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Clearance on rear tire.


Fleetwood

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Hello folks,

 

Just had a new set of tires mounted, and I'm reinstalling the wheels. The manual refers to having 20mm clearance between rear tire and the muffler (silencer). I seem to have that clearance at the rear end of the muffler and the tire, however there is very little clearance between the top profile of the tire and the front end of the muffler. Anyone know if this is normal? I do recall it being tight on removal, but I did not measure the gap.

 

If the manual is referring the exit point of the exhaust, at the rear of the rear tire I'm golden, however if it referring to the front of the rear tire, where the muffler flares out , I am nowhere near having 20mm (almost and inch) of clearance.

 

I did search the forum, but did not see anything of this nature.

Thanks for the help!

 

Gary

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Afternoon Gary

 

Kind of conflicting info-- BMW service manual shows 15mm & riders manual shows 20mm (BMW service manual shows clearance measurement at rear of tire).

 

1200RT%20rear%20muff%20clear._zpszkndilzn.jpg

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I have about that on the front. Perhaps the muffler is installed incorrectly.

Took a picture of mine, but don't know how to post it here.

Ed

 

 

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Dirtrider, that photo is the perfect illustration of what I have , what I would call typical gap on the rear of the bike. So I'm correct on that front. The front of the wheel/tire has me a bit concerned..but I don't recall the gap size pre tire removal, but it was tight.

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The Rocketman

Gary, When you removed the rear wheel did you loosen up the muffler clamp, and the muffler hanging bolt, and pivot the muffler out of the way? If you did, there should have been no tightness at all.

 

Video here:

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You are correct Larry, the muffler rotated down and away from the tire. When I say tight, there is some clearance between the front of the muffler, just not 20mm (or 15mm worth). The wheel turns freely, without rubbing on the muffler. Now that I'm clear that the shop manual is referencing the clearance between the rear of the muffler and the wheel, I'm less concerned.

 

I do have the clearance (15mm+) at the rear of the muffler.

 

Without clicking on the link...is that max BMW's rear wheel video...guess how I know? Seriously thanks for the support.

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Oh and another interesting factoid...in the vireo he references two clamps, one before and one after the butterfly, on my bike no butterfly, just a single clamp joint. I'm guessing due to different emission regs?

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Oh and another interesting factoid...in the vireo he references two clamps, one before and one after the butterfly, on my bike no butterfly, just a single clamp joint. I'm guessing due to different emission regs?

Not emissions, but torque curve improvement. The butterfly valve was added when the camheads were introduced; your 2009 hexhead pre-dated it. As I recall BMW's statements at the time, the butterfly provides increased back pressure at lower rpm to increase torque, and is opened at higher rpm to permit increased flow/top end power. My 2012 RT was definitely stronger in the mid-range, without the mid-range dips in the powerband my 2009 had.

 

It was probably a combination of many individual changes associated with the entire camhead update, to which the butterfly valve was but one contributing player (cam timing, valve size, port shape? -- I don't know the details, but I can't believe the only thing the engineers did was drop in OHCs without tweaking anything else).

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Dirtrider, that photo is the perfect illustration of what I have , what I would call typical gap on the rear of the bike. So I'm correct on that front. The front of the wheel/tire has me a bit concerned..but I don't recall the gap size pre tire removal, but it was tight.

 

 

Morning Fleetwood

 

On my personal 09 1200RT the rear muffler clearance is about 18mm or so (guess on my part as

I have no measuring device where I'm at now) & I can just get my fingers in between muffler & tire

on the front.

 

Your muffler should have a flat spot on the tire side of the front to give it a little extra clearance

in that area (does your muffler flat spot line up with the tire fat spot?)

 

If you need MORE clearance just loosen the REAR muffler band & slide it around the muffler a bit

(CAUTION: loosen band & OPEN IT UP as well as clean muffler under it before moving the band or

you WILL scratch the muffler finish)

 

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I'll have a look again on days off, tough to get much done on the night shift...I think I'm just over analyzing it!

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Several hundred Km test ride complete, and it's all good. The new tires are good so far, can't wait to try them on good roads down south next week.

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