Ive got a saito 90, about 1 gallon of fuel through it. Every 3 flights I have to adjust the tapped because the gap is too big... Done this 6 times now,and there is no further thread left to adjust further!!!! The pushrod has shortened (I think) to the pon that it barely protrudes into the head!!!

WHAT THE HECK!!!???

Ive never seen this before. Im taking it back to the hobby shop today. What can explain this strange behaviour!!!???

Im worried there might be some burr on the cam, and perhaps it is grinding down the pushrod? If thats the case, there were likely metal particals floating in the crankcase...

Anyone with input?? I figure I should get a new motor, no?

The other pushrod has never needed any adjustments.

Bent pushrod? Happens. Doubt the tappet could grind down that fast. But I have had a bent push rod and the symptoms are as you state. I think it happened from overrevving the engine. If its under warrenty you probably are required to send it in for service.

nope, pushrod is perfectly straight! Tappet isnt bent either. Only 2 options:

1)pushrod getting shorter
2)cam wearing dramatically

any other thoughts?!

99% chance you are wearing cam. Could have been a soft cam installed from factory, pushrods dont srink, they bend.

It does sound like a wearing tappet or cam (both?)
If you have a known good engine for comparison you can check for the net valve lift with the same clearance set on both engines.Open up the good engine clearance to match the one in question if you have to.
Are you SURE there is no carbon build up under the valve. It sounds strange but we did see it happen on a Saito 91. The carbon prevented the valve from fully seating but was sealing well enough for the engine to still run . It is worth checking.
Let us know

The lift is pretty much the same on both lobes so with the plug out turn the moter over slowly the. the valves should open the same amount with the valves at the proper clearance. Also the pushrods should be the same length. Are there any metal particles around the bottom of the questionable pushrod?

Check to make sure the end of the valve stem isn't mushroomed over

Just a thought, but would it make any difference if the push rods were upside down so to speak. I know there is a difference on my 65.

Some pushrods have a ball end on both ends. Some have ball on one end and a cup on the lifter end . I think my old, old Saitos have a ball on both ends.

Thanx guys...I think I have to send it in for repair...This motor is basically brand new. I hope they get it back quickly...

If you get a chance let us know .