AERMACCHI-WORLD

As I couldn’t find a correct steering lock for the Aermacchi I tried my luck with something that looked similar and made it fit with a lathe. Surprisingly it worked on the first attempt.

Paint code MG645.30 Standard Glasurit 90 CPS2

Before you start:
There is no guarantee for the correctness of the information provided. That following steps describe the procedure for my 1970 GT-350. It’s a different procedure on other model years!
To my knowledge (again, without guarantee) this is valid for 1969 to 1972 Sprint 350cc street bikes and not for earlier bikes and not for the 1973-1974 electric start!
Please ailways use a few drops of oil to fit the parts together.

Pic 1.

• We start with an empty right side crankcase. Only the shifter pawl carrier (C) is already put in, as it must be inserted before the primary drive gear.
• Pull out the connecting rod (A) to tdc (top dead center), this will move one of the three notches (B) on the flywheel shaft to 3 O’clock position.

Pic 2.

• Slide clutch drive gear (D) on shaft of flywheel. It will stop in the correct position because of the conus of the shaft. Don’t turn the shaft! The mark on the clutch drive gear (arrow) is of no meaning at this point.

Pic 3.

• Put the woodruf key (E) into notch of the shaft. It must be the notch at 3 O’clock positon while connecting rod is at tdc position!

Pic 4.

• Slide pinion gear (F) on shaft with woodruf key in position at 3 O’clock and make sure the mark on the pinion gear points to 3 O’clock also (arrow)! It sits correctly if the surface of the pinion gear touches the surface of the clutch drive gear.
• Put the lock ring and nut on the shaft. One latch will be bend into the notch of the pinion gear the other around the flat side of the nut after the nut is tightend! (These steps are not pictured)
• When tightening the nut you must make sure the shaft will not turn.

Pic 5.

• Next we  put the primary drive gear on the transmission shaft. On that picture you can see what parts must be fitted inside the gear. A thick spacer (G) that must have the correct thickness to arrange the primary gear in one line with the clutch drive gear (D).
• Inside the gear are two roller bearings. On top of the bearings will fit another distant spacer.

Pic 6.

• Put the primary drive gear (J)  on transmission shaft and don’t forget the stuff explained in Pic 5. You will need probably 2-3 trys to make the two marks fit the one mark of the clutch drive gear. For that operation you may turn the flywheel shaft with the clutch drive gear.
• The marks on the primary drive gear (J) and the clutch drive gear (D) however are not time critical. It’s just the way the teeth are fitted together by factory. That’s the reason for using gears always in matched sets! If you don’t, you will risk damage to gears.

Pic 7.

• Next we put the roller bearing (L) for the camshaft into crankcase and also set the two tappet guides in (K).

Pic 8.

• A spacer will be used on camshaft to allign the camshaft gear exactly to the pinion gear.
• I will not describe how to fit the camshaft gear to the camshaft as it can only be fitted in one direction

Pic 9.

• Put the camshaft with gear (N) into the roller bearing (Pic 7.) and arrange the two marks with the one mark on the pinion gear (F).

Pic 10.

• Screw the oil pump into case (4 screws) and make sure the O-Ring is still on the oil pump for a sealing to the crankcase. Put the gear on the oil pump shaft. It is not time critical and has no mark so it doesn’t matter how it will fit together with the pinion gear.

The new ballerings, the new rod and the overdone flywheel getting back together. Rudolf than trued the flywheel to 0,01 mm which is much better than factory Defaults.

We polished the crankpin so the new bearings do not have to cut off material. The original bearings which consists of two parts rollers in each cage we replaced with “one-part only” bearings as you can see on a later picture.

Here you can see how we pressed the crankpin from the flywheel and the oil dirt we found inside the crankpin after drilling out the plug. This is a typical 4-Stroke-Aermacchi problem and the reason you really should change the oil once a year or every 1000 miles. Rudolf decided the rod is used up and that I will need a new one.

A lot of fresh grease and 50x new bearing balls (8854) for the NOS fork stem. The fork stem I got with the bike obviously got pressed together in the wrong way as the notch for the steering lock was on the wrong side.
The parts shown on the last picture like airfilter housing, kickstarer and some other stuff went out for rechroming that day.

I have replaced every bearing in the engine case with new ones. The front wheel hub is also redone and waiting for new stainless steel spokes and a brand new 1.85×19 front rim. I have also replaced the bearings and the dust seals here. At the moment I am working front fork.

Left to right: 98302, 16006, 6305. Tony Foale suggested to use C3 bearings for the flywheel (3305 and 6305) and so I will do.

I needed help from a machine shop to get the large doublerow bearing out of the right engine half.

Oil seal 15x24x7. In a later right side cover (71) it is 15x32x7

The wheels are totally disassembled. I will give them out for cleaning (sand blasting) and I will probably have the hubs polished. Cylinder head and barrel will also be sand blasted.
Yes, there is a X-90 cylinder head also on this picture. 😉

I bought a cheap tool set to remove the ball bearings from the engine case (left picture). I totally regret it. It was a waste of money. The tool is from a much to soft metal and it bends while the bearing still sits tight. I now own a professional bearing puller that worked like a charm.

The engine case is open now and it looks like I did no damage. *Happy*

Almost ready for splitting the engine.

Before disassembling. Rear wheel bearings: SKF 6204-2RS1

I built myself a pinion gear puller that worked good. As you can see on the last picture the piston rings are totally baked into the piston.

The inside of the engine looks not very good at all. Spark advance is broken and the primary gear is totally worn out. I am pretty sure more bad surprises will come, going deeper into the engine. I also noticed that the left engine cover has a 1971 production time stamp and the right side a 1968. I am pretty sure someone had the engine disassembled before me.

It is done, the bike is very handy now and easily fits into a large rack. The hardest part was getting the fork out of the frame. Heat and pure force did the trick. The weldseams look like having been done by an apprentice in his first year. Never seen such bad weldseams on my other Aermacchis.

The tires, rims and spokes will be replaced later. Hubs will be polished and reused. The oil in the front fork – or better what is left – is just mud, but there is hope that the fork may be repairable. The shocks are totally broken and can’t be reused.

There – the idea of the cafe racer is back in my mind…
No, not this time. I will restore it to factory defaults. 😉

I took some pictures before disassembling as construction plan for a later assembling. 😉