Successfully tuning my Lifan LF200GY-5

JimShortz · 05-11-2017, 12:44 AM

I have been doing a lot of lurking on here, but not much posting. Time to fix that by sharing my experience of tuning my four year old Lifan LF200GY-5 X-plore (same engine as the Cross, but different air filter; mine is a nice foam pod within a case as standard). Hopefully my experiences will give some other people a better starting point than I had.

So... what I have done is fitted a nice wide-open slip-on that I picked up cheap secondhand (Leo Vince X3), followed by lots of carburettor (standard PZ30) and intake modding. With that exhaust in place, I did the following:

First I drilled out the standard slow jet (K40A) a little. I found that the drill #78 (0.406mm) slid through the jet, whereas #77 (0.457mm) didn't. I gently hand drilled it out to #77 size. I did this simply on the assumption that the bike would have been shipped lean to meet emission standards, and the plug certainly didn't indicate running rich.

I moved the needle clip down one to increase fuel flow in the throttle range beyond that covered by the slow jet (I tried the bottom clip position too, but this proved to be too much and I went back to second position from the bottom).

I reset the mixture screw from 3.75 turns out (how I found it) to 1.75 turns out. This is where my engine runs fastest (as tested with idle screw at higher revving pace than normal).

With these three changes the bike ran great from idle through to about two thirds throttle, but hesitant/bogging at higher revs still.

Next, to play with the main jet:

Mine was marked as 98, but from measuring with drill bits I had it became clear that it had been drilled out to somewhere between 1.05 and 1.1 - I'm assuming somewhere in the middle then, say 1.08. This was not working well, and I wondered if with the new exhaust it might need a larger jet still. I tried drilling it out to 1.1 - even worse; clearly going the wrong way...

With an ebay jet kit in-hand I next tried a 1.02 - amazing! Sounds and runs superbly. Time to "stick", but of course, who doesn't want to try a little larger... Tried 1.05 - boggy and nasty. Okay, just add more air... replaced standard foam filter with a 44mm neck pod filter.

Aah, no longer boggy, actually runs very well, BUT after a few good long rides out I felt that although now louder it was somehow all airy sound and not as much actual GO, as the 1.02 had been; it somehow lacked throttle response and felt "flabby" instead of "tight" (excuse my adjectives, I am struggling to explain!). I also didn't like the air intake sucking sound, and the thought that it wouldn't be filtering the dust as well as the standard foam filter - not good for engine longevity.

So, out with the 1.05 and this time in with the 1.03 that had just arrived as part of my super cheap (3 dollars?) PZ30 rebuild kit that I had bought from ebay just to have in-hand. Put the standard foam air filter back in (nicely cleaned and re-oiled). Oh baby - that's what I like!

I only made this last change yesterday, but I believe I am "sticking", unless it proves very slightly too rich and I go back to the 1.02. She pulls beautifully right through the rev range with this setup, from what I can tell so far; she sounds "tight" and has a beautiful little burble when the throttle is blipped!

Please feel free to offer advice and share your experiences - share the Chinese tuning love!

05-11-2017, 12:44 AM	#1
JimShortz Join Date: Apr 2017 Posts: 7	Tuning my Lifan LF200GY-5 with PZ30 carb I have been doing a lot of lurking on here, but not much posting. Time to fix that by sharing my experience of tuning my four year old Lifan LF200GY-5 X-plore (same engine as the Cross, but different air filter; mine is a nice foam pod within a case as standard). Hopefully my experiences will give some other people a better starting point than I had. So... what I have done is fitted a nice wide-open slip-on that I picked up cheap secondhand (Leo Vince X3), followed by lots of carburettor (standard PZ30) and intake modding. With that exhaust in place, I did the following: First I drilled out the standard slow jet (K40A) a little. I found that the drill #78 (0.406mm) slid through the jet, whereas #77 (0.457mm) didn't. I gently hand drilled it out to #77 size. I did this simply on the assumption that the bike would have been shipped lean to meet emission standards, and the plug certainly didn't indicate running rich. I moved the needle clip down one to increase fuel flow in the throttle range beyond that covered by the slow jet (I tried the bottom clip position too, but this proved to be too much and I went back to second position from the bottom). I reset the mixture screw from 3.75 turns out (how I found it) to 1.75 turns out. This is where my engine runs fastest (as tested with idle screw at higher revving pace than normal). With these three changes the bike ran great from idle through to about two thirds throttle, but hesitant/bogging at higher revs still. Next, to play with the main jet: Mine was marked as 98, but from measuring with drill bits I had it became clear that it had been drilled out to somewhere between 1.05 and 1.1 - I'm assuming somewhere in the middle then, say 1.08. This was not working well, and I wondered if with the new exhaust it might need a larger jet still. I tried drilling it out to 1.1 - even worse; clearly going the wrong way... With an ebay jet kit in-hand I next tried a 1.02 - amazing! Sounds and runs superbly. Time to "stick", but of course, who doesn't want to try a little larger... Tried 1.05 - boggy and nasty. Okay, just add more air... replaced standard foam filter with a 44mm neck pod filter. Aah, no longer boggy, actually runs very well, BUT after a few good long rides out I felt that although now louder it was somehow all airy sound and not as much actual GO, as the 1.02 had been; it somehow lacked throttle response and felt "flabby" instead of "tight" (excuse my adjectives, I am struggling to explain!). I also didn't like the air intake sucking sound, and the thought that it wouldn't be filtering the dust as well as the standard foam filter - not good for engine longevity. So, out with the 1.05 and this time in with the 1.03 that had just arrived as part of my super cheap (3 dollars?) PZ30 rebuild kit that I had bought from ebay just to have in-hand. Put the standard foam air filter back in (nicely cleaned and re-oiled). Oh baby - that's what I like! I only made this last change yesterday, but I believe I am "sticking", unless it proves very slightly too rich and I go back to the 1.02. She pulls beautifully right through the rev range with this setup, from what I can tell so far; she sounds "tight" and has a beautiful little burble when the throttle is blipped! Please feel free to offer advice and share your experiences - share the Chinese tuning love! Last edited by JimShortz; 05-14-2017 at 07:01 AM.
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