The Highs and Lows of Airhead Restoration if you are a dip stick

[byron]

It was a lovely sunny afternoon yesterday when I decided to strip the R90S engine down a bit further. Prior to this point my issue has been how to get the aluminium casting looking fresh and smart . My preferred choice looks like I will buy a soda blaster and mask off the engine with face plates and gaskets.
My plan is to leave the crank in the block and replace all the oil seals and gaskets after blasting.
Anyway yesterday I decided to try out my new flywheel locking jig and remove the said wheel. I had already removed the clutch on Sunday and found it in great condition -- SO WHAT COULD GO WRONG?

Bolts came out easily and I centre punched the crank and the flywheel for relocation . Well the flywheel came off a treat with just a few taps of my hide mallet. Just popped inside and wrote a few school reports as teachers like to do in the evening and then looked on line at airhead flywheels with Chris Harris on YouTube Holy shit !!!!! - stop crankshaft end float and I had forgotten to do it. Well I was almost as upset as when England beat Wales this season!!!!!!
I may be mistaken but I cannot find this in my Clymer manual.

I was very upset with my stupidity and then spent 2 hours online looking it up and reading with "snowbum"

 

[byron]

Tonight's efforts

I just was not aware that there were two floating thrust washers on very small dowel pins and what had happened to the inside one as my crankshaft appeared to have floated about 3 mm forward.
So here I am at 11pm last night thinking oh shit I will have to give the bottom end to someone to strip and reassemble for me as the inside thrust washer has moved off its dowels. However in desperation I plugged the front end of the crank and set about measuring males and females! Then again we all like measuring females!!!
Mr Snowbum says the crank spigot must be longer than the flywheel hole by a minimum of 0.05mm
Well my crank/thrust washer measurement is between 11.17 and 11.64 and the flywheel recess is between 10.34-10.94mm , as you may be able to see from the pictures.
I am also measuring with only a vernier depth gauge.
The article also says if the inner thrust washer has fallen off the pegs there will be a 3-4mm difference and you can check their location by removing the left cylinder.
So my question is to the great and good is-- Am I ok now?

 

[Rob Farmer]

If the barrels weren't on you would be able to see the inner thrust washer and see if it was in place or not.

Worst case scenario is you take the conrods out. Take the camchain off and pull the front bearing cover. Its no big deal and is a good opportunity to inspect the rest of the engine - you have spent longer worrying about it and writing this thread than it takes to rectify. Snowbums site is great for burning your retinas out and terrifying you but he does make a mountain out of a mole hill. Lots of good stuff on his site though.

While you at this stage - undo the four bolts holding the cover plate on, take the oil pump cover off and inspect the oil pump housing and the rotors. Its the plate under the crank in this shot of yours

You need to be checking out the condition of the housing. If there are any deep grooves then it may need to be repaired. I had to ship this one to Motoren Israel

 

[byron]

Thanks

Thanks so much for making me feel at ease Rob. I have forgot to say that I also reattached the flywheel and the engine turned freely with the plugs out, so fingers crossed. Just for my own piece of mind I will look inside after removing the barrels , but due to commitments that is a couple of weeks time. This is the first time I have ever been near an airhead engine, so all is new to me. I always intended to remove the oil pump cover and replace the gasket, but can you tell me what I am looking for with the rotors and the housing. As far as all the owners can say this is a 50k engine and before I tore the bike down was smoke free.
Also another cheeky ask-- any tips for seal removal and replacement or am I going to have to make the gargantuan bmw seal removal tool!!!! to hook under the lips of the seal
Many thanks again

 

[Rob Farmer]

If you've clamped the flywheel up and it turns then the inner thrust bearing is fine.

Www.cycleworks.net sell a tool for the rear seal. You can carefully knock in a section of the seal and lever it out. I think it was Fritz who made a wooden tool for pulling in a new deal. A search may find it.

The oil pumps are prone to scouring if the oil isn't changed or the filter gets bypassed. The scouring in the housing or on the pump will be obvious.

 

[Beemerboff]

Some people seem to think these clutch bolts are single use items and should be replaced every time too - might not be true but they are not that expensive compared with a real flying wheel.

 

[chrisshrops]

talking of dip sticks ,I have a full rolling bike now just need too sort out the wires ,all good you think
However as my bike came in bits I have never had too wheel out through the alleyway between our house and next door ,well its too wide too fit through the bloody door,looks like I need too make a new door and frame before I can ride it lol

 

[solidstate100]

talking of dip sticks ,I have a full rolling bike now just need too sort out the wires ,all good you think
However as my bike came in bits I have never had too wheel out through the alleyway between our house and next door ,well its too wide too fit through the bloody door,looks like I need too make a new door and frame before I can ride it lol

Something similar happened to me - before you get involved in mass DIY, here is what I did (if its the bars only that are to wide!) - I removed the handlebars (left all cables etc connected) spun them out of the way and used a 1/2 inch drive breaker bar in the handlebar clamps as a temporary handle bar and wheeled mine out. Put the bar back in on the other side and, as Rob Farmer would say, Jobs a fish. Course, if you need to wheel it in and out on a permanent basis this wont help!

 

[chrisshrops]

Thanks for the tip bud alas It's the cylinders that are two wide ,so I shall have to make a new door and slim frame ,then no doubt my lady friend will want a font door too match

 

[byron]

Bit of an update

When I got home from work I decided to try my new crankshaft end float tool out.
It is just a bit of 6mm bar with some steel strip brazed to it and the top powder coated.
I am very pleased in retrospect and the front cover screws on leaving a 2/3 mm gap.
Just for good measure I made 2 of slightly different lengths - now lets see that crank float

 

[byron]

Just could not resist

So after dinner I popped to look at the beast and try to plan a home made tool to remove the oil seal and having seen various almost military grade ones on line.
I was using my spare crankshart end float stop to think about some sort of hook idea - WHEN SUDDENLY

Then with only very light leverage against the end of the crank I was able to coax out the seal, by working in a radial manner. After all the hassle of the past few days this was a real piece of luck.
Oil pump cover came off easily - but that is for another day.

Just a thought though--- the "cycleworks" seal removal jig looks like it uses self tapping screws to attach to the oil seal. I tentatively tried to attach a variety of screws last night, but none located through what I suspect is a metal ring under the plastic .
Do they expect you to drill a pilot holes in the seal first ? If so I would be worried being a fully fledged "dip stick"
Anyway onwards and upwards to laser cut a oilseal fitting tool after work tonight .

PS- that man Rob Farmer is ace isn't he ?

 

[solidstate100]

PS- that man Rob Farmer is ace isn't he ?

Yes he is.

I have previously recommended him for a knighthood on here. Arise Sir Farmer!

Glad its back on track. When (a long time ago) I used to be a professional mechanic, it was common practice to sharpen an old screwdriver to a point, bash it through the plastic part of the seal and yank em out with brute force (not on these seals tho - just general like) rarely did a specific tool be needed. Did, probably, quite a few hundred that way, some of them big old buggers as well.

 

[Rob Farmer]

easy lads! You're the ones out there doing it.

You now know as much as I do about airhead oil pumps Byron

 

[B Murr]

talking of dip sticks ,I have a full rolling bike now just need too sort out the wires ,all good you think
However as my bike came in bits I have never had too wheel out through the alleyway between our house and next door ,well its too wide too fit through the bloody door,looks like I need too make a new door and frame before I can ride it lol

Could always just do a cutout either side of door to accomodation the cylinders, would be a classic giveaway for anyone visiting that you have an airhead lurking out back.

 

[solidstate100]

Could always just do a cutout either side of door to accomodation the cylinders, would be a classic giveaway for anyone visiting that you have an airhead lurking out back.

I really, really, like your style. Wish I had thought of that for the handlebars.........

 

[Beemerboff]

chrisshrops, depending on how far you are out sliding the bike through at an angle might work - my mates at school played a trick on me, carrying my Tiger Cub through a narrow lane with the bars on full lock ------.

 

[chrisshrops]

Could always just do a cutout either side of door to accomodation the cylinders, would be a classic giveaway for anyone visiting that you have an airhead lurking out back.

ha ha that would be my solution alas I'm not sure my other half would be too pleased it won't go through on full lock every other bike I have had goes in and out no problem.
I will just make a new door and frame I guess,lucky I have a woodworking business so its not a big deal just a pain in the arse lol