advice on total overhaul of 84 K100RT

[JP]

Hey all,

I inherited an 84 K100RT that had been standing still in a garage for over 10 years and brought it to a garage to get it back in good working condition.
The guy charged me almost 900 euros for getting it back into good condition and assured me the bike was more then fine, sadly after 200KM the startmotor died and off the bike went back to the garage.

Now the bike is showing problems again and I'm a bit tired of going back and forth to the garage so I decided to get the know the bikes innards and do a total overhaul myselve.
I'm a technical engineer so I am pretty confident in my ability to rebuild it once I take it all appart but I have never disassembled an engine so I'dd really appreciate any tips any of you guys could give me.

I am using the BMW Haynes workshop manuel and this video series as a guideline.

The main problem at this point is that the bike generates a huge white/blue smokescreen as exhaust (means oil in the combustion chamber if i'm correct) and when I did a compression test myselve it showed that one of the cilinders only has half the compression of the rest (so don't really trust the guy who worked on my bike if he never noticed this himselve while ensuring the bike was in perfect state).

So any pointers/advice anyone can give me whould be really appreciated.
Thanks in advance, JP

[riots100]

You could reference some my engine innards adventures here: http://www.motobrick.com/index.php/topic,7661.0.html

[Laitch]

So any pointers/advice anyone can give me whould be really appreciated.

Welcome, JP.

Don't do a complete overhaul unless it's necessary. Get an instrument to do a cylinder leak down test to determine what is causing the loss of compression in that cylinder. Plenty of YouTube explanation on that procedure. Some of us might be interested in viewing the mechanic's list of what exactly was done to the bike for the price.

[JP]

What he did was replacing the battery/filters/fuelpump/sparkplugs did a spline lube and changed all the oils.
The most expensive part was the fuelpump for nearly 300 euro's.
He only charged 10 euro's for gaskets so i don't think he changed many of them.

Went with the bike to my work to perform a series of tests like the leakdown test you advised and after that an endoscopic search.
Appearantly the cilinder with low compression has a chipped exhaust valve that is going to need to be replaced and the leakdown test showed some small leaks in all other cilinders but couldn't determine from where exactly.

[wmax351]

I'd buy a used head and go from there. If you have cheap machining available, then it might make sense to do the valve and seat.

If you're feeling adventurous, tear down the engine, inspect and reseal. Deglaze the cylinders.

[Martin]

After you have fixed the valve you could just run it, Bricks do not like sitting and benefit from been ridden. Often the smoking will settle after you put some mileage on it. They also do not like being left on the side stand and will complain by smoking. There are high detergent oils that might speed up the process.
Regards Martin.