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Message started by justin_o_guy2 on 01/13/21 at 15:42:56

Title: Begging your pardon.
Post by justin_o_guy2 on 01/13/21 at 15:42:56

I got a Lifan 200 CC Xpect dual sport. It had under700 miles. It's not at800 yet.
The chain had not been serviced and was so sloppy I was feeling the links catch on the sprocket and dismissed the surging as a carburetor issue or the chain. Later I discovered the little thing is injected!!
Coupla days ago it stranded me at the store. It started, but it would only idle around500 rpm and then when I gave it gas it died. After about an hour of poking and trying, it fired up and acted like it had from the first time. Hold the throttle still. Watch the teach wobble JP and down sweeping more than400 rpm.
I've slipped the wires to an LED into the fuel pump connector. It lights when I turn the key on, till the pump kicks off. Start the motor and the pump gets continuous power.
I've disconnected and used electrical connection grease on every connection I can find fuel pump, coil, throttle position sensor, oxygen sensor, injector. Total of nine,,
I pulled the throttle position sensor and tried to get electronic contact cleaner in it.
Next step is to put some jumper wires into the throttle position sensor connection and see if I can see the resistance changing there. If not, the only thing I can see to look at is the crankshaft position sensor.

The symptom is not unheard of at all with these.
I have no idea where the
Computer, if it exists and can be called that, is located.

Anyone who knows about injected stuff and can offer advice
Please call me
Junior Samples
BR549

Title: Re: Begging your pardon.
Post by Gary_in_NJ on 01/13/21 at 17:03:44

My FZ6 is fuel injected. When the key is turned on you can hear the fuel pump pressurize the system (40 psi) and then the pump goes idle until the engine fires. Idle speed is adjusted by the ECU by reading the coolant temperature. There is a sensor and if it fails, the default is a low idle.

Title: Re: Begging your pardon.
Post by DieselBob on 01/13/21 at 18:16:39

Don't know this bike at all. But, if I'm understanding the symptoms you're describing, it's the inability to come off idle and a drop in RPM when advancing the throttle. Is that correct?
Appears to be a license built (or knock-off) of the Honda CG125 (you'll still find some of the internal parts stamped CG125). One thing to consider is a faulty CDI. Instead of advancing, they allow an idle, but fail to advance and begin to miss-fire when advancing the throttle, as evidenced in the drop in RPM (these fire every revolution and the dropped firings are causing the tach to drop). If you had a catalytic converter on this bike, you'd see a cherry red cat from it's burning of the hydrocarbons that weren't burned in the combustion chamber due to the faulty firing of the CDI. Not at all uncommon with this engine.
I know it sounds weird, but for a few bucks it's a cheap rule-out in the diagnostic process and saves chasing a bunch of phantom symptoms. It was puzzling to me until the drop in RPM started to make sense when I first encountered them. Likely something like the one below. Your Lifan dealer should have a whole bin of them.

https://www.ebay.com/itm/6-Pin-CDI-Unit-Ignition-CG125-150cc-200cc-250cc-Go-Kart-Dirt-Bike-ATV-Honda-/254600135654?vxp=mtr&hash=item3b4759c3e6

Title: Re: Begging your pardon.
Post by justin_o_guy2 on 01/13/21 at 19:25:25

No...
It hunts up and down, no matter where the throttle is
Held steady.
It would not run when I came out of the store.
It would Start, but idle rpm was so low it was unable to accept a throttle bump.

Title: Re: Begging your pardon.
Post by Armen on 01/14/21 at 21:22:07

Not trying to be mean, but basically you are saying you bought a cheap POS and it sucks, yes?
And you are surprised?

Title: Re: Begging your pardon.
Post by justin_o_guy2 on 01/14/21 at 21:53:48

I don't TRY to be short.

I just AM..

Interpret that how you will.

I'm not surprised. Or shocked. This problem isn't unheard of. I have been without a bike for over a year. I have enough parts to get one going, but the body just isn't willing to do that work in a reasonable amount of time, so, I grabbed this. It was obvious it needed something, but it Being such a cheap POS I didn't think it was injected and I thought I could Richard with the carburetor, adjust the chain and smooth it out..

Ooopsies...

Next step
Test throttle position sensor
If it's not changing values from vibration
Then crank position sensor

Since it idled with the TPS disconnected but was hunting up and down, I'm expecting it to pass.

Owners manual says they have a magneto,,
I'm not defeated, yet, but it's been disappointing to do so much and affect it exactly zero.

Title: Re: Begging your pardon.
Post by Dave on 01/15/21 at 03:14:08

With so many good used motorcycles available at bargain prices - I am never tempted to buy a Chinese clone copy bike. I would prefer to go with proven reliable Japanese motorcycles......or maybe even a Buell!
https://cincinnati.craigslist.org/mcy/d/cincinnati-2001-harley-buell-blast/7258858776.html

https://cincinnati.craigslist.org/mcd/d/cincinnati-1981-honda-cm400-custom/7259371245.html

https://cincinnati.craigslist.org/mcy/d/morrow-suzuki-gs500f/7255431749.html

I wonder if ditching the fuel injection and installing a carb would be a better way to resolve this issue? The Lifan engines are on a lot of motorcycles with carbs.......maybe you can find one. OR - maybe a carb for a lawn mower or chain saw would be possible? Try to get a carb for a similar engine size and HP, and also the same engine type (2 or 4 stroke).

Title: Re: Begging your pardon.
Post by justin_o_guy2 on 01/15/21 at 12:23:27

Dave, that's a direction I had not even considered!
Gonna hafta digest that a while.
Thank you.

Title: Re: Begging your pardon.
Post by springman on 01/15/21 at 16:53:10

Those are some pretty good prices you found on those bikes. For a while I was considering a GS500 but never found a decent one at a reasonable price.

Title: Re: Begging your pardon.
Post by Dave on 01/16/21 at 03:53:12

121113080F060C000F610 wrote:

Those are some pretty good prices you found on those bikes.

If you are not picky about whose names is on the tank or how many HP the bike has - you can buy some well cared for and reliable bikes at good prices. You can even get nice a nice BMW or Sportster in the $3,000 - $4,000 range. I live in a rural area with several large cities within a 2 hour drive (Cincinnati, Louisville, Lexington, Columbus, Dayton, Indianapolis) - there is a huge number of motorcycles for sale in this area.

If I had more garage space and the state didn't charge me yearly taxes on each one that I own.......it would be fun to have a few more!
https://cincinnati.craigslist.org/mcy/d/cincinnati-1981-honda-cb-125s-cafe-style/7258910539.html
https://cincinnati.craigslist.org/mcy/d/cincinnati-1975-honda-xl250-enduro-dual/7257347560.html