Boxer four?

[tibork]

Since this question involves all boxer riders (and not specific to any sub group of them) I decided to post this question here. What people think about a boxer four or six instead of the twin? Most reviews I see or people talking about the boxer twins complain about the same thing: the cylinders sticking out so far to the side, interfering with leaning in curves (not like those Harley running boards don't touch ground even faster) and if you scrape it, it's a pricey fix. Why not reduce the individual sizes by going to four or six cylinders (like Goldwing did)? Any advantage to a two cylinder vs. a four or six? Any thoughts, any feedback?

 

[akbeemer]

I think the number of riders who are concerned about the valve covers of their boxer hitting the road surface in a corner is close to zero.

 

[pglaves]

I never had that problem with either of my Subaru cars.

 

[52184]

Why not reduce the individual sizes by going to four or six cylinders (like Goldwing did)? Any advantage to a two cylinder vs. a four or six? Any thoughts, any feedback?

Simplicity, weight, manufacturing complexity & cost, increased maintenance cost (4vs2 of everything to check/adjust/replace), increasing the length of the engine means either lengthening wheelbase or taking the extra length back in the trans/swingarm design, etc. A Goldwing has a 66.5” wheelbase, an R1200RT has 58.5” wheelbase—and that definitely affects handling and “feel”.

Back in the day there were stories about BMW working on an opposed 4 but abandoning it for the brick-K design after Honda released the Goldwing. I have no idea if there was an iota of truth in the stories but they made the campfire rounds. I’m quite happy they stuck with the big twin boxer!

Best,
DeVern

 

[lkraus]

IME with my R1200RT, the valve covers do not restrict the lean angle. Even my Wunderlich engine guards, which hang a bit lower and further out, have never touched ground while in motion. The footpegs touch first, and at that point I'm on the edge of the rear tire, which is as far as I am inclined to incline. When I want to corner faster it's simple enough to move my upper body toward the mirrors, or move my butt out of my seat to the inside to save 5 or 10 degrees of lean. My left footpeg has lightly touched twice, the right, never.

But I am curious about how this valve cover protector was scuffed:

(Internet pic, not mine. Maybe a MOA member?)

Maybe lean angle was an issue with the Oilheads that was corrected with the R1200 engine?

 

[motodan]

If it isn't broke, there's no need to "fix" it.

 

[stevenrankin]

Boxer

I have been riding twin airhead boxers for 50 years and never touched the valve covers to the pavement nor my engine guard bars. Then again, I don't ride like a race bike rider on public roads.

The few times I have been on a race track posed no problems either.

Forgive me but didn't BMW with the start of the oiled boxers raise the cylinder height?

If BMW wants to make a four or six engine, they could do it and there would be only the problem of cylinders hitting the rider's legs maybe? St.

 

[dduelin]

I think one big reason BMW never pursued a boxer 4 or 6 is cooling issues for the second or third row. In the 1980s the BMW boxer faithful desired air cooling with fins on exposed cylinders and still do on R bikes. The WC boxer twin is still 65% air cooled with 35% of the cooling being liquid coolant strategically cooling the hottest areas of the engine in the cylinder head. A boxer 4 or 6 would require liquid cooling for the rearmost cylinders and cylinder head. Might as well build an inline 4 with a cooling water jacket enveloping the entire block and head.... which they did and called it the K100.

 

[tibork]

I think one big reason BMW never pursued a boxer 4 or 6 is cooling issues for the second or third row. In the 1980s the BMW boxer faithful desired air cooling with fins on exposed cylinders and still do on R bikes. The WC boxer twin is still 65% air cooled with 35% of the cooling being liquid coolant strategically cooling the hottest areas of the engine in the cylinder head. A boxer 4 or 6 would require liquid cooling for the rearmost cylinders and cylinder head. Might as well build an inline 4 with a cooling water jacket enveloping the entire block and head.... which they did and called it the K100.

Cooling the rear cylinders reminds me I watched a video by a Harley owner (oil + air cooled cylinders) where one cylinder is behind the other, the difference in temperatures measured front and rear cylinders were 239 F and 264F respectively, but they also have air scoops and even cooling fans available (aftermarket) to solve this and after installing one on his bike the temps were exactly the same - so they do work I guess.

Going to inline 4 would change a lot more like torque output so that would be a different animal.

Nice to read though that nobody had issues with the heads scraping the road, again, i brought up the question because several reviews I watched pointed out as a potential problem of the cylinders sticking out to the side limiting leaning in corners. But then again, most Harleys are low enough that their pegs, foot rest boards or even exhaust pipes will touch the ground way before anything else on any bike - like my neighbor pointed out his pegs already half scraped off. I am also sticking with the twin boxers.

 

[tibork]

Forgive me but didn't BMW with the start of the oiled boxers raise the cylinder height?

Yes I believe you're correct on this one.

 

[lee]

But I am curious about how this valve cover protector was scuffed:
View attachment 87772
(Internet pic, not mine. Maybe a MOA member?)

It came from the factory that way.

 

[lkraus]

It came from the factory that way.

Wow!

 

[dduelin]

My R100 didn't come from the factory like that.

 

[lkchris]

But I am curious about how this valve cover protector was scuffed:

You aren't viewing a scuff but rather a metal insert in the carbon fiber cover.

 

[lkchris]

Inline four and inline six engines are available from BMW.

Had you been around in the 1980s you would recall the sales disaster that was the K-bike, a bike with inline four expected by BMW to supercede the boxer twin. Just like old formula versus new formula Coca Cola, the market demanded the classics. It was astounding how the R100GS quickly became BMW's best selling bike ... and the rest is history.

 

[milo]

My understanding is that BMW was considering a liquid cooled, opposed 4, maybe even had started development, then Honda Goldwing beat them to the punch. BMW at the time was absolutely not going to "copy" so ditched the idea and started over. The eventual result was the in-line 4 mounted on its side.
But since BMW is no longer opposed to using common engine configurations I've wondered the same thing, especially after Honda turned the Goldwing into a huge 1,800cc, 6 cylinder motorcycle, and BMW opposed twins are now 1250cc and liquid cooled, what about a liquid cooled, 1,000cc opposed 4?

 

[robsryder]

Honda made a 4 cylinder boxer in 1975. It was called the GoldWing GL1000.

 

[milo]

Correct which is why I said:

My understanding is that BMW was considering a liquid cooled, opposed 4, maybe even had started development, then Honda Goldwing beat them to the punch.......

 

[stevenrankin]

Next

The way things are going BMW's next big project will most likely be an electric bike, Then the battery shape will be the big thing to worry about. St.

 

[52184]

The way things are going BMW's next big project will most likely be an electric bike, Then the battery shape will be the big thing to worry about. St.

Easy peasy: two batteries,one sticking out on each side!

Best,
DeVern