I have OS 91 FS that at one time had some damage to the rocker box cover and broke out the thread boss on the front hold down screw. I want to install stud and nut to retain the forward edge. The epoxy that I build thread boss out of probably won't hold up to many valve adjustments. Does anyone know the size and pitch? I have been flying this for 4 years on a Flying King without any problems but it is time to fix it. Thanks in advance, this forum is great!

You could convert the engine to Open Rockers....There have been several done and it doesn't hurt anything. To fix it right you would need to buy a new head and you said that you've been running it for about 4 years with the broken cover...

If you know a machinist you could have him mill the flash off and clean up the head so it would "look" factory...

One problem with using some kind of epoxy to repair the head is the epoxy expands and contracts at a different rate than the aluminum. It will usually come loose. Another problem is that the cast aluminum head is somewhat porus and the oil(s) used in the fuel are real hard to get out of the pores. It doesn't stick real well.

A model like the Flying King will look real nice with open rockers.

Just my opinion.....

'Broken Wings' thanks for your input.....
My rocker cover is in good condition. I ran it for the 4 years with just one screw and silicon gasket maker. Looks to me like it is an easy fix. Need to get a screw with enough threads and make a stud. JB Weld or MarineTex will secure the stud to the remainder of the stud boss. There is an area between the screw thread boss the rocker stand base that will retain any epoxy very securely. My experience with MarineTex rebuilding motorcycle primary sprocket enclosures has been very positive. JB Weld with thorough cleaning will do pretty much the same thing.
Don't want to go with open rockers, don't care for extra cleanup and there is times when I fly off of dirt fields.
Anyone with dimensions or source for screw?

Beagle,
Here's the screw set from Tower, it looks like the rocker cover is the 14 X 2.6mm.

You will have to buy the entire set.


http://www3.towerhobbies.com/cgi-bin...?&I=LXCV56&P=Z

Hello,
I was wondering if anyone could tell me the correct way that the rear bearing goes into the OS 91FS Surpass? A friend took mine out and didn't make note as to the direction it went. There is a metal side that is enclosed. The other side you can see bearings. Does the closed side face the rear or front of the motor? Please email me at [email protected] cause I am not sure if I can find my way back here. LOL