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#478339 - 02/24/13 2:51 am GS valve train help!  
Joined: Mar 2007
Posts: 1,152
Swan Offline
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Swan  Offline

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Winona, MN
All, I need your help on a problem I just spent many hours try to solve but I am simply lost. Any advice, troubleshooting and answers are appreciated. I am so close...

The problem arose after I tightened down my cylinder head and rocker box and began to set the tappet clearances. I rotated the motor to get the point where I could adjust the intake tappet clearance but the push rod was always under sprung tension and I could not rotate it or measure any clearance at the tappet tube. Looking down the inlet port with a flashlight I noticed the inlet valve was not seating all the way and therefore the push rod was under tension all the way through the motor's rotation. I rotated the eccentric valve rocker pin to lessen the valve gap, but could still not get the valve to seat all the way. I used a flashlight in the spark plug chamber to illuminate the gap between valve and seat.

Looking down inlet port. Note light leak around valve and valve seat.

Here is what I have:

NOS inlet cam 65-2442
Phil Pearson exhaust cam 65-2446
Phil Pearson tappet tubes
Phil Pearson light weight tappets
NOS inlet valve 65-1844
NOS exhaust valve 65-1845
Phil Pearson valve guides
New standard springs
Original pushrods, later type 9.25" long
Original valve collers, collets etc
And remember I have a 1962 DBD motor fitted with a smaller, earlier CB head as discussed here.


So this morning I did the following:

Adjusted both eccentric rocker valves (inlet valve did not seat completely)
Confirmed push rods are seated correcting in tappet holders and rocker arms
lifted the rocker cover to ensure the rockers are seating on the valve stems correctly. They are lined up correctly with valve stem ends.


I then removed the cylinder head, rocker cover, timing cover and plate. I triple checked top dead center, the camshaft positions and lined up the correct dot and dash on the camshafts to the crankshaft end. The tappets and guides worked perfectly.


With the cylinder head off, the valves seat correctly and I tested them by inverting the cylinder head, filling the valve chamber with parts washer solution for 5 minutes and did not lose any fluid, therefore no leaks.


I carefully replaced the cylinder, gasket, head, rocker cover and push rods and tightened all down to factory spec. Still the inlet valve is not seating all the way and now with the exhaust tube off, I noticed the exhaust valve is also not seating all the too. WTF???? I am lost and do not know what else to try or do to solve this.

Perhaps the earlier head with later components is part of the problem? Maybe this is why the bike failed years ago? Do I need to raise, shim or alter the spring pack? In the link above to my cylinder head ID, Rick E. and Boomer mentioned getting the "the valve tip dims correct and the spring pack height". How do I do this?

Last edited by Swan; 02/24/13 2:56 am.

1966 Triton
1962 BSA DBD34 Gold Star
1966 Triumph Bonneville
BSA Gold Star eBay items

BSA Gold Star forum This board is dedicated to BSA Gold Star motorcycles.

#478341 - 02/24/13 3:19 am Re: GS valve train help! [Re: Swan]  
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goldstarfreddie Online content
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new jersey USA
common problem Push rod is to long try changing them around When you take apart a single always paint red on ex push rod or if assembling a parts motor you can remove tip and change it to correct length

#478348 - 02/24/13 5:01 am Re: GS valve train help! [Re: Swan]  
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Gordo in Comox Offline
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Comox BC Canada
The eccentric type of rockers do not give you a lot of leeway for adjustment as compared to the earlier type that are adjusted at the bottom end of the pushrods. If your valves seats were cut too deep you could just be running out of adjustment. The springs should not make any difference to the closed position of the valve.

It is hard to tell in the photos just how deep the seats are. However in your head the seats themselves appear to be quite deep into the alumimum. The photo below of my small port head has seats that are flush with the aluminum.

Gordo



Without frequent roadside repairs there is no fun in riding!
#478349 - 02/24/13 5:06 am Re: GS valve train help! [Re: goldstarfreddie]  
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Magnetoman Online content
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Originally Posted By: goldstarfreddie
Push rod is to long
From Eddie Dow's "Gold Starlets":

"The length of the engine push rods should be checked every time the cylinder head is lifted, or if the minimum tappet clearance cannot be obtained. The standard length, excluding the spigot is 9.0625 in. Replace if more than 0.025 in. shorter than standard length. Part No. CB, DB and DBD models 65-18581"

#478354 - 02/24/13 5:59 am Re: GS valve train help! [Re: Swan]  
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Posts: 1,875
Ron - in California R.I.P. Offline
In Remembrance
Ron - in California R.I.P.  Offline
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California
Most likely the valves are recessed in to the seats...

First if you take the cams out, measure the distance to the cam spindle, then you can measure the thickness of the cam from the bushing to the closed side of the cams. This will give you an estimate of how much negative clearance you have. The easy fix would be to use thick rocker box gaskets (all 3 of them).

Or, I would suggest you take the valves out and have a cylinder head machine shop or a race car machine shop take that negative amount plus about 0.015" off the top of the valve stems...

Ron

#478355 - 02/24/13 6:13 am Re: GS valve train help! [Re: Swan]  
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Boomer Online content
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Orygone
It would not matter what big fin head you used. As Gordo stated there is not much room for the free length of adjustment so it seems either the pushrod is too long or possibly the cam followers have been altered. Did you have them refaced or replaced?


Bill AKA


Boomer
#478368 - 02/24/13 2:33 pm Re: GS valve train help! [Re: Swan]  
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Kerry W Offline
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Middle East,
Simple answer would seem to be shortening of the pushrods...I'd suggest the bottom, a bit at a time. Easy to replace if a bit much is rermoved, and they'll work with whatever goes in the head, though if the valve stem length is altered, and re-hardened, it's a more complicated thing.


No generalisation is wholly true, not even this one.
Oliver Wendell Holmes
#478408 - 02/24/13 7:31 pm Re: GS valve train help! [Re: Boomer]  
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Swan Offline
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Winona, MN
All,

Thank you very much for chiming in on this problem. I was obviously getting frustrated, not thinking logically and am glad I walked away last night before I did something stupid.

Originally Posted By: Gordo in Comox
If your valves seats were cut too deep you could just be running out of adjustment.

It is hard to tell in the photos just how deep the seats are. However in your head the seats themselves appear to be quite deep into the alumimum. The photo below of my small port head has seats that are flush with the aluminum.

Gordo


Yes, my valves are set deep and most likely causing my problem.


Originally Posted By: Boomer
It would not matter what big fin head you used. As Gordo stated there is not much room for the free length of adjustment so it seems either the pushrod is too long or possibly the cam followers have been altered. Did you have them refaced or replaced?

Bill AKA


The cam followers are new from Pearson and appear thicker than original.


original cam followers

It appears my pushrods are stock length, but are too long for my cylinder headset up. They are approximately 9.094 and 9.058" long, excluding the spigot. The shorter push rod was in the inlet side, so switching them will not make a difference.


So my two choices are to remove material from the end of the valve stem (and harden them) or to remove material from the bottom of the push rod, above the spigot. This makes sense to me now. I am going to consult with Skip my machinist. He has owned two Goldies, each with large and small heads, has a beautiful lathe and mill and knows infinitely more than I do about valves, guides and seats. I am leaning towards shortening the push rods because it is easier than modifying and hardening the valve stem tips. Rather than trial and error, is there way to precisely determine how much material to remove from the push rods? I will post my results, thanks again!


1966 Triton
1962 BSA DBD34 Gold Star
1966 Triumph Bonneville
#478414 - 02/24/13 8:16 pm Re: GS valve train help! [Re: Swan]  
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Magnetoman Online content
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Originally Posted By: Swan
Rather than trial and error, is there way to precisely determine how much material to remove from the push rods? I will post my results, thanks again!
If I were doing this I would fabricate an adjustable length pushrod. This would be easy to make, and could be as simple as length of rod tapped to mate with a bolt (socket head cap screw). With the eccentric adjuster in mid range and the cam set off the lobe (i.e. on the round part of the cam), screw the cap screw out of it until the proper clearance is obtained. Then measure the length of the adjustable pushrod. Repeat for the other valve.

#478417 - 02/24/13 8:42 pm Re: GS valve train help! [Re: Swan]  
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Gordo in Comox Offline
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Comox BC Canada
Swan: Below is an unused NOS cam follower. For comparison to the Pearson version the total length of this one is 3.774" and the distance from the bottom of the foot part to where it becomes a shaft is about 0.269". The thickness of the foot measured at a scalloped area is about .078". I Would think that the thickness of the foot would really not matter if the total length was not different.

Gordo



Without frequent roadside repairs there is no fun in riding!
#478418 - 02/24/13 8:42 pm Re: GS valve train help! [Re: Magnetoman]  
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GS DAVE Offline
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england
Good idea at least then you could get the new push rods made to size to suit the bike, Easyer than getting the valve seats done. Plus it would give more peice of mind than extra rocker gaskets. ( rocker gets a good hammering over time.

#478420 - 02/24/13 9:07 pm Re: GS valve train help! [Re: GS DAVE]  
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Magnetoman Online content
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You almost certainly already know this, but I thought I would mention it anyway. Once the right pushrods are in position, the eccentric can be rotated to give the proper clearance in two orientations. Only one of those orientations is correct. Since you likely already know this a longer explanation is unneccessary. But, if this comes as news to you, ask for details before you brush on the gasket cement.

#478432 - 02/24/13 10:56 pm Re: GS valve train help! [Re: Swan]  
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Posts: 1,851
dave - NV Online content
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dave - NV  Online Content
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Elko, Nevada USA
Swan .. Your issue with valve clearance is certainly not unique and I believe the guys have covered the issues and the fixes. I would suggest having a machinist lathe the flat face pushrod end as you've mentioned. I've done that in the past and it works.

Just for sake of talking about Goldie stuff ... I and others are using the nice rigid ABSAF double ball ended cro-mo steel tube pushrods and the associated ball socket cam follower.

Anyhow .. to be able to arrive at the correct steel tube length, I found some alu tubing the correct size in my 'junque' that I used to make dummy push rod tubes with the ABSAF ball ends lightly pressed in and cut for optimum length. I could then use that test length to cut the steel tubing to fit. Having a bolt on easily removable rocker box is priceless at times like this!

But here's a rub much the same as your issues. When swapping heads oftentimes different pushrod lengths are needed. I try to stay fairly close to the upper limit of the valve adjustment excentric's range. If you need to shorten or replace the tube you must pull out the pressed in ball end that's very difficult to do. My son Joel the crafty design eng. made GStarRon and I each a unique 'ball end pullers' that work great with no damage to the tube or end.

I hope you understood MagMan's warning on adjusting valves. You can easily get off on the 'wrong side' of the excentric and mess up the rocker arm geometry causing wear problems. There's a good step by step adjustment procedure in the owners manual and if you get confused just ask and I/we will walk you through the drill.

Last edited by dave - NV; 02/24/13 11:14 pm.

dave - NV
#478433 - 02/24/13 11:09 pm Re: GS valve train help! [Re: Magnetoman]  
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Swan Offline
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Swan  Offline

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Winona, MN
Originally Posted By: Magnetoman
You almost certainly already know this, but I thought I would mention it anyway. Once the right pushrods are in position, the eccentric can be rotated to give the proper clearance in two orientations. Only one of those orientations is correct. Since you likely already know this a longer explanation is unneccessary. But, if this comes as news to you, ask for details before you brush on the gasket cement.


I believe I understand this and know each eccentric pins must rotate either clockwise or anticlockwise and can give a false reading. But first I need to sort out the pushrod length.

I really need to buy a lathe, but I will use my machinist's lathe to make an adjustable push rod or several sized dummy rods to get the length correct.

Thanks again.


1966 Triton
1962 BSA DBD34 Gold Star
1966 Triumph Bonneville
#478504 - 02/25/13 3:25 pm Re: GS valve train help! [Re: Swan]  
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Swan Offline
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Winona, MN

The plot thickens... I met with Skip Green, my neighbor and machinist, last night. He is nearing retirement after a lifetime of working as a motorcycle mechanic, VW mechanic, machine tool salesman for Winona Van Norman and other machine companies, a world traveller, vintage radio and electronic equipment genius and a man of many more talents. Not to mention has owned two Goldies along with any other bike I mention. He is setting up his shop so he can do high end machine work on vintage motorcycles in his retirement. http://apparatusmc.com

We pulled the cylinder head and he examined everything and we discussed several possible solutions including shortening the push rods, shortening the valve stems, adding shims and/or additional gaskets to rocker cover etc. But rather than treating the symptoms, I wanted to address the cause, which we both agree is that the intake valve seat is too deep. So he is going to replace and properly re-cut the valve seat. Here is the old one and obviously someone has been in here before:


He would like to know, what is the correct valve stem heights and spring pack heights (from the head or the insulating washer)?

Currently, the valve stem heights are;
1.685" exhaust
1.703" Intake

We measured the old intake valve stem height and it is 1.668", .034" less than new valve stem height. This I believe is why the new valve is not closing all the way.


Someone removed quite a bit from the old valve stem:

old left, new right

crude grinding

Intake valves, new left, old right

The exhaust valve seat looks much better, but he is going to cut it to properly match the new valve. The exhaust rocker however shows wear. Should I regrind it, replace it or have it stellited and reground?



This is 100% my fault for failing to measure valve stem height heights or re-cutting (rather than lapping) the valve seats to the new valves. I was anxious to get the motor done but am glad I am taking the time to have a new valve seat installed and cut now while there is still snow on the ground. This is what happens when you overlook something or cut corners. Live, learn and move on.


1966 Triton
1962 BSA DBD34 Gold Star
1966 Triumph Bonneville
#478507 - 02/25/13 3:49 pm Re: GS valve train help! [Re: Swan]  
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Magnetoman Online content
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Originally Posted By: Swan
This is what happens when you overlook something or cut corners. Live, learn and move on.
How much better it would be if only we actually did learn from our mistakes. Since in your previous post you mentioned needing to buy a lathe, ~2 years ago I bought one for my home. I've always had full access to lathes ever since college, and still do, but they are so very useful for motorcycle work that I decided to have one in my garage. Anyway, I had to rebuild the lathe when I got it and the last step was to reassemble the apron on the carriage. It needs to be sealed to keep the oil in, but all I could find when I got to that point late one evening was an old tube that still had some unhardened stuff at the bottom of it, and a new tube with unbroken seal for a bike's toolkit.

Even though it "shouldn't" take much to seal two machined surfaces, I knew from past experiences that I should open that $5 tube to get a small amount from it, even though that meant the rest of it would be bad by the time I needed it for something else. But, did I learn from my previous mistakes? No. Even though I knew better, I used the old stuff and, as a result, the apron has slowly leaked ever since. At some point I'm going to have to spend at least an hour to redo the work properly.

"Live, learn, and move on." If only...

#478521 - 02/25/13 4:57 pm Re: GS valve train help! [Re: Swan]  
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Ron - in California R.I.P. Offline
In Remembrance
Ron - in California R.I.P.  Offline
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California
Well.. that new magnified picture tells a tale for sure.. That head has been worked on a LOT in the past. And it was better that the person ground down the valve, as that is the "least damage" method long term, as valves are the standard replacement item. Notice that the aluminum around the seat has also been ground down.. this will make a new Proper seat protrude up from the head a bit.. Now you see what some back yard guys do... Seems your intake seat is far below the original...

So, is the exhaust OK..?? Can't really tell from that picture..

Ron

#478528 - 02/25/13 5:39 pm Re: GS valve train help! [Re: Swan]  
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Swan Offline
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Winona, MN
The exhaust valve looks much better, seats higher without the butchery of the intake. We still need the valve stem height tolerances (CB head) to know for sure.


1966 Triton
1962 BSA DBD34 Gold Star
1966 Triumph Bonneville
#478551 - 02/25/13 8:13 pm Re: GS valve train help! [Re: Swan]  
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rick e. Offline
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Earth
Swan,

I too have an engine 1962 engine# 64xx with the same type head you have. Also from Texas!

Anyway, the grinding around the valve seat, mine looks exactly the same. Even rough finish around the fins are the exact same. Makes me think this is all factory done...

I had my seats re-done by a shop that has been doing GS machine for decades. He has been keeping a log of stem heights on all his work. (distance from the v-tip to the machined area on the head)

I have these numbers and will post them so we can compare. But note, I do not have my engine together yet.

#479037 - 02/28/13 8:19 pm Re: GS valve train help! [Re: rick e.]  
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Swan Offline
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Winona, MN
Rick e, looking forward to those dimensions.

A tiny chip on the exhaust seat turned out to be a tiny crack, so both seats are going to be replaced. Skip wants to test the valve stem heights using a weak valve spring in a mock up to ensure they are correct and the eccentric rockers function as designed. We will get it right and I will post the heights.


1966 Triton
1962 BSA DBD34 Gold Star
1966 Triumph Bonneville
#479405 - 03/02/13 6:43 pm Re: GS valve train help! [Re: Swan]  
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rick e. Offline
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Earth
Somehow work got in the way, so I am a bit tardy on a reply..


1.585 for the intake. (original seat with grind)

1.660 for EX. (replaced seat)

#479412 - 03/02/13 7:13 pm Re: GS valve train help! [Re: Swan]  
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Swan Offline
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Swan  Offline

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Winona, MN
Thank you very much Rick e.

I am traveling, but got an e-mail from my machinist last night and he ended up with 1.640" exhaust height and 1.625" intake with new valve seats in both. We plan to test Monday evening with weak valve springs with the goal of using standard push rods near the bottom of the adjustment range. He will make more cuts if necessary and I will post our results.

Last edited by Swan; 03/05/13 12:57 pm.

1966 Triton
1962 BSA DBD34 Gold Star
1966 Triumph Bonneville

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