Misfit Board Tracker

Ralph hop

Well-Known Member
Nov 14, 2019
207
553
93
IMG_20200729_125630242.jpg
It's rainy today and my back is a bit stiff so I'm sitting here staring at the bike and figured I'd share some thoughts and ideas and ask for some helpful knowledge. The engine will get some 18 pound springs and I found a 10 horse power Briggs carb that looks like an old marvel shebler with the air inlet down low and the carb to intake flange up top and I'll weld an elbow intake to mount it. These style carbs seem to atomize the fuel pretty good, I've seen frost forming on the intake manifold of a tractor on a warm day. I'm also planning using an offset key on the flywheel to advance the timing some, not sure how much? I haven't researched it yet. I'll keep the fly wheel but add some sheet metal inside the cover for added protection and I'd rather not rev much higher than 5500 rpm. Just keeping it a mild cruiser with a little umphh hopefully. The ratio I have is 7:1 but I might have to get a blank sprocket and drill it for fitment to get more gearing. The largest available is a 54 tooth sprocket. As it stands I won't have pedals so the gearing is important but I don't need it to do wheelies either haha! Before any major decisions can be made about the bottom bracket the bike needs to be up on two wheels ideally. The front wheel matches the rear wheel in a 36 spoke count so I plan to copy the cross pattern of the front while building the rear wheel. My major question is about measuring the offset spoke holes in the rim and how to enter that measurement in the spoke calculation. The spokes are in a zig zag pattern on the rim and the spokes will all be the same length with the rim centered on the hub, but I'm unsure how much length the offset adds to the spokes. Hope this makes sense, thanks everyone.
 

Tony01

Well-Known Member
Nov 28, 2012
1,386
819
113
sf bay area
With that big a secondary pulley so close to the engine you might have belt slip issues. Possibly go to a 5” pulley with an AX type belt (looks cogged), and run a 54/12 so you can go down to an 11 or 10 when you decide that ratios in the 7s are too tall. 7:1 is great for going 65mph of course. Just takes off so slow and burns the clutch faster. Cruises great at 40-45. Flywheel key you can expect a degree advance per .006” I think it was, I think I went about .030”, depth should be just enough for it to clear maybe .070”
 

Ralph hop

Well-Known Member
Nov 14, 2019
207
553
93
Good info Tony. Yes, the belt is concerning to me as well. After making some correct measurements it looks like an A-24 belt will fit nice and snug with having to be levered on and the belt touching the top and bottom of the clutch pulley. I'm willing to give it a go. From the info found online the A belts and AX belts are measured the same so an AX-24 it would be. The gearing I have at the moment is 3.20" clutch to 7.00" pulley and 11 tooth to 44 tooth. It didn't seem like adding ten teeth to the rear added much to the ratio in my calculations but I'm just dividing the numbers. Perhaps I'm way off. Was going to at least put the 54 on it but maybe going bigger and just drill an industrial sprocket. My calculations showed roughly 7:1 with the 54 sprocket.
 

Ralph hop

Well-Known Member
Nov 14, 2019
207
553
93
Hi Ralph,
Not sure if it really matters but here goes. EZ Q matic transmission offers a 56 tooth drive sprocket.

Ask Lynne about wheel building. Her wheels are very good and very concentric. https://mbrebel.com/
Tom
Thanks Tom, I've considered some type of mounted transmission and haven't cut anything on the frame yet so it's very much an option. I was thinking of mounting a plate on the engine TAV mounts and using some block bearings. It would have to be custom built with how everything is on the bike currently.
 

MEASURE TWICE

Well-Known Member
Jul 13, 2010
2,414
499
83
CA
Good info Tony. Yes, the belt is concerning to me as well. After making some correct measurements it looks like an A-24 belt will fit nice and snug with having to be levered on and the belt touching the top and bottom of the clutch pulley. I'm willing to give it a go. From the info found online the A belts and AX belts are measured the same so an AX-24 it would be. The gearing I have at the moment is 3.20" clutch to 7.00" pulley and 11 tooth to 44 tooth. It didn't seem like adding ten teeth to the rear added much to the ratio in my calculations but I'm just dividing the numbers. Perhaps I'm way off. Was going to at least put the 54 on it but maybe going bigger and just drill an industrial sprocket. My calculations showed roughly 7:1 with the 54 sprocket.
I thought this for ratio. (7" / 3.2") * (54 tooth / 11 tooth) equates to (2.1875) * (4.909....repeating) equals 10.73863636363636

7.096590909090909 this is if added, but it is multiplied to be correct.

So really close to 11:1 ratio on your 26 wheel if that is what I see.

I hope to set up my 20:1 ratio using my 3hp on 26 inch wheel again, currently using 12:1 and get by, just real steep hills doing trail riding it won't do.

You however have what I think is one of those 6.5hp jobs and are probably not going to encounter much problem with 11:1 if going on moderate hills.
 

Ralph hop

Well-Known Member
Nov 14, 2019
207
553
93
Knew I was missing something, thanks! My plans are to get licensed as a motorcycle but mainly stay on roads with 40mph speed limit max and only seeing fifty plus occasionally on short stretches of highway to get to the next road. I know having the bike papered is in a way the antithesis to motored bikes but I'd rather not have to worry about the hassle of being impounded or charged with something.
 

Tom from Rubicon

Well-Known Member
Apr 4, 2016
1,148
2,094
113
Rubicon, Wisconsin
Knew I was missing something, thanks! My plans are to get licensed as a motorcycle but mainly stay on roads with 40mph speed limit max and only seeing fifty plus occasionally on short stretches of highway to get to the next road. I know having the bike papered is in a way the antithesis to motored bikes but I'd rather not have to worry about the hassle of being impounded or charged with something.
Ralph, you echo my thoughts of being a legitimate motor vehicle. So far in SE Wisconsin, I am dodging arrest. Knock on wood.
Tom
 

Ralph hop

Well-Known Member
Nov 14, 2019
207
553
93
Here lately I've had time to work on the motor mount plate assembly getting the correct angle on the engine using some brass bushings and sanding on the top block mount. Also, work has begun on the bottom bracket reduction. For the bottom bracket I made use of a 1 3/8" step drill bit with 1 3/8 being the last step on the bit to bore away the BB threads. Some length also had to be removed from either side. My first idea was to use a close quarters pipe cutter but the cost for one of these to cut this diameter of 1.58" tube was a whopping cost of 150$. I chose the six dollar route by using two hack saw blades and a stainless steel hose clamp. It takes some practice with the cutting, really have to start slow and make sure not to cut into the clamp. After the first quarter of the cut the clamp acts as a good cutting guide as long as it's on straight. I found that a 1" inside diameter schedule 40 pipe lines up with the outer bearing races and also slides into the bottom bracket with a bit of play. I will use a section of this pipe as an inner bearing support inside and I'll wrap a layer of 24 gauge galvanized sheet metal around the pipe so it will fit snug inside. If 24 gauge is too thick then I'll use some thin copper sheet.
 
  • Like
Reactions: indian22