CPI Oliver City 50cc to 103cc

[190mech]

I finally decided to start a project I've wanted to do for a while.
A 50cc scoot with a 100cc engine,geared so it will cruise at 60
without turning a million RPM.I ordered a NCY 54mm cylinder
kit for a 90cc engine,have a 45mm stroker crank on the way.
Cases must be cut to fit both the larger cylinder and crankshaft.
Got the engine off and mostly apart;

Here is the 50cc,70cc,and 54mm(103cc with stroker crank)cylinders;

This is how much metal must be removed for the cylinder to fit the case;

Will post more when my work schedule allows me to tinker,,,

[stepthrutuner]

Cool. I think you should call this Project Echo Chamber. ;D

[190mech]

Thanks Reg!I am planning on a new quiet pipe for it,want to
ride un-noticed by all the anti scoot types

[stepthrutuner]

Hello Hello Hello. This is my new Big Big Big Bore Bore Bore.

[jimh]

Dang, that's a big pot!

[90GTVert]

I'm very glad to see you getting this project underway. I have no doubt that it will be a beast with you building it.

[190mech]

Thanks!I ordered the cylinder studs and shroud last night,hope to
have some time today to split the crankcase(why do they call them 'carters'?)and figure out a fixture to mount it in the milling
machine..

[2strokd]

I dunno, but im looking forward to seeing this puppy
run ;D! Gonna be interesting to say the least

[190mech]

Got some time to 'make chips' today.Setup the cases in the mill to cut the cylinder mouth;

After many chips,here is what it looks like;

Here is the cylinder test fit,Whew,it fit!

Started roughing out the transfer tunnels;


Here is the cylinder in the case,ya'll think that web under the boost port needs to be cut straight down?

[stepthrutuner]

Hard to say. You say you're building a mild motor. It would very slightly decrease primary compression wouldn't it?

[drawkward]

Seems a little sketchy to me. How thin of a wall would you be talking here at the bolt hole?

[190mech]

I have a 'stuffer' crank ordered,so that should keep the primary compression up..
Might cut a little more on that case channel,but worry about the
bolt hole and case support there.Ive also seen where guys are
cutting a 'scallop' out of the rear cylinder skirt to aid in boost
flow.Like this;
i34.photobucket.com/albums/d101/MomoMexicano/More%20Taz/CaseTuning17.jpg
The 50cc case appears to be restrictive in these areas for proper
cylinder filling and I think some time spent here will make a stronger running engine..

[90GTVert]

:drool:

You made that look easy.

I agree that you are getting a little too close for comfort to that case bolt hole if you cut it straight. I'd definitely look to alternative methods for increasing flow.

[2strokd]

When this thing done its gonna be like , and everybody that want to race is gonna be like .
And John will be . I think this build is And a .
.
Should be fine to cut a U in the skirt i would think?
Now im gonna sit back and let the master work

[jimh]

Hahahaha...............this is going to be great.