Lifan G20-5 built for tough trails

[Shytluk]

Hi, it's been years since I posted anything.

I recently picked up an 08' Lifan G20-5 to do some basic trail riding and it's been great. I got a great deal and it only had 1600 miles on it.

I recently got invited to run with a bunch of guys who do serious hard trail riding. They all run high dollar machines.
But I decided to try to work with what I have so I've been reading up on the forum here and used quite a bit of info to "upgrade" the bike.

I went with the eBay mikuni vm26 carb and jetted it 110 & 25, removed the air box and went with the UNI pod filter. Drained out the factory fork oil and replaced with 275 ml of full synth ATF. Installed a Perelli 110/100 18 MT16 on the back and a Shinko F546 on the front, basically MX tires.
Stripped it down a bit to remove weight but added some back with bark busters and bars.

So were I live is right around 400 feet above sea level and it seemed to be running pretty well here. But this past weekend I was invited on a trip up to the central Pennsylvania mountains where we set up camp at the top at 1800 feet and rode anywhere from 1300 to 1800 elevation. Some climbs were pretty steep 300 foot elevation changes going up hard rocky trails and the bike did not perform well. It was not running that great period up there but these climbs would just bog down the bike unless I had it almost full throttle in first gear.

We got log jammed at one point going up and I stalled, the bike would start right up no problem but it wouldn't take off up the hill on about a 30 degree hill. It would just stall out. I had to turn around and go back down.

I obviously don't have the jetting correct, I tried adjusting the air mixture the best I could up there but with little success.

I'm definitely changing my sprockets for more torque on the bottom end, either a smaller front or bigger rear. But after reading many many threads about jetting I think I may be more confused than ever.

The suspension had a lot to be desired also, some trails were like riding on rocks the size of baseballs or baseballs on sand. It did not like those trails at all.

I rode my buddies Beta 300RR and it seemed to glide over those trails.

Any help would be great, I'm not looking to go fast and have top speed like most guys, I need power that won't bog down right from the throttle to the rear wheel.

Thanks!!

Here's the bike

[Weldangrind]

Counter-balanced goodness! I have the same bike, but the non-CB version. One of the first things I did was remove the tank shroud and the fake rad fins on the downtube.


I agree that it is most likely a jetting issue. Since it was starting well, I'd leave the slow jet alone and just change the main jet to a 105; that should deal with higher elevations nicely.


Does it run properly at your home base 400 foot elevation?

[Shytluk]

It does seem to run a little better. But I did the carb swap only a week before that trip and I really don't have a lot of room around my house to test ride.

I'm going to try putting the stock 100 pilot jet back in since I have it and leave the main jet as is like you suggested. If that's too lean I'll get a 105.

Now I need to try and tune the suspension a little better.

Thanks for the reply, much appreciated.

[Ariel Red Hunter]

Originally Posted by Shytluk

Hi, it's been years since I posted anything.

I recently picked up an 08' Lifan G20-5 to do some basic trail riding and it's been great. I got a great deal and it only had 1600 miles on it.

I recently got invited to run with a bunch of guys who do serious hard trail riding. They all run high dollar machines.
But I decided to try to work with what I have so I've been reading up on the forum here and used quite a bit of info to "upgrade" the bike.

I went with the eBay mikuni vm26 carb and jetted it 110 & 25, removed the air box and went with the UNI pod filter. Drained out the factory fork oil and replaced with 275 ml of full synth ATF. Installed a Perelli 110/100 18 MT16 on the back and a Shinko F546 on the front, basically MX tires.
Stripped it down a bit to remove weight but added some back with bark busters and bars.

So were I live is right around 400 feet above sea level and it seemed to be running pretty well here. But this past weekend I was invited on a trip up to the central Pennsylvania mountains where we set up camp at the top at 1800 feet and rode anywhere from 1300 to 1800 elevation. Some climbs were pretty steep 300 foot elevation changes going up hard rocky trails and the bike did not perform well. It was not running that great period up there but these climbs would just bog down the bike unless I had it almost full throttle in first gear.

We got log jammed at one point going up and I stalled, the bike would start right up no problem but it wouldn't take off up the hill on about a 30 degree hill. It would just stall out. I had to turn around and go back down.

I obviously don't have the jetting correct, I tried adjusting the air mixture the best I could up there but with little success.

I'm definitely changing my sprockets for more torque on the bottom end, either a smaller front or bigger rear. But after reading many many threads about jetting I think I may be more confused than ever.

The suspension had a lot to be desired also, some trails were like riding on rocks the size of baseballs or baseballs on sand. It did not like those trails at all.

I rode my buddies Beta 300RR and it seemed to glide over those trails.

Any help would be great, I'm not looking to go fast and have top speed like most guys, I need power that won't bog down right from the throttle to the rear wheel.

Thanks!!

Here's the bike

Except for the rather garish plastic bits, a nice looking bike. How is the front fork doing since you changed to Synthetic ATF? Some of that harshness in the suspension could be from too much air in the tires. What Pirelli are you running in the rear? Is it the MT-43? If it is, rear tire pressure should be 6 - 10 lbs. If you have a comperable front tire, 4-8 lbs. You will have to have rim locks mounted in the wheels to keep the tire from spinning in the rim. The front is unlikely to slip unless you use the front brake heavily. But the rear will slip from engine power. If you only buy one rim lock, mount it in the rear wheel. Put it so it is diametricaly opposed to the valve stem. Good luck, and keep us posted.

[Weldangrind]

Originally Posted by Shytluk

It does seem to run a little better. But I did the carb swap only a week before that trip and I really don't have a lot of room around my house to test ride.

I'm going to try putting the stock 100 pilot jet back in since I have it and leave the main jet as is like you suggested. If that's too lean I'll get a 105.

Now I need to try and tune the suspension a little better.

Thanks for the reply, much appreciated.

To be clear, the 100 is the main jet. The 25 is the pilot (or slow) jet.

Your bike was imported as a dual sport, so you might be able to get a license plate for it if you wish. That really expands your riding areas.

[wilserchinarider]

Originally Posted by Shytluk

I rode my buddies Beta 300RR and it seemed to glide over those trails.

Well, the Beta 300RR at $8,500 vs an 8 year old china bike likely worth maybe $500. I'm impressed you didn't just see their rooster tails at the beginning of the ride, never to see them again lol. The Beta at 54 HP is over three times that of the lifan and likely 30 - 50 lbs less weight.

All that said, I have the same bike, a 2008 Lifan GY-5 and have likely 10000-15000 miles. A good runner for sure, of course heavy and slow compared with more costly bikes...

[Shytluk]

Thanks Weld, got the jets mixed up.

Ariel, There was a notable difference with the Synthetic ATF in the forks. I really wasn't sure how much to put in though. There was less than 200ml of this really thin dirty fluid in the forks that I believe was from the factory. No leaking seals so that's all that was it it.
There were much more spongy before so I went with 275ml just to try. It seems ok, no seal leaking after the mountain trip.
And I am going to look into those wheel locks for sure!

Wilser, good to know you have many miles on your machine!
Yes, very heavy for sure. Very noticeable unbalanced power to weight ratio compared to the other bikes there. Not nearly as nimble as what I saw other guys doing.

[Weldangrind]

Any interest in dual-sporting your bike?

[Ariel Red Hunter]

Originally Posted by Shytluk

Thanks Weld, got the jets mixed up.

Ariel, There was a notable difference with the Synthetic ATF in the forks. I really wasn't sure how much to put in though. There was less than 200ml of this really thin dirty fluid in the forks that I believe was from the factory. No leaking seals so that's all that was it it.
There were much more spongy before so I went with 275ml just to try. It seems ok, no seal leaking after the mountain trip.
And I am going to look into those wheel locks for sure!

Wilser, good to know you have many miles on your machine!
Yes, very heavy for sure. Very noticeable unbalanced power to weight ratio compared to the other bikes there. Not nearly as nimble as what I saw other guys doing.

I think you are supposed to have 175 cc in each fork leg. If the front forks are not compliant, try less ATF. Changing the fork oil again might be a good idea. It will get rid of remainder of the presurvitive oil out of the forks. Are you running a Pirelli MT 43 in the rear?

[Shytluk]

Originally Posted by Ariel Red Hunter

I think you are supposed to have 175 cc in each fork leg. If the front forks are not compliant, try less ATF. Changing the fork oil again might be a good idea. It will get rid of remainder of the presurvitive oil out of the forks. Are you running a Pirelli MT 43 in the rear?

I really do wish I could find solid information about the fork oil. It wouldn't hurt to change it again you're right, I just wish I could find some documentation that states exactly how much they need. Maybe I'll drain them again and try 200ml which is just about what I drained out of the factory stuff.
I have an MT16 on the rear.

I'll get everything figured out. I seem to have this penchant to try to do more with less.


No Weld, I stripped all of the dual sporty stuff off of the bike. She's strictly for the dirt. I actually wish that I could strip more weight off of it.

I have a Road King to get my pavement thrills.

[Weldangrind]

I recommend that you follow Spud's guidance. I did.
http://www.chinariders.net/showthread.php?t=10266

[Mudflap]

Here's how I determine fork oil level on the upside down Lifan forks:

Support the bike under the engine so front wheel is barely off the ground. Remove fork caps. Lower the front of the bike as low as it'll go which will push the dampeners (with fork caps attached) up. Pour ATF into the forks until the level is about 3" below the top. Raise the bike and screw on the fork caps. Done.

You can do the same thing with the fork tubes off the bike which you'll have to do anyway if you're going to drain the existing fork oil.