jets for the Keihin carb on my Honda Benly 125 cc twin 55 years ago, and nothing has changed. Still can't get all the jets I would want to have. There is nothing wrong with the basic design of the Keihin. The devil is in the details. Both of these carbs are bottom feeders. I wouldn't use either one. I'd spend 80 bucks to get the Mikuni with the start enrichment jet, which gets rid of the choke shaft and the butterfly. The choke shaft and butterfly cause air turbulance and restriction. Look at the pictures of both of these carbs. Notice that big shaft going across the mouth of it. Think about getting around that shaft and butterfly, if you were an air molecule. The 80 buck Mikuni will whup up on either of these lawn mower carbs. Especially on top end. So you pays your money and takes your choice. Sincerely, ARH

Yes
Smooth smooth smooth it's got to be smooth..
is why I use these on 2 of my bikes.. And they are no darer
than the stuff some of you fella's put on....
Smooth bore/flat slide/ power jet... no prob getting main & pilot jets for
about $1 each..

compaire the pics with these other carbs....diffrents is night & day...
https://www.aliexpress.com/item/PWK-...608.0.0.4dxWLG

https://www.aliexpress.com/item/KOSO...7-fafd1aede4fa

Main jets....
https://www.aliexpress.com/item/New-...608.0.0.4dxWLG


Pilot jets....
https://www.aliexpress.com/item/10pc...608.0.0.4dxWLG



......

[Ariel Red Hunter]

Originally Posted by pete

Yes
Smooth smooth smooth it's got to be smooth..
is why I use these on 2 of my bikes.. And they are no darer
than the stuff some of you fella's put on....
Smooth bore/flat slide/ power jet... no prob getting main & pilot jets for
about $1 each..

compaire the pics with these other carbs....diffrents is night & day...
https://www.aliexpress.com/item/PWK-...608.0.0.4dxWLG

Main jets....
https://www.aliexpress.com/item/New-...608.0.0.4dxWLG


Pilot jets....
https://www.aliexpress.com/item/10pc...608.0.0.4dxWLG



......

Thanks for the info, Pete. The problem for me is that the OKO flat slide carb you showed us does not have available slides with different cut-aways. I was informed that if you are too lean, down low, change to a smaller carb. If too rich, go up one size bigger carb. That's not very practical for over here. I'm going to take your word for it that the flat-slide carb gives better snap acceleration than a round slide Mikuni. I would be surprised if it didn't. Most of my readers are either first bike motorcyclists, or have been away from the sport for many years. I try to help them out. I have found a Mikuni flat slide carb with different slide cutaways available, but the $119.00 price is too steep for most of my readers to hang on a $1200.00 motorcycle. I wish you had a Hawk, as I'd love to see the results of mounting one of these on it, and acceleration tests to 100 KMH , or 60 MPH, and a snap acceleration from a steady 15 MPH or 25 KMH on up to, oh 50 MPH/80 KMH. I think that the snap acceleration with the correct flat slide carb would be substantially better. Your friend, ARH

[hnu13]

Speaking of hawk carbs....
Just looked inside of mine, and i have a 40 pilot jet!!!!!!!!
Why the heck is it that size? I thought it would've been a 20 or so.... :-/
NO wonder why I have to crank in the idle screw to start it...

[pete]

Originally Posted by hnu13

Speaking of hawk carbs....
Just looked inside of mine, and i have a 40 pilot jet!!!!!!!!
Why the heck is it that size? I thought it would've been a 20 or so.... :-/
NO wonder why I have to crank in the idle screw to start it...

cranking in the idle screw dose the same as holding the throttle open a bit...
or are you meaning the air/mixture screw?

the size of the pilot jet is inter linked with the size of the main jet..
The pilot jet dosn't suddenly turn off after a certain rev range is hit
it feeds fuel all the time... " theres no tap or switch on the pilot jet
to shut it off"

big pilot/small main .. colder climits...
small pilot/big main .. hotter climits...
but the combined fuel flow of both combinations
at high rpms should be the same..

thats could be a lot of the issue with the china bike jetting...
they will be prob jetted perfectly in some climits...

The Yamaha TTR250 sold in the UK/europe have diffrent jet combinations
the the ones sold here & Ozzie...



...

[hnu13]

Originally Posted by pete

cranking in the idle screw dose the same as holding the throttle open a bit...
or are you meaning the air/mixture screw?

the size of the pilot jet is inter linked with the size of the main jet..
The pilot jet dosn't suddenly turn off after a certain rev range is hit
it feeds fuel all the time... " theres no tap or switch on the pilot jet
to shut it off"

big pilot/small main .. colder climits...
small pilot/big main .. hotter climits...
but the combined fuel flow of both combinations
at high rpms should be the same..

thats could be a lot of the issue with the china bike jetting...
they will be prob jetted perfectly in some climits...

The Yamaha TTR250 sold in the UK/europe have diffrent jet combinations
the the ones sold here & Ozzie...



...

I live in Florida, it's always warm for the majority of the year... after I ride for a while a I have to turn the idle down . When I start the bike again't the idle is too low for it to start without throttle or adjusting the idle screw

[pete]

Originally Posted by hnu13

I live in Florida, it's always warm for the majority of the year... after I ride for a while a I have to turn the idle down . When I start the bike again't the idle is too low for it to start without throttle or adjusting the idle screw

try a size or two bigger pilot jet...

to set the air screw....
get it warmed up.. idle set & play with the air
screw till yer get the highest idle speed then
turn it in 1/4 of a turn.. if the idle drops back to much
try1/8 turn from highest idle speed...



...

[Ariel Red Hunter]

Originally Posted by pistolclass

Hey ARH you start spending $80 on a carb around here and you might get tossed from the forum. Those are for them 1 percenters 😁

Just kidding, had I known about them I might have gotten one before the $30 one.

Hah! Always appreciate a sense of humor.

[Bill1]

Originally Posted by pete

try a size or two bigger pilot jet...

to set the air screw....
get it warmed up.. idle set & play with the air
screw till yer get the highest idle speed then
turn it in 1/4 of a turn.. if the idle drops back to much
try1/8 turn from highest idle speed...



...

I tried to tweak mine last night. On my carb, the pilot mixture screw is on the bottom and hard to reach. The flat head screwdrivers I had were too long, and I couldn't get a good enough grip on a screwdriver bit to turn it with fingers.
What tool have you guys found that works to adjust these?