Why a Mikuni Carb for Hawk?

tomalak007 · 01-10-2017, 06:24 AM

I know one of everyone's favorite mods for the Hawk 250 is a Mikuni Carb. But no one ever seems to explain why? Why is it better than the stock carb and why does it give the bike more power? Thanks!

**JerryHawk250** · 01-10-2017, 06:36 AM

That's a good question. I just used the stock carb and change the jet. I would like to know too if there was a big difference. Has anyone tried both to see the difference.

pistolclass · 01-10-2017, 07:10 AM

Because for about $30 I don't have to grind slots in the other carb.

**JerryHawk250** · 01-10-2017, 07:37 AM

Quote:

Originally Posted by pistolclass

Because for about $30 I don't have to grind slots in the other carb.

I wouldn't grind the slots either. A fine tooth hacksaw is a lot safer and does a cleaner job. takes less than 5 minutes to do. As far as the two carburetors, is there any difference between the two?

ben2go · 01-10-2017, 07:45 AM

If I'm not mistaken, the throat on the Mikuni is a little larger and flows a little better on top end.

bogieboy · 01-10-2017, 10:14 AM

You get better top end flow, and the jets for mikunis are far more readily available locally...not to mention some of the keihin clone carbs used funky non keihin sized jets to make it even more coomplicated... you can go to any powersports store and get mikuni jets...

2LZ · 01-10-2017, 10:28 AM

Quote:

Originally Posted by bogieboy

You get better top end flow, and the jets for mikunis are far more readily available locally...not to mention some of the keihin clone carbs used funky non keihin sized jets to make it even more coomplicated... you can go to any powersports store and get mikuni jets...

Yep. Every one of my Keihin clones have greatly varied in quality and build. The one on my Rhino was pure junk. For the 30.00, you can get a "known good" carb, that has readily available jetting for your particular mods and elevation....and every one I've replaced makes the bike/quad run stronger. Some folks have noticed this, some have not.

The other upside is you can do as many or as few mods as you want, and keep the bike breathing properly with the available Mikuni jetting.

That said, my neighbor is perfectly happy with how his new TT250 runs with the stock setup....but we're at 3000'. These CB's have a tendency to come horribly lean.

OUTERLIMITS · 01-10-2017, 12:40 PM

It seems like main jets are regularly available for the PZ30, but I have not heard of anyone having a definitive source for the pilot jets that will fit that carb.

culcune · 01-10-2017, 02:14 PM

Quote:

Originally Posted by 2LZ

That said, my neighbor is perfectly happy with how his new TT250 runs with the stock setup....but we're at 3000'. These CB's have a tendency to come horribly lean.

You hit the nail on the head, kinda sorta, without even trying. About 10 to 12 years ago here, but more and more on mychinamoto, many westerners traveled, or moved to China, bought cheap CG bikes (mostly enduros) and took them on grand tours of the country. This was before the authorities really cared (not as many accidents) as well as before more westerners moved to China who obtained licenses and shamed anyone even suggesting to try an unlicensed bike trip ("Would you take a vacation to England and ride without a license??" came up more and more often when people on horizonsunlimited or advrider asked about doing moto-vacation tours in China).

Off subject, but getting to the point--those riders who passed high elevation passes reported how great their 150cc (sometimes larger--i.e. 200cc Zongshen enduro that Spud made famous--i forget the model but it was popular as well) did on the passes; not to mention how great the engines performed overall at all elevations. But, yes, they were lean from the factory. OK, memory lane over--back on topic...

Ariel Red Hunter · 01-10-2017, 02:31 PM

Quote:

Originally Posted by tomalak007

I know one of everyone's favorite mods for the Hawk 250 is a Mikuni Carb. But no one ever seems to explain why? Why is it better than the stock carb and why does it give the bike more power? Thanks!

Because pilot jets are easy to get. Because Mikuni has online tutorials on how to set up carburation. Because it is better made.

You can make the PZ carb work from 1/2 throttle and up, but without replacing the pilot jet and (some times) the throttle cut-away, low end is either soggy, or just something you go through to get to 1/2 throttle, and above. If you ride 90% on road, the PZ will do all right. Off road requires much better low end carburation. Now, if you've never ridden a bike with a good carburetor, like an Amal, or a Del'Orto, or a Mikuni, you won't know what you are missing. Even electronic fuel injection can't match what one of those carbs can do without re-mapping. A very expensive process. EFI is used mainly for emissions compliance. If you are worried about exhaust emissions from a vehicle that gets 80-100 miles per gallon, well, switch to efi.

ben2go · 01-10-2017, 08:40 PM

This is just my experience with similar bikes with carbs vs efi. I'm not trying to get anyone worked up.

I have a CB500X and it runs rich with the EFI system from the factory.Member McRat on advrider did a lot of testing from OE and using various exhaust systems and air filter set ups. If I'm not mistaken he also tried a a fuel management unit as well. All was dyno'd. I was surprised by his findings. I have a GS500, that I did a lot of air intake and exhuast work to, and it has dual 33mm Mikuni carbs. In good tune, it will beat the pants off my CB500X hands down. The CB500X has dual 34mm throttle body injection. The specs from factory shows that the CB500X should be more powerful than the GS500. I can verify that even a stock GS500 will run down a stock CB500X. I think it lies in three areas, the GS is 30lbs lighter than the CB. Plus the GS has an 11,000 rpm redline, where the CB has a 9500 redline. Also, the GS is tuned for mid and top end similar to a sport bike. The CB is tuned mostly for low to mid-range similar to and enduro. The CB is a water cooled engine and the GS is an air cooled engine. I know the GS runs hotter. To some extent, comparing the CB and GS is like comparing apples to oranges.

I agree with Ariel Red Hunter on tuned carbs providing more power than OE EFI set ups, when comparing the same motorcycles. However, a properly tuned EFI can be way more powerful than carbs, because it can more precisely meter fuel through out the rpm range. There's not many people willing to spend the kind of money it takes to actually tune an EFI motorcycle properly. I was quoted $1300 to properly tune my CB500X, on a dyno, from Pro Boys Toys. Not worth it. The CB500X cost me $5400 OTD brand new.

Those that think programmers and fuel management controls are tuning EFI, they are not. They simply fool the OE engine management into providing more fuel at preset RPMs. Some of the more expensive units can handle small changes in ignition timing. All of this is preset in the unit, and to some extent, it can be changed. It's not at all like someone dialing in a bikes EFI and ignition, through out the engines entire rev range, while running it on a dyno.

If you're really interested in this kind of stuff, I urge you to do the research. It's very interesting.

pete · 01-10-2017, 09:56 PM

The japs jetted there carb rich for a very good reason...
For the brain dead buyer that thashes a cold motor
then bad mouths the bike/brand because it seized....

The Yamaha RD350LC came with 220 main jets..
I was racing mine with 190 mains...

...

humanbeing · 01-11-2017, 01:51 AM

Quote:

Originally Posted by culcune

those riders who passed high elevation passes reported how great their 150cc (sometimes larger--i.e. 200cc Zongshen enduro ...

Good old days ≠ Today's blended gasohol / Environmental

here & there

Ariel Red Hunter · 01-11-2017, 06:17 AM

Quote:

Originally Posted by ben2go

This is just my experience with similar bikes with carbs vs efi. I'm not trying to get anyone worked up.

I have a CB500X and it runs rich with the EFI system from the factory.Member McRat on advrider did a lot of testing from OE and using various exhaust systems and air filter set ups. If I'm not mistaken he also tried a a fuel management unit as well. All was dyno'd. I was surprised by his findings. I have a GS500, that I did a lot of air intake and exhuast work to, and it has dual 33mm Mikuni carbs. In good tune, it will beat the pants off my CB500X hands down. The CB500X has dual 34mm throttle body injection. The specs from factory shows that the CB500X should be more powerful than the GS500. I can verify that even a stock GS500 will run down a stock CB500X. I think it lies in three areas, the GS is 30lbs lighter than the CB. Plus the GS has an 11,000 rpm redline, where the CB has a 9500 redline. Also, the GS is tuned for mid and top end similar to a sport bike. The CB is tuned mostly for low to mid-range similar to and enduro. The CB is a water cooled engine and the GS is an air cooled engine. I know the GS runs hotter. To some extent, comparing the CB and GS is like comparing apples to oranges.

I agree with Ariel Red Hunter on tuned carbs providing more power than OE EFI set ups, when comparing the same motorcycles. However, a properly tuned EFI can be way more powerful than carbs, because it can more precisely meter fuel through out the rpm range. There's not many people willing to spend the kind of money it takes to actually tune an EFI motorcycle properly. I was quoted $1300 to properly tune my CB500X, on a dyno, from Pro Boys Toys. Not worth it. The CB500X cost me $5400 OTD brand new.

Those that think programmers and fuel management controls are tuning EFI, they are not. They simply fool the OE engine management into providing more fuel at preset RPMs. Some of the more expensive units can handle small changes in ignition timing. All of this is preset in the unit, and to some extent, it can be changed. It's not at all like someone dialing in a bikes EFI and ignition, through out the engines entire rev range, while running it on a dyno.

If you're really interested in this kind of stuff, I urge you to do the research. It's very interesting.

Good points here! My only nit picks would be that while EFI can provide marginally more horsepower than a carburetor, I've run injected and carbureted engines on the track, and on a dyno. Trouble is the dyno isn't the track. Cars didn't benefit from injection until they had so much side bite in the turns that fuel sloshing in the float bowls was causing mixture problems. There was a reason for the phrase "Winners wear Webers". American championship cars went with fuel injection so early was because we didn't have any decent side draft carbs made in this country to feed our Offenhauser engines. The benefit of injection is it does not require a venturi to get the fuel in the airstream. Less drag. You know, like certain chicks you met in your young and stupid days - high speed, low drag.

wilserchinarider · 01-11-2017, 07:58 AM

Here is an easy method to remove the tamper proof bowl screws. The stock Keihan carb looked decent to me, but I also took the easy route and bought a mikuni and jets. My Lifan GY5 has ran very well for years with a Keihan clone. Certainly cheaper and perhaps easier to just re jet the stock carb like has been documented here on the forum by Jerry Hawk 250.

01-10-2017, 06:24 AM	#1
tomalak007 Join Date: Dec 2016 Location: Rochester, NY Posts: 28	Why a Mikuni Carb for Hawk? I know one of everyone's favorite mods for the Hawk 250 is a Mikuni Carb. But no one ever seems to explain why? Why is it better than the stock carb and why does it give the bike more power? Thanks!
	1

01-10-2017, 06:36 AM	#2
JerryHawk250 Moderator Join Date: Oct 2016 Location: Houma, La. Posts: 11,552	That's a good question. I just used the stock carb and change the jet. I would like to know too if there was a big difference. Has anyone tried both to see the difference. __________________ 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel
	0

01-10-2017, 09:56 PM	#12
pete Join Date: Jan 2012 Location: ChCh , NZ Posts: 2,261	The japs jetted there carb rich for a very good reason... For the brain dead buyer that thashes a cold motor then bad mouths the bike/brand because it seized.... The Yamaha RD350LC came with 220 main jets.. I was racing mine with 190 mains... ... __________________ 09 XT660R ... 06 TTR250 ... 80 Montesa H6 125 Enduro... 77 Montesa Cota 348 MRR "Malcom Rathnell Replica"... Current resto projects.. 81 Honda CT110... 80 Kawasaki KL250A1... 11 Husaburg TE125 enduro... "sold" along with another 31... Lifan 125 Pitbike.. "stolen" ... KIWI BIKER FORUM...... http://www.kiwibiker.co.nz/forums/content.php All the best offroad rides in NZ... http://www.remotemoto.com/ E-mail... xtpete1@gmail.com
	1

01-10-2017, 07:10 AM	#3
pistolclass Join Date: Oct 2015 Location: connecticut Posts: 978	Because for about $30 I don't have to grind slots in the other carb.
	2

01-10-2017, 07:45 AM	#5
ben2go Join Date: Jun 2011 Posts: 1,335	If I'm not mistaken, the throat on the Mikuni is a little larger and flows a little better on top end.
	0

01-10-2017, 10:14 AM	#6
bogieboy Join Date: May 2013 Location: finger lakes NY Posts: 2,042	You get better top end flow, and the jets for mikunis are far more readily available locally...not to mention some of the keihin clone carbs used funky non keihin sized jets to make it even more coomplicated... you can go to any powersports store and get mikuni jets...
	1

01-10-2017, 12:40 PM	#8
OUTERLIMITS Join Date: Oct 2015 Posts: 75	It seems like main jets are regularly available for the PZ30, but I have not heard of anyone having a definitive source for the pilot jets that will fit that carb.
	0

01-10-2017, 08:40 PM	#11
ben2go Join Date: Jun 2011 Posts: 1,335	This is just my experience with similar bikes with carbs vs efi. I'm not trying to get anyone worked up. I have a CB500X and it runs rich with the EFI system from the factory.Member McRat on advrider did a lot of testing from OE and using various exhaust systems and air filter set ups. If I'm not mistaken he also tried a a fuel management unit as well. All was dyno'd. I was surprised by his findings. I have a GS500, that I did a lot of air intake and exhuast work to, and it has dual 33mm Mikuni carbs. In good tune, it will beat the pants off my CB500X hands down. The CB500X has dual 34mm throttle body injection. The specs from factory shows that the CB500X should be more powerful than the GS500. I can verify that even a stock GS500 will run down a stock CB500X. I think it lies in three areas, the GS is 30lbs lighter than the CB. Plus the GS has an 11,000 rpm redline, where the CB has a 9500 redline. Also, the GS is tuned for mid and top end similar to a sport bike. The CB is tuned mostly for low to mid-range similar to and enduro. The CB is a water cooled engine and the GS is an air cooled engine. I know the GS runs hotter. To some extent, comparing the CB and GS is like comparing apples to oranges. I agree with Ariel Red Hunter on tuned carbs providing more power than OE EFI set ups, when comparing the same motorcycles. However, a properly tuned EFI can be way more powerful than carbs, because it can more precisely meter fuel through out the rpm range. There's not many people willing to spend the kind of money it takes to actually tune an EFI motorcycle properly. I was quoted $1300 to properly tune my CB500X, on a dyno, from Pro Boys Toys. Not worth it. The CB500X cost me $5400 OTD brand new. Those that think programmers and fuel management controls are tuning EFI, they are not. They simply fool the OE engine management into providing more fuel at preset RPMs. Some of the more expensive units can handle small changes in ignition timing. All of this is preset in the unit, and to some extent, it can be changed. It's not at all like someone dialing in a bikes EFI and ignition, through out the engines entire rev range, while running it on a dyno. If you're really interested in this kind of stuff, I urge you to do the research. It's very interesting.
	1

01-11-2017, 07:58 AM	#15
wilserchinarider Join Date: Jun 2010 Posts: 380	Here is an easy method to remove the tamper proof bowl screws. The stock Keihan carb looked decent to me, but I also took the easy route and bought a mikuni and jets. My Lifan GY5 has ran very well for years with a Keihan clone. Certainly cheaper and perhaps easier to just re jet the stock carb like has been documented here on the forum by Jerry Hawk 250.
	3