Tested it again today. I cut and shortened the pipe and made some other adjustments and this was the result...
![159478]()
The purple curve is the one with the long 820mm exhaust. Promising rev capability but little power.
Then blue curve with the original 725mm(ish) exhaust length, finally 4HP and pulls a lot harder. Sounds crazy as h*ll
And the red curve after I modified the combustion chamber, 4.2 peak hp and even more high rpm power. It reved to almost 14800 in the curve, and it sounded like it still would have got more.
I can imagine how the bike feels to ride now. Right from takeoff there is 0.5 horses more than previously
Regarding max rpm, still 1200 to go to break CAM2's rumoured 16000rpm (presumably with nitrous/alcohol and no proof of it). And yes the bike is running pump gas, 98 octane.
The combustion chamber modification was to machine it a bit larger because the plug was shrouded in the hole. After machining looks like this
![159479]()
Apparently less compression ratio can give better power. It can be due to the exhaust pipe getting more heat (smaller compression ratio leaves more heat that didn't convert as pressure on the piston) . Other possibility is that the combustion chamber shape was simply bad before, as the plug was about 2mm inside the hole.
The mad bike, removed the head for machining and checked inside cylinder that all is ok
![159480]()
Cylinder looks perfect now and no detonation marks but we will see how long...
![159481]()
The bike has now a problem with the carburetor. It only pulls with the choke on. I tried to put a 98 main jet but that's still too lean. I think it is caused by my stupid idea to drill the air jet hole previously, trying to fix the problem. I need to somehow resize the hole with a plug.
Then my CDI fried again. Apparently the RPM is a bit too much and need to revise some part of the schematics...
I think there is still significantly more power to be had by fixing the carburetor issue and fine tuning the ignition.
The purple curve is the one with the long 820mm exhaust. Promising rev capability but little power.
Then blue curve with the original 725mm(ish) exhaust length, finally 4HP and pulls a lot harder. Sounds crazy as h*ll
And the red curve after I modified the combustion chamber, 4.2 peak hp and even more high rpm power. It reved to almost 14800 in the curve, and it sounded like it still would have got more.
I can imagine how the bike feels to ride now. Right from takeoff there is 0.5 horses more than previously
Regarding max rpm, still 1200 to go to break CAM2's rumoured 16000rpm (presumably with nitrous/alcohol and no proof of it). And yes the bike is running pump gas, 98 octane.
The combustion chamber modification was to machine it a bit larger because the plug was shrouded in the hole. After machining looks like this
Apparently less compression ratio can give better power. It can be due to the exhaust pipe getting more heat (smaller compression ratio leaves more heat that didn't convert as pressure on the piston) . Other possibility is that the combustion chamber shape was simply bad before, as the plug was about 2mm inside the hole.
The mad bike, removed the head for machining and checked inside cylinder that all is ok
Cylinder looks perfect now and no detonation marks but we will see how long...
The bike has now a problem with the carburetor. It only pulls with the choke on. I tried to put a 98 main jet but that's still too lean. I think it is caused by my stupid idea to drill the air jet hole previously, trying to fix the problem. I need to somehow resize the hole with a plug.
Then my CDI fried again. Apparently the RPM is a bit too much and need to revise some part of the schematics...
I think there is still significantly more power to be had by fixing the carburetor issue and fine tuning the ignition.
