Topic: Running only on cylinders 3 and 4

[pipeguy]

Hi, bike is 70 cb, was running fine then all of a sudden lost power some backfiring, and now only 3 and 4 run, fuel isn't issue or spark. popped tapped covers and none of valves from cyl 1 and 2 are moving, could the cam be broken? Thanks in advance.

[754]

Of course this means you have to pull the motor..unless you are willing to cut the frame.

[halllzy]

This reminds me to ask if anyone knows if you can you install a
Gordon frame kit with the engine in place?  I'd assume yes, but I'm not good at basing cutting a frame up on an assumption.

For this thread, I'd start with a compression test on the cylinders for the sake of it; if the cam broke on the 1/2 half, you shouldn't have all your valves fully closed and should get super low compression on half and good on the other.

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[754]

I know I can cut my frame, to install the weldless frame kit, without even removing the carbs.
Should take around 2 hours, total.
 I then pulled out my oil starved cam, rockers etc... And replaced it all... Had it running, later the same day.

[PeWe]

I know I can cut my frame, to install the weldless frame kit, without even removing the carbs.
Should take around 2 hours, total.
 I then pulled out my oil starved cam, rockers etc... And replaced it all... Had it running, later the same day.

I used a tiger saw. Carbs were on.
http://forums.sohc4.net/index.php/topic,62832.msg1516243.html#msg1516243
http://forums.sohc4.net/index.php/topic,62832.msg1515491.html#msg1515491

Pull engine is easier when head, cylinder are removed. One man job with a lift strap