I have an r50/2 1969 that I just replaced all motor bearings, oil seals and gaskets and cleaned the slingers. I also installed new pistons and rings one size over. The motor ran before I disassembled it. I have checked the timing and valve adjustment several times, It will not start wont even backfire. I get plenty of spark and the carbs are cleaned. Compression is around 50 lbs. rings need to be seated, Any help or suggestions would be appreciated.
If compression is only 50 lbs something is wrong, even w/unseated rings compression should be in the 130 lbs range. If you don't have compression, the spark won't have a dense enuff mixture to ignite. Here's a few things to check: Piston rings staggered ? (gaps at 2, 7, and 10 oclock is best). Check valve timing, and make sure that the timing marks on the gears make sense. Make sure that you are setting valves on compression stroke. Set them on the loose side; re-torque and reset after the motor's (hopefully) run for a few minutes. Good luck!
Thanks, I will recheck. I did set them when the top dead center mark on the flywheel was in the opening on both cylinders. I made sure the gears were on the timing marks before I closed up the engine.
Note too that checking compression requires that you at least open the throttles to wide open...best to remove the carbs totally. Otherwise, you'll restrict the air going in resulting in a low reading.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
I assume you mean you set one side at TDC, then rotated 360 and set the other side? You can't set them both on the same stroke. Just wasn't clear from your explanation.
If you set them both on the same stroke, you will have one side very loose. It will be now hard to tell just by feel which side is the proper one to set at the TDC stroke you are on. You'll have to watch pushrod movement to see which set is retracted completely, there are other ways to tell also.
When assembling the motor. as long as the timing marks line up on the crank and cam shaft. Do you have to have the crank in any certain position. The tec. book does not state that it should be in any certain position only that the marks should line up.
I just finished rebuilding a r50/2. I had to have the heads bored to 1 oversize. Should I change the carb main jets to acomidate the new pistons? If not what # jets should be in the carb?