Author Topic: GB is not OK, again!  (Read 3995 times)

Online RoyC

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Re: GB is not OK, again!
« Reply #75 on: 14.06. 2018 16:27 »
Is the valve seated properly ?
Give the engine a few revolutions and re check it.
Is the distance between the valve and rocker arm the same as the other one ?
My bike is a 1958 A7SS
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Offline RogerSB

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Re: GB is not OK, again!
« Reply #76 on: 14.06. 2018 16:37 »
Only thing I can think of (ruling out valves, guides, pushrods, everything seated ok, etc.) is if the adjusting screw in the rocker arm is shorter than the others

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Online bsa-bill

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Re: GB is not OK, again!
« Reply #77 on: 14.06. 2018 17:38 »
Quote
is if the adjusting screw in the rocker arm is shorter than the others

or rocker arm is bent / not cast right ( I have one on my sgf that is always at odds with the rest)
Swap the adjuster with one of it's mate - that will confirm / eliminate the adjuster
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online Greybeard

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Re: GB is not OK, again!
« Reply #78 on: 14.06. 2018 18:45 »
Quote
is if the adjusting screw in the rocker arm is shorter than the others

or rocker arm is bent / not cast right ( I have one on my sgf that is always at odds with the rest)
Swap the adjuster with one of it's mate - that will confirm / eliminate the adjuster
Yes, I did that. No difference. Anyway, I have news.

Online Greybeard

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Re: GB is not OK, again!
« Reply #79 on: 14.06. 2018 18:50 »
Is the valve seated properly ?
I filled the combustion chambers with petrol yesterday; they didn't leak
Quote
Is the distance between the valve and rocker arm the same as the other one ?

They looked the same.

I tried Johns advice; with the valves closed I tried levering the valve down. They all moved a similar amount; about 1/8"

Online Greybeard

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Re: GB is not OK, again!
« Reply #80 on: 14.06. 2018 18:57 »
So, I put the bike back together. Started well. Sounded good so I was full of joy! I went out for a test ride. Stopped after a mile to listen to the engine; sounded great. Repeat after another mile; still ok. Stopped at a junction; still ok. I must have done about 10 miles when I heard the dreaded rattle/knock again! I managed to ride home. The engine doesn't misfire. I've made a short video of the bike ticking over in my yard. I'll upload it to Facebook and post a link when I've had my tea. I will not be camping in West Yorkshire this weekend!

A short video: https://youtu.be/9AdUATO7uRI

Could this be down to excessive end float on the camshaft?

Online JulianS

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Re: GB is not OK, again!
« Reply #81 on: 14.06. 2018 19:56 »
Could be a lazy closing valve, damaged or carbon build up on the stem.

Online morris

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Re: GB is not OK, again!
« Reply #82 on: 14.06. 2018 19:59 »
There’s definitely something rattling. Plungers are somewhat rattlyer than later SA’s (at least mine is) but this is excessive. Have you had a look at the valve clearances yet?
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Online RoyC

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Re: GB is not OK, again!
« Reply #83 on: 14.06. 2018 20:17 »
Have you had a look at the valve clearances yet?
I must agree, it does sound like tappets.

Is the oil getting round ?

Can you pin it down a bit with a stethoscope ?
My bike is a 1958 A7SS
Stafford UK

Online morris

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Re: GB is not OK, again!
« Reply #84 on: 14.06. 2018 20:55 »
Have you had a look at the valve clearances yet?
I must agree, it does sound like tappets
Sticky valve? Might explain the pushrod dislocating (already suggested earlier I think)
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Online muskrat

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Re: GB is not OK, again!
« Reply #85 on: 14.06. 2018 20:59 »
G'day GB.
It does sound like a tappet. When you replaced the collets and springs did you check the fit of valves to guides. Just thinking with all the pounding of the other tappets onto the top of the guide may have swagged the guides a little, just enough to grab a valve and give a loose tappet sound. Strange it's only when hot as things expand, what's it sound like once cold again? She is running quite warm, left more than right, going by the blue header pipes.
The tappet adjuster is strange as well. If it was a pushrod out of a cup (as before) it would be wound right out. I would be very surprised if it's a bent rocker arm, you said the pushrods are straight.
May have to get someone else to look at it. Your brain would be in overload by now.
Cheers
morris got in first and could be.
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Online Greybeard

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Re: GB is not OK, again!
« Reply #86 on: 14.06. 2018 21:40 »
Apart from the original reason for the engine work, the little end bush, the current problem seems to be related to the new camshaft. While assembling the cases I noticed quite a bit of end-float on the shaft. I fitted a washer as a shim under the camshaft pinion but someone said the breather cork controls the camshaft end-float so I took it off. If there is too much end-float how might that be causing this horrible noise?

If this engine has eaten my SRM followers I will be a tad cross!

Online chaterlea25

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Re: GB is not OK, again!
« Reply #87 on: 14.06. 2018 21:50 »
Hi GB,
Somethings not right *problem*
Why the noise appeared after some distance is peculiar??
Have you rechecked the tappet clearance?
I assume you checked the pushrods for straigtness? and that they were all the same height once installed
Did you turn the engine over and watch each pushrod rise and fall
If the rocker is that far "up" it might hit the cover? or because the angle is no extreme a pushrod is fouling something
Or a rocker is fractured ??

Last but not least  *ex*
Once or twice I have come across  a situation where the top edge of the piston(s) clout the head gasket *warn*
It don't half make a racket *eek*

John

PS
Just saw your latest post,
I need to go look see what could lead to endfloat on the cam?? ( I have a SA case with the cam fitted
in stock)
If the cap is too far one way or other the followers may get tangled with the wrong lobe??
As I said before they do not match up 100%
1961 Super Rocket
1963 RGS (ongoing)

Online RichardL

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Re: GB is not OK, again!
« Reply #88 on: 14.06. 2018 22:19 »
Well, minimally, the rocker covers need to come off for a look-see. I know this is nearly impossible after all the chatter about it, and I don't want to offend by even thinking to mention it, but could it be the sound made after a lip-riding pushrod finds home 10 miles in?

Other thoughts:enough oil to the rocker box to keep the guides lubricated? Forgot to tighten a lock nut after setting the gap? Thread stripped on adjuster or rocker?

Can't think of others based on sounding good and going bad.

Richard L.
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Online metalflake11

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Re: GB is not OK, again!
« Reply #89 on: 14.06. 2018 22:58 »
Blimey! *sad2*

Sounds very top end to me, as in rocker box.

Is the rocker with the screwed in adjuster 'tapping' on the inspection cap GB?

Run it with the covers off for a short while, have a listen. If the noise goes........Bingo!

 If not you may be able to locate the noise easier ie front, back, or from down the tunnel.

Good luck!
England N.W
1960 A10
England