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Valve clearance for 125cc Lifan engine.

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Hi. Usually .003-.005. Set mine at .004 ...no noise at all should be heard from valves .. no clatter

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My engine is chinese made, (SSR) copy of honda or yamaha mini 125 cc motor,  It should be close to the same valve settings, but you should check with engine manufacturer.  heck even 250cc bikes are .003-.005 mm, Millimeters not inches.  Again, very little noise detection of valves is ever heard, if more than that, you need adjusting right away.  Note: too tight of valves with little or no clearance, robs you of power, and makes no noise.  A big gap, of lets say .007 or bigger, will make noise as rocker arm hits top of valve stem.   I have heard looser settings (bigger gap) give you more power due to less time for the cam to be pushing against the valve equals higher RPMs.  I HEARD.. but its not good for engines life expectancy, and can burn a valve.  So while adjusting valves, lean towards the larger setting, within limits, like .005 as a MAX. When manufacturer suggests .003-.005 mm.   Tappet noise can also be from worn out oil, and or too light of oil, or not enough oil.  I change oil about every 15 to 25 hours of riding time, or about once a month, depends on how much your ride and how hard you rev that motor.  keeping track of running time is hard to do, mostly its guessing, but if you do not remember when your last oil change was, ITS TIME to do it.  haha

Have fun riding.   Keep off the ground too.  

Gary

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Thanks Gary,

I did my valves and no more clatter, it feels like it has a bit more power to, could it be because having a smaller clearance increases how far your valve goes in, which could increase how much fuel goes into the cylinder??

Cheers Jake :)

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Yes to a point. If too tight the valve will not close in time. It can get burnt too stay

within spec's. I too had horse power increase. Have fun jake

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Jake, I got an intake manifold trick for you, that should add some horsepower to your bike.  Its simple no cost improvement. If  you have a Dremel tool or one like it, or even an ordinary drill will work.  Buy a dremel tip, that has a round end, and or looks round or almost round. you put DIVOTS into the metal of your intake going from the carb to the engine.  These Divots look just like what you see on a golf ball, make them like that, put as many of them inside the metal intake as you can reach with your power tool. Take care to not go in too deep, because the metal is thinner than it looks, (less than 1/8th inch I think). A 1/16th inch deep divot should work fine.  What does this do you ask?  As with a golf ball, the divots allow air to move over a surface easier, faster.  This will improve the amount of gas from the carb to the intake to increase, it also increases the total volume of the intake.  This allows more gas to get into the cylinder per each opening of the valve.  You should not need to rejet afterwards, you might notice you pop wheelies easier once done.  Take care to not damage the gasket between the engine and manifold, the other end at the carb has a rubber "0" ring, and will be ok on removal. IF you do damage the thin gasket, you must go buy GAS proof, high temp gasket maker at auto parts store, for about 7 bucks to fix the gasket,  Reuse the gasket but apply maker to both sides of it.  Once done.. check for possible air leaks by running the bike, and dripping or squirting on the intake areas gasoline, if idle goes up, or down you have a leak that needs fixing.. take care to do this in ventilated area with fire extinguisher near by.    You should always have one near you bike anyway.  Check out the pictures, I probably could have saved 1000 words, ha ha   HAVE fUN.

intake dimples.JPG
Air fuel screw.JPG   I also show where the AIR fuel adjustment screw is located.  turning out from stock 1/2 turn (richer) will help in throttle response, and cut down on backfire on deceleration. Total turns out about 1 1/2 to 2 turns out from dead stop. (that is when you turn in the adjusting screw all the way to the STOP)  just incase you did not know.. no insult intended at all.  
Does your bike steer ok in dry sand?  mine does not, and i am working on the problem.  Mine sorta is all over the place and requires constant input to go straight.  SUCKS.  Also after each ride I keep finding loose nuts and or bolts, last ride it was the locking ring on my rear shock adjuster that came loose and the spring was just bouncing around between the stops with NO pre load at all.  Keep an eye on rear drive sprocket bolts too, the lock tabs are not doing their job, bend them over more, and check for a loose one first. .
Now go have some garage fun, then go ride.

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Hi Gary,

I will definitely give that horse power trick a go, as I am always in the need of more power :)

But I have never had any problems with loose bolts on my bike and my bike was a $400 new off eBay, it came with lock tite on some bolts too, if I was you I would lock tite the bolts that come loose. My bike handled badly in sand due to the tread pattern that came with the bike, I put on a Vee rubber 60/100 14 on the front and a Vee rubber 80/100 12 on the rear, with these tyres it makes the engine work harder going thru deep loose sand but it handles perfectly. The thing that onnoys me with my bike is the chain needs adjusting every hour or so, is it because the chains are bad or are the adjusters not holding?

Cheers Jake

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Hi, as soon as I am sure I can not get a 17 inch front wheel for my mini, I will buy the tires you spoke of.   My bike cost 1250 delivered and delivery was free..  I sure feel like I got ripped off some, for like 400 bucks, there just was not 400 dollars worth of extra parts on it.   OH well..  crap does happen.  ha ha

Most of my bolts had lock tight on them too.  Maybe I ride it too hard.. ha ha  fat chance of that.. but I do push it to go as fast as I dare, so I can learn the bikes handling flaws and good points.  so far its steering, it totally sucks. I got two more items to try yet, like lowering the fork tubes about 1/4 inch into the triple clamps, thus changing the rake some.  it acts like there is too much weight over the front wheel.  I got the rear sac at as much as possible, to lower the back of the bike, but that is not helping, so probably is not the problem.   Someone said put 20 pounds of pressure in front tire...  shit, why not.. worse that could happen is I will wash out allot. 

   yes the chains suck, its cheap Chinese iron that is the problem, they cant make a nail for construction that wont bend, why would I think this steel would be any better than there nails are. ha ha  I have to adjust mine every two hours of ride time. Eventually it will NOT need adjusting very often, when it gets to this point, take it off, its about to break because it can no longer stretch out.  I lost center cases on my race bike because of that little mistake.  So as soon as you no longer need to adjust the chain get a new one.  a DID or Diamond, or RK, or some other top of the line brand, do not put another chinese one on, or any cheap chain on.  Never use roller bearing "0" ring chains either, they eat up horse power and are basically for street bikes not dirt bikes.

   There is some issues with the adjusters not staying adjusted, trick: once you loosen the axle nuts, tap on right side nut to  push axle in a little bit through to be sure it is loose. now, loosen the adjuster locking nut. OIL everything so it all moves smoothly, (wd40) adjust each side a little bit, like one turn each time, until chain is at recommended sag, usually one full inch not less, not more than 1 and 3/4 inch play from pushing it up, then all the way down, (at middle of chain) that distance should be about one inch and a quarter... one inch is ok too, since our chains get loose really fast. now, to set the locking nut, this is tricky part. if you just tighten them where they are, it will come out wrong. You now need to just SNUG up the axle nut, not tight, then HIT (KICK HARD) the back of the wheel with your foot, pushing it inward to seat the adjusters against the stops, NOW tighten the axle, and re check the adjuster to be sure they are still snug.  Check alignment of chain at this point, stand behind the bike about 10 feet back, eye up, right down the center of chain rollers, to see if they are in line with the front sprocket and back sprocket.  IF so, you are done.   OILS, I use first WD40, to penetrate, then wipe grit off with nylon brush, then put regular chain lube on, let it SET UP, then put Axle grease on the rollers, rubbing it in the rollers from top and bottom, and the chain will stay lubed longer.  IF when you get back your chain is shinny, it is dry of all oil at that point, and wear takes place.  You can also use 90 weight gear oil for car manual trannys, followed with Chain spray, that will set up stiff when dry, thus locking in the oil some.   Chains should be removed after every long ride, (or every 5-7 hours) washed in gasoline then kerosine, then drip dry, soak over night in OIL, 40 to 90 weight over night or for as long as you can, then spray it with chain spray, followed by axle grease.  that is the best you can do for any chain.  When you buy a new chain, I would wash off the manufacturers oils, and soak it in oil over night, like when you cleaned the old one.

  My chain is not requiring much adjusting now, so its time for me to go buy one and be ready. But first I must make it steer, or I will be forced to sell it, to someone that will ride it slow.  ha ha

Have a good one.   Time to go turn some wrenches to be ready for the next ride.  I should call it TEST ride.. 

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Hi Gary, sorry about all my questions, I was wondering if I put a bigger carb on my pit bike engine would it make it more powerful, and if it would, what size would you recommend. As the carb I am currently running is a jingke carb and it is a 19mm carb I think and it is probably to small because I hear a sucking sort of noise from the carb.

Thanks, Jake.

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I posted a solution to your chain tension issue but in the wrong place so here it is.. found these in a random parts bin at a local bike bone yard for 5$ and drilled and tapped for carriage bolts just cause I have lots. Now I don't even need to loosen the back wheel to adjust tension. Just make sure if you try this to account for the width of the tensioner and remove or replace washers to keep the wheel in line.

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Mikuni Carbs are the best way to go.  I would try 24 mm or 26 mm not bigger, it wont help.  You probably will end up reducing all the JET sizes to get it tuned right, thus defeating your purpose of increasing power with bigger carb.  I believe mine is only 22 mm aftermarket copy and not a Mikuni, but a copy of one.  You are limited by size or volume of intake manifold, and valve intake sizes.  IF you could increase those sizes too, then ya got something going in the  horsepower department.   Maybe someone made a CAM for it.. if so, let ALL of us KNOW WHO and Where to get one.

Thanks

Gary

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Hi Gary and others,

You can get a more aggressive cam on TB Parts, they sell tons of upgrades for Chinese pit bike engines like domed pistons, bore kits, carb kits, engine breathers, cams and heaps more. They sell heaps of cams for all types of 125cc Chinese engines.

Jake

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T Bolt?  as in TEE Bolt, or as in TBolt.   I assume they sell after market parts.  I think I shall check that out NOW.   

* I test rode my mini for about 20 minutes for front end problems and none showed up,but I really was only on a loose sand, dry dirt road and those are not a problem for my mini, its lots of loose rocks and deep dry sand I have yet to test ride in.  As suggested by others, I lowered the fork tubes about 1/4 inch, yes recessed into the triple crown, then added recommended 20 psi of air for the front tire, followed by 12 cc more fork fluid making the total for inverted forks to be 222 cc each leg. of 20 weight.  Sure wish I had adjustable forks, like the AD said came with the bike.  which to me, sucks, or I read it wrong, or they listed my bike wrong at the sales web page.  Still checking on that one..

* thanks for the CAM and other aftermarket parts location, I will go there now and check it out.

And as always, rubber to the dirt, not to the sky.. ha ha

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