Can't get neutral when hot

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Dan in IL
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Re: Can't get neutral when hot

Post by Dan in IL » Thu Nov 16, 2017 10:28 pm

It's been a few years since I've had a bike but I remember switching to a heavier oil to solve hot tranny shifting problems in one of my airheads. I'm thinking I went to a 90w140, or something in that range.

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Gibson
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Re: Can't get neutral when hot

Post by Gibson » Fri Nov 17, 2017 11:55 am

I found this to help. The collector "box" under the transmission puts a lot of heat into the transmission. It is very close to the housing and transfers heat through convection and radiation. Especially when in traffic. I find the performance of these transmissions overall gets worse the hotter they become due to expanding case and oil thinning. On my bike, I fitted a Kehin "Y pipe" to eliminate the box. The transmission runs noticeably cooler with this set up and shifts better because of lower temp. Oil changes are also a bit easier.
On bikes with 2 mufflers I have seen pipes to eliminate the pre-muffler box. Perhaps this may help.

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ME 109
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Re: Can't get neutral when hot

Post by ME 109 » Fri Nov 17, 2017 2:39 pm

As already mentioned, try clutch adjustment first. Half a turn on the handle bar adjuster might be all it needs.
Any time I have difficulty selecting neutral, which is not very often, I know my adjuster has moved (because I didn't tighten the lock nut) and I give the adjuster a tweak.
Never had an issue with tranny heat and 80/90 oil is all I've ever used.
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Wobbly
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Re: Can't get neutral when hot

Post by Wobbly » Fri Nov 17, 2017 9:22 pm

Gibson wrote:
Fri Nov 17, 2017 11:55 am
On bikes with 2 mufflers I have seen pipes to eliminate the pre-muffler box.
Yes, those can be had from Keihan Systems (England) or Bob's BMW (USA), a Keihan reseller.

http://www.keihan.co.uk/
Last edited by Wobbly on Sat Nov 18, 2017 5:23 pm, edited 1 time in total.
After 20 years as a professional bike mechanic and 30 years as an engineer I know just enough to be dangerous !

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George Ryals
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Re: Can't get neutral when hot

Post by George Ryals » Sat Nov 18, 2017 9:28 am

pxc433, How did the clutch adjustment go? hopefully it fixed the problem.
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ME 109
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Re: Can't get neutral when hot

Post by ME 109 » Mon Nov 20, 2017 5:20 am

BMW may have revised their end float clearances due to the fact that there is no such thing as 'absolute zero' on which to base measurements.
The variables of cover warp, pocket depth variation within the one pocket, shim plate to bearing depth variables on the same bearing, and shim thickness variation on the same shim. There is also the affect on the cover of torquing the cover bolts.
The formerly recommended clearance of 0.0 to .05mm can be lost due to just those variables, without considering any inaccuracies of measurement by the person measuring, and their methods.

BMW just widened the goal posts but still give a maximum clearance so too much clearance can't be good either, otherwise they would have specified an even greater clearance to cater for all the above.
I aim for .07mm clearance after determining the range of measurements and selecting a figure, based on the particular item measured.
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pxc433
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Location: Edinburgh, UK

Re: Can't get neutral when hot

Post by pxc433 » Tue Nov 21, 2017 8:50 am

Afternoon guys

I have not done anything yet. The roads outside are covered in salt now, and this has a tremendous ability to dissolve motorcycles. I'll be servicing the bike at Christmas.

Besides, I will not know if the problem is fixed until the summer and I go abroad. Until then, it will work perfectly I would think. Scotland does not get hot enough ever.

What I'll be doing is adjusting the bolt/locknut and re-adjusting the cable tension, and seeing how it goes.

I thought Gibson's comments above were really interesting. He's right - the heat from the collector box is amazing. I may try this.

Can I ask: are there any other considerations if fitting a H pipe there on a monolever? These are not OE as far as I know, and the carburation on my bike is really nice at all times and temps.
1988 R100RS with Blue/Silver 1979 paint job
2011 F800ST in White/Black

pxc433
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Re: Can't get neutral when hot

Post by pxc433 » Tue Nov 21, 2017 8:55 am

1988 R100RS with Blue/Silver 1979 paint job
2011 F800ST in White/Black

Wobbly
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Re: Can't get neutral when hot

Post by Wobbly » Tue Nov 21, 2017 10:49 am

I am looking at the exact same pipe for my bike. The original H piece is part of the muffler system, in fact I think the BMW parts book calls them "front muffler". So I would expect a slightly louder report from the rear of the main mufflers with this part removed. Hard to tell if this would be annoying or not.

IMHO, any carburation changes experienced could be overcome with a idle mixture adjustment... IF you have already updated, tuned, and balanced the carbs to your local fuel and riding conditions.

Hope this helps.
After 20 years as a professional bike mechanic and 30 years as an engineer I know just enough to be dangerous !

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Gibson
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Re: Can't get neutral when hot

Post by Gibson » Tue Nov 21, 2017 2:02 pm

If you buy Keihan pipes, order from Moto Bins. It is a LOT cheaper even with shipping than Bob's. I have the Y pipe and the stainless headers. Quality is good and they don't rust. I have not had to do any jetting changes on my R100R M.

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