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"E.C." 2 Cycle Engine "TRIX"



By "E.C. Birt"

E.C. Birt sitting on a log somewhere in the Santa Clarita Sandwash.


" Lets make some Horsepower "

Matt asked me to do a thing on Wet bikes … Ok, Wet or Air Cooled it makes no difference they both can use some TLC treatment… Air cooled bikes will go just as fast as a wet bike…

The only advantage a Wet Bike has over the Air Cooled Bike if there is any wet might hold it’s over all power longer; but if you screw up on your tuning needs you can stick it also big time…

But the Wet Bike was a good way for the big three to shove a lot more costly bike down you throat… One of the real bad things about the wet bike is, you’re out trail riding with your friends or even in a race, and doing your Roger De Coster thing and fall off and wind up eating your shorts… That wet box thing hanging on the forks gets hurt; you’re done, and have to leave engine shut off now… Try pushing out of the Desert 20 plus miles to your haul my ass home hauler will be no fun either… Wet bike riders, better carry a towrope with you…

Right off the start there is 2 categories that you can cross over into to making your bike better and dig out a bunch of little things that will give you more over all performance…

The first one is Blue Print… This does not mean you grab up your handy dandy do all stuff and start hogging out the cylinder or head, or worse yet the cases…

Second step is Modify…  Here is where you need a complete equipped machine shop, porting tools and etc. and ready to step into the Twilight Zone and try to out Smart the Engineers that designed your engine… With out years of experience and a shed full, of well it was suppose to work scrap… It all winds up like taking a piss with your zipper up, it felt good but you still got it all over you, and wound up in Pony Land with a broken leg…

So what were going to do for now is how to Blue Printing your Engine… This in short this is what the Engineer that designed that cylinder, head and cases would do if he had 40 plus hours per engine to just take all his production designs to the last step… don’t have a clue on how many parts this tech piece may take me to do… But if not done right would be like being ½ Pregnant… So hang on and drop in once in a while for all my ramblings for the full ride…

You will wind up Going Longer for less $$$$$$ and have to FACE BEING FASTER; from a 80cc ride to a 501 Ground Shaking Maico…

I know why didn’t I lay this info on you around HALLOWEEN day when it was colder then a Witches tit, and your bike was laying in the garage with a blanket over it… I have a good reason. Rick and Matt hadn’t dug me out of the weeds yet… Well your going to have that weekend where rain is in the air and 2 day’s to work on your ride… Or worse yet one of those Honey do days which screws up everything and you can maybe get some time to work on bike a bit after chores are done…

Ok, Heres where were going first…  The first one is Blue Print… This does not mean you grab up your handy dandy do all stuff and start hogging out the cylinder or head, or worse yet the cases…

In short were going after free horsepower just laying there to get, and you don’t have to be a Brain Surgeon to do it… Just a little TLC will get the job done… In fact you don’t even need my Crystal Ball because I’m going to tell you all the Speed Secrets no one will share with you… 

just "E.C."

Rest Of This Will Fallow Soon...

just "E.C."


Hi ec birt…5/11/10

     I found your email on superhunky website.   I have a 74 CR-125 . Found a gem reed setup for it.  now I want to find out the appropriate porting specs for piston and cylinder to best take advantage of the reeds.  Can you help? Do you still do such modifications? If so I would mail you my cylinder and piston. Any help would be most appreciated. Thanks for your time.



When you add a reed-valve assembly to a piston-port motor, you are in essence installing a one-way valve in the intake tract of a two cycle motor, that prevents spit-back and gives the motor a wider power band. While I have stopped performing this modification to the general public. Find you a local machine shop and some one good with porting tools that is good to modify your CR's barrel to accept the reed-valve setup ... This is not a 1st. reader project...

 CR125 Piston mod_530.jpg


Windows have to be machined into the intake side of the piston skirt, along with feeder finger ports up the back side of the cylinder to be fed off the intake port when the piston comes down on the power stroke.... These piston mods needed will shorten the life of the piston so keep a close watch on it for cracks in piston skirt...  

Thanks for the question.

just "E.C."

Dear E.C.

My 1969 Hodaka Ace 90 has been sitting in my grandparents garage for about twenty years now, and I'm in the process of getting it ready for vintage MX racing. I've replaced the crank seals, and had the cylinder honed out with some fresh rings installed. The timing is spot-on, and it runs OK, but seems to be really slow.

What can I do to the porting to get some more beans out of the motor? A buddy said to raise the exhaust port a milimeter, and machine about ten thousandts off the cylinder head, to make up for the lost charge that gets squirted out the exhaust port. Does that sound right? Also, should I get rid of the dinky 19 mm Mikuni and run something larger? Do you know where I can get an expansion chamber built too? The stock pipe sucks.

Nice to see you back in circulation EC, last time I saw you was in Lawndale back in about 1970 something, you almost kicked me out of your shop when I knocked over a magazine rack.

Anyway thanks in advance.

Pat Feagans, Hawthorne CA.


I remember you making that club foot move. Sure your safe enough to race a bike now ? No way on grind a milleter one way or the other NEVER just because someone say’s that the hot tip… To answer your needs right have to go rub on my Crystal Ball for that info. Will be back to you LTR on this one.

just "E.C."

I have a 1971 AJS Stormer 410 that has seized up solid on me, and was wondering if another piston from some other dirt bike might fit, a buddy said one from a 250 TM Suzuki would fit, but I don't believe him. Do you have any line on AJS pistons? I've looked everywhere.

You rock! Bill, Toledo Ohio.

On A Suzuki piston swap out very possible. Just find you a Suz. Dealer that will let you paw around in his stuff and match up to the one you have… Or try this. www.bikeboneyard.com.

 NO luck with these two way’s God doesn’t want you to have it.

just "E.C."

Mr. Burt, HELP! I have a Steens-Allstate with the 100cc Hodaka motor that needs a new top end. Do you still work on these bikes? Mine broke a rings and scrathed up the cylinder pretty bad, so I might need a new liner. Any idea when I could find a new top end for my Steens?

Thanks, Armando, Sarasota Springs, FL.

Putting a sleeve in a cast Ion Cylinder is a no 1st reader project. For your Hodaka you would have to make sleeve from a blank. I’m sure Paul can bore it a fit with a new piston. Contact him.www.strictlyhodaka.com

Dear EC,

Glad to see you're not dead yet, and are working with Super Hunky. I have a vintage Bultaco El Bandito (the black tanker) and the damn thing ate a piston on me, and now I can't find a replacement. Do you have a line on Bul pistons? Mine's a '68 with the Spanish Amal Monobloc carb & the up-pipe. Any help would be greatly appreciated.

Tom, Boston MA.


Gary Bailey more then likely has a box full under a bench in the back room. www.garybailey.com

just "E.C."



I have a 1971 BSA 441 Victor that got the valve-lifting mechanisim stuck and it bent an exhaust valve on me. Do you know where I can get a new one? The place where I use to buy parts went out of bizniss about two years ago, and I'm stuck with this broken down Beezer. HELP!

Rick Santos, Highland Park, Los Angeles

Rick, here's the straight skinny;

The first guy I'd call is "Ralph" at REV (Racing Engine Valves). #(800) 398-6348.  They have around 2 million valves, in stock. Even if not in, Ralph can have it made, or spec order.

Ralph is very professional, whether you buy a single valve, or a 1000.  Lots of times I've bought only one valve. Recently I went nuts and bought a whole 20 five mm lash caps.

They are located in West Palm Bch. Fl.

Hope this helps, If not I'll be thinking of alternatives.

just "E.C."