066 Rebuild, Port Job etc

[Brewz]

I dont have a lathe. I will be getting a friend who has a lathe to do the work and he is a very busy man running a business.
I would love to have time to make a PCV rod, but I cant see it happening at this stage.

I forgot to add that I plan to measure the port timings and post them up for advice on exactly how much to cut. I have a drill chuck in the mail to set up my degree wheel.

I started off planning for a lower compression saw but I plan to keep my red light as a 160 psi saw for general work.

I would like to see this one up around 220, set up for torque for running longer bars

Transfers can be raised, I have grinding stuff

 

[Moparmyway]

Getting the cylinder port timing will be key to deciding what to do next.
When my 661 showed nice numbers, it changed my plan of attack for machining .............
A real good cylinder can alter your perception enough to cause you to allways check and never assume

 

[Brewz]

A real good cylinder can alter your perception enough to cause you to allways check and never assume

Very true!

I am in no rush to do the work.
To be honest it runs awesome as is with an OEM jug and piston, but I want to bump the power while keeping it fairly reliable.

I will report back with timings when I get my degree wheel up and running.

 

[Mastermind]

Getting the cylinder port timing will be key to deciding what to do next.
When my 661 showed nice numbers, it changed my plan of attack for machining .............
A real good cylinder can alter your perception enough to cause you to allways check and never assume

You said a mouth full right there brother.....

 

[mdavlee]

So much variation in those jugs. Could only need to cut .035" from the base to make a real good runner or it may need .070" to get timing better.

 

[Brewz]

I have decided to fit a 288 piston to the 066
Jug is planned to be cut by someone well in the know!
Meteor 288 piston turned up today, ready to bolt in.

@Red97 has been contacted to send some cool deflectors so I can add a 3rd port to it neatly.

I cant wait to get it done

 

[Brewz]

Right!

The jug is off, the 288 piston is out, the vernier calipers are zeroed off and its time to port this bad boy.

First up the stock port timings were:
95
117
81

I was going to get it done professionally but with recent pay cuts, I am going to have a go at destroying the nice OEM jug myself.

First up I got my plate set up so I can put it in a lathe to cut the band, and I have a length of 60mm hard nylon stock to make a bore mandrill with to get the base cut.



I was a bit concerned about the piston turning up as a larger diameter "B" piston, but I found my jug is also a "B" jug so that works out well.
First thing I did was recess the inside lower lip of the piston skirts so they clear the crank lobes.
I then would several bits of solder together and measured the squish with the 288 piston fitted.
I got 0.060" with a gasket fitted. (initial .020 + .040 less compression height
I then checked how much I would need to remove from the base to raise the ring up out of the intake port. I was told about 0.090 and this was close. I will need to tale off 0.100. This will put the bottom of the ring level with the top of the intake port so it wont catch.



Now to my calculations, when I cut my base by 0.100, I will now have squish of negative 0.040 (the piston will now hit 0.040 before TDC)
0.060 - 0.100 = -0.040

So to get my squish back to 0.020, I need to cut 0.060 from the band.

Do my numbers sound right?
Am I doing this the right way around or is there a better way to work it out?

 

[Brewz]

With the stock numbers I posted above, will 90 to 100 thou be OK or could/should I take more off the base?

 

[Moparmyway]

With the stock numbers I posted above, will 90 to 100 thou be OK or could/should I take more off the base?

I'd pull the gasket, less cutting that way

If you're trimming the base of the cylinder yourself, I'd say to cut .050, then check the intake and the other port timing numbers.

Mark the piston at BDC and your desired ring height, then measure from the marks to get the amount that the base needs to be cut.

I'm curious about the rest of your port timing numbers after you get your base cut

 

[Brewz]

Pistons compared.
She has skirts!

 

[Brewz]

Have you also figured out what your port timing will be ?

I dont know how

 

[Moparmyway]

I dont know how

Drop the stem of a long stem dial indicator down the spark plug hole and measure, then put a ring in the cylinder and see where .100 less would be on your wheel, plus see where your port will be

It's tedious but it can be done

 

[Brewz]

Oh good lord

I dont have a dial indicator so I guess it will be like a surprise baby.

I will find out what it it when its born

As long as mu 100 off the base and 60 off the squish is right It should turn out ok

 

[Moparmyway]

Oh good lord

I dont have a dial indicator so I guess it will be like a surprise baby.

I will find out what it it when its born

As long as mu 100 off the base and 60 off the squish is right It should turn out ok

Take material off in steps and check each time. You'll get a better feel for the port timing this way

 

[Brewz]

Well I have to take 100 off as a minimum to get the 288 piston ring up out of the intake port.

 

[drf256]

Well I have to take 100 off as a minimum to get the 288 piston ring up out of the intake port.

I think this is your rate limiting step.

 

[Brewz]

What do you mean by Rate limiting mate

You lost me.

 

[drf256]

It's the mandatory step that all other steps are based upon.

So lower the jug till the ring is tucked under the intake roof.

Bolt down jug with or without gasket (whatever you're gonna run), scribe a line on the piston at BDC at the intake roof. Measure the distance between the bottom of the ring and your line. Take that off the base. Then cut the chamber till the piston fits and has .020 squish.

 

[mdavlee]

You can mark the distance on the piston with a pencil through the exhaust port. I do that so I know how much to grind for where the crank is relative to the ports since there's dwell time at bdc and tdc. I cut the base first but you could cut .060" out and then cut the base to set squish. Be more trial and error but it's quicker set up than the squish on a lathe. That's the nice thing about cutting squish by hand. pop 2 bolts off and cut a little and check.

 

[Brewz]

Cut by hand?