New Last Build Thread "maybe"

halfmile said:
Today I removed 2 of the front motor mount boss`s to use as center mounts for the lower motor mount (as used on 70-73). This may present a problem because of the 3 3/4" ground clearance to the lower rail. If I put the mounts in the center of the lower rail the starter blots will only have about 2 3/4" of ground clearance.:shrug: I can mill off the lower starter bolts and part of the lower starter end plates and take 1/4" off the drain plug and get it right at 3". I welded in the plugs to the rear lower tubes and tack welded the tubes to the axle plates. I left the front tubes unwelded for now so I can fit the cross tubes and main tube with rear motor mounts. Made a couple of cross tubes and Red Green`d a piece of PVC to the steering neck just to see how the main center tube would look. Don`t like it at all. Too tall. I thought I might consider being able to take the motor in and out by lifting it up and forward. Just a thought. I also decided to final weld nothing before I put on the rear wheel and chain to make sure everything lines up. After I get the motor in the frame and the center tube in place the rest should be downhill from there. In fact my wallet is all the way down the hill and has hit rock bottom.:yikes:
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If you go the route of the removable head studs (Yamaha factory racing mod), it opens up all sorts of possibilities far as removing the engine goes.
 
halfmile said:
Road it around the block once! When I heard that I knew this guy was for real.:thumbsup: My new hero.
https://www.google.com/imgres?imgurl=https://cdn.motor1.com/images/mgl/L30k1j/s3/superfastmatt-s-failed-motorcycle-project.jpg&tbnid=Z51E3JyNwYJ_TM&vet=12ahUKEwjnnIHThuCDAxW9mokEHeWzBAgQMygMegQIARBs..i&imgrefurl=https://www.rideapart.com/news/615933/what-project-failures-teach-us/&docid=V-j1HqiXGPETkM&w=1280&h=720&q=unsafe and unwise&ved=2ahUKEwjnnIHThuCDAxW9mokEHeWzBAgQMygMegQIARBs
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The guy was very entertaining. Plus he was very honest about the mistakes he made and kept making.
Everything he said about projects was very true, especially about time and money. You never have enough of either.
 
GLJ said:
The guy was very entertaining. Plus he was very honest about the mistakes he made and kept making.
Everything he said about projects was very true, especially about time and money. You never have enough of either.
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I guess I should have documented all my drag race endeavors. I could have sold it to the Discovery Channel for a million dollars and recovered about 10% of the money I spent.:yikes:
 
A little warmer today so I made the main lower cross tube. 1 1/2"-120 wall so it had to be squeezed down to 1 1/8" before I coped the ends to match up to the frame rails. It actually came out right the first time.:thumbsup: I also made a drill bit guide to drill the lower rails for the motor mount. I might actually get it centered. Motor mounts are next. My coffee buddy is reloading a bunch of amo just in case the ground hog can`t get his shit together on Feb 2nd. I need spring to be right around the corner not 6 weeks later.:yikes:
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Once in a while something actually go`s right around here. Today I marked the hole location for the lower mounts, leveled and tightened the drill guide I made yesterday and removed the lower front upright (rail) and drilled them in the drill press (1/4"). Then I replaced the rail and did the same on the other side. When I put it all back together I took a 1/4" stainless rod and inserted it in the left rail and it came through the right rail perfectly. The chances of me doing that again are slim to none. Took it all back apart and used a 5/8" hole saw to drill for the 10mm bosses I removed from the donor frame. Everything fit and the motor case bolted right up and moved freely in the holes. Next I`ll find the centerline of the motor and spot weld these mounts. (maybe). I`m considering a 5 degree forward tilt. That will almost eliminate the starter bolt to ground clearance below the lower rails?:thumbsup:
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halfmile said:
I`m considering a 5 degree forward tilt. That will almost eliminate the starter bolt to ground clearance below the lower rails?:thumbsup:
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Iirc, Tony Halco used to use about 10-15° of forward tilt to his motors... so you could go more if you wanted.
 
halfmile said:
I`m considering a 5 degree forward tilt.
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I'm sure you understand air resistance is a major enemy for what you are doing. Tilting the engine will cause all the fins on the head and cylinder to act as air brakes. I know 5 degrees isn't much but it all adds up.
 
GLJ said:
I'm sure you understand air resistance is a major enemy for what you are doing. Tilting the engine will cause all the fins on the head and cylinder to act as air brakes. I know 5 degrees isn't much but it all adds up.
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Tilting it forward also decreases the frontal area. Maybe a wash?
 
Jim said:
Tilting it forward also decreases the frontal area. maybe a wash?
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I wouldn't be so sure of that. When you tilt the motor it will bring the back of the head up into the air flow. But that will depend on how the rest of the front end is made.
A few years ago I read about someone doing LSR racing. He mentioned he used ceramic bearings in the wheels because they turn easier. I thought how much resistance does a steel bearing with lightweight grease have especially when it gets hot. He set a record for his class so he must know something. Must be all the little things that add up.
 
My $0.02 re tilt. Air flowing through the fins is so turbulent as to be the engine looks essentialy a brick to the air. One obvious solution would be to remove alternating cooling fins entirely to free up cooling airflow. The CD sucks on a motorcycle so the effort should probably be to minimize the frontal area of a sucky CD, tilting does lower the frame and CD somewhat. In a perfect world the frame down tubes and head pipes would be for/aft oval. Same for fork tubes. Honda has some oval piston machining experience here.:smoke:
 
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Experiment RE cooling above. Anyone with an oil temp guage? Run 40 minutes in stop and go traffic and record max temp. then run 40 minutes at 65 mph/100kph. I ask because I do not know the answer.
 
Tilting the engine 15° lowers the ceter of gravity also shifts the weight forward making the bike have better handling. Think that would offset any loss due to a little extra turbulence through the fins. Could also argue the fins act as an airfoil creating slightly more downforce, again better handling.
 

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