how to identify engine

[KARSTEN]

Posted a similar thread yeasterday.I purchased a 1985 R80RT yesterday,the jugs on the bike have a stamped 10 close to the engine,which would indicate 1000CC,the bike was mfg. 10/84, so it can not be a R100RT,the vin indicates the frame to belong to the 85 R 80.Question is now what engine do I have and how can I tell?is it a 800 with displacement enlarged to 1000 cc or it could be a 100 engine transplanted into the R 80 frame? Is there a way to id the engine,which is a must when it comes time to order parts?thanks Karsten

 

[acejones]

I think I told you this already. It is a 800 cc motor with the 1000cc jug kit. Go over to the adventure rider web site and go to the Old skool forum and then do a search. Thats where I found the info when I was looking at that bike.

 

[NEALART]

If you post some photos and the numbers on the engine and frame, you will get your answer.

 

[KARSTEN]

located engine #

I have located two sets of #'s on the bottom left side of the engine,they are : 45 84 000 the second set is:FBM079842A4; do these tell what engine is in the bike?Any Idea where I can look them up.Someone suggested that the big simply had the larger jugs installed.I hope that that is all and not that someone stuck an engine with unknown mileage in the frame.Speedo works and shows only almost 29K on it.

 

[20774]

I have located two sets of #'s on the bottom left side of the engine,they are : 45 84 000 the second set is:FBM079842A4; do these tell what engine is in the bike?

Snowbum talks about these numbers. I believe that the "45 84" means the engine is a 84 model and the 45 might mean the 45th week of the year it was built...or not. You can kind of confirm that by entering the 7-digit VIN into the various websites and it will return the month/year of build...should agree with the 45th week. The other numbers don't really mean much. More here:

http://bmwmotorcycletech.info/IDnumbrs.htm

 

[LOSTBOY]

Identifying Engine

It seems to me that it is more important to determine which pistons, cylinder heads and perhaps camshaft are in the engine than what this engine was when it left the factory.

 

[NEALART]

But, lets start with checking if this engine number matches the frame number and go from there.

Karsten, the engine number is at the dipstick.

 

[PHMARVIN]

Hi, Nealert,
Sometime around the '84 model year BMW stopped putting the engine number at the dipstick hole. Neither of my two '84 R100RS's had engine numbers at the dipstick, and neither had an engine replacement, as I picked them both up at the delivery point in Munich.

 

[The_Veg]

Sometime around the '84 model year BMW stopped putting the engine number at the dipstick hole.

My '95 has the number down low on the left side near the front corner.

 

[535IS]

My '95 has the number down low on the left side near the front corner.

The number or A number? Earlier Airheads had engine numbers that matched the VIN. Later ones did not (match). I wonder if that is the OP's problem.

 

[The_Veg]

The number or A number? Earlier Airheads had engine numbers that matched the VIN. Later ones did not (match). I wonder if that is the OP's problem.

I agree. By the time my bike was built, the frame and engine numbers were not matched. I have no idea if they were in '85, although I suspect that they were not.