Ht Performance Porting Success

[210061741]

Andrew

You wouldn't be wasting your time you will see some gains.
However adding a SBP Expansion Chamber will get that engine running sweeeet.

Here is what i do to my cylinders and it has worked very well for me.

Tools tools tools

A degree wheel and indicator help to find your current port timing.
http://i887.photobucket.com/albums/ac72/RidingRich/SDC10841.jpg


YOU NEED A SET OF CALIPERS OR VERNIERS TO MEASURE.

http://i887.photobucket.com/albums/ac72/RidingRich/SDC10955.jpg
http://i887.photobucket.com/albums/ac72/RidingRich/SDC10956.jpg

#1 check the clearence between the piston and the head.
A) use a piece of plumbers solder stick it through the spark plug hole and roll the bike to squish the solder between the piston and the head.
It needs to completly turn 1 stroke.

Measure the thinnest part of the solder where it is crushed. That is the squish clearence.

I set mine between .020 and .025 don't get any closer.
You can change the gasket, sand the head, or sand the top of the jug to do that.
http://i887.photobucket.com/albums/ac72/RidingRich/SDC10848.jpg



#2 I cut the exhaust port roof to measure 1.060 inches from the top of the cylinder.
If you take a piston and turn it updise down you can slide it in the cylinder and measure down to the flat edge of the piston. Then hold it in place and use a permanent marker to set a guideline.
http://i887.photobucket.com/albums/ac72/RidingRich/SDC10851.jpg

Rough it out with drill burrs or a dremel and use files when you get close to the line.

Polish it to a mirror finish
http://i887.photobucket.com/albums/ac72/RidingRich/IMG_0515.jpg

#3 The intake port i cut to (got to look it up) roughly about 3 mm off the bottom.

The trick is to cut the ports more of an angle so that you raise and lower the most at the cylinder bore.

Otherwise you get the gasket sealing surfaces cut too thin.

Make sure to chamfer the edges of the port in the cylinderbore.

Don't touch the transfers or you ruin the thing.

When i am all done i cast moulds of the ports using canning wax.
http://i887.photobucket.com/albums/ac72/RidingRich/SDC10857.jpg
That way i get a very very accurate Area Measurement and know exactlly what i have.

You can widen the exhaust port too. Just watch the threaded holes and don't go to wide or you risk breaking the rings.

The intake i would only clean up the sides and not really remove alot of material.

I will start a new more deatiled theread on porting.

YOU WILL HAVE TO TUNE YOUR CARB INCLUDING CHANGING THE JET POSSIBLY.

 

[andrew88rmz]

thanks man i appreciate it.

 

[210061741]

Much more details to come in the futere as my time allows.
And in case your wondering....

Yes i am currently running that cylinder in the picture with the reed block welded on it.

Running quite well.

Gonna adjust the carb a little tonight.

Hopefully i'll have a nice video this weekend

 

[andrew88rmz]

I was wondering that and i have read that you were biulding one and that you would soon post a video. I didnt want to pick your brain 2 much. Thats sweet man i cant wait to see it!

 

[andrew88rmz]

To 210061741

Dude! DUUUUUDDDDDEEEEE! Thanks a lot for the advice! I tore into it this morning and started in with my die grinder. I matched the transfer ports, Smoothed out the cases around the transfers alot, took .030 off the top of the exhaust port and smoothed it all up, and i made i took .090 off the piston skirt on the intake side(more of a notch). I put it back togerther checked everything and took off. First i noticed that it idled much smoother. I let it warm up and took off down my street. I instantly noticed the torque increase. I was kind of expecting to loose some down low put it was pulling nicely. Next thing i now i am hauling ***! I decide to get the gps and make sure it wasnt a mental thing. 36mph on flat ground! It was 26 outa the box. I havent even tried to tune the carb yet but it ran great. The power delivery was smooth and clean with no hesitation. Thankyou again for the advice and hard work you have put in to these motors. I havent spent a dime on parts yet, just tweaking what i got and i have pick up 10mph, no telling how fast it will go downhill!

 

[210061741]

Andrew

If your not running a SBP expansion chamber you should seriously look into it.
It will double the power of that port job and add about another 10 mph.The engine will be able to revv way way higher.

You probably coulda took more than 1 mm from the EX port top.
I measure from the top of the cylinder to the top of the exhaust port.
1.06 inches. Don't go any higher than that.

Cutting the piston skirt will work and is good to do.
But that only increases the Intake duration in degrees.

Cutting the port increases the Duration and the Area of the port yeilding the correct TIME / AREA / ANGLE.

Taking it easy and doing what your doing is the way to go.
If you go too far you start to loose some of the gain.
Any further and it won't run right.

And Never Never touch the transfers in the cylinder bore.
If you want to smoothe them be very careful not to hit the top or sides of the ports.
I messed with the transfers a couple of times and ruined a couple of cylinders that way.

Also i cut the tunnels on the bottom of the jug out 1 time too.
took about 1/2" off the bottoms.
That cylinder wouldn't run at all.

I'm going to start a new thread on a complex build.
It will be very technical and detailed but if you follow it you will undersatnd all the how's and why's.

Good Luck and happy Rippin.
Best thing to do is get some rubber fiber gray gasket material that is thinner and use it for the base gasket.
It drops the transfers down a little and increases the bottom end.

And dont forget to check the clearence between the piston and the head.
If you can sand the head and get it down to .020 to .025 inches your golden.

 

[andrew88rmz]

Thanks man. By the way, On my 66cc the top of the exhaust port is much higher than 1.06. That is why i only took away .030. I am very happy with the results and i will probably order a pipe hear soon. What do you think about the jnm pipes or jet pro?

 

[210061741]

I have only run the sbp chamber and a very expensive bennasar pipe.
Any pipe should help dramatically.

 

[andrew88rmz]

I know this is a little off subject but does anybody make a pipe that isnt put together with copper fittings? If i have to buy one i would like it to be a little more finished. I realize that they have to be somewhat universal to fit many applications but i dont like it.

 

[210061741]

If you go here.
http://www.woolfaircraft.com/

You can get bent elbows and tube.
All stainless nice stuff.
Get the pipe tuned and then have it all welded together.

i would use 1" od pipe minimum.
And then if you get 1 foot of the next tube size up like 1"id than you can make slipjoints.

Get it all together using that rubber or even foil and hose clamps work temporarily.

After you have the pipe fitted and tuned the way you want get it welded.

Other than that im pretty sure spooky tooth chamber bolts on.