1974 800cc V twin in BMW R80 Frame.

[Sphere]

Eagerly awaiting the post that claims this project lives once again

[smokyjoe]

Hey Mouse,

I hate to admit doing this.... but I've taken a couple of engines it this condition and scraped the aluminum scudge out of the bore, given it a light honing, cleaned up the scuffed piston with a little emery paper and a ring groove cleaner, thrown in a set of new rings and away we go! Not at all the best fix, but if the bottom end and the wrist pin are OK that's half the battle. Maybe the rings aren't scuffed bad and they can be re-used also. If this is done, of course you'll have to provide for venting the possible increased blowby, venting it as is usually the case back into the intake isn't the best idea as the engine may keep running away when hot on it's own blowby! (Ask someone who drilled out the restrictors in the breather lines on his VW Diesel to "take care of" too much blowby )

Hate to say it, but I agree that it does look like heat seizure, of course it could also be a lack of lubrication, which is really what happens when the piston over-expands from too much heat forcing away it's oil film.

Of course, that's if you can't get the correct parts for that beast! I think you've built the coolest bike, and after all your hard work and passing MOT, etc. I hate to see it not running.

[Mouse]

It's working again!
Been a long battle locating parts, paying for them and then getting them shipped safely from Germany. Anyway I managed it and the rebuild cost me about £120 for a 'new' barrel, head and piston which I'm happy with even if the original engine was £150.

It then took two hours to copy the whole chapter of the Czech manual into Google Translate and then try and work out what the spewed out gibberish meant.
The only technically difficult bit was setting the compression which involved setting the gap between the piston top and cylinder head by getting the correct shims under the barrel. You are supposed to assemble it with a piece of lead stuck to the piston top then dismantle it and measure the thickness and adjust the shims. I used lead free solder but it worked the same!


Photo of the compression setting jig.

I needed between 0.8mm and 0.9mm between the piston top and cylinder head. I managed an average of 0.85ish after taking the barrel off three times and trying different shims. I was also glad the bloke who sold me the bits included some shims so I had a selection to chose from without resorting to cutting new shims from beer cans.

The test ride was a joy. A perfect August summers day and just over 150 miles of country roads from Newport through, Chepstow, Monmouth, Forest of Dean, Gloucester, Tewkesbury, Worcester, Ledbury and the last 20 miles back home to Newport were unfortunately on the the dual carriageway as it went dark and the headlamp had vibrated loose and was good only for blinding low flying aircraft or deafend bats.

The only hiccup was my replacement fuel filler cap has no breather hole and caused the bike to splutter to a halt and need bleeding before it would run again. This happened three times before I realised the problem and put a twig under the sealing washer to let the air in.

Top speed was about 63mph and it cruses happily at about 55mph and still able to maintain speed up hill which would suggest the need for an extra gear but as I'm using BMW transmission I'm stuck with it as it is.

The cylinder head temperatures averaged about 125 - 130 Deg C and after I'd been riding for over an hour and then did a long labouring climb of several miles the head temperature was just about 150 Deg C so I'm happy that cooling / overheating is not an issue.

I've put much thought and effort into working out what happened in the first place and have come to the conclusion that there were two separate and largely unrelated failures of the engine and then a third that finished it off.

The first fail was the oil cap falling off. it was loose and I was a fool for not securing it. This lead to the classic piston / cylinder oil breakdown from lack of lubrication and cooling after it spat all its oil out. This was fixed with new rings and a tarting up of the piston and a light hone of the cylinder.

The second failure was due to the reassembly of the engine. The starting aid valve that puts about a cc of oil into the inlet manifold to increase compression when hand cranking did not re-seat due to the rubber being 34 years old and probably me not checking properly because I didn't know it was super critical. This allowed a continuous feed of sump oil into the inlet of the right hand cylinder and dangerously over-fuelled it. This caused the epic overheating and I later realised the permanent annealing of the ally head. The softened ally head explained why the inlet valve and exhaust valve were out of alignment without the valves themselves being bent. The valve guides had moved in the now soft and very hot aluminium.

The third fail was caused by the annealed head being reworked to make the valves seal and then reassembled unwittingly not realising the hidden annealing damage. The softened head then warped under the pressure of the head bolts and the running stresses of the engine. I noticed the head bolts came loose and tightened them down a couple of times in the doomed trip until the centre of the cylinder head had sunk down enough to close up the 0.8mm gap and the piston to touch it on each rev of the engine. Very quickly the valves became bent and out of alignment again and the shock caused the piston shirt to crack. I was on the motorway and carried on with a mild lack of power until I pulled off into a supermarket carpark and let the revs drop and that was the end of it it was never going to start again.

The interesting thing is that the replacement head doesn't have the oil injecting cold hand cranking valve thing so at the earliest opportunity I'll be removing the one from the other side and plugging it with a grub screw or something equally as permanent.

I need to do some more miles and take note of the fuel used to get an idea of MPG. I know its going to be up above 80mpg but it's the one thing people ask me when I pull up anywhere after being aghast at such a beast should exsist or telling me they had one like that in the war.

Its been an interesting learning experience and I hope I'll be a better diesel engine operator because of it.

[Sphere]

I know its going to be up above 80mpg but it's the one thing people ask me when I pull up anywhere after being aghast at such a beast should exsist or telling me they had one like that in the war.

Hahahaha, that's hilarious

The only thing I'm missing from your account is the part where you took off to have a few pints.

[Anorak_ian]

Surely different gears can be found from stock to improve the BMW gearbox ratios? Maybe Ural etc as they copied BMW.

If nothing can be done in that area, then maybe a smaller back wheel / rim and lower profile tyre will gear it up a tad.

Good to hear it's on the road again.

[coachgeo]

[bad Italian Accent] Mucho Congratulato [accent off]

[smokyjoe]

Yay! I'm happy fer ya', Good work!!! I wish you many happy miles, that's a great beast you got there.

[zarquon]

Congrats!

I had to declare: "I really like your V-Beemer!"

[Sphere]

Just try to keep the beast on the road, I hear that is the hard part in Britain these days

http://www.dailymail.co.uk/news/article ... ivers.html

[Crazymanneil]

Absolutely superb Mouse, I really admire your determination and your writeup is interesting.

Neil

[Stuart]

Great news mate Really good to hear this beast is back on the road

[Mouse]

It broke again : (

So I planned a long weekend on the diesel bike to get some more miles on it. Went from Wales to London mostly on the A4 which was a vey pleasant and uneventful ride. I was able to use the bike in varied road conditions and it was almost perfection. A constant 80 MPG and a very usable bike indeed and keeps up with everyday traffic even on the hills.

The bike went very well up until I hit the mortorway to go home when I thought I'd simply blatt back to Wales as it was early evening and I wanted to be home before midnight at which point I hit 60 mph and held it there for a few mins and after a brief rattle the collets popped out of a valve retaining bit and it was all over and I called the recovery wagon! I've gone this fast on it before and even got it to 63-64 a few times This would have been over revving it by about 200rpm so I'm guessing the springs were not man enough to keep up with the cam movement.

Some photos....



The ugly mess


The bits I could find under the rocker cover. I'm counting 1 lost collet floating about in the engine somewhere.


Arty shot withthe motorway in the background.


I kept my self busy by having a picknick of tinned slop with the end ripped open with a multi tool some tea and a chocolate bar.

The head would have hit the valve square on as the valve stem is parallel to the barrel so I'm hoping there is not much internal damage and a new valve and spring bits will get it going again.

I'll be investigating stronger springs.....

[coachgeo]

Ahhhhh yes.... how lucky you are. Another character building experience to put under your belt.


keep us posted

[TimppaX]

it´s like dnepr variants (original - are there any?) it´s not the distance but speed that kills them

[Mouse]

As a friend said on a different forum,

Time to call the FAIL BRIGADE!



BTW It's powered by the same engine!

[Zem]

Hey Mouse, I wish you more luck with that engine!
Anyway, I'm still looking for Warchalowski parts around Vienna at the moment.

[Crazymanneil]

Aww man. I hope you get lucky with the valve not marking the piston too much like you say. Can't imagine it went far like that.

Neil

[johnfireball]

Hi Mouse,
Are you sure its a collet issue? looks to me like the valve spring cup broke up (they look thin and flimsy in pic). Great looking bike by the way, can you gear it up for less rpm?
John.

[Mouse]

Yea, I've been thinking that. Bit it is a chicken and egg thing as to which bit let go first. Also the springs might have been on their limit at max RPM as you can open the valve by pressing on the rocker with your thumb. There is the chance the valves were not shutting fast trough and the pressure on the collets was reduced causing them to float free. I can only guess.....

I'm rebuilding it with BMW R80 spring cup bits as they are well made hardened things and not ordinary mild steel like the original ones and just about fit.
I'm also using BMW R80 springs as they are stronger and newer and just about fit.


Its a BMW gearbox and final drive. I already have the 33/11 bevel box so there's not much chance of up gearing it without major surgery inside the gearbox and thats beyond my grasp at the moment.

[Mouse]

It lives again!

Took the bits to South Wales pistons last Tuesday. They swapped the valve guide and valve from the warped head to the good one and re-cut both valves for the princely charge of £20



This is the collet retaining bit. Obviously knackered but the million dollar question is did the collets fall out first or did the centre of the retaining bit break off first??

More of the same! You can see that the collet retaining bit is made from normal steel!


The bent valve, The stem is bent like a thin 'S' and the valve guide is broken.


There is an indentation of the valve on the piston head but that's just about all the damage there is to the piston. I took the barrel off and checked the top edge of the piston had not been damaged and could scratch the bore. The valve guide was soft metal and the broken bits were mashed up saving the head from more gruesome damage.


Looking for spare bits I go rummaging through my selection of dead heads I've collected over the years.


And emptying bean tins that have been on the useful shelf since before time was invented.


It didnt take long to determine that the BMW R80 spring lookes very very similar.


Yep, The BMW R80 springs and collet retainer (Left) are the same diameter as the Diesel engine ones (right). The added advantage is that the BMW R80 springs are much stronger and the collet retaining bit is hardened steel!


Assembled with BMW R80 springs and collet retaining bit using the original Diesel engine collets.


Then it was the issue with the sump oil injecting valve that failed ont he other cylinder head and caused the overheat and warping. The replacement head was not fitted with such a dangerous contraption so this one has to be eradicated!


Tapped out to M8


Allen bolt inserted and done up tight! Try leaking now you b......d!


The bike was assembled and runs as well as it ever did. Test drove it 8 miles and I'm going to change the oil and take it out for another test ride before the sun goes in for the night!

[pietenpol2002]

I admire your perseverance. My fear was that you would bin the whole works and we all would be the less for it. Thanks for hanging in there and with such a unique and admirable project.

[Mouse]

Just finished a 20 mile test ride in the rain and it survived including a 5 mile stint on the motorway with the throttle at max doing 60 - 62 mph .

Before going out I was able to change the springs and collets of the other side to BMW R80 without taking the head off So now I have stronger valve springs all round. The interesting thing is that at 60 and just above, which is flat out, there was always an odd little rattle that was slightly more pronounced just before the last failure. This rattle is now gone after fitting with the stronger springs. I'm assuming it was related and I have made the engine more reliable but time will be the only real teller of that.

[Stuart]

I'll echo everyone else and say well done You may well have had an untempered collet there that broke down under the stress of the higher revs maybe. Always good to find interchangable parts - especially when they come from a company such as BMW

[smokyjoe]

Good job Mouse!!!! But what about the "missing" valve stem locking collet piece that was down in the sump? Did you find it? I hope it isn't still in there waiting to jam up between a moving and an immovable object deep down in the bowels of that beast.

Your bike makes me want to use an old Beemer for the basis of my next project with the Kubota D950 sitting in my shed.

[Mouse]

I should have said, the collet was inside the banjo bolt that the head oil drains through

[Dan J]

Great news and the outcome both the bike and you deserved after all that effort.

I think I can now speak for all of us when I say... try not to bugger it up this time

Going to dare brave the trip to Hamm?

[johnfireball]

Hiya Mouse,
Great your goin again, you now have classic diesel hands. No sex for a month after you get the bike sorted.
John.

[pietenpol2002]

Looks like you have a kindred spirit somewhere in Estonia. And don't you love those leaf spring suspensions. Also take note of the oil cooler down front.

http://static2.album.ee/files/922/41/or ... 7_rnQ1.jpg
http://static2.album.ee/files/922/41/or ... 1_tF0R.jpg
http://static2.album.ee/files/922/41/or ... 9_jaqx.jpg

Comes from a discussion on page 3 of the board below where there's also reference to the Yanmar powered bike we've looked at before. Use your Google translating tool.

http://forum.automoto.ee/showthread.php?tid=24555

Soon you'll be hosting the 1st Annual International M22 Rally. And I'd love to attend.

[coachgeo]

...Comes from a discussion on page 3 of the board below where there's also reference to the Yanmar powered bike we've looked at before. Use your Google translating tool.....

Translate from what laungage? I tried German but it was a no go.

[pietenpol2002]

Estonian - as evidenced by the URL suffix ee.