Latest Lunacy--Honda CT70 Clone Build

Those split collars I just found out about recently and they are great as they do not scratch up the jackshaft with set screw as the kind that set screw goes direct on to the shaft.

In some cases I found that a pulley is already in just the right position to eliminate the need for the collar as it act as one while also being used for its original purpose, the pulley.


http://www.use-enco.com/CGI/INSRIT?PMAKA=990-3537

5/8 ID,1 5/16 OD,7/16W CLIMAX 1PC CLAMP COLLAR


http://motorbicycling.com/showthread.php?p=393202#post393202 see post #47

I don't know how I missed this thread. It's a good one. So many things to comment on, but one for sure is to second your vote on the k-10 fork. What a great, solid fork that is, absolutely smoothing out the ride.
The first build came out very nicely, an under the radar light motorcycle...now I'm watching this second one.
SB

CB, I did see how you used the collars that must be the two part type from:

Re: 1900s Vintage Style Build Page 13


In the picture I see the nice weld to two of these clamps that hold the pillow bearings in their holder for the short jack shaft. They go on the frame seat post tube near the bottom.

I have these seat post clamps I got for cheap that are OK that I can spread the steel enough and put them in the same place as you did in the picture. Only that you can’t do that with the cast single split collar, but the type that are two parts and have two set screws to assemble, that is probably what you have. Nice! To make adjustment up and down or removal is quite simplified with this construction.

From the posted link above in #64 the jackshaft has a pulley that is on that same jackshaft as the sprocket. It seems that an idler 3rd pulley tensions up the belt, or is used as a manual clutch like the old style motorcycle stuff with a clutch without any wet or dry pressure plates attached to the engine.

I see that the center space between the pillow bearings have nothing on the jack shaft which I understand is just necessary for a firm mounting for the jack shaft.

The chain on the sprocket and the belt on the pulley are on one side and the other side the jack shaft does not protrude and only goes far enough into a pillow bearing making a good set up. I would think that a sideways force right to left, which there does not seem that there would be any, could have the jackshaft not stay in the pillow bearing on the right as there are no collars on the jack shaft anywhere.

The sprocket on the jack shaft, if it is directly up against the left side pillow bearing would not allow the shaft to go sideways to the right, but not visa versa. At least one collar on the right side of that pillow bearing or the pillow bearing on the right if the jackshaft protruded enough, would set it not to move left or right.

How are any possible sideways forces not to affect the jackshaft?

Just normal running the belt and chain would I suspect have it eventually creep sideways and the whole thing come apart, which I am not thinking you have happening, but how do I get this wrong? What keeps if from moving sideways?

MT

I noticed that the right side jackshaft bearing has a snap ring flange. I think these bearings have an integeral collar, on the opposite side from the snapring, with 2 setscrews, for fixing to the shaft.

In reference to the 125cc build, why do you need a jackshaft, is it just for alingment purposes? Couldn't you get the right gearing through the engine sprocket and the driven sprocket on the rear axle? I don't understand the need for it. I'm sure there is one or you wouldn't be doing it.

Staring at that engine should looked familiar and I realized that an engine I picked up is almost exactly like it with some different markings, but same shape, 125cc, kick start, gears. It had been on a dirt bike with direct drive from engine sprocket to rear axle sprocket. Mine is also 17" long. Which of course got me thinking fast thoughts...

... and also reminded me of a build I have sitting way out on a back burner which I started last summer. I believe you commented on the thread at the time. It is an old AMF Roadmaster frame with K10 fork and a 2 speed Tomos engine (also 17" long) hung under the belly. I have another one of those frames, too, and also another K10 fork. I just checked that 125cc engine and it urns over with the kick start, so is not frozen up. Carb and exhaust are missing. Looks like someone was "fixing it", got in over their heads or lost interest and it ended up at the landfill, briefly as I brought it home with me to steal parts from.

So that's why I'm curious about the need for a jackshaft. I don't know that I would do this as a build or not, but I have most of the stuff sitting around already and yours sounds like a killer ride. I'd cut the engine mounts off of the dirt bike and reuse them. Maybe off in the future a year or two away.
SB

Here are photos of that AMF/Tomos. Frame might need to be stretched a bit.
SB

cannonball2 said:

SB, to keep the engine centered the jackshaft was necessary. I wasnt happy with where the engine was if directly driven. I believe there have been other clone engined bikes that were driven directly, just wouldnt work for me with this frame. Was originally to be driven on the left side, but had a much better chain line on the right. Was kind of a quirky build but yielded a nice bike. These are wonderful little engines. Was very impressed with the internals of the one I am repairing. You should build one if you have the parts. The stuff you are missing is not very $$. I saw a new carb on ebay for $20. It takes a minimum of a 3" stretch or more depending on the frame to keep the engine out of the front wheel, but the K10 fork almost makes it work as it kicks the wheel forward with the tripple tree. Best to keep the engine as low as possible@ 45lbs. If low the weight actually makes an excellent handling bike.

The AMF/Tomos build is cool! If yo look carefully at the front wheel on the 125cc bike you will see it is extended past the original axle line. Maybe a similar set up would get you the distance you need with the Tomos. Was easy to do.

Click to expand...

The Tomos is OK for wheel clearance as I intend to run either 24" or moped wheels or about the same diameter. I made horizontal dropouts for it this winter which gives more clearance in back. Your build is inspiring me to get this AMF/Tomos on the road to see how it handles.

I took a couple pictures just now of the 125 cc 4 speed. See what you think it is. Looks similar, but not quite the same. I think it would fit under the other AMF frame about the same since both engines are the same length. It looks to me like the engine sticks out a bit more on the right than on the left, so it is not perfectly centered, but also not bad. I don't see how it would be possible to have pedals unless the frame was stretched a good bit to leave room for a pedal chain ring. On the other hand, extending the frame is possible. Sometime this summer I'll pull the engine and do a little more research on it. Don't mean to be diverting your thread. As always, your builds provoke thought and inspire.
SB

Must have missed CB2's reply to needing jack shaft on post 71 ... oops

anyway what I wrote:

From: MT

SB, see post 61 above that CB2 mentions about a messed up gearing in the engine that he I suppose salvaged as best as can be without major overhaul and maybe prohibitive cost. It limits to 1 speed at a 16:1 ratio. He goes on to mention that he feels it to be a little low. Also another engine bought and in the wings, he mentions as a possibility that he may use instead and maybe that would not need the jack shaft.
I was expecting maybe wanting more gearing down ratio, but I’m more for dirt bike hill climbing so I guess it can do with less gearing down than 16:1 for a faster bike.


CB2, I understand about pics from in the works. (I have posted pics also where like I have the brake lever 180 degree the other side of the handle bar… just so that it will fit in my truck and fit)

The page 7 of the old beast shows very nice light blue paint and the jack shaft end sticking out partially even after the 1 piece clamp.

I really noticed it was a mock up from the other side also in some pics where close up. I know you would want at least the shaft to be even at the end or a little more, but no less. You surely would not have left about ¼ the distance inside the pulley for enough shaft contact!

Something not quite analogous to this but worth mentioning, rule of thumb is to have when having drilling two holes to have at least half the diameter of the largest hole for separation between the two.

MT

PS Centering by weight rather than volume if necessary by use of jackshaft also a reason for good handling. I though did ride a direct drive with belt, no clutch at all, and the engine hanging off the right side with my leg over the engine... kind of crude ride but was fun back in my teens!

CB2 I had mentioned the centering by weight as I heard from a friend that said that something about handling at speed and I think turning there was some connection.

I definitely agree that looks count so if it does not affect too much a degree go with it.

I also thought wind resistance at speed I suppose could be also a consideration for symmetry. Anyway the friend had one of the newer Indian Motorcycles that since he sold. He got it from another friend that worked for Indian to get them licensed for the use in USA. Part of the deal was he got two of these machines and gave him one. So this friend told me how the Indian Motor Cycle had this as a consideration for weight centering.

My build that is for off roading and did not get much in the way of great looks as I am to be covering it for art mobile and to do riding in the woods. The thing I have too is the vehicle must go slower than 5mph and without the greater gyro affect at speed, the weight with extra skeleton and fabric cover I want it to be stable.

I do want to mention the welding to those small clamps you made such a neat connection without any distortion from the weld. Bravo! I got all the sheet metal almost ready to weld to make a cover over the 10inch pulley that will spin around 500 rpm on one of the dual stack jackshafts so I get a 44:1 ratio and my centrifugal clutch will not heat up by my otherwise need to let it slip by pulse throttling.

MT

The 44:1 I would pull out a pulley of where going between a larger and smaller pulley which are about a 2:1 reduction and replace either of the two so that they match for 1:1. This would effectively halve the 44:1 to 22:1 and that would be my realistic hill climb for the woods off roading bike.

As for welding, I got for my Miller Auto Darkening helmet the optional magnifier lens so that you don't have to wear glasses under the hood. I do however have this low profile gas mask that will fit under the hood while I weld.

I wonder if you know beside wire brush and grinding what would take off chrome. Chrome and stainless steel are very bad vapors to breathe. Actually chromium is in stainless steel and it is poisonous to breathe. Gas mask and some good ventilation necessary for welding, but if as I have heard using that pool additive that is acidic can remove zinc of the plated stuff that you have to rid of for a good weld and also minimize the harmful fumes to be lessened.

I know chrome is supposed to be quite inactive so I don’t know if I can do it that way.

I took a stainless steel bowl that I think has chrome on it and also a steel or stainless steel part from a BBQ cover for some nice already shaped pieces I cut and shaped a little. They are for a cover I will weld up as a safety cover. I got some steel sheet metal to fillet the parts so there are no gaps and a slightly thicker smaller sheet metal part that has enough rigidity even without curved surface to make it cover the 500 rpm 10 inch pulley and the centrifugal clutch pulley with belt concealed so no danger of pant leg getting caught up in it.

MT

And after the murtiatic soak does what you want, flush the part for a while with water. Then do a soak in straight household ammonia for about 30 munites, then flush again and prep for paint ect. Beware that the chromium /acid efleuent is very toxic, so be careful with it and how you dispose of it..