Converting my Morini S6 C to a S6 S

[Easy Rider]

The next race is only a week and a half away and I plan on racing "legally" in the mid class. My Air cooled motor S6 S has a bad crank and since parts are expense, I'm going to buy the bare basics to get by.
So far I've took off both cylinders and heads and inspected the hot spots and surfaces on the pistons. Both pistons look decent but since my C has been bored out, I have to use the old air cooled piston. New piston cost $100. I should have got one but my order has been shipped out already and I can get by with the old one. I got a set of rings, wrist pin bearing, base and clutch cover coming soon. Just those items cost $60.

 

[Easy Rider]

After looking over the difference between the ports on both cylinders, I only noticed that the exhaust ports were different. It's clear that the S6 C (h2o) exhaust ports are better by design. It has two ports instead of one and is much larger.

 

[Easy Rider]

Here's the S6 S (air) exhaust port. It's much smaller. I'm tempted to clean up the ports and port the exhaust but that wouldn't be fair unless I get the ok from Neil.

 

[Easy Rider]

Next step to do is exchange the cylinder studs. The h2o cooled Morini has longer studs than the air cooled motor. I'm going to work on it tomorrow. There's no need to rush because my parts from Florida aren't here yet.

 

[MotorBicycleRacing]

Here's the S6 S (air) exhaust port. It's much smaller. I'm tempted to clean up the ports and port the exhaust but that wouldn't be fair unless I get the ok from Neil.

You kidding?
it's all good for some fun racing and Brian needs some competition.

Thanks for being one of the 7 racers that bothered to pre register.
I don't remember Dean ever actually racing on the track?

Dean can have #4

 

[Easy Rider]

Thanks for being one of the 7 racers that bothered to pre register.
I don't remember Dean ever actually racing on the track?

Dean can have #4

He'll take it. I'm not sure if he has ever been on the track.

 

[Easy Rider]

Here's a picture of both pistons. The one with the ex is off of a Kawasaki. Its the one that I used for my big bore h2o cooled motor. I had to trim the skirts a little so the piston wouldn't bottom out. If I had the time and dumping money into my truck for my son's first ride, I would have bored and nikasill the air cooled cylinder instead!

 

[Easy Rider]

Today I only had a chance to remove the cylinder studs and of course just when I was about to install the correct ones, I ended up spending 30 minutes looking for the blue Loctite before giving up.

 

[Easy Rider]

it's all good for some fun racing and Brian needs some competition.

Cool, I'll do a light port job then.

 

[GearNut]

I bet you are having alot of fun with the swap/ rebuild!
If you don't mind me asking, why is there an extra hole in the transfer port ramps on the opposing case halves?

 

[Easy Rider]

The holes go down to the crank bearings for lubracation.
I forgot to check the mail when I got home but this came in today.
$60 doesn't get you a whole lot these days...
...but at least I got some cool stickers for the tool box!

This place in Florida sells motors too.
$549 for an air cooled and for $50 more, you can get a h2o cooled motor!

 

[Easy Rider]

Today I did get a chance to install the cylinder studs and cylinder.

 

[Easy Rider]

After installing the studs, it was time to install the rings. When installing the rings, make sure the opening of the rings match up with the pins in the piston.

 

[Easy Rider]

If the notches in the rings don't align with the pin in the piston, the piston will not fit inside of the cylinder and damage the rings.

 

[Easy Rider]

As a rule of thumb, I never install any bearings dry. I'd rather have the motor smoke a bit during the first minutes of run time then fry the wrist bearing. I usually dip my bearings in two cycle oil.

 

[Easy Rider]

Install the cylinder stud bolts with blue loc tite.

 

[Easy Rider]

Make sure all cylinder bolts are torqued n at the same ft/lbs.

 

[Easy Rider]

What's nice about the S6 S is you can adjust the squish by adding or removing these aluminum gaskets without having to remove the cylinder.

 

[Easy Rider]

One of the important performance tips is to always check you squish.
I use the solder method. Spin the motor so the piston is above the exhaust port then insert the solder so it's reaching the side of the cylinder wall.

 

[Easy Rider]

After the piston has passed TDC, remove the solder and measure with calipers or a micrometer. Since the measurement was twice the thickness of each head gasket, I decided to remove one and it brought the squish down to a respectable .19 thousands of an inch.

 

[Easy Rider]

A little trick I've been doing for years is seating the rings ASAP. I spray some WD40 inside the cylinder to quickly seat the rings. I know there's people out there that disagree with this technique but I don't have time to slowly break in a race motor especially if its only used on the track.