ADVrider

Go Back   ADVrider > Bikes > Old's Cool > Airheads
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 01-13-2013, 02:14 PM   #16
Lornce
Lost In Place
 
Lornce's Avatar
 
Joined: Aug 2003
Location: Way Out There.
Oddometer: 16,986
It's a BMW engine. No idea of the displacement, it could be anything from an R50 through R100, they all have identical outward appearance/dimensions.


Quote:
Originally Posted by China2wheels View Post
Hi

I need some help distinguishing between an R60 and an R75 engine.

I bought a sidecar bike with a refurbished BMW engine in it, supposedly with a 750cc engine (well, that is what I paid for). The builder claimed it is an R75 (750 cc) but he put an R60 badge on it because he had "run out" of R75 badges. The builder puts various sizes of BMW engines in CJ750 sidecars.

Is it possible that this is an R75 but badged with an R60 plate?

Is there a difference in the outward appearance of these two different engines? Is it possible to mount an R60 badge on an R75 engine (e.g., are there any holes that are supposed to line up, etc?)

Here are a few pics of the left side (sorry, I don't have any right side pics of the engine)







Thanks for any help you can provide.
Lornce is offline   Reply With Quote
Old 01-13-2013, 03:19 PM   #17
ritetwist
Gnarly Adventurer
 
ritetwist's Avatar
 
Joined: Jun 2011
Location: North AB, CDA
Oddometer: 163
EMW ? (With the red insignia) ?.
__________________
Afraid to sleep for fear of missing something.
ritetwist is offline   Reply With Quote
Old 01-13-2013, 08:18 PM   #18
Bill Harris
Confirmed Curmudgeon
 
Bill Harris's Avatar
 
Joined: Sep 2008
Location: backwoods Alabama
Oddometer: 4,892
Quote:
Originally Posted by Lornce View Post
It's a BMW engine. No idea of the displacement, it could be anything from an R50 through R100, they all have identical outward appearance/dimensions.
Looking on the 'Net for a match, I tend to agree. The engine doesn't look "quite right", but it might be that the photos are "product shots" from a brochure and have been airbrushed ('Shopped) to look more appetizing, so they aren't real world kosher.

The transmission is aftermarket since it has a reverse gear (hand lever above the shifter), along with the /2-style air filter built into the transmission top.

We'll know more if/when the OP gets back.

--Bill
__________________
'73 R60/5 Toaster

Bill Harris screwed with this post 01-14-2013 at 04:22 AM
Bill Harris is offline   Reply With Quote
Old 01-13-2013, 10:57 PM   #19
China2wheels OP
Adventurer
 
Joined: Jul 2010
Location: Great Leap Backward
Oddometer: 46
Thanks again, guys. I am a total noob with respect to BMW airhead engines, so I thought I'd get some impartial advice from the experts around here.

It is indeed a Chang Jiang with a BMW motor put in it.

When I first got it, it seemed to have considerably less power than a 750cc conversion I had previously ridden. In fact, it had only slightly more power than the CJ's original 24hp engine.

At first, I mistakenly thought it might be a 650cc (R/65), and I asked the builder. He replied with an offensive email, saying:

"BMW doesn't make a 650cc boxer motor in that era, so again you are just showing ignorance."

But maybe it is an R/60 (599cc) or maybe some franken-thing? It seems that the engine case across the R-line is quite close in dimensions? I have heard that the Chinese do indeed copy many BMW things, including the heads. Maybe it is a poor copy? The bike was built/converted in China.

Again, thanks for your help. Appreciated.
China2wheels is offline   Reply With Quote
Old 01-14-2013, 04:07 AM   #20
Big Bamboo
Aircooled & Sunbaked
 
Big Bamboo's Avatar
 
Joined: Sep 2010
Location: Big Island of Hawaii
Oddometer: 2,180
I'm still curious what the VIN number on the case is...
Big Bamboo is online now   Reply With Quote
Old 01-14-2013, 04:39 AM   #21
China2wheels OP
Adventurer
 
Joined: Jul 2010
Location: Great Leap Backward
Oddometer: 46
Quote:
Originally Posted by Big Bamboo View Post
I'm still curious what the VIN number on the case is...
Sorry I didn't answer before.

Actually, the builder seems to remove/change the numbers on the engines because I don't think they come into China legally, or perhaps they have dubious origins. Not sure where they come from, although I think it is the USA.

Yeah, yeah ... I know, I know. Live and learn.

I was hoping that the case would be different between models, but I guess not.
China2wheels is offline   Reply With Quote
Old 01-14-2013, 04:40 AM   #22
Bill Harris
Confirmed Curmudgeon
 
Bill Harris's Avatar
 
Joined: Sep 2008
Location: backwoods Alabama
Oddometer: 4,892
Good thought on the engine #-- that will nail the original engine type (but not subsequent mods.

I guess the big, easy to check difference between 600cc and 750cc heads would be the intake stubs where the carbs attach. R60 is smaller and different "shape" than an R75 (unless they have been modded to accept the non-Bing "mikuni"-clones). Intake and exhaust valve diameters will be larger on a 750cc head. I _think_ that there may be a casting number on the cylinders to show which displacement it is, but I disremember what it is. Or you might run the cylinder down to BDC and see what volume of kerosene or mineral spirits it take to fill it.

The only definite test is to pull a head and measure the cylinder bore. For a noob, that is a job for a wrench.

--Bill
__________________
'73 R60/5 Toaster
Bill Harris is offline   Reply With Quote
Old 12-22-2013, 12:14 AM   #23
Falang
Singapore
 
Falang's Avatar
 
Joined: Nov 2013
Location: Singapore
Oddometer: 94
If all the good suggestions so far have don’t work for you you could try a science experiment the next time you are doing a tune-up. You’ll need a few feet of quarter-inch tubing from an aquarium shop, a drill bit same diameter as the tubing, three corks (or for two of them use the water bottle tops), and two one-liter water bottles. Drill holes in the cork(s) and set the stuff up like this, using silicone rubber to seal the tubing if necessary. My drawing is a little crude:



Remove the spark plugs. Turn the engine over with a wrench (or the back wheel in top gear) until the intake valve on the side nearest you opens, then closes. That should be near the bottom of the intake stroke. Shove the cork into the right into the spark plug hole and manually crank the engine half a turn to top dead center as per the flywheel mark. Wait until the air pressure finishes pushing the water from the half full bottle into the empty one. Measure or weigh the water that was displaced; double for two cylinders. Even with a bit of air leakage it ought to work well enough to see if it is a 600 or a 750. If there is more than 300 ml (or 300g) of water in the left hand bottle afterwards, you have a 750. It is impossible for water to flow back into the engine, so it is safe.

When you are done, you can use the leftover parts to make a water pipe by reversing the direction of flow.

Just a thought.
Falang is offline   Reply With Quote
Old 12-22-2013, 12:43 PM   #24
Pokie
Just plain Pokie.
 
Pokie's Avatar
 
Joined: Apr 2013
Location: Fort Collins, CO
Oddometer: 564
Yes, that's a BMW engine. It may have some changes like the front cover to suit what the builder had available, they all interchange. The fact that it has slide type carbs is the first thing that I would find questionable.

Yes, folks did change over from the CVs to slide types but I prefer the CVs. There are no marks that indicate model on the heads (except for later years), there is a part number on the heads on the bottom, between the fins of the head and cylinder but this number is the mould number, not the part number of the head. The easiest way to determine if that's a 750 head is to remove one of the carbs and measure the diameter of the mounting spigot. A 750 has a spigot of 1.652" OD or 41.95mm OD.

The engine is BMW, the front cover is /5 or /6 BMW, the emblems are /6 BMW, the intake tubes are Chang Jing as is the trans and air filter. The exhaust nuts are /5.
Pokie is offline   Reply With Quote
Old 12-22-2013, 07:54 PM   #25
bmwhacker
Still on 3 wheels
 
bmwhacker's Avatar
 
Joined: May 2009
Location: MONTANA NATIVE from NATIVE MONTANA
Oddometer: 3,997
I've had correspondance with a guy (from Connecticut) in China who rebuilds / sells CJ's. He installs BMW engines in the bikes and mates up BMW engines to the CJ transmissions all the time.

the bike could be one of his creations:



With the interchangeability of BMW parts, it is always hard to tell. I installed 1974 R90/6 cylinders / pistons / heads on my R75/5 years back. They appear identical. I suppose there are serial numbers on the parts which could bear witness....
__________________
http://555navigator.blogspot.com

Living proof you shouldn't play with matches
ABC# 1992
bmwhacker is offline   Reply With Quote
Old 12-22-2013, 09:47 PM   #26
tlub
Adventurer
 
tlub's Avatar
 
Joined: Oct 2012
Location: Madison, WI
Oddometer: 83
Definitely BMW, I suspect 600

This looks a lot like a BMW/CJ combo I saw at a re-enactment last fall. It was a 750 with 90/6 badges. The guy did not have the correct badges either, but in this case it was in the other direction, size-wise, from yours. So that part of the story actually sounds consistent with at least one other situation. With those carbs, I would suspect it is an R60, but really the only way to tell is to measure the displacement. The setup with the two water bottles sounds intriguing but a slight leak may throw you off. If you can get a scope in the plug hole, and the pistons are realtively new, the diameter is stamped on the crown and maybe you can read that. If you can't read the numbers, then the only way to tell is by physical measurement of some kind.
I have 750 jugs on an R60 bottom end and no one can tell it is an R60 except by the number on the case. There were no external differences in the cases, but the carbs and spigots are indeed different.
tlub is offline   Reply With Quote
Old 12-23-2013, 04:10 AM   #27
AntonLargiader
Beastly Adventurer
 
AntonLargiader's Avatar
 
Joined: Aug 2003
Location: Charlottesville, VA
Oddometer: 3,982
Quote:
Originally Posted by China2wheels View Post
"BMW doesn't make a 650cc boxer motor in that era, so again you are just showing ignorance."
It's not an R65, but his admonishment would carry a bit more weight if he could put the valve covers on right for the picture.

Do you actually have the bike yet?
__________________
Anton Largiader largiader.com BMWRA.org
AntonLargiader is offline   Reply With Quote
Old 12-23-2013, 04:33 AM   #28
ontic
 
Joined: Jul 2008
Location: LaoPDR/Australia.
Oddometer: 1,027


subscribed!
I've seen a CJ hybrid clone kinda frankenbeemer sidecar thing (imported into australia from one of these kinds of sellers) getting pulled apart up close. Although they interest me and have a bit of charm I wasn't overly impressed and came away with the impression that only the brave, silly or deep of pocket should dare enter those waters. No offense intended, and I really hope things work out well with this bike.


OP, where are you?
Also, the seller sounds like a jerk.
Good luck with it. I look forward to hearing more about it.
__________________
1974 R90/6
1981 R80G/S
1994 XLR250R
ontic is offline   Reply With Quote
Old 12-23-2013, 11:20 AM   #29
AntonLargiader
Beastly Adventurer
 
AntonLargiader's Avatar
 
Joined: Aug 2003
Location: Charlottesville, VA
Oddometer: 3,982
I just checked my shop and all of the R75/5 cylinders except one have a 7 stamped on the top left corner. That one has been painted so I might just not be seeing it.
__________________
Anton Largiader largiader.com BMWRA.org
AntonLargiader is offline   Reply With Quote
Old 12-23-2013, 11:55 AM   #30
DanMay
Adventurer
 
Joined: May 2012
Oddometer: 31
The 750 cylinders have a "7" stamped on the left top near the crankcase.
The 600 cylinders have a "6", the 500's a "5", and the 900's a "9".

The 500 and 600 cylinders have a smaller intake spiggot, for a 26mm Bing carb.
DanMay is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 10:13 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014