New Project

[Stirlingmoz]

Big push today to get the engine back together in one big piece.

I replaced the exhaust valve guide on the right cylinder head and did a bit of cleaning of the crankcase where you can’t get to with a cylinder fitted.

And finally reassembled

It’s ready to go back in the bike now.

The bike’s electrics now all appear to be working. Had a bit of a fight with the clutch switch which turned out to be a pattern part. Replaced with a used but genuine item and it now works a treat.

I’ve no idea how to statically time an airhead engine with a bean can ignition system.

My other boxer still has points and is very straightforward in this respect.

Some research required.

Then I just need to round up some friends to help me lift the engine in.

The left carb is completely refurbished and I have sent the right side carb body away for vapour blasting. Fingers crossed that will be back soon.

 

[Stirlingmoz]

I’ve never worked on airhead gearbox before.

As the engine is now back together, I decided to have a sort out and see what I had.

The gearbox was already dismantled, I assume by the previous owner, and the parts were rolling about in a big plastic box.

I am definitely missing the input shaft and speedometer drive and probably lots of smaller parts.

I need to print off a parts diagram and work through it.

The case needs a darn good clean inside and out but I quite fancy having a go at rebuilding this.

 

[Stirlingmoz]

I’ve given the larger main case of the gearbox a good clean inside and out.

Having watched several very informative YouTube videos and read Steve Scriminger’s book several times, I’m pretty confident the lay shaft, output shaft and associated gears and bearings are in good condition.

The shifter forks and shafts all look good.

I now have an input shaft and some of the required parts but missing the all important kick starter gear. This shaft is still very much a work in progress.

The shifter mechanism needs a rebuild but I see Motobins do a kit to refurbish it.

The rear gearbox cover and kick start mechanism still need cleaning and checking but some progress made.

 

[mikeyboy]

Might be just the photo but that input helical gear looks to have some wear and breakthru on the case hardening.

 

[Mad Hatter]

Big push today to get the engine back together in one big piece.

I replaced the exhaust valve guide on the right cylinder head and did a bit of cleaning of the crankcase where you can’t get to with a cylinder fitted.

And finally reassembled

It’s ready to go back in the bike now.

The bike’s electrics now all appear to be working. Had a bit of a fight with the clutch switch which turned out to be a pattern part. Replaced with a used but genuine item and it now works a treat.

I’ve no idea how to statically time an airhead engine with a bean can ignition system.

My other boxer still has points and is very straightforward in this respect.

Some research required.

Then I just need to round up some friends to help me lift the engine in.

The left carb is completely refurbished and I have sent the right side carb body away for vapour blasting. Fingers crossed that will be back soon.

The patina on your cleaned up engine cases looks absolutely brilliant, I really like it. Great job!

 

[Stirlingmoz]

Maybe a little on the inner edge.

Do you think too much ?

I was going to install it like that.

 

[Stirlingmoz]

Had a go at the gear selector mechanism this morning.

Got a kit from Motobins to replace all the springs and clips.

Mid strip and parts clean up

All back together with a rather natty bearing for the gear detente arm.

Lightly greased all the pivots so it all moves nicely though this may wash out with gearbox oil ?

I’m now warming up the gearbox case in the oven so I can get the intermediate and output shafts installed.

 

[Stirlingmoz]

I had the gearbox case in the oven and the output and layshafts in the freezer.

It just sort of fell together.

For the eagle eyed, the selector mechanism in the previous photo was 1 tooth out, confirmed with reference to Steve Scrimingers very handy book.

That was a quick fix.

Getting all three forks to engage in the selector mechanism was a bit fiddly but no real dramas.

And here we are now. The good news is I am able to select neutral and all 5 gears so we’re golden so far.

I’ve cleaned up the rear case and I’m now happy with that cosmetically.

Next step is getting the input shaft assembled and shimming.

For that I think I’m going to need pro help.

 

[Stirlingmoz]

Fitted a new Heidenau front tyre this afternoon.

Made sure to fit the arrow on the tyre pointing in the same direction as the arrow on the rim.

Put the wheel back in the bike and something didn’t look quite right..

The disc is on the wrong side !

I hadn’t noticed before and just boshed the wheel in.

Swapped the disc to the opposite side and we’re good.

The disc itself is shot.

Been looking at a Siebenrock copy to keep the stock look.

 

[durneyj]

I have the Siebenrock disk on my ST. Can vouch for the quality and a great improvement over the worn out one the bike came with

 

[Stirlingmoz]

Right hand carb came back from the vapour blasters today.

Something for the weekend

 

[Stirlingmoz]

Tipping with rain here this morning so no running or mountain biking is on the cards.

Opportune moment to get the engine in the frame.

I find it just about do-able on my own if I take the starter motor out and remove the engine covers to lower the weight.

It’s in.

It’s only loose and nothing connected up yet, but it’s in..

Pause for tea and toast and then get it built back up.

Just realised I’ve got no engine mounting bolt spacers so it can slide from side to side in the frame.

 

[Stirlingmoz]

And here we are now..

Starter motor back in.

Engine electrics connected up.

Engine covers back on.

Exhaust fitted.

The gearbox is just a spare empty case so I can fit the airbox and carbs.

The actual gearbox is still on my workbench.

No oil in the engine yet so I have avoided connecting the fat starter cable to the battery and have taken the keys out so I don’t make a mistake.

 

[Vulpine2]

Looking good

 

[Bubb]

Looking good Pete.

Wont be long now til it’s on the road

 

[Stirlingmoz]

Managed to find time to do some more work on the G/S this morning.

I have now installed the engine crank case spacers to positively hold the engine in the frame.

Filled the engine up with mineral 20/50.

Removed spark plugs placing them on the cylinder to check for spark and spun the engine over on the starter motor.

So far so good. The oil pressure light extinguished readily and it takes a few moments to come back on.

No spark visible - but it’s a bright sunny day. I’m kidding myself here. There was no spark :-(

Checked the compression and both cylinders indicated 100psi.

I did these with carbs on but no cables fitted so the butterflies were closed.

Probably not a true reading in the circumstances but was hoping for something a bit higher than that.

The positives are the engine spun over readily on the starter, no horrible noises and seems to be making good oil pressure.

Time to troubleshoot the lack of spark.

 

[Mad Hatter]

The low compression is probably due to the butterflies being closed. Can you wedge them open with something (something that won’t get sucked in!)

 

[Stirlingmoz]

The low compression is probably due to the butterflies being closed. Can you wedge them open with something (something that won’t get sucked in!)

Next weekend I’m going to troubleshoot the lack of spark.

Remove ignition coil and measure resistance. Check I’ve wired the coil correctly.

Is there a test for the ignition control module and bean can ?

Research needed (my other boxers have points so I’m in uncharted waters)

I will pull the carbs off completely and do another compression test while I’m at it.

Fingers crossed.

 

[Stirlingmoz]

Bit of progress this morning.

Removed the carburettors and did another compression test.

This time it was just shy of 130psi so I’m happy with that.

Moved on to trouble shooting the ignition.

The coil and H/T leads checked out for expected resistances.

I read about a test you can do cycling the engine kill switch - and hey presto a spark at both plugs.

Checked the connectors at the bean can and the ignition module and I’ve now got a spark when cranking

Didn’t find the smoking gun but could have been a dirty connector or maybe not pushed all the way home ?

I had bought one of the Hall effect testers from Motorworks and used that to set the ignition timing.

I think I can call the ignition system sorted - at least for the time being.

Next step is hooking up the carburettors with various cables and fuel hose.

Will get yet more parts ordered up but we’re getting ever closer.

Still looking for the kickstart gear on the input shaft of the gearbox which is proving quite elusive.

 

[mikeyboy]

How many splines on the input shaft,?
I’ll have a look see for a kick start gear