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1979 R100/7T (S)



I owned it and sold it - a 1979 BMW R100/7T

BMW Repair Modification Restoration R80G/S R75/5 R100GSPD
An amazing classic 2V boxer

You are looking at a black gold-striped R100/7T, manufactured/registered June 1979 (VIN 6051010), (first registered 03-09-80 in the UK), just under 34.000mls (77.000mls on speedo). I acquired this bike on 3rd September 2003 as a rolling project, about 85% completed.

The specs are slightly different from the US model of the T:

Together with the silencers which are stainless Breakwell & Green (34mm opening creating a throaty Norton-type twin sound) and the factory drilled airbox the bike develops something between 65 and 70bhp, I guess (stock is 65bhp).

When going through the bike (as I did not know its history) I found the following had been done by the previous owner:

That left me with doing the following work to get the bike perfect for my taste:


Driving impressions: The gearbox is smooth (it is a post-1981), the rear drive is absolutely quiet, no funny noises anywhere. The Breakwell & Green give a thumping sound when idling, roooaaaring on acceleration ...
I measured the compression which is in the low 90s (but the same on both sides) but she runs superb and does not blue AFAICS or consume excessive oil. A sport cam could be the reason as the valve overlap can affect the compression measurement at cranking rpm. It may give an artificially low reading. I have no means of obtaining further historic information and will continue observing the oil consumption in particular.
This bike can easily be rev'ed beyond 6600rpm even in 4th gear if you're not careful. I could imagine the mufflers are a bit more open. The airfilter is the round one with the S-type drilled airfiler box. It behaves very much like my father's '93 R100R and likes to be rev'ed so I would assume it has got a lighter flywheel.
Never been officially on the road here in England after finishing the restoration in November 2003. In April 2004 I moved to Canada. The bike followed in August 2004 and was immediately safety checked and registered with a Year Of Manufacture 1979 in Ontario.


September 2004 ...
The bike has seen its first 500mls on Canadian roads since registered in Canada in September 2004.


More high resolution pictures ...
Even more high resolution pictures ...
Here are the last ones ...

March 2005 ...
Winter got long and I was getting bored so I did work which I always wanted to do and never came round to:

May 28, 2005:
Checking the bike for the coming trip: big surprise! The output splines of the beveldrive are nearly gone (guess they would not survive 2500km), the o-ring protecting the wheel bearing was gone as well, so the wheel bearing is toast. Nice surprise for a Saturday afternoon, two weeks before going on a 2500km trip. Luckily, I have just gone through all of that with the R75/5 so it will all be taken care of within the next week.

Three days later: rear spline replaced on beveldrive (Bruno was out of stock with splines, but he had an as-new one with only very little visible wear available, forgot to take a picture), rear wheel bearing replaced, front wheel bearing checked and OK'ed. Now it is finally done. Bike's ready.


June 10-20, 2005:
5700km Ontario Loop 2005 Trip Report
June 24, 2005:
Having returned from the trip, I was eager trying to find out what the cause of my bad compression was. After all, I used only about 250ml of oil on 1000km which is at the lower end of the scale. The previous owner worked on the engine quite a bit (at least he said he was) so I was puzzled. To cut a long story short: first I checked compression again. Surprise, surprise: 10.5bar/150psi on left cyl and 10.5bar/150psi on right cyl. That concluded my attempted repair successfully. My only explanation/guess is (as the PO said he worked on valves and stuff) that the engine needed a good run-in and 5700km in 10 days at 80-110km/h obviously did the trick.
Observations after 10.000km:
The electronic ignition is absolutely perfect for cruising along at any speed although the advance curve is quite rudimentary. When you really crank the throttle, it may miss a beat though. I have yet to perform a test, whether it behaves similar if using the stock points ignition. Secondly, above 6400rpm, it feels like starving a bit on fuel. Given the fact, that the stock main jet is 175 and the silencers are very open, I could imagine that going higher to maybe 180 or 185 could cure that. Again, I have yet to check this out and as said before if you stay within the specified rpm you would not experience any such behaviour. Only if you really (aggressively) crank it above 6400rpm you will feel a slight hesitation sometimes or a missed beat. I am usually a "good boy" so it does not happen very often.
Update: For some reason, I used premium gas on my latest trip and to my surprise, the above described effect was completely gone! No more hesitation, no more cutouts. Well, I should have though about this earlier: a high-compression engine certainly needs high octaine gas, so me using regular gas all the time just wouldn't do the trick. I am glad I don't have to fiddle around with carbs and ignition now!
November 2, 2005:
I did my end-of-season ride on the Halloween weekend: a flawless ride of nearly 1900km, using only 0.5l of oil and 5.45l/100km (42.3mpg) of premium gas, not bad for a 26year old beemer! Upon my retun I checked the valve clearance: both exhaust valves were too tight and there was some axial play on the rocker arms. I will correct that.
On my trip, I visited a prospective buyer and most probably the future owner of this bike.
November 15, 2005 (km 84844):
New front tire is needed: again a 100/90-19 Bridgestone BT45 is the choice, it was on the bike before and its performance was excellent. The brakes as you see them, have done approx. 12.000km since new.


November 26, 2005:
Cleaned and ready to hibernate.
March 16, 2006:
The bike was sold.
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