50cc to 100cc kit Problem

[frankwallace2003]

I have upgraded a 50cc to a 100cc kit the problem im having is, it had a 69mm valves
And head the kit came with the 64mm valves and head. The rocker off the 69mm will
Not fit, called the dealer he said I had the wrong rocker so I ordered another rocker
That he said should work with this kit, BUT the scooter will not start. set set timming
.004 intake ex. Set .004.. Thinking maybe put the 69mm valves and head back on.

[GrumpyUnk]

There is no functional difference between the 69mm and 64mm. But. The rocker arm/cam follower that will work with each is different. But. If you adjust the clearance properly, the cam lobe will move the valves exactly the same.
The clearances of .004 (in inches...) is larger than specified in some service manuals. It should insure that you don't burn the valves due to having a too-small clearance.
If you remove the cam cover, and remove the blower housing, you can re-check your cam timing. With the piston at TDC, verify that the T mark aligns with the rib on the block. The cam can be 180 out, with the big hole down towards the crankshaft, and it will still be timed correctly if the piston is at TDC. You can verify TDC by using a Bic pen, pencil or plastic straw down the spark plug hole. Rotating the blower wheel clockwise, you will feel the piston come to the top, and then start to drop again as you go through TDC. Depending on cam phase, you will then be on intake or burn stroke, piston going down... Either way, the cam should line up with the gasket surface of the cam cover. If 180 out, rotate the blower wheel 1 complete turn, and the cam will rotate 1/2 turn, and be timed properly.
It is very easy to get the cam timing off by a tooth, so get TDC using a straw, check the mark on the flywheel, and if TDC is correctly indicated, toss the straw, and depend on the flywheel mark. Then check cam timing.
If you are using the old carburetor, you should be able to start w/o problem. Make sure the float bowl is full of fuel. Put a vacuum on the petcock vacuum line and watch for fuel to fill the filter, wait 10-15 seconds to allow time for fuel to fill the float bowl(or longer, actually), and then reconnect the vacuum line and try to start. If concerned about spark, you can crank the engine with the spark plug out, and the plug stuffed into the plug wire/coil connection. Laying the plug on the engine, and cranking, you should see spark upon each crank revolution.
tom