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1992 r 100 r

chasmrider

not lost til out of gas
morning all, I am thinking about buying a 1992 R 100 R , can anyone tell me where I can get detailed info about this model? the owner says it has 40 mm carbs, what size valves should be on this bike ? how can I tell? and the big question, will there be a major improvement over my 1990 R 100 GSPD with 32 mm carbs ? thanks in advance Chuck PS I love my PD, I just wish for a little more top end, for safe passing!
 
yes that's what he says, I will go look at it soon, I just want to familiarize myself with it before I go.
 
The US R100R had the same engine (and valves) and carbs as your GS, but the owner may have fitted 40mm carbs to it (as I have to mine). I wish I could give you a direct comparison, but I also upped my compression to 9.5 and dual-plugged it. It runs really nicely, but I don't know what the 40mm carbs alone contribute.

You could put 40mm carbs on your PD and have the same engine.
 
thanks, I was hoping if it had big carbs it would have the big valve heads as well, I was wondering how to tell if it had big valves? the reason I am looking at this bike, it is the super motard version of my bike, and I thought it would be fun to play with a more street oriented bike that can still ride to a fire tower and camp.
 

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There are two possibilities:

If you have the straight 40mm intake spigots, it is probably a big-valve head. There is a remote possibility that someone machined a small-valve head to accept the 40mm intakes but there's no reason for doing so.

If you have the tapered 40-into-32mm intake spigots, it is a small-valve head. Of course, someone could have fitted larger valves to this head.

Of course the only sure way to know is to remove the head and measure, because it's already a modified bike so you can't really know where the modifications stopped (unless the owner can tell you definitively).
 
I checked it out on my 92 R100R. The Euro bikes came with 40mm Bings.
The US got the 32mm Bings. Everything else heads, valves were the same on both Euro. and US.
 
thanks for the info, I understand making a bike ride better/go faster involves many things, I just want to know where I am starting. since I am new at this it is an experiment anyway, thanks again for sharing your knowledge.
 
I checked it out on my 92 R100R. The Euro bikes came with 40mm Bings.
The US got the 32mm Bings. Everything else heads, valves were the same on both Euro. and US.

That is the 'tapered intake' configuration I described above. It's not all that uncommon for people to retrofit US bikes that way. Of course, they are still small-valve.

I hear that a larger intake valve is a popular modification to this engine in Europe.
 
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