holding in clutch all the way?

Discussion in 'General Questions' started by bikes4ever, Mar 22, 2016.

  1. bikes4ever

    bikes4ever New Member

    I just recently got my 80cc motor bike and love it! I have a couple of questions about using the clutch.
    I noticed when I press in the clutch and use the locking pin and while peddling for a quick minute I feel a little bit of resistant.

    Now while at a bike park downtown there's always park rangers and cops on bikes. So I need to peddle for maybe 10 minutes until I pass the downtown area. Is this ok for the clutch or bike?

    Also I noticed when not using the locking pin and pressing in the clutch all the way I dont feel any resistant and makes peddling easier when Im in the downtown (cops on bikes) area. Is this also ok for the bike?

  2. skyash

    skyash Active Member

    Just need to set the clutch / cable and you can ride all day with it in
  3. bakaneko

    bakaneko Active Member

    There are good YouTube tutorials on how to adjust your clutch and eventually you will have to do a full adjustment. Here is guy that gives a brief overview of how to do it. There are many videos to watch on this maintenance procedure. Pressing in the clutch and riding does not hurt the motor...

  4. Hello Moto!

    Hello Moto! Active Member

    Sounds like you just need to tighten your clutch cable a bit. On mine, I pulled it out enough that it wouldn't engage the drive while in the locked position on the lever. Once it's there I draw a little black mark on the cable with a permanent marker so I know just about where to pull the cable to if I have to remove it for any reason.
  5. lazylightning@mail.r

    lazylightning@mail.r Active Member

    Unfortunately it is a design problem in these Chinese bicycle engines. The clutch handle radius should be a little longer than it is. So, if you adjust the cable so that the clutch doesn't rub (create resistance) when you have the clutch handle being held by the pin (not pulled all the way in), then this will cause the clutch to actually slip alot if you have a powerfully modded engine (7 + HP), during extreme acceleration. There is a spring pressure adjustment under the clutch cable post (it is removeable) and it is possible to deal with this problem to some degree by tightening it. Unfortunately it is easy to overtighten it and if you tighten it enough so that the clutch never slips even at optimal cable and daisy nut adjustment (during extreme acceleration), then it means that your spring pressure is so high that your clutch pin will become 4 mm shorter and stop working(even after multiple tightenings) and will have to be replaced every 5 - 6 days with moderate riding. I used special conrod stud bolts for good steel and made several of these stronger clutch pins and tempered them with a blow torch and oil repeatedly. Still yet, with the spring pressure high enough so that the clutch never slips when the clutch handle pin can hold the handle so the clutch doesn't rub and the clutch doesn't slip during high tourque racing like loads, these little special made super tough clutch pins also wear out in no time. So I had to release some of the pressure off of the spring in the clutch mechanism. What I did start doing was to continue using the super tough clutch pins (tempered high strength steel, speed steel), and at the same time I always hold the clutch in manually(when pedaling/coasting). With the cable adjusted so that I have to hold the clutch all the way in to prevent rubbing(resistance), I was able to acheive proper functioning of the clutch so that it doesn't slip when under high torque load/gnarly acceleration -with occaisional wheelies n stuff. Now after I got all of that sorted out, I discovered that with my new big 22mm carb, I could actually pull the clutch in just a little/enough and let it slip on purpose while revving the engine way up there and it will actually begin to accelerate really fast. Incredibly and frighteningly fast! I purposefully started letting the clutch slip a bit to acheive this, but it is all controllable by squeezing the handle how much I feel I need at each mili-second. It does not slip at all if I don't want it to.
    If you have not built your engine for maximum power with a specially tuned pipe, then you can just adjust the cable and daisy nut on the clutch and you will be fine. If the factory personel accidentally forgot to adjust the pressure spring to "within ballpark" adjustment, then you may have to access that hole under the clutch cable post, insert small screwdriver at angle-out(snag the slot) and push the bike back wards 1/2 a wheel turn while the clutch is engaged. You will feel the spring tightening through the whole bike/your hand on the seat i.e.) If you overtighten it, you will regret it. It is very difficult to get that cable threaded back through the cable holder post becasue it is all crimped up from use on the end. So accessing the clutch spring pressure adjustment is not convenient.
  6. butre

    butre Well-Known Member

    I find adjusting the preload to fix the problem pretty well, not just "to some degree"
  7. lazylightning@mail.r

    lazylightning@mail.r Active Member

    I'm glad it works for you, but the preload/clutch spring pressure is only capable of holding up to the super power of a racing engine at full acceleration if it is tight enough. If you make it tight enough so the clutch never slips at full racing power output acceleration and yet the clutch handle doesn't rub when the handle is held by the pin, then it is so tight that it will kill the clutch pressing pin and the beveled shaft that presses it when youpull in the clutch cable. That will happen within a week and that's if you are using specially made pins from special flame tempered steel.

    With most people, the system can be adjusted so the clutch does not rub when the pin is holding the handle in and the clutch does not slip noticeably much. When you get into high output of 7 - 15 HP on one of these China girls, you will definitely notice the slip. The preload(spring pressure adjustment that I mentioned) can help only if you adjust the clutch so it is partially engaged when you have the pin set to hold the handle in. This means you will have to hold the clutch in all the way then if you want to pedal around or coast when you want a guarantee of no slip during high HP output.

    I've built a few engines here and spent alot of time and engineering into this clutch problem. Several other engine builders I know noted the same thing. Actually it is amazing how much torque the little clutch and dry gears on these things can handle. I'm not the only racer to have noticed it. The design just needs to be tuned a little for maximum output engines.

    The best solution will be to weld a little 4 - 5 mm bump onto the handle so that when the pin is pressed in and holding the handle in, then the handle will be really all the way in. Or get a handle that has a little more travel in it. I know that 99% of the people on this forum will never get up over 5 HP and they will never feel the clutch slipping. I go racing up hills like the ones in San Francisco at full speed and weigh about 175 lbs. My bike will pull a wheelie on me if I'm not careful. I had to really tighten up that preload spring to keep the clutch from just slipping out under such loads. But overtightening it would just kill the parts, so I had to loosen it back up a little. Thus I ned to adjust the clutch so that it is partially engaged/rubbing when the handle is held in by the pin and not held in all the way by hand. There is no other way to it.
  8. butre

    butre Well-Known Member

    with the right pucks it takes a fair bit more than 5 horses to make a properly adjusted stock clutch slip unintentionally. my homebuilt inertia dyno measures my bike at around 7.2 horsepower give or take depending on all the hundreds of variables that go into a dyno pull, and I don't get an ounce of slippage using the old black fiber reinforced pads. can barely move with the newer orange pads though.

    the biggest problem with the clutch in my opinion is the cam mechanism is only really useful as a full on or full off system. it's not really designed for feathering. a minute with a grinder fixes the problem.
  9. lazylightning@mail.r

    lazylightning@mail.r Active Member

    I've heard the black fiber pads have rubber in them and that they wear out fast. I rode all the time intentionally pulling in the clutch handle to make it slip while trucking up incredibly steep hills so it wouldn't lose momentum and as much as I abused those orange pads they just dont wear out. At least something doesnt wear out fast on this engine. So what do you mean about "can barely move with the orange pads though"? They slip? That may be why I had to 1. increase the spring tension inside of the clutch mechanism and 2. Adjust the clutch so it is completely disengaged with the engine only when my clutch handle is pulled all the way in.

    Making a gradually rising cam surface for the clutch cable lever to pin cam is a great idea! I do kind of feather the clutch as is, but I concentrate and feel it in my hand. A graduated cam would be just a delight! I'll make one! It would definitely make it less vulnerable to wear, and put less wear on the end of the pin without the sharp edge.

    So you are a serious builder if you've been on the dyno with the bike! Cool! Would you consider making and trying a newer recent pipe design by our man Jaguar? I made one of his pipes and it rocked. Now he has designed a better version. Mine is a little different since it's for higher transfers and exhaust.

    Next build in the works will have a nice big reed. Have you changed the balance and or bearings, rod, etc.? I changed the balance and got rid of the shaking. I'm using a shorter rod, from a Yamaha Jog now(80mm). All Japanese parts. The next big project will be making cylinder inserts from instrumental steel and hardening them while pressed onto a solid form of the same metal, to prevent warping during the tempering/quenching process. A cylinder for an eternity that can be used with any rings. Probably will cast the finned cylinder myself so I can enjoy bigger passages without having to dremel for weeks....
  10. butre

    butre Well-Known Member

    first thing I do when I pick up a new engine is tear it down, balance the crank, stuff the case, replace the rod bearings with bushings, and start porting. I've found so much junk in the cases from the factory that I'll never consider not at least tearing down the engine before running it.

    I haven't experimented with different rods but I've considered it.

    my next motor is going to be sleeved case reed with a mikuni about as big as the jug
  11. lazylightning@mail.r

    lazylightning@mail.r Active Member

    Yes. Honestly these "engines" are just blanks from which a real engine can be made =-) My Kheihin 22mm was huge. I loved it but could not find jets for it and I needed to hit a spot between drill brit sizes where there was a large interval. Only later I learned about soldering wires of varying diameter to the outside of the jet and threading the free end of the wire into the hole. These are hair thin fine wires of known gauges of course.
    Now that I found out that 21mm is the largest size for the 66cc engine with a reed on it, I bought a Dellorto 21mm PHBG, which was basically the only thing that was available on the market due to the small nature of motoparts merchants here and the crisis in effect. There were plenty of jets for it on the market though. I'm happy about the purchase. It cost considerably less than the Dellorto Direct site, it was in all original Dellort packaging and I didn't have to order it from over seas. It was their last one in stock, so I think they were just trying to get rid of it. The Polini CP 21mm was the one I had wanted to buy, but to my chagrin wasnt in stock when I arrived to buy it, despite it having been listed as in stock and I had reserved it.
    So how do those bushings hold up? Have you though about trying techline racing coatings? http://www.techlinecoatings.com/hi-performance/bs-internal-engine-coatings.html I use the DFL-1 coating for moving surfaces and the "ceramic" thermal barrier for the crown of the piston and the inside of the head. Some of the coatings they sell are purchasable only by businesses, but they have everything that the amatuers need. The surfaces of the metal have to be sandblasted by an aluminum oxide grit of a certain size range. Man does it ever change the way the engine runs and behaves. I highly recommend it.