After a couple of guys here helped me get my CB400F headlight squared away a couple of weeks ago, I had time to get back to this build:
Late May 2015:
I posted very few pictures anywhere of the '75 H1 that I just completed porting and assembling the engine for this past Sunday. If all my porting calculations are correct, it should give my turbo, even with it's 18PSI, a good run for the money! I've done some pretty radical things inside the engine. This was actually a joint effort between 3 guys. I was joined by a friend on the other side of the country and another up in Canada. One contributed the fantastic head work and Canada provided lots and lots of math calculations to verify that my dimensions would even work. He also provided me with providing being a free PITA but it served to be a good check and balance for me as I worked on developing this beast. This has been a "proof of concept" since I began the engine design 9 months ago. The goal was to see if it all worked together then go back to strengthen other components such as the clutch and tranny. The heads slip right into the cylinders with no head gasket and he allowed for the perfect amount of space to allow two different expansion coefficients. As soon as the heads were bolted on, even before mounting the carbs or pipes, I measured the secondary compression. We were aiming for 155PSI so the 148/149 as shown is perfect for a non-started static measurement. It will rise by 6-8 psi once it's been started and the rings have seated.
This is a "Proof of Concept" engine and as many of you guys know....THEE most important part of a 2 stroke is that the expansion pipe matches the cylinder porting. Most expansion chambers were built for stock or nearly stock engines and while they added maybe 7BHP for an engine such as that, they were all useless for a highly modified engine. Most actually hurt more than they helped. This engine utilizes a lift kit for the cylinders while at the same time lowered the combustion chamber into the cylinder along with several other "secrets" so the pipes for it were built to my measurements but the builder forgot that I needed one very special feature so while that part is getting resolved, I'm hoping to bolt a set of race pipes to it this weekend which SHOULD be at least enough to prove the concept.....if it does, and the engine is as powerful as I (and a highly respected tuner who I used to race with)have projected, then in all likelihood, I'll disassemble the engine to beef up the gearbox and clutch. I figured there was no point spending time and money on those things until we knew if this was going to work or not.
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All the above was written a week ago.....fast forward to this past weekend:
Well, with the bike fully assembled, it was time to start it this past weekend. I temporarily installed a set of pipes just to make sure the engine runs, then I'll complete the special pipes for it. My girlfriend and I went downstairs Sunday morning so she could video the "main event". She held the camera at the ready and I turned on the fuel flow, applied the choke to all three carbs, gave it two kicks with the key off, then told her to turn on the camera...I flipped the key on and gave a mighty kick resulting in the most ear-splitting silence you ever heard.....2 hours later, after she had left and I had replaced all the cheap Chinese parts in the Flatside knock-offs I had bought with genuine Keihin parts....the beast awoke!
I've got to get these carbs squared away but the engine is just plain wicked. When I hold the rpms at 3000, it sounds like its at the staging line! Another BADA*SED two stroke nearly completed!
Once I get the carbs replaced and the correct pipes installed, I'll take it up the ramp out of my shop and see how it flies on the street!!
For a video of the beast running:
the popping is the camera trying to compensate, not the engine!
Not too bad_zpsvqybo47d.mp4 Video by jeffkushner1 | Photobucket
Since the weekend, I ordered and received a set of PWK flatside carbs to replace the cheap Chinese knock-offs. My advice? NEVER waste your money on those knock-off carbs....they are junk! I've removed the temporary pipes and the cheap carbs and took all my good Keihin parts out of them and wrapped them up and set them on the shelf. I've stripped the new carbs to prepare them for the correct size jets for this engine. Hopefully this weekend will be spent welding my pipes.
jeff
