Repairing A Saito 91S

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Category: Sports
     
 

Presentation Description

This Power Point presentation shows the vier how to change bearings, set the timing and grind a valve

Comments

By: tee_sir (108 month(s) ago)

Thank you for this presentation, I will be using it to replace the bearings on my Saito FA-80. I just need to find the details for the alignment tool.

Presentation Transcript

Saito FS 91:

Saito FS 91

FA 91 Purchased on E bay :

FA 91 Purchased on E bay

I Needed to change the bearings, replace a bent push rod cover and a dented intake manifold.:

I Needed to change the bearings, replace a bent push rod cover and a dented intake manifold .

Remove the back screws being careful not to damage the gasket. Then unscrew the cylinder head screws:

Remove the back screws being careful not to damage the gasket. Then unscrew the cylinder head screws

Pull off the cylinder head. Mark the back side of the piston rod before removing it from the crank shaft.:

Pull off the cylinder head. Mark the back side of the piston rod before removing it from the crank shaft.

Remove the cam housing screws being careful of the gasket.:

Remove the cam housing screws being careful of the gasket.

After removing the collet tap the crank shaft out. If necessary heat the housing to get the bearings out:

After removing the collet tap the crank shaft out. If necessary heat the housing to get the bearings out

To get the new bearing in easily freeze the new bearings and heat the housing and they should just fit right in:

To get the new bearing in easily freeze the new bearings and heat the housing and they should just fit right in

Oil the new bearings and replace the crankshaft :

Oil the new bearings and replace the crankshaft

Setting the timing on the Saito 91:

Setting the timing on the Saito 91 The timing mark is shown on both the front and the back of the timing wheel I made this timing tool as suggested by Graham Rice “ A guide to Saito Models 4/strokes.” which fits into the oil hole shown below.

Using a stiff wire push the intake cam follower out. :

Using a stiff wire push the intake cam follower out.

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Place the special tool in the forward or intake brass cam follower guide Once it is in the oil hole the cam gear will not move and the timing mark will be in the 6 o'clock position. Place the housing back on the crankcase keeping the crankshaft at Top dead center.

Replace the cam follower in the brass guide. Use machine oil. Place the cam housing back on the engine block making sure the camshaft does not move.:

Replace the cam follower in the brass guide. Use machine oil. Place the cam housing back on the engine block making sure the camshaft does not move.

Replace the push rod housing.:

Replace the push rod housing. Replace the piston with the mark you made facing back.

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The push rods have a tapered end which faces up to fit in the rocker arm Place them in the housing and push back the cylinder head.

Tighten up all the bolts:

Tighten up all the bolts

Seating the Saito 91 valve:

Seating the Saito 91 valve Having taken the engine apart we found that the exhaust valve was leaking compression when the valve was closed. We decided to regrind the seat.

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We removed the rocker arm by unscrewing the pin.

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Once the pin was out we depressed the spring. We used a block of wood inside the cylinder placed against the valve to prevent it from opening. We removed the lock clip and the spring retaining cap and then removed the spring. Using a small Allen key pushed the exhaust valve out.

Clean the valve seat and the valve to make sure either seat is not damaged.:

Clean the valve seat and the valve to make sure either seat is not damaged.

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To reseat the valve we used car polish which is a mild compound. We attached a hand vice to the valve and turned it until we had a good seat. Less is more.

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Once a clear seat was seen on the edge of the valve and the cylinder, we replaced the piston and checked the valve seal. We use machine oil to check the seal. Push the piston up and hold the valve tight in the closed position. Once there was full compression the job was complete

Reassemble the parts in the same order you took them out:

Reassemble the parts in the same order you took them out

Replace the covers:

Replace the covers Make sure the spring cap is the right side up.

Start the engine and go flying:

Start the engine and go flying

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