DDK - Die Deutschen Klassiker

I so want to get this bike done and sold! (I don't keep these little projects)

The primary crankcase pressure is fundamental to a 2 stroke and the compressed charge as the piston comes down just before the port is uncovered will try to escape via the easiest way, and the crank seals are that route.
I will have to remove the magneto and possibly the clutch to get to these seals, but it will be worth it and not difficult, just re-doing what I've done before, so clean at least!

I need to find the garage space as the 911 has to come apart soon for it's repaint.

fingers crossed - looking forward to a "first ride" video!

I can't see that far head yet!

Did some probing this morning. Set the piston at TDC and put some air pressure into the case via the inlet manifold having removed the magneto and the clutch side cover.
This exposes the 2 crank seals so with some soapy water drowned the magneto side. Air simply gushes out of the seal!
On the clutch side there is no air passage at all, possibly because the other side leaks so much.

next stage is to try to seal the mag side seal to force the pressure against the clutch side seal.
The crank case gasket seal is leak free.

Hard to take a picture while pumping air into the engine by hand!

I've reached the stage of willing it to start every time I think of it. Nobody deserves such punishment.

Except a Boxster owner!

It gets worse.

A French Man insisted I try a test. A latex glove sealed to the carb-less inlet manifold and turn the plug-less engine over quickly using a socket set spin handle.
Did this, and the glove inflated!
No wonder no fuel was getting into the engine there is a +ve pressure blowing OUT of the inlet.
So, as the 2 stroke cycle goes, the piston coming down from the explosion compresses the charge in the crank case, the inlet is supposed to be masked by the piston to stop this compression leaking out, so the piston could be simply worn out allowing the passage out of the engine via the inlet and carb.

This could explain a lot.

I took the bloody engine apart this afternoon. there is no seal on the magneto side. It is a brass bush with a screw groove machined in it so any oil leaking out of the case is 'scrolled-back' to the bearing of the crank shaft. I can do nothing to seal this bush, it is not designed to seal! (tight).
The clearance of the crank shaft to this bush is at worse transitional, no play at all.

The engine is now 1/2 rebuilt. The unsealed kick start shaft will not line up and I'm fed-up with the thing, so walked away for the day.

I can see me buying a new piston which is available for 100 euro.

What a game.

It's disappointing BUT it's progress in the right direction..

I assume that the piston is on the correct way round which if the engine was not a runner when you got it may not be the way it was when you got it?

Been through that one John, definitely in the right way round!

Put it all back in the bike only to find the kick start gear will not dis-engage, so all apart on the bench again.
Wife wisely suggested we go out for a meal.
She is good to me.

Racing the Lola this weekend, soooooo much more fun.

Going to put it back together next week and if it does not work it's going in the shed until deep winter.
I have the 911 to strip for paint, have until Nov 1st to prep it.

I cannot remember ever being so frustrated with a machine before as this stupid bike and the idiot who wanted to restore it!

It sounds like Brit two strokes of the era. They were desperately cheap because there's wasn't much money around and they were as frustrating as you're finding. We all hated them, all except Ariel, which were very good.

I had a trip from Eastington, Gloucester to Hitchin Herts every weekend in the sixties and a Greeves with a Villiers 2T engine. It fouled plugs or tightened up on almost every trip after about thirty miles or two breakdowns every trip. My Ariel Arrow was utterly dependable.

Thank you all for watching and commentating, it certainly helps in these 'dark' hours!

IT FIRED!

Yep, I kid you not, it actually went bang several times, though did not run.

MY PLUG IS WET!

Yep, miracles do happen on a wet Tuesday.

so, what have I done to get to this high level of restoration?

Not sure TBH. Stripped the engine down fully and built it back up. The kick start gear is drawn incorrectly on the factory diagram, so having fathomed out how the mechanism works I did a dry build, confirmed the assembly and simply screwed it all back together.
Decided to try and effect a better case seal and close off the scroll bearing on the magneto side using a stack=up of O rings. There is a 0.25/0.5 compression on these when the flywheel is on, so I hope (with some oil in them) to effect a better seal that might last. I oiled well the clutch side felt seal while the cases were apart.

Set the timing at 4mm BTDC (a Frenchman says it should be 5mm).
Popped the carb back on. Fuel in the bowl.
Gave the kick start some hard shoves and it felt/sounded different.
After some more enthusiastic shoves it started to fire and stopped. Rested my arm and repeated, and bang it went several times and even a trickle of about 6 ignitions then no more.

I have left the exhaust pipe off so I can hear any changes more accurately.

going to ry 5mm BTDC and see if that helps.

Anyway, a few steps forward. Maybe the bloody thing will stop fighting me now.

I'll sleep easier tonight, knowing the little rat is showing signs of surrender. I hope the mental damage is containable.

Well, since that moment of euphoria, it has not fired since!

The battles between the French and the Brit continue.

So, so a very brief moment it fired. I think the changes to the crank seals have made a big improvement, so that is +ve.
The mixture obviously was close enough to sustain a combustion or two, so that is a +ve also.
Every time I try to run it or check the 'mm BTDC', currently at 5mm) the plug is wet, even flooded!

The consistency obviously is not achievable. So, why not?

Back to the fuelling for a moment. It fired with the original carb on, drip fed with fuel.
A while ago I read Zoe in France had fitted a Dellorto 21mm carb to he 100cc as the original was missing. The bike runs well looking at the videos.
I bought a cheap Chines 80cc carb for a 2 stroke, new, for £10 delivered (in 3 days) so decided to give it a try on this bike.

A change is as good as a rest, so mad an inlet adaptor and put it all together. It looks great on the bike.
Pity the bike will not start! Had to try it, but a shame as that would have been quite a good solution.

Put the old carb back on and the engine sounds like it is 'just' about to fire but not quite.

Next step I feel is to drop the bike to the ground and kick start it with my leg and body weight.
I think this will increase the speed and number of revs the kick starter throw will turn the engine over. I've read it is supposed to be 6 revs of the engine to one kick start stroke.

This added velocity(?) might encourage any combustion to be joined up....

Tired of it today. Need to get the Boxster prepared for a nice road trip next week.

Have you not tried paddling it along with your feet, like I suggested? That is how many owners start these little bikes.

I have considered it, but it's a sign of failure!?
With it off the table it will be obviously be easy to try it.
The road into my Cul de sac is a good slope, so could take it to the top and roll it down.
However, I don't have a gearbox sprocket as it is in France with a parts specialist, Chambrier, to see if they have a new one, so obviously cannot fit a chain yet...
I'm too old for this!