Manufacturing your own ht engine?

Will'smotobikes19

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Apr 9, 2018
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1,760
My idea is to build my own engine. These bike engines are quite simple. Plan is build a foundry and cast the crankcase and tap the holes to 1/4 and maybe 5/16 instead of metric. I'll get a drill press and probably belt sander. I already have a grinder but it needs a new spindle and stone. Then machine a crankshaft from 41-40 steel and source a rod from an 80cc dirtbike or such. I also planned on using jap bearings. Seems like a good beginner machinist project. I could get the port timing right too unlike the china ones. Some people might ask why not just run the regular china ones. They wouldn't understand. I don't do this because I can't drive or got a dui or am too young, its kind of an annoying hobby actually. I have been thinking of getting an actual motorcycle lately. Looking for a 250 cafe racer but didn't like the ones I saw. Too much chrome or too old looking. I saw a china one that's 1,700 but with how crappy mb parts are I don't really trust it.
 


FNTPuck

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Jul 2, 2018
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879
This would be an awesome project!

I don't have a CNC mill, but I do have a 3D printer and am now considering making a mini Chinagirl model for my desk :). I would go straight to milling everything vs casting, but it would be big bucks just for the aluminum blanks.

Imagine a billet aluminum iron cylinder true 80cc chinagirl with all quality bearings and properly balanced...it would be insane.
 

MotorBicycleRacing

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Jul 3, 2008
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2,344
This would be an awesome project!

Imagine a billet aluminum iron cylinder true 80cc chinagirl with all quality bearings and properly balanced...it would be insane.
China girl Billet cases have already been made.
Iron cylinders are inferior to nikasil lined aluminum cylinder.

This is a billet case reed with a standard cylinder on SoCal Racer #108 show bike.
37657571_10155348712541540_6461395048310243328_n.jpg
 

Sumsloppymeet

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Aug 7, 2017
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712
if one wanted to invest or have one of these billet bottom ends built for them who can i contact plsss id kill for one
 

Sumsloppymeet

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Aug 7, 2017
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well i do happen to live in Land O Lakes Florida bout 20 min ride from st.pete with good traffic lol and tax time isnt too far off how can i find him
 

JerboaJohn

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Jul 29, 2018
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1,266
This would be an awesome project!

I don't have a CNC mill, ... milling everything vs casting, but it would be big bucks just for the aluminum blanks ...
get a HF mill or mini lathe and die grinder, sturdy it up and get some good calipers and mics. that's the expensive part. you could convert it to cnc for not too too much later.
6061 aluminum stock really isn't that expensive when you re-use cutoffs for future projects. you end up with lots of chunks and bits you make stuff with down the road at no cost.
so then you have like ~700 in tooling. drop 80-100 in materials and make anything.
stainless, brass, copper now that's expensive
 
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