How to run a Saito 56/62/72 in Reverse
Page # 2
By Bob Reeves
Once the Cam Housing is assembled it is a good idea to oil the Shaft, Spacers and Lifters to be sure it isn't dry the first time it's started with the new Cam. I use a pen oilier but you can just slop it on if you don't mind getting oil all over your hands. Be sure and get the oil hole in the Cam Gear.
Now comes the fun part, getting the timing set properly. I have not found any of the timing marks on the new Cam Gears to be allot of help and always end up just setting the timing by trial and error. I didn't get a photo but if you set the crank at Top Dead Center and position the Cam Gear so both lobes facing you (looking at the bottom of the Cam Gear Housing) an even amount you will probably be writhen a tooth or two of having it correct.
Install the Cam Gear Cover on the case with only one screw just snuged down. Get the push rods in position and install the Cylinder on the case, again just use one screw. Be sure the push rods are in the rocker arms properly and you can remove and install the rod on the Crank without removing the piston. You can push the valves down far enough to line up the push rod tops with the recess in the Rocker Adjustment Screws.. This is a lousy photo but it does show the Push Rod properly seated in the screw recess.
The reason you only use one screw to hold the Cam Cover and Head at this point is because I found it fairly easy to remove the screws and just tilt the Head and Cam Cover to allow moving the crank (to adjust the timing) without completely disassembling everything.
With the engine together and the push rods in place you can start checking the timing. Remember this engine now runs Clockwise and you need to turn the crank Clockwise. A good starting point is to compare the Reverse engine with a stock Saito. You may not have another engine but not to worry we will get it right. The ultimate goal and sure way to tell if your engine is timed properly is if both valves are open the exact same amount with the Crank at TDC.
What I did the first time was remove the back plate, glow plug and valve covers from a stock Saito 56 and noted the position of the crank when the intake valve just started to open. This worked the first time because I was lucky but the second time I ended up with the timing off by one tooth. In any case it will get you in the ball park.
The photo is showing a stock Saito on the right with the crank positioned just as the intake valve starts to open. The one on the left is the one that ended up being off by one tooth. Only explanation I can come up with is I must have missed the valve movement. You can start here but double check by looking at the rockers from the rear of the engine as you rotate the crank back and forth through TDC and stop at the point where both valves are open the exact same amount. When you feel you have both valves open the exact same, look at the crank. It should be at TDC. If it isn't, note which way the crank needs to turn, remove the two screws holding the Cam Cover and Head, rotate one side of the Cam Cover up just enough to be able to move the crank, rotate the crank as needed and drop the head and Cam Cover back in place and replace the two screws to hold everything together so nothing will move. Check and repeat as necessary.until you have both valves the same when the crank is at TDC.
Once you feel you have the timing correct check and adjust the valve lash per Saito's instructions, put the engine back together with a muffler and bolt it on a test stand. If your engine is a 56 or 62 and you ordered a JFX reverse 13-6 prop running muffler pressure, Power Master YS 20-20 fuel with an RC carb you should be able to duplicate the results I had. A 56 turned the JFX at 8900 RPM or there abouts and the 62 should turn it at about 9200. As a reference point, when I had the 56 off by one tooth it would only do 8500, a 400 RPM loss..
I have not done this mod to a 72, and can't help with the 72 numbers. If you modify a 72 and would like me to add anything to this article just drop me an email. Personally I am getting all the power I need out of my 56/62's flying Legacy size stunt ships and see no need for the 72 nor would I want to have hold of the handle on something that would require a 72.
A few notes from my experience with Reverse Saitos.
Martin says he has used JFX Electric props on IC engines and they worked fine, this was not my experience. When I placed my initial order with HiModles I ordered a couple JFX 13-6 reverse pitch electric props to test. I found the blades flexed a considerable amount and the resulting vibration was unacceptable. I have had success with the JFX 13-6 Beachwood on both the 56 and 62. This is the prop I would recommend you start with.
This mod along with the JFX prop works best with the carb mod I use on the stock Saito intakes. I tried to run the 62 in my Latency with a choked Dixon intake and it just didn't work out, ended up converting it to a modified RC carb per the instructions found here. Follow the instructions at the end of the Carb Mod article to set up your Saito. Sorry, I neglected to note the ground RPM I was flying at with the JFX prop and next chance I get to fly will check it and update this to give you a starting point.
I ordered and compared the two Cam Gears Horizon lists, SAI182TD34 for the 62/72 and the SAI130T34 for the 56 and was not able to see or measure any difference what so ever. I did notice the actual gear is slightly thinner than the stock gear out of a 62 but the over-all length is the same. I don't feel the difference in gear width will make one iota of difference in performance or longevity and at this point I wouldn't hesitate to use them interchangeably.
That's all I can think of for now, will update as I gather more experience.
