The Lifan engine thread

Discussion in 'Battle Scooters' started by hugemoth, Feb 22, 2011.

  1. Cat0020

    Cat0020 El cheapo

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    Nicely done!
  2. ErikDK

    ErikDK Been here awhile

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    Now you can get up to 50MPH quickly, and the drum brakes will allow you to enjoy high speed for a long time. :)
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  3. AGAUBERG

    AGAUBERG Adventurer

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    Looks awesome. I just bought the same engine myself for my '81 Passport C70 swap. Things are coming along. I only fired up the bike once, but I noticed the same thing with the throttle. It would idle fine, but as soon as I twisted the throttle a 1/4 turn, it would bog and die. I saw that you ordered jets from jetsrus, but when I checked their site, I wasn't sure how to search for the right jets for this carb/engine. Got a walkthrough?

    Also, love what you did with the main/reserve petcock mount. I was thinking about how I was going to do that. Thanks for the tip!
  4. CA_Strom

    CA_Strom Cunning Linguist Supporter

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    Yes you definitely need to up the jetting on the clone carb supplied with the Lifan motor. Check the needle jet too, mine came shipped all the way rich, so maybe they were trying to make up for the shoddy jetting. I ordered the jets that DRconvertible spec'd in his Passport/Lifan thread:

    **38 and 40 pilot jets (Keihin 3J style) from www.jetsrus.com
    **105, 108, 110 main jets (Keihin N424-35 style), 3.9mm threads from www.jetsrus.com

    These fit my clone kit carb perfectly. Just search jetsrus for those models. The 110 main seems just about right, so you probably don't need to bother with the 105 and 108. I'm running the 38 pilot right now, and it still stumbles a bit off idle, so I'll be trying out the 40 pilot this week.

    The petcock mount is working great. I just used a small piece of predrilled aluminum strap you can find in the hardware bins at Lowes.
  5. mischief

    mischief misadventurer

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    So, you guys have inspired me. I'm wanting to put one of the lifan 140 motors in my ct90. I looked on ebay and there seems to be 2 different ones, one shifts 1 dn 3 up the other shifts 4 up and says it can start in any gear. Does the 1dn3up not start in any gear? The 1dn3up is also about $100 cheaper than the 4up. I've also read of dissatisfaction with the 150 motor due to hard starting. Is the 150 no longer available or is it renamed 140?
    Thanks
  6. hugemoth

    hugemoth Big Brother is watching you!

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    4 up just makes it easier to get into neutral but 1 down/3 up is what mine is and works fine. The 150 has quite a few differences from the 140 which can also take some effort to kick over and tends to kick back. Not a good engine for a light weight person with whimpy legs. There were some 120cc engines sold as 140cc so be sure you get one of the real 140s that have an engine number prefix of 155FMJ.
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  7. mischief

    mischief misadventurer

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    Thanks hugemoth, I've eyed your bike with jealousy for long enough. The one I ordered has that prefix. I'm fine with 1dn3up. I was just wondering if the other model was worth another $100. The 4dn shifting was one of the things I really didn't like about the stock motor. Not that it was bad in itself but it was always a little confusing to go back and forth to other machines. If you don't mind more questions, I see you have a cooler mounted above the head. Where did you source it and is it necessary? Also do you use a regulator/thermostat with it or just let it full flow all the time?
  8. hugemoth

    hugemoth Big Brother is watching you!

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    The Lifan 140 is designed to run with an oil cooler and has output and inlet ports on the crankcase. Yes, it's necessary although I've heard of people running just a bypass hose in very cold climates. Do not start the engine without either a cooler or bypass hose installed or the cam won't get oil flow. Source for the cooler is ebay searching for pit bike oil cooler. Usually about $30. Don't trust the hoses that come with the cooler, get some made at your local hydraulics shop. There is no thermostat in the system, oil is always flowing when the engine is running.
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  9. mischief

    mischief misadventurer

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    Thanks, I'll be back :y0!
  10. kirkallen143

    kirkallen143 Adventurer

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    WOW!! Must be something in the air/water, I am doing the same thing, but with the Piranha 140cc. Only thing, the oil cooler is optional on the Piranha (as told from Vince at TBolt). My will be a dedicated trials/trail bike (yes, something similar to Scott Kirn's version he built some time ago). It is a slow going process, especially as money permits.

    - Piranha YX140 engine w/ 22mm Mikuni carburetor, 4UP gears
    - SL100 forks and triple tree using AllBalls stem bearings (cut stock springs 1" and added 2" preload spacer)
    - CL100 swingarm extended 3", relocated mount on frame 1 1/2" lower
    - '66 CT90 rear hub with 68 tooth overlay sprocket
    - Stock hubs laced to 21"/18" aluminum rims (with a little help from Buchanan Spoke): in process
    - Handmade welded aluminum fuel tank (@ 3/4 gallon): in process
    -- Should have a roller hopefully next week, minus tires.

    What I got so far, more things to come as soon as my mind thinks of them.

    Good luck on your conversion mischief...

    Kirk
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  11. mischief

    mischief misadventurer

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    Cool. I have a 68t sprocket that I'll trade for a 40t, or buy it outright if you or anyone else has an extra. I haven't decided exactly what to do with my swingarm yet. I think I could lengthen the ct one but I don't know that I'll need to. I want to retain the cush drive and the fixedtotheswingarm sprocket carrier. I'm not building a trials bike so much as a trail bike. Something I can ride where I would ride a mountain bike. My f'ed up knee won't let me ride mtb's like I used to.
  12. kirkallen143

    kirkallen143 Adventurer

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    Man I heard ya on the F'ED up knee, had a fun little accident on a '84 KTM125 vs. a 2" diameter vine hanging from a tree back in the '90s. Guess who won? Even after ACL surgery, still f'ed up and I can't find a good knee brace/support that doesn't cost out the wazoo. Give me a couple of Aleve, a Walmart brand knee brace and let's get to ridin'!

    Thought I'd give a couple of progress as of yet photos:

    [​IMG]


    [​IMG]

    Have a good one,

    Kirk
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  13. mischief

    mischief misadventurer

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  14. mischief

    mischief misadventurer

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    What jetting are you guys running? I'm at 5000'. I'm asking for both a 125 semi auto and for a 140. On the 125 I'm using the keihin that I had on the 90, I think it's a 19mm. I have a 72 main that is too small and one that is bigger but I can't find a # on it that is better but also too small. I have the needle all up and it idles and picks up ok but won't spin. I haven't decided what carb to use on the 140. I have one of the mikuni vm22's
  15. hugemoth

    hugemoth Big Brother is watching you!

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    I use a 94.5 main jet in the 26mm Keihin copy carb on my Lifan 140. It has a foam Unifilter and pit bike muffler with little restriction. It's been run this way for over 11,000 miles with good plug color. It's important that the carb outlet, intake tube inlet and outlet, insulator block, all have the same internal diameter with no steps, which is 26mm on the 140cc head. I think the 125cc engine uses the same head. There are intake tubes which are 22mm on the intake end and 26mm on the outlet which should work fine for use with a 22mm carb.
  16. mischief

    mischief misadventurer

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    Thanks. You're in Bend, right? 4000ft? I think someone was saying #110 at sea level but I don't remember where I read that. I ordered some jets in that range so I guess I'll just experiment until I get it right.
    I put a 125 semi auto in my '68 and I'm putting the 140 in my '69. The second install was certainly easier than the first :dunno but the '69 is getting some more serious modifications than just the engine
    The 125 runs ok but I think a little bigger main will improve it. I ordered a 26mm Keihin for the 140 so when I get it the 94 main jet should be about right

    [​IMG]
  17. hugemoth

    hugemoth Big Brother is watching you!

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    Yes, 4000' but I've used the same jets from 200' below sea level to 10,000' above. The 140 requires premium gas at anything below about 6000' but at least it gets great gas mileage.
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  18. CA_Strom

    CA_Strom Cunning Linguist Supporter

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    On my Lifan 125 I'm using 38/110 jetting with the needle in the middle position and it runs great. That's on a 22mm clone carb that came with my kit and the stock ct200 air box. Pretty close to sea level here in So CA. I have a 14t front sprocket and I think I'm going to go up a tooth or two to get more top end. There's plenty of torque down low.

    Today I finished up the wiring and got the battery back in the bike. I used a two position, 4 wire, ignition switch from the good Dr to replace the OEM ct200 3 position switch. That works great and I added a start/stop switch on my bars as well since the Lifan harness had a hook up for it and I had a switch. I can now shut down with the key or switch.

    I used the 12v-6v regulator from the Dr and that went well. Very bright brake and neutral light now. For some reason, no headlight. I think I missed a connection and I'll have to chase that down.
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  19. mischief

    mischief misadventurer

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    So any thoughts as to why a 125 needs a 110 main and a 140 needs a 95 main? Other than elevation? Both small keihin clone carbs?
    I used the 12-6 volt r/r on my '68 with the 125 also but I'm just using a on/off toggle for a kill switch and another for the lights
  20. Pete-NZ

    Pete-NZ Long timer

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    pilot jets.... the pilot jet keeps working though the whole rev range...
    Pilot jet dosn't shut off as the revs increass... '
    so if you have big pilot jet you need a smaller main jet..
    it's the combined size of both jets.....



    ..
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