Friction Drives

Unsolved Rubix said:
Egor I like the build. I too have a 21cc. Mine was running good till recently.
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Let me know what it is doing and maybe we can figure it out. There are only a few things that can go wrong. I had to lean mine out, I don't remember it running bad on the GoPed but it was rich so it was 4 stroking on top end. There is a small screw on the top of the carb in the middle of the part that moves when you throttle up, in for lean out for rich, only a 1/4 turn at a time. 4 stroking is like how it runs with the choke on. The other thing that it could be is after you have put a lot of miles on one of these engines they will start to plug off the muffler and make the exhaust port smaller with carbon. Let us know and see if we can find out what it could be. Have fun, Dave
 
Egor said:
Let me know what it is doing and maybe we can figure it out. There are only a few things that can go wrong. I had to lean mine out, I don't remember it running bad on the GoPed but it was rich so it was 4 stroking on top end. There is a small screw on the top of the carb in the middle of the part that moves when you throttle up, in for lean out for rich, only a 1/4 turn at a time. 4 stroking is like how it runs with the choke on. The other thing that it could be is after you have put a lot of miles on one of these engines they will start to plug off the muffler and make the exhaust port smaller with carbon. Let us know and see if we can find out what it could be. Have fun, Dave
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oh my motor I am pretty sure had went out because of age. The issue started with it not wanting to run unless the choke was on full or 3/4. It would run normal at that and when i would get it to 1/2 choke I would get a great burst of speed for 10ft or so then it would die asap. Now I have fixed that issue with it but once the engine gets to operational Temp (about 1 mile) the engine loses all power and can only be kept alive by pedaling. after 1/2 a mile you can really feel and hear it losing power. but if I just wanna drive around the driveway and the yard I can get some good speed almost lost it pulling into my work area too fast once haha. So i think the engine is just too worn and when it gets to temp it loses compression hence why my power is out gone.
 
I have a 25cc I bought on ebay (stupid move) It ran but had a carb without any adjustments. I switched the carb and it doesn't start now. I am pretty sure I have an air leak. I think you should check for that as well. If you can get it started at all, just shoot some cleaner or wd 40 on the carb. See if the revs change.

I also drilled some holes in my exhause on the 31cc and it took off and never bogged down that was a new engine and I just wanted more power.

Your muffler may be clogged that is pretty common and it chokes the engine down. You can take it off and pour gasoline through it as long as isnt hot.

Im sure others know even more things to check.
 
If the engine is a real Tanaka they are built pretty tough, they last a long time but there is a limit. I have one that has so many miles on it that the chrome on the cylinder is getting thin and starting to peal, it still runs good, but I know that the chrome will get into the piston and ruin it soon. This engine is old enough that I can't seem to find a replacement part for it. If your engine has no compression after you have run it for a while, you might be able to put in some new rings, but if it is one of the aluminum cylinder with a chrome piston it might be a goner. (Just as a note, the manufactures use these engines on all kinds of stuff, if you use a larger one you get the torque but you don't need the speed, so they restrict the exhaust. You can throttle a 2 smoke at both ends. For an experiment just after you get it started cold put your finger with a glove over the exhaust opening and with the throttle wide open, open the tailpipe with your finger, works just like the carb. Thats why when you punch out the opening you get the power increase. Have fun, Dave
 
Most likely only has one ring. My 33cc chainsaw from poulan only has one and the ryobi's I took apart only had one as well.

Well good luck sorry I can't be more help im still trying to learn about this engines as I go along.
 
Unsolved Rubix said:
oh my motor I am pretty sure had went out because of age. The issue started with it not wanting to run unless the choke was on full or 3/4. It would run normal at that and when i would get it to 1/2 choke I would get a great burst of speed for 10ft or so then it would die asap. Now I have fixed that issue with it but once the engine gets to operational Temp (about 1 mile) the engine loses all power and can only be kept alive by pedaling. after 1/2 a mile you can really feel and hear it losing power. but if I just wanna drive around the driveway and the yard I can get some good speed almost lost it pulling into my work area too fast once haha. So i think the engine is just too worn and when it gets to temp it loses compression hence why my power is out gone.
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I'm wondering if you are running the right oil to gallon ration ?? maybe 20/1 instead of 40 or 50 to one. Or possibly the brand, etc of oil thats being mixed.
 
Right now I am running 28/1 I was running 24/1. I have been trying to lean it out a bit so I can get more power...which is true both happened about the same time.
 
There Were Some Recent Posts On The Forum That Running Too Much Oil (thicker) Causes The Motor To Run Lean.!!?? Anybodies Thoughts On This ?
 
Unsolved Rubix said:
Right now I am running 28/1 I was running 24/1. I have been trying to lean it out a bit so I can get more power...which is true both happened about the same time.
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If that is a FeatherLite... I'm guessing that it's 25cc or close to that. While 25cc will work (I'm using a homelite 25cc), don't expect miracles. If you weigh in close to 100, it will do great. I'm at 230 lbs.. While I can get it to do a nice cruise of about 18 to 20 mph on the flats with a 1 inch drive gear ( friction drive), and it can still help ( a little) over hiway overpasses, it's definitly no hill climber. A smaller drive gear will lower your speed but will help more on the hills. Also you can get a reasonable educated guesstimate of what to expect from other sizes of drive gears.. IE.. 1/2 drive gear will give me about 10-11 mph, but much better help on the hills...

A 1.5inch drive gear will get me up to around 30-35 mph ( with peddling) but is of no help at all on even slight inclines.

Also, pressing the drive gear to the tire... if using too much pressure , uses a lot of the power of the engine and could be causing overheating, which it what the problem sounds like. I did that originally when I made mine, then found if I lightened the pressure, it may slip a lil on the hills, but then it got me me another 3 mph.. I just don't expect it to do much on the hills.

hope that helps..
Handy
 
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It is a 21cc, I do have the 1.5 inch. The most I was getting out of it was 18mph. I weigh roughly 150. I have the pressure worked out on the bike after many many testing drives.

I use to be able to handle some inclines with the 1.5 if I throttled it correctly.
 
I`AM USING 49CC WITH 1 1/4" DRIVE ROLLER. I`M CLOSE TO 300 LBS. (ALL MUSCLE rotfl ) ITS ALMOST TO MUCH POWER. STARTING IN THE GRASS I DON`T EVEN MAKE OVER 1 TURN ON THE PEDDLES AND EASE INTO THE THROTTLE AND AWAY WE GO ! WE GUESSTIMATE IT TOPS ABOUT 45 MPH.:ride2: WE ARE USING THE 78 MM CLUTCH. I AM AMAZED AT THE PERFORMANCE. OF COURSE THE GAS MILAGE SUFFERS. THOSE SMALLER ENGINES WOULD REALLY BE A BENIFIT FOR LONGER CRUISES. ANYWAY , REALLY IMPRESSED BY THESE LITTLE ENGINES.:bike2:
 
Oh ! Forgot To Mention, I Was Planing On Selling These Friction Drives. I Have Bought Approx 10 Of These Motors (new), I Think They Are To Fast !! Will Get Jack Roush To Make Some Restrictor Plates Or Something.
 
I thought the 31cc was hard to wind out. I have only had mine wide open climbing a hill. I'm scared to death of the thing on the flat at about 3/4 throttle. I had it there today and I couldn't see the potholes coming at me fast enough to avoid them.

I rode my test track and didn't pedal once. Then of course things started falling off lol.
 
we clocked the 49cc friction bike with my pickup this afternoon, 35 mph would be very close. i have not ridden it wide open, the guys were saying 45 mph before we checked it. we could use 1 1/2" or larger drive roller for better fuel milage, don`t need more speed, but would get it. ron
 
The 31cc is on that blue junker mt bike with pull brakes on the rear wheel. No front brake. However the 33cc chainsaw bike is on that the orange test bike now. It is set up and it runs, the gravity clutch is rigged and ready. I just need to hook up the uncle kudzu shifter to the throttle and its ready to go.

It has a 20" coaster break wheel. I gave up on the monster huffy, I never could get a good balance with any additional weight anywhere. The huffy is longer than either of the other bikes so it's hard to handle for some reason.
 
NEAT TIMES said:
we clocked the 49cc friction bike with my pickup this afternoon, 35 mph would be very close. i have not ridden it wide open, the guys were saying 45 mph before we checked it. we could use 1 1/2" or larger drive roller for better fuel milage, don`t need more speed, but would get it. ron
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smaller roller = more help on hills, less speed
bigger roller = more speed less help on hills
the normal range is 7/8" to 1.5" on rollers
if you have lots of hills (i do revelstone) use the the smaller sizes.
 
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