futaba1024

Hi Guys.
A good friend of mine has just come to strip down his latest model Saito 56, in order to fit a new crankshaft (lost an argument with a tree and bent the crank!), and on removing the cam housing discovered that there was no gasket fitted.

Now that came as a shock to me as I was under the impression ALL Saito's had this gasket so as to set the correct engagement with the cam and crank gears.

The motor is only about six months old, is the latest model purchased from one of our official dealers (Just Engines) here in the UK and has not been stripped before now.

Question is, have Saito modified these motors so as not to need a gasket or has this one slipped through without one fitted, anybody got any ideas.

Cheers.

w8ye

My Feedback: (16)

The gasket is a thin piece of Mylar. May be clear and hard to see?

enjoy,

Jim

futaba1024

Hi w8ye.
Thanks for the fast response, no checked for that, definitely no gasket.
Cheers,

gjeffers

call the guys at hobby services and they will tell you first hand

William Robison

My Feedback: (3)

It may be different in the UK, bit our Saito distributor in the States supplies only one thickness for the cam cover gasket. I'm sure they are selectively assembled at the factory, I've found gaskets from 0.002" up to 0.005" thickness.

It is possible that your engine was at the outer edge of tolerances, the gears at the smallest diameter and the crankcase and cam box at maximum height. This way the lash could well be right with no gasket at all. I have never seen one this way.

Since you are replacing the crank that means one of these (possibly) minimum diameter gears is going to be replaced. The clearance should be checked.

Install the crank and bolt a prop on to seat the prop drive, then take the prop off. Mount the cam box with no gasket, don't worry about timing it now. Snug the four screws and turn the crank. If it wont turn, or feels "Notchy" as it turns, there is too little clearance. Loosen all four cam box screws evenly just a little, and try again. Keep working them out until the shaft turns smoothly. Then snug them down just a little to be sure you've reached the zero lash point. Always turn the crank at least two turns to be sure there's not a tight spot.

When you're sure you are truly at zero lash, use a feeler gauge and measure the clearance between the cam box and the crankcase. If you were careful you should have the same clearance in front and on both sides. The gap is even? Good. Now cut two small bits of shim stock the same thickness as your measured clearance, put one in the gap on each side, evenly snug the screws again for a final check. All OK? Great.

Now, remembering the measurement you just made, take your micrometer and hie yourself off to your local stationer's shop. Typing paper comes in various thicknesses depending on the "Bond," or weight of the paper. Pick a sheet that's 0.002" thicker than your measurement. That's your gasket material, scientifically selected for thickness. Why thicker? 0.001" for clearance, and 0.001" for the paper's compression when you tighten the cam box to the crank case. If you smear both sides with a light coat of RTV it will seal better, and more likely wont be damaged the next time you take the engine apart.

William Robison

My Feedback: (3)

A little more:

As W8YE said, you could well have had a thin Mylar gasket in there, and had it fall out with your neer knowing about it. Once it got away from you you'd never find it. It is indeed that hard to see.

Bill.

futaba1024

Tanks Bill, for your ( as ever ) comprehensive reply, will investigate further over this weekend.
Cheers Martin.

Rudeboy

I have seen one Saito without cam housing gasket... namely the one I have... my 1.50. The gears on mine don't interfere without gasket, so it is possible.