Reed Valve Breather

[RPGR90s]

A few years ago I installed the updated reed breather valve in my '74 R90s as the stock disc was making the turkey gobble.

Come to find out I need to orient it to point to the 11 o'clock position when sitting on the bike. Of course, I installed it pointing at the 4 o'clock position.

Can someone suggest a tool to pull it out so I can rotate it?

See attached photo (note, I've removed the reed itself and cover).

Thanks,

RPGR90s

[Kurt in S.A.]

A little heat around the edges of the case might provide enough expansion to let the valve come out. As for removing, I would think the way you removed the original breather might work here...my old one didn't want to come out. I was able to wrap some wires/steel cable around the webs of the old one and use a slide hammer effect to jerk it up and out. I realize there's nothing obvious to grab on to, but something that you can slip in, a small plate, a high strength bolt, tool steel, and then turn 90 degrees could be used to bear against the underside of the valve. Be careful that nothing can drop into the hole. Then grabbing that tool with some wire, etc., use a slide hammer to provide some momentum to pull it up.

https://www.amazon.com/OTC-4579-9-Way-H ... B0015DMNIS

Kurt in S.A.

[RPGR90s]

Good info. Kurt. Thanks for your help.

[Rob Frankham]

Where did you find the information that the valve needs to be orientated in a particular direction? None of my references (Haynes, Clymer, BMW repair manual) has any mention of orientation and I can't see that it would make much difference.

Rob

[Kurt in S.A.]

I heard the same thing about orientation...Tom Cutter was the one who mentioned on the Airhead email list...I believe Snowbum states it also on his website. My understanding is that it orients the outlet to more in line with the hoses, etc., for extracting the oil mist. If the breather releases the mist and it has to turn 180 degrees to head out, that's just a restriction in the flow. Couldn't hurt I suppose to streamline the flow of oil mist.

If your reference information was written only at the time of the older style breather, it would have nothing about orientation of the reed style. The picture in my Haynes actually shows the reed valve oriented the "right" way...the screw holding the metal tab is pointing towards the rear of the right cylinder.

Kurt in S.A.

[RPGR90s]

As it turns out, the open slot is 3/8", which means a 3/8" socket extension fits perfectly. Per Kurt's recommendation, I applied some heat with a gun and used a long handled 3/8" drive torque wrench to rotate it to it's correct position. Didn't even have to remove it.

Thanks again,

RPGR90s

[Rob Frankham]

I hate to be the one to point this out but...

If the issue is with aligning the reed with the outlet hose... and I really don't think it would make any difference but never mind... then the reed should be aligned facing aft... i.e. at the 06:00 position for the early machines. Late machines, the ones fitted with reed valves as standard, have a different arrangement, with the ejected air passing forward from the valve towards the front of the engine where it is picked up by a longer hose. for these machines the reed pointed at 11:00 might make a little sense. In other words, you have just moved your valve from a position few degrees from where it should be to a position nearly 180 degrees away from it.

Attached two screen dumps from the BMW parts system to illustrate the difference between the two breather setups...

If you are really worried about the issue, I would suggest you need to rotate the breather back to an 06:00 position.

Personally, I believe this is just another piece of airhead lore that has no basis in logic or science. The stream of air from the valve will not be particular great or violent and any restriction in flow will be so slight that the result would be negligible. The path in the later engines is, by design, far more tortuous and this doesn't cause any problems.

Rob

[RPGR90s]

good points Rob, It's probably negligible in terms of orientation.

I'm chasing down a poor idling issue that appears to only effect the right cylinder.
Stock Dellorto's. Starting the bike and idle is rough. Left side carb responds to mixture screw settings (bike will stall if screwed in completely). But the right side carb mixture doesn't seem to have an effect. I can't stall the bike when turning in completely.

Went to my parts bin and pulled my spare right side Dellorto that's almost like new. Installed it and immediately had a smooth idle. Had the bike on my workstand with cooling fans and dialed in both carbs. Mixture screws 1 1/2 turns out both sides. And yes, screwing in the right side mixture stalled the engine. Went for a ride and after warming up, the idle got rough again.

Rode home and again, the right side mixture screw doesn't change anything. And closing it completely had no effect nor did it stall the motor.

Is it possible that I have a sticky intake or exhaust valve?

[Rob Frankham]

I think a stuck valve is unlikely, given the symptoms. I also think that you need to widen your investigation a bit. Idle problems when the bike is warm are a symptom of a coil, plug lead or plug breaking down as well as carburation problems. There is also the chance that you are getting too much oil in the breather causing idling circuits in the carb to get blocked.

The breather issue is easy enough to check... Thorughly clean the carb then re-route the breather outside the air box. If the problem goes away, that's a pretty good diagnosis. Unfortunately, that diagnosis means that there is something else wrong with your engine... worn rings, scored bores or seal problems so hopefully that isn't it.

The ignition issue is also easy. Simply swap all of the ignition components from side to side... you can probably do this simply by moving the plug leads across the bike provided the leads are long enough... also swap the plugs. If the problem moves with the leads, that would be a pretty good indication.

Rob

[RPGR90s]

good info. Rob.

I don't think the breather is an issue either since my last test had the air tubes removed, so I don't think the oil mist would have even got to the right carb.

I'll report back what I find.