GY5 swing arm mod

Q · 10-18-2008, 09:18 PM

The GY5 has a design flaw that causes the chain to be pulled tighter and tighter as the rear suspension is compressed. Consequently the chain has to be adjusted very loose, 3.25" of play with no weight on the bike, which in turn causes a lot of slop in the drive train. Most or all other motorcycles have a different geometry so the chain gets looser as the suspension is compressed.

Today I removed the engine, swing arm, air box, etc.. and fixed the problem on my 07 GY5. The fix involved moving the swing arm pivot bolt down .5".

First I welded steel plugs into the existing holes. I then added more metal to the bottom of the flange that supports the swing arm bolt and drilled new holes exactly 1/2" lower. After grinding things flat I painted it to match the existing silver color and reassembled.

The result is that I can adjust the chain to 10mm play with no weight on the bike. Instead of the chain getting tighter as the suspension compresses, it gets slightly looser like other bikes. The slop in the drive train is gone and the drive is smoother and quieter.

My conclusion is that the Lifan factory should improve the design by moving the swing arm pivot hole lower by 3/8" to 1/2".

Q

tigertamer · 10-19-2008, 08:07 AM

Did you tell "Super Dave" at A.L.?

Tigertamer

chrism1 · 10-19-2008, 08:28 AM

There is no way you could have improved that setup.Just ask the reps at the American Lifan forum.It is the best it can be, btw we can sell you parts......................someday. :roll:

Q · 10-19-2008, 08:42 AM

I posted the recommendation that the pivot be moved down on the Lifan Forum last year. Also posted about actually doing it yesterday in the Mods section. It's such a simple change that won't cost anything, you would think the factory would have done it by now.

Q

Quote:

Originally Posted by tigertamer

Did you tell "Super Dave" at A.L.?

Tigertamer

TeamCheap · 10-19-2008, 11:34 AM

I'm sure A.L. is very thankful to you and everything but they are still going to break your rice bowl for speaking up to them.They would have caught anyway....once they actually have an engineer there that starts working on these bikes.

A.L. will first ask this question :will improving the bike increase sales ? and what will the improvement cost ? will anybody really notice ?
(they're thinking: drilling the hole in a slighty different spot sounds to expensive and dull----forget about it----up production.....)

Q · 10-19-2008, 01:08 PM

Here's a picture.

Q

Alaskan-Dad · 10-19-2008, 02:38 PM

Cool great mod idea thanks for the pic!
I fixed the html so the pic loads on this page

phil · 10-19-2008, 04:56 PM

boy, you guys sure are tuff on american lifan :wink:

TeamCheap · 10-19-2008, 06:11 PM

That is some nice and simple work to get the swingarm set right, good work Q.

So what is really needed is a kit.
A kit that has a legal, registerable frame that is actually functional and sturdy and properly setup.
A cycle kit that you can put various china bike and other assorted parts onto to make a very decent bike once its all together.

I still think putting a new chinese engine into an old honda frame and resurrecting the bike is far better than buying a new china bike.(JMO)

Jim · 10-19-2008, 06:33 PM

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Quote:

Derogatory comments against Chinese bikes

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10-18-2008, 09:18 PM	#1
Q Join Date: Sep 2007 Location: Bend, Oregon Posts: 348	GY5 swing arm mod The GY5 has a design flaw that causes the chain to be pulled tighter and tighter as the rear suspension is compressed. Consequently the chain has to be adjusted very loose, 3.25" of play with no weight on the bike, which in turn causes a lot of slop in the drive train. Most or all other motorcycles have a different geometry so the chain gets looser as the suspension is compressed. Today I removed the engine, swing arm, air box, etc.. and fixed the problem on my 07 GY5. The fix involved moving the swing arm pivot bolt down .5". First I welded steel plugs into the existing holes. I then added more metal to the bottom of the flange that supports the swing arm bolt and drilled new holes exactly 1/2" lower. After grinding things flat I painted it to match the existing silver color and reassembled. The result is that I can adjust the chain to 10mm play with no weight on the bike. Instead of the chain getting tighter as the suspension compresses, it gets slightly looser like other bikes. The slop in the drive train is gone and the drive is smoother and quieter. My conclusion is that the Lifan factory should improve the design by moving the swing arm pivot hole lower by 3/8" to 1/2". Q
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10-19-2008, 08:07 AM	#2
tigertamer Join Date: Jul 2008 Location: Wheeling, West Virginia Posts: 683	Did you tell "Super Dave" at A.L.? Tigertamer __________________ 07 H-D XL883C 06 LF 200GY-5 Yin and Yang CAUTION Obey The Traffic Regulation. Always Wear a Helmet. Don't Ride After Drinking Wine. Before Operation, Read The Owners Manual Carefully.
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10-19-2008, 08:28 AM	#3
chrism1 Join Date: Sep 2007 Location: Bevely Hills,Florida US of A Posts: 138	There is no way you could have improved that setup.Just ask the reps at the American Lifan forum.It is the best it can be, btw we can sell you parts......................someday. :roll: __________________ Lifan LF200GY-5
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10-19-2008, 02:38 PM	#7
Alaskan-Dad Join Date: Sep 2008 Location: Thorne Bay SE Alaska Posts: 131	Cool great mod idea thanks for the pic! I fixed the html so the pic loads on this page __________________ Three Greys Lifan GY-5's
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10-19-2008, 04:56 PM	#8
phil Join Date: Jun 2008 Location: wise va Posts: 636	boy, you guys sure are tuff on american lifan :wink: __________________ halls auto l coolster, modcycles, yanmar & zongshen, dealer fired roketa,lifan and jet moto and apollo quit me who's next
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10-19-2008, 11:34 AM	#5
TeamCheap Join Date: Jun 2006 Location: directly under the earths sun............NOW Posts: 2,302	I'm sure A.L. is very thankful to you and everything but they are still going to break your rice bowl for speaking up to them.They would have caught anyway....once they actually have an engineer there that starts working on these bikes. A.L. will first ask this question :will improving the bike increase sales ? and what will the improvement cost ? will anybody really notice ? (they're thinking: drilling the hole in a slighty different spot sounds to expensive and dull----forget about it----up production.....)
	0

10-19-2008, 01:08 PM	#6
Q Join Date: Sep 2007 Location: Bend, Oregon Posts: 348	Here's a picture. Q
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10-19-2008, 06:11 PM	#9
TeamCheap Join Date: Jun 2006 Location: directly under the earths sun............NOW Posts: 2,302	That is some nice and simple work to get the swingarm set right, good work Q. So what is really needed is a kit. A kit that has a legal, registerable frame that is actually functional and sturdy and properly setup. A cycle kit that you can put various china bike and other assorted parts onto to make a very decent bike once its all together. I still think putting a new chinese engine into an old honda frame and resurrecting the bike is far better than buying a new china bike.(JMO)
	0