Huawin cheetah 200

jayr · 08-02-2017, 05:58 PM

I'm about finish getting this bike back in shape after sitting for so long.

It already had a PZ30 carb. Added a uni pod filter. Opened the muffler and took out the two silencer in the middle.

Added front led trun signals. And rear led integrated tail light.

I'm having a slight problem with tuning it tough...

It was really hard to start and from idle if I gave the throttle a quick snap it bogs down really bad? it had a 98 main jet and a 40 pilot jet.

Bought a 10pcs jet kit off eBay.
Installed a 125 main jet and 42 pilot jet mix screw set to 1 1/2 turns out. Needle clip in the middle.

Starts up way better. But that bog is still their?

Any recommendations will be appreciated.

jayr · 08-02-2017, 06:07 PM

When I bought her.

Ariel Red Hunter · 08-02-2017, 06:43 PM

Quote:

Originally Posted by jayr

I'm about finish getting this bike back in shape after sitting for so long.

It already had a PZ30 carb. Added a uni pod filter. Opened the muffler and took out the two silencer in the middle.

Added front led trun signals. And rear led integrated tail light.

I'm having a slight problem with tuning it tough...

It was really hard to start and from idle if I gave the throttle a quick snap it bogs down really bad? it had a 98 main jet and a 40 pilot jet.

Bought a 10pcs jet kit off eBay.
Installed a 125 main jet and 42 pilot jet mix screw set to 1 1/2 turns out. Needle clip in the middle.

Starts up way better. But that bog is still their?

Any recommendations will be appreciated.

You can try lowering the needle one notch, but this style carburetor was never designed to deal with "snapping the throttle". You would have more success, if snapping the throttle is important to you, with a square slide carb, preferably a Mikuni because you can get different slide cut-aways for them....ARH

humanbeing · 08-02-2017, 08:40 PM

Valve clearance OK?

jayr · 08-02-2017, 09:49 PM

Quote:

Originally Posted by Ariel Red Hunter

You can try lowering the needle one notch, but this style carburetor was never designed to deal with "snapping the throttle". You would have more success, if snapping the throttle is important to you, with a square slide carb, preferably a Mikuni because you can get different slide cut-aways for them....ARH

ok, i try lowering the needle one notch down. see if it improves.

pistolclass · 08-02-2017, 09:49 PM

Definitely start with the valves.

125 main and a 42 pilot on a 200 seems too fat too me. I would start with dropping that pilot to a 25. Then start moving things around based on what the plug and throttle are telling you.

jayr · 08-02-2017, 09:49 PM

Quote:

Originally Posted by humanbeing

Valve clearance OK?

you know what i havent checked. do you know the specs?

jayr · 08-02-2017, 09:59 PM

Quote:

Originally Posted by pistolclass

Definitely start with the valves.

125 main and a 42 pilot on a 200 seems too fat too me. I would start with dropping that pilot to a 25. Then start moving things around based on what the plug and throttle are telling you.

I was thinking that too. Im going to down the jet sizes. just thought with the pod filter and the muffler gutted it would be to lean. it was running lean when i got it. it was hard to start. the 125 main & 42 pilot. seemed to help it out a lot.

humanbeing · 08-03-2017, 12:17 AM

Quote:

Originally Posted by jayr

you know what i havent checked. do you know the specs?

Don't know exactly BUT follow modern Honda's spec https://goo.gl/photos/Q25geNhmyA9PvTps9 seems reasonable (btw. old cb125s... is in/ex 0.05mm. Taiwanese SYM still quoted those in their manual

)

Weldangrind · 08-03-2017, 12:09 PM

Quote:

Originally Posted by pistolclass

Definitely start with the valves.

125 main and a 42 pilot on a 200 seems too fat too me. I would start with dropping that pilot to a 25. Then start moving things around based on what the plug and throttle are telling you.

I agree, start with the valves.

The 42 slow jet is really close to ideal on a Keihin (or Keihin clone). They are quite a different animal from the Mikuni, which would be somewhere between 25-30.

pistolclass · 08-03-2017, 01:46 PM

Good catch weld. I just noticed it isn't a mikuni. I defer to folks that run Keihin's.

jayr · 08-03-2017, 01:47 PM

So keep the 42 pilot jet? To check the valve clearance, just line up the T mark with the line in the peak hole. And check for 0.05mm?

Megadan · 08-03-2017, 08:37 PM

Quote:

Originally Posted by jayr

So keep the 42 pilot jet? To check the valve clearance, just line up the T mark with the line in the peak hole. And check for 0.05mm?

Going up from a 40 to a 42 is similar to my going from a 25 to a 27.5 on my Mikuni clone. If 1 1/2 turns works well on the 40, then likely you will need to go in on the mixture screw and might be closer to 1 turn out. This is just a general rule of thumb. Was the 40 giving indications that it was too lean?

If the Keihin Jets are true to size then you can still use peoples Mikuni setups to help get a good starting point for your carburetor.

Here are a few Mikuni (M) and equivalent Keihin (K) jet sizes.

100 M - 110 K
102.5 M - 115 K
105 M - 118 K
107.5 M - 120 K
110 M - 125 K
112.5 M - 128 K
115 M - 130 K
117.5 M - 135 K
120 M - 138 K
122.5 M - 140 K
125 M - 145 K

Keep in mind that this ONLY applies to genuine or high quality aftermarket jets. I am under the suspicion that many Chinese made jets don't follow the same sizing standards, but I could be wrong. I always recommend genuine jets if at all possible.

One advantage of the Keihin jet system is that it covers a few inbetween sizes that the Mikuni jets do not if you really wanted to get in there and super fine tune the carburetor. An example of this is the step between a 115 and 117.5 Mikuni jet, aka a 130 and 135 Keihin jet, you will find a 132 Keihin jet size that has no mikuni equivalent - which I guess you could call a 116.25 if it existed.

Megadan · 08-03-2017, 08:49 PM

Not to make too many posts, but separate question here. When you say it bogs when you try to snap open the throttle, are we talking a hesitation, or it just falls on its face and stops revving, maybe even sputters a bit?

If it is the second of the two, then there are two possibilities.
1. Main jet is too large and overloads the engine with fuel. - This would mainly show itself past 3/4 throttle.
2. Your choke is not open all the way, or somehow snapping closed.

If it is more of a hesitation, then the others have already covered it fairly well.

That said, with the carburetor jetted and dialed in well, you should be able to aggressively blip the throttle and only have a small delay in its reaction, that is just the nature of this style of carburetor, but it should be only a slight delay less than a second. If you snap the throttle open and it just does nothing and then suddenly surges, it's a fueling issue.

jayr · 08-04-2017, 01:45 AM

I actually read a post of yours about the Keihin jets being different than mikuni jets. That's what made me keep those's jet numbers up. So thanks for clearing that up.

The 40 pilot had to be set at 2 1/2 turns out with the 98 main & stock air box it was pretty hard to start. And the bog was there

With the uni air filter I thought I'll try bigger jets. Install the 42p 1 1/2 turns & 125m it starts up way easier.

Correct, It just falls on its face, stops revving, sometimes it will even stall out if I try to hold it there. This happens from closed throttle to about 1/2 throttle.

08-02-2017, 05:58 PM	#1
jayr Join Date: Jul 2017 Posts: 18	Huawin cheetah 200 I'm about finish getting this bike back in shape after sitting for so long. It already had a PZ30 carb. Added a uni pod filter. Opened the muffler and took out the two silencer in the middle. Added front led trun signals. And rear led integrated tail light. I'm having a slight problem with tuning it tough... It was really hard to start and from idle if I gave the throttle a quick snap it bogs down really bad? it had a 98 main jet and a 40 pilot jet. Bought a 10pcs jet kit off eBay. Installed a 125 main jet and 42 pilot jet mix screw set to 1 1/2 turns out. Needle clip in the middle. Starts up way better. But that bog is still their? Any recommendations will be appreciated.
	2

08-02-2017, 08:40 PM	#4
humanbeing Join Date: Mar 2008 Posts: 2,436	Valve clearance OK? __________________
	0

08-03-2017, 08:49 PM	#14
Megadan Join Date: Apr 2017 Location: Omaha, NE Posts: 7,998	Not to make too many posts, but separate question here. When you say it bogs when you try to snap open the throttle, are we talking a hesitation, or it just falls on its face and stops revving, maybe even sputters a bit? If it is the second of the two, then there are two possibilities. 1. Main jet is too large and overloads the engine with fuel. - This would mainly show itself past 3/4 throttle. 2. Your choke is not open all the way, or somehow snapping closed. If it is more of a hesitation, then the others have already covered it fairly well. That said, with the carburetor jetted and dialed in well, you should be able to aggressively blip the throttle and only have a small delay in its reaction, that is just the nature of this style of carburetor, but it should be only a slight delay less than a second. If you snap the throttle open and it just does nothing and then suddenly surges, it's a fueling issue. __________________ Hawk Information and Resource guide: http://www.chinariders.net/showthread.php?t=20331 2018 Hawk 250 - Full Mod list here. http://www.chinariders.net/showpost....62&postcount=1 2024 Royal Enfield Shotgun 650 https://chinariders.net/showthread.php?t=34124
	0

08-02-2017, 09:49 PM	#6
pistolclass Join Date: Oct 2015 Location: connecticut Posts: 978	Definitely start with the valves. 125 main and a 42 pilot on a 200 seems too fat too me. I would start with dropping that pilot to a 25. Then start moving things around based on what the plug and throttle are telling you.
	1

08-03-2017, 01:46 PM	#11
pistolclass Join Date: Oct 2015 Location: connecticut Posts: 978	Good catch weld. I just noticed it isn't a mikuni. I defer to folks that run Keihin's.
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08-03-2017, 01:47 PM	#12
jayr Join Date: Jul 2017 Posts: 18	So keep the 42 pilot jet? To check the valve clearance, just line up the T mark with the line in the peak hole. And check for 0.05mm?
	0

08-04-2017, 01:45 AM	#15
jayr Join Date: Jul 2017 Posts: 18	I actually read a post of yours about the Keihin jets being different than mikuni jets. That's what made me keep those's jet numbers up. So thanks for clearing that up. The 40 pilot had to be set at 2 1/2 turns out with the 98 main & stock air box it was pretty hard to start. And the bog was there With the uni air filter I thought I'll try bigger jets. Install the 42p 1 1/2 turns & 125m it starts up way easier. Correct, It just falls on its face, stops revving, sometimes it will even stall out if I try to hold it there. This happens from closed throttle to about 1/2 throttle.
	0