Latest Lunacy--Honda CT70 Clone Build

cannonball2 · Jan 27, 2012

This build with the engine low on a standard type bike frame complicates the use of pedals. Mainly because of the engine wont clear a pedal drive ring even as small as 22t using the BB location. Originally this bike was a LH drive on the engine chain leaving the RH side for a pedal drive. I had thought of a pedal shaft mounted in bearings or even oilite bushings behind the original BB, but then reaching the shifter would have been problematic, and I didnt really want a hand shift. The fact pedals are not required in my state cooled the head scratching over the pedals early on. This has turned out to be a great riding and handling bike due to the low engine configuration. The engine could have been higher in the frame I guess like jschattes build, but I wanted a nice handling road bike and low weight positioning is the key. I weighed the bike using bathroom scales(I know about the accuracy), it weighs 102lbs. Amazingly by luck alone it is 52lbs on the real wheel 50 on the front. This build with one of the 49cc pedal engines would make the pedal requirement and is very easy to do. The plentiful and cheap straight top tube MTBs are the best candidate for this type build.

BigBlue · Jan 28, 2012

Here's another picture that I gleaned from the Internet. Looks like they removed the single downtube and replaced with two small tubes and attached at the bottom bracket - can't tell for sure. Tabs are welded for mounting motor.

http://motorbicycling.com/attachment.php?attachmentid=44355&stc=1&d=1327727232

Chris
AKA: BigBlue

cannonball2 · Jan 28, 2012

Thats a nice clean mod there, thanks for the pic. The cantilever tubes help strengthen the front end, sharing the load with the curved twin down tubes. This makes the marriage of a slant cylinder engine and a cruiser frame easily doable. The horizontial engines big drawback is its length some 17". Has to go into some from of stretch. Moped engines are the hot ticket for a legal bike when pedals are required. They are strangely pricy sometimes, cheaper to buy the whole ped. The horizontial engine with the pedals CrazyHorse referred to is cool too. To be totally legal across the states legal you need a 48cc as a few states have 48 as a max. My sons engine is actually a 48cc.

cannonball2 · Feb 4, 2012

Bit of an update on the build. Added lights, head, tail and brakelight. If anyone needs help wiring similar to one of these type engines will be glad to help out. There are other small changes that dont show in the pics but help complete the build. Had Sportscar Pat work me up a 34t rear sprocket, dropping down from a 40. I finally found an online repair manual(read free) for a CT 70 that had the final drive ratio listed as 2.5, the 34t will give a 2.6, a little bit on the performance side. Am waiting on a set of NOS made in the USA fenders to complete the bike. One installed and the bike is ridden a bit will tear it down for paint. Also is a pic of my sons bike in its roughest form. Looks like we will be able to run the freewheel with all but the 28t sprocket removed. Coupled with an 11t driver it will give a final ratio fo 2.54. Talk about a cheap build, no adapters or sprockets to purchase for the rear wheel.

lowracer · Feb 4, 2012

CB2,
They both look great!
I really like the way you mount these engines in the lower part of the frame...
-Lowracer-

BigBlue · Feb 4, 2012

Cannonball,

Lookin good! What size is that headlight?

Chris
AKA: BigBlue

cannonball2 · Feb 4, 2012

Thanks LR & BB.

BB, the headlight is a Bates style bobber light left from a Sporster build I did, I believe it is a 5 3/4". Its actually a side mount flipped 90 degrees. Gotta work with what ya got sometimes.

cannonball2 · Feb 4, 2012

Forgot to mention LR the engines are mounted on heavy duty 1 1/8 split bearing retainers welded to the engine mount. The top half is welded to the frame. This has proven so far to be quite stout. The engine is easily removed with four bolts, and basically self aligns when reinstalling it. The rings spread the load on the tubing better than a weld.

lowracer · Feb 5, 2012

CB2,
I'd like to see a closeup of the split bearing retainer engine mount. I'm very fond of the 'When Simple is Best' Approach'...
Thanks
-Lowracer-

cannonball2 · Feb 5, 2012

Got the 34t sprocket installed and got a short test ride in this afternoon. This sprocket is perfect. The bike is quite quick on acceleration and has a great top end. Still taking it easy on the engine, but it cruises easily at 45(GPS) Top speed @ 7500rpm is 56, in theory havent done it. If I was to believe the hype on this engine it has a redline of 9500rpm which would compute to 71mph. Its continous output rating is 7500. So 56 seems realistic. If it would twist to 8000 its good for 60. What all this amounts to is a useable cruise range of 45-50 which is what I was after. In reality I will probably stay around 40. Its just nice to know I can handle some of the faster roads I avoid now.

cannonball2 · Feb 10, 2012

Got and installed set of NOS American made McCauley fenders, probably from the 60s. These are great quality, thick and well plated, with heavy gauge stays, Was going to paint them but the chrome is such good quality kinda hate to. Ah the good ole days of American manufacture! Just couldnt do the paper thin import fenders on this bike. Is running well and I have put quite a few miles on it. You get where you are going pretty quick on this one. Finally got a voltage regulator that could tame the lighting coil, now have running and brake lights. I guess its done except paint.

BigBlue · Feb 10, 2012

Lookin mighty fine! Can't wait till the paint.

Chris
AKA: BigBlue

cannonball2 · Feb 10, 2012

I generally ride a bike about a hundred miles to sort it out. Is getting close, then paint time. Got to figure out about painting the fenders though.

cannonball2 · Feb 17, 2012

Now have about 150 guestimated miles on the bike. Hasnt required anything but 2 final drive chain adjustments as the sprocket and chain became accquainted. Swapped out the low temporary bars for some half moon cruiser bars. The upright position is much more comfortable. Strapped the GPS to the bars for a top end run. Showed 61mph, somewhat lower than its calculated top speed. I dont believe it was totally wound out, and the engine is not totally broken in, I also was sitting upright and not laying down to reduce wind resistance. Truth is that was as fast as I was goin on it, handles and rides very well, but 60+ is too fast for me on something of bicycle origin, dont heal like I used to! What is nice is the relatively relaxed 45 cruise, and I can jump up into the 50s on the faster roads if somebody starts chewing my rear fender. I only ride roads like that short duration to get to slower traveling roads. Have a few more details to add, and a few more miles, then its paint time.

LS614 · Feb 17, 2012

that's too fast for my taste but I'll hand it to ya that thing looks wicked cool!

cannonball2 · Feb 17, 2012

Thanks LS! I really mostly ease around on it in the 35-40 mph range. Whats nice is being able to flatten any hill that comes along, and have some top speed if needed. The faster traffic is now doable and the German Shepherd down the street is no longer a threat.

LS614 · Feb 17, 2012

Yeah, with me I get spooked at 37. That's my lucky number, can't go faster without needing fresh undies lol. but HAVING the extra pep can help in stick situations sometimes

cannonball2 · Feb 25, 2012

Lastest in the continuing saga of what ever this thing is. Added a K10 front end. The rigid front was a little rough over choppy surfaces. The longer bars helped by geting my weight off the grips, but still felt it would benefit from a front suspension. Since this bike is capable of some fairly high velocities began to think a true hydraulic front end would be the way to go. No better deal than a K10! Was not a real issue to install. Added 1.5" to the wheel base, shes gettin a little long now. Since I sit so far back and had spent a good deal of time getting the bars to my liking, I incorporated a bike neck mated to the normal bar mounts to keep everything in the same position. Also added fork stops with a hole for a padlock to lock the fork. Installing the fender took a little modding, and worked out clearing the lower tree when bottomed. End of story, with the front susp. and the long wheel base it has a Lexus ride. Still running the original oil in the fork. May change to thicker, but since there are no bottoming issues the softer ride is nice.

cannonball2 · Mar 20, 2012

Couple of updates on the motorbikecycle. Welded a tab to the frame to hold a pad lock to lock the front end with. A vintage speedo. Frame mounted air pump, that will likely be black when finished. A Triumph/universal hi/lo headlight and kill switch. Wiring run through vintage style asphalt cotton conduit(not totally finalized). Moved the brake light into the tail light since the seat bag obscured it in its original position. Added a Gyes leather seat, which is breaking in and Im liking it. Also added a Honda m/c small tool box that will hold a tool roll. Have about 325mi on it now with no issues, just normal adjustments. Its a very comfortable smooth rider.

cannonball2 · May 24, 2012

Well my son bailed on finishing the CT70 clone build he started so it has passed to me. Figured Id just build it in this thread rather than start a new one. It will use a 70cc, which is from the factory I kid you not marked as a 48cc. A 3sp auto. Will be a bare bones bike, no lights, fenders, speedo etc. This one will have pedals. Will be using a jackshaft and 5/8 bearings in the bottom bracket. The unusual thing about this one is it will have a belt primary drive. Will be smoother, ratio changes are cheaper/easier, and will have an idler tension arrangement. Tensioning 2 chains can be an issue. The belt will also act as a form of cush drive. Geared for a top speed of 35@7500rpm, though the engine will surely turn more, just want to cruise comfortably around 30. Got parts coming from everywhere. Will post pics as the build goes on. Here is a link back in the thread of the bike, its the one leaning against the shop door. It is also now back on 26" wheels from the 24" in the pic.http://motorbicycling.com/showpost.php?p=361975&postcount=44

Latest Lunacy--Honda CT70 Clone Build

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