somethings wrong


Local time
9:08 PM
Jun 4, 2008
I did a mild port on my HT engine cleaned up the buildup on the piston and cylinder head. before starting it I noticed that the engine was much easier to turn over while the spark plug was in.I can almost get it to start just by turning the tire with my arm while hold the bike up with the other. WHile riding it i noticed that the power is way down. . in porting the motor I widened the exhaust ports and lowered the intake port. i did not touch the top of the exhaust port. maybe that my file removed about .5m off accidently. But even when i added epoxy to the roof of the exhaust I still had low power. is it possible
that the carbon buildup was responsible for the stock performance?
I'm with Pablo on his one.

heh...we used to jokingly refer to the carbon, as free compression.:LOL:

Sleeve valve engines using the knight system used actually to gain in performance when they started to coke up.

There is a scene in the original 'flight of the phoenix' film where the pilot uses the cartridge starter with fuel off/switches off to clear all the sand and **** out of the motor - you see a huge pile of black soot out of the exhaust stub. In the case of the aircraft concerned the R2800 engines are poppet valve type not sleeve-valves

I dont know where I read it now, it was years ago, but I understand that with aircraft using a sleeve valve motor in the RAF that procedure was avoided since it could drop an engines actual output by up to 100-150hp depending on the engine because of lost compression (remember these are very large motors) it could also damage an engine.

In the case of the Napier Sabre and Dagger engines they would toast sleeve's at an alarming rate in the abaft cylinders cos they got too hot and would have to be run every two hours in cold weather as low quality oils didnt work and the result of trying to start a cold engine would generally be to wreck it because of lubrication failure...

just another pointless factoid lol

Jemma xx