Latest Lunacy--Honda CT70 Clone Build
- Thread starter cannonball2
- Start date
Thanks RC! Got more parts in yesterday, if I can get free from other duties, hope to move it along some more.
Got the repaired/modified engine back together. Cleaned the bike a bit as it has been sitting a while. Hung the engine. Installed the Sportsman sprocket adapter. Finished the pedal crank assembly and cut and installed the pedal chain. Threw on a temporary seat and bars and pedaled around a bit. Was super happy with my work until I found the corner I usually back myself into. There is slight interfrernce between the right crank and the kick starter. I can actually crank the engine as it is, but it aint right. So either I shorten the right side pedal shaft or bend the kick lever- to be figured out a bit later. Thats what happens when you use an electric start only(no kick lever) engine as a mock up. Oh well keeps it interesting. Im really liking the simplicity of this bike. I bought a 2 gal. chopper gas tank called an axed alien, I think back in the day we called em an alien egg. If the measurements given on the listing are correct should fit pretty well, if not I will ride it any way. Gonna paint the black side cover silver, for some reason black ones were nearly 10 bucks cheaper! Got a set of pull back beach cruiser bars and another leather seat on the way for it.
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Heres a pic of the tank on a Triumph chopper. Dimensionally it fits the bikes top tube well. Just hope it doesnt look too big.
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If the tank you ordered looks too big, your tubular pvc tank would look good hung from the top bar.
SB
SB
Strangely SB, I have an under the bar tank made from 3" exhaust tubing from another build so I guess I have it as a back up. I had thought about building a fitted tank to fit in the triangle section of the frame tubes, but I find tank building more of a PITA than the bike build. Guess we will see how this tank fits. This is a functional type bike and though looks are always important to an extent they are not the primary focus of this one. Up side is its a 2.1 gal tank-lotta range! Am only gonna draw fuel from one side. The fuel left on the other side of the tunnel will act as a reserve tank. When you run out you just lean the bike on its side to get the fuel to the drawn side, then search for a gas station.
A little more done. Got both chain lines finalized. Got the belt installed, trimmed the side cover. Hung the exhaust temporarily. The tank came and I think its about right, maybe a tad large, but I like it and the fact its 2 gals. Still waiting on the cruiser bars, will change out the stem at the same time. Seat came, might be a tad out of period, but these seats are so darn comfortable and a deal @ $34.
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Excellent job CB! I always enjoy your projects.They are always unique and your innovative use of materials and methods are very interesting and inspiring.
I think you're right about using a belt primary to "cushion" the drive train.
Who is your vendor for the seat?
I think you're right about using a belt primary to "cushion" the drive train.
Who is your vendor for the seat?
Thanks for the comps Wayne! Heres the seat listing. http://www.ebay.com/itm/280803449616?ssPageName=STRK:null:IT&_trksid=p3984.m1542.l2649
Bike is basically complete now. Still needs a few details like fuel fittings and line and a throttle cable. Had to order a manifold rotator to get the carb to clear the frame tube. Its several days away, so just put it all on hold for now. Got the side cover painted. This bike has an adjustable pulley for ratio adjustment. Has a range from 3.5-4". An unthought of benefit is that it will tension the belt with out an idler, much the same way as a VW Beetle adjusts the fan belt tension(it uses shims but is a similar concept). I have one belt for high range, and another for low range, Changing them is as simple as unscrewing the pulley. Not as easy as a spring idler but much cleaner. Tank looks more in proportion now with the bigger bars.
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Well got this thing up and running. Had to wait several days on the tank sealer to cure. I am really blown away by how well it has worked out. The cobbled together junk engine runs perfectly and my one speed auto clutch drive works great. I started with the low 16+:1 ratio and found it too low for cruising. Would actually work perfect for easy trail riding, its between say 2nd and 3rd on a 4spd. The higher ratio in the 14:1 range is great, top speed of 35(wound tight) gentle cruise at 30, and good hill climbing capability. Pulls with authority from stop. The engine will pull a higher ratio for more top, but I was looking for a relaxed cruiser. This actually is a legal bike if believing the 48cc cast into the cylinder. I guess they bored 48cc cylinders to the 70 bore? Who knows. Any way I cant say enough about what a great MB the little Honda clone engines make. Smooth, relatively powerful, tough, and will even run lights, plus there is nearly 350mi of range in the tank!
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Nice! I'm glad it's worked out for you. And to think it had gears, too. What kind of vibration are you getting through the frame? Any of the tingling fingers as with a China girl?
SB
SB
SB this the smoothest of my bikes. Just about as vibe free as they get. My other Lifan bike is smooth but this one trumps it. I think the belt primary is probably the difference. There is virtually zero lash in the system once the chain seated and I readjusted it. This bike is also nearly silent drive wise. The 2 chain drive has a definite wah-wah thats missing on this one. I have probably put 40+ miles on it since this morning. I have climbed all the killer hills in the area. If you get it on its power peak, it climbs with authority. Spec wise it produces 5.08hp @ 7500rpm, it climbs like it. Im more than pleased. Give consideration to a belt primary for your shifter build, its well worth it!
Cant stay off this thing. Was out on another run when the unmistakeable sound of running out of fuel began. I had forgotton I had only poured a small amount of test ride fuel in this morning. When it finally quit I stopped and leaned the bike close to horizontal to allow the fuel on the other side of the tunnel to flow to the picked up side. Cranked her up and rode the 6 or so miles back home. The reserve tank concept worked as planned.
I'm a believer. I don't see any easy way to do that with the current China girl motor (this is on the 34 Elgin Velocipede), but when I change over to a different engine, preferably the 98cc Villiars Midget, the belt primary would be a natural. The Qmatic drive on my 50 Panther has a belt primary and works nicely.
It looks like you've come up with a great engine and drive line for a reliable and smooth runner. Congratulations!
Kind of amusing from where I sit that with that big tank and it's impressive cruise range you forgot to put the gas in. Sounds like something I'd do. Ha!
SB
Thanks SB! I guess I had ridden the thing more than I thought. Its been a while since Ive had hands on a China girl but making a pulley for it wouldnt be hard. I guess the question is pedal starting it. The belt on my Vintage build had enough bite to spin the 5hp over. It might be possible to lock the CGs clutch and use an idler type clutch with a belt primary. Something to ponder.
Well Ive got over a 100mi on this thing since yesterday. Went on along round about today. Its just incredibly pleasant. Smooth, quiet, and quite powerful. I no longer plan my route avoiding certain hills, it climbs anything in my area. I believe all my future builds will be based around this type engine. Its in a whole different relam than most of the MB engines. I know there are good engines being used, Preddys, the little HS, B&S etc., but these are industrial based engines. To be able to build a legal MB(with the 49cc) using a motorcycle designed engine kicks it up a notch. You really cant appreciate one of these engines until you have torn it down. Fully counter weighted roller crank, running in huge ball bearings for its size. OHC with the cam running in ball bearings and pressure fed. Hemi head. Oil bath auto clutch. Lighting coils. See where I am going with this? These engines have moved the third world for years with good reason. The one in this bike was built in 2003 and was in an ATV(had a thumb throttle) no telling how long it baby sat kids tearing around until they tore the tranny up. It went into the scrap heap some where(outside, water filled intake) until a friend brought it to me. Some time, a $12 gasket set, and a $7 exhaust valve and its back doing what Mr. Honda intended it to do, providing dependable well engineeried power even in a pirated manufacture. Can you tell I like this engine(sniff)?
All good selling points. That comes as a three speed? Or is it four?
What do they sell for new? When you figure in gears and what it takes to turn a China girl into a geared bike it adds up fast and it's still a China girl.
SB
What do they sell for new? When you figure in gears and what it takes to turn a China girl into a geared bike it adds up fast and it's still a China girl.
SB
SB, Im no expert on the engines, but I have learned a lot during these builds. There are a lot of different versions. They range from the little 49cc up to heavily modded 185cc HP monsters. The 125cc is the most common and generally the cheapest. The 49, 70, and 90s are least common and cost as much or more as a 125. The smaller ones are generally 3spds, but also come as 4spds. Both semi-auto and manual clutches. There is a full auto version with a set top speed of 35mph( basically what I turned mine into). I believe they are elec start only which I didnt want. If legallity is not an issue a 70-90cc would be a good choice as they are slightly more compact/lighter than the bigger engines and produce 5-6+hp which is plenty for an MB. If you need a replacement engine(ie. have the carb ignition etc. already) I have seen 88cc auto 4spds for as low as $159, or $229 complete. @ $229 your entire power unit is complete(except exhaust usually $40more) and all you have to do is attatch it to your suspect MB. They have 4bolt holes on the bottom for foot pegs that will allow them to be mounted on a flat plate as well as the hung method. The biggest draw back is the 17" length, you have to build around it. Thats why my bikes look as they do, but they were made to be daily riders not a theme type bike. These fit beautifully in a stretch low rider frame. If anyone wants do a build with one of engines I will be happy to go into more detail on the process.
Yes, this engine does want a certain kind of frame to fit. It is not a plug and play in that respect, but in all others it is. A well made, powerful engine with gears. Gears is a big deal in my thinking as you can do more with a smaller engine. Easy starts from a dead stop, no need to wind it out before a steep incline so you might be able to make it to the top (with two implications here... one is going too fast to build up enough speed to attempt the hill and also putting the engine in jeopardy by winding the heck out of it) and being able to baby the engine by letting the gears do the work. Better fuel economy with less RPMs. Longer engine life.
I don't even know what a China girl engine costs now, but if gears is what you want and you have a single speed cruiser type frame (stretch or whatever) the you have not only the cost of the engine, but also a shift kit and geared hub for the rear end. That is well more expense than the engine with gears you are working with. (I realize with this particular build the gears are down to one).
And a real lighting coil is no small deal. Yes, you can run a couple of LED lights off a China girl, but it is minimal. Sidewall generators tend to burn up in my experience as they are designed for lower speed pedal bikes. A dynamo hub is another and better way for electrical juice, but again is not cheap and requires building a wheel.
So aside from the frame needing to be able to accommodate the extra long engine, it is plug and play. Even with the really good deal one can get on a 99 Predator, add in a lighting system and gears and once again the price is up there higher than the Honda clone. I think for what you get it is a real bargain.
As you have pointed out, there's something to be said for a motor designed to be used in a motorcycle as opposed to an industrial motor designed for low RPM stationary use.
SB