Valve Adjustment issue R50

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Frenia
Posts: 28
Joined: Mon Jul 31, 2017 9:13 pm

Valve Adjustment issue R50

Post by Frenia »

Hello,

I am making final adjustments on my '56 R50 and I have an issue with the left exhaust valve adjustment. The heads are newly rebuilt from Bob's BMW. The right side was already set to spec clearances. I have the engine at TDC on the compression stroke (left side) and the exhaust valve end is still tight against the rocker arm with the the rocker arm adjustment fully "loosened". So, I cant set any clearance. The left intake was adjusted to spec. The only thing I notice is that the cylinder head sleeve which the top rocker block contacts seems to be seated a bit further forward than the others. The push rods are new.

Since the rocker arm block sits on the sleeve, if the sleeve is too far seated, it seems this could cause the issue? Can this sleeve be adjusted or can a shim be placed between the rocker arm block and the sleeve? Other causes I guess could be if the rod was too long or the tappet isn't seating fully, neither of which seem to be the case.

Any help would greatly appreciated.

Doug F

Frenia
Posts: 28
Joined: Mon Jul 31, 2017 9:13 pm

Re: Valve Adjustment issue R50

Post by Frenia »

Hello, I measured my my previous push rods and they are 2 mm shorter.

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schrader7032
Posts: 7245
Joined: Fri Oct 27, 2006 3:00 am

Re: Valve Adjustment issue R50

Post by schrader7032 »

I'd make sure that you have the proper pushrods. That said, if the rocker arm is fully loosened, it has way more movement than just 2mm I would think. Be sure that the pushrod end at the lifter has fully seated into the pocket on the lifter.

I'm not clear on your concern for position of the cylinder head sleeve. Pictures of both sides would help show what you're seeing.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Daves79x
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Re: Valve Adjustment issue R50

Post by Daves79x »

Unless your original ones are bent, I'd re-use them. The R60 pushrods are longer, but I don't know by how much.

Dave
Dave

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wa1nca
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Location: Ashfield Ma

Re: Valve Adjustment issue R50

Post by wa1nca »

Daves79x wrote:
Sat Oct 17, 2020 8:06 am
Unless your original ones are bent, I'd re-use them. The R60 pushrods are longer, but I don't know by how much.

Dave
Salis site shows r50 series pushrods are about 24cm
https://bmwclassicmotorcycles.com/index ... 1320033170

Salis site shows r60 series pushrods are about 25.3cm
https://bmwclassicmotorcycles.com/index ... 1320033174
Tommy
Tommy Byrnes
54 R51/3 55 R50 64 R27 68 R69US

Frenia
Posts: 28
Joined: Mon Jul 31, 2017 9:13 pm

Re: Valve Adjustment issue R50

Post by Frenia »

Hello,

I had purchased the new rods for an R50 from Salis. They are 24.2 cm. My old rods are about 24 cm. Two of the old ones were slightly bent. I used the two good ones on the exhaust valves and was able to get them into spec.

The intakes are to spec but with very little room to increase the gap. Ill give it a try as such.

Thanks for your help everyone!

D Frenia

Daves79x
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Joined: Sun Aug 09, 2015 8:13 pm

Re: Valve Adjustment issue R50

Post by Daves79x »

Another thing that occurs to me is that the rocker arm supports are sunk into the head, as in the mid '60s 'butterheads' But if your heads are indeed original to your '56 model, that should not be an issue. In any case, the towers can be shimmed to give you more adjustability.

Dave
Dave

Frenia
Posts: 28
Joined: Mon Jul 31, 2017 9:13 pm

Re: Valve Adjustment issue R50

Post by Frenia »

Yes, thanks. I think they are a bit sunk. I can get to spec, but barely. I don't know if there are purpose made shims but I found M10 shim washers of all sizes.

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