The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: anjimehra on 05.01. 2011 12:31

Title: 1952 Plunger Flash
Post by: anjimehra on 05.01. 2011 12:31
Hi
Back again after a gap of 2 months.The bikes been on the road for about 3 months now & has logged on about 300 kms. Everything appears to be fine, except for noisy valve gear.The bike runs silent for the first 5 mts & then this distinct rattle from the valve gear.
Have tried increasing the oil flow to the rockers by blocking the return hole in the tank but not much joy.
The cam bushes are OK & the followers are old.The rocker shafts & rockers are also old, but did not show much play when tested by hand before assembly.
Any suggestions
Anji
Title: Re: 1952 Plunger Flash
Post by: terryk on 05.01. 2011 13:20
Take off the oil feed to rockers and while the bike is running get an oil can or plastic bottle oiler etc and squirt oil under pressure into the rockers shaft holes. If the noise goes away you know you need more oil there.
If the oil return to tank is a good pressure make sure the oil line to rockers and the rocker shafts are not blocked.
Sometimes old oil pumps dont have enough pressure on the return side to feed enough to the rockers. Maybe need a new pump?
Try the oil to rockers thing for a starter if the noise is still there with plenty of oil check tappets and on it goes.
These bikes are a bit noisy in the tappets anyway is there another bike near you to compare tappet noise.
Terry
Title: Re: 1952 Plunger Flash
Post by: LJ. on 05.01. 2011 13:34
Anji... What a lovely looking restoration that is! congratulations... Now all you need to do is take a nice long ride to run it in and get us a photo of the bike just in front of the Taj Mahal. That would be super! Cheers. LJ.
Title: Re: 1952 Plunger Flash
Post by: bsa-bill on 05.01. 2011 13:44
Hi Terry

Nice work

Just a suggestion

Sounds like maybe tappets after warm up?
what gap are you running on them, I would try closing them a bit,  some bikes ( Triumph I think) used to have no clearance on tappets when the bike was cold, they were set so they just turned then as everything reached running temp the clearance was right.
Title: Re: 1952 Plunger Flash
Post by: RichardL on 05.01. 2011 17:18
Anji,

Good to hear from you again. Almost a guarantee that you would win Best Picture 2011 with the bike in front of the Taj Mahal, or one of the other exotic locations (from the viewpoint of the American midwest)  to which you tour. Yes, it is a fantistic looking bike, but what exactly did you not like about the pre-resoration version?

Regarding the valve noise, it occurs to me that if it were simply oil starvation, the noise would occur right at startup, having already been starved at the previous shutdown. It would be interesting and important to pinpoint the origin of the noise. Have you tried a noise probe between the engine and your ear? I use a long 3/8" ratchet extension with the male end closing my ear by pressing against the tab of cartilage that you would press if you were closing them with your fingers. The other end is then touched to vaious points on the engine. The ability to discern noise localization this way is amazing versus just pointing your nose in the general direction.

Richard L.
Title: Re: 1952 Plunger Flash
Post by: a10gf on 05.01. 2011 21:41
Nice to see you on the forum, happy new yesr, and nice to see the bike, what a good work ! As mentioned, why not try taking a picture of the (great) bike in a great surrounding, and enter it into the best picture contest ?
e
Title: Re: 1952 Plunger Flash
Post by: muskrat on 06.01. 2011 07:47
G'day Anji,
              gee that's a great looking bike.
 I think you will find the tappet clearances close up when hot so don't go any smaller than what is recommended for your model.
 Might be a sticky exhaust valve that grows a little when hot, just enough to give a tappet noise.
 Just another thought.
Cheers
Title: Re: 1952 Plunger Flash
Post by: A10Boy on 06.01. 2011 11:40
If it only happens when the engine warms up it could be a loose valve guide. Tight when cold but when the head heats up and expands it goes loose and rattles around.

Beautiful resoration BTW, it looks lovely.

Title: Re: 1952 Plunger Flash
Post by: bsa-bill on 06.01. 2011 14:42
Terry sorry if I sent you a bum steer there, now I always thought tappet clearance grew as the engine got up to temp hence the setting to just have the pushrod turn when cold.
Now your all telling me this is wrong and I do respect your knowledge on here - well you live and learn, although I'm not 100% convinced as of now - more research needed  *computer*
Title: Re: 1952 Plunger Flash
Post by: MG on 06.01. 2011 14:53
The valve stems expand with temperature, so clearance can only become smaller (assuming that the barrels and push rods expand for about the same amount).

Anji, very nice bike, great work indeed.
Title: Re: 1952 Plunger Flash
Post by: chaterlea25 on 06.01. 2011 18:27
HI All,
My  ?0.02 worth
MG, the valves are only a couple if inches long and I would think that because of their smaller length compared to the cylinder / head and pushrods, the clearance increases when hot (I know the ex valve will be the hottest item in the engine!!)
My reasoning is backed up by observing that (as others have mentioned ) some engines are set with zero clearance cold
Also modern Harleys engines have allowances made for the expansion lengthways of the head and cylinder
Special "stretchy" head bolts are used, also hydraulic tappets to take up the bigger gap when hot!

Regards
John O R
Title: Re: 1952 Plunger Flash
Post by: beezalex on 06.01. 2011 18:44
Judging whether or not the clearance opens or closes when hot depends on the bike.  Comparing an iron head A10 with other models to justify a supposition about this is pointless.  The temperatures in the engine are not uniform, so you can't just draw conclusions based on that.  What DOES matter is measurement and conclusions.  The one data point I have is that at the extreme, the exhaust valve clearances close up on an Iron head A10.  When pushed hard (and I mean 100+ mph), my somewhat tuned motor would open up the exhaust clearances and fire into the pipes.  Larger exhaust clearances cured this.

Now, Anji, first of all, what a great looking bike.  And they are a joy to ride, aren't they?  About the noisy valve gear, some of this may be relative.  Be sure to check oil delivery to the top end and your clearances, but it is normal IME for the valve gear to get a bit noisier as the motor warms up.  This is because the oil gets much thinner.  Just how much noisier is hard to say, but all you can do is check and make sure everything is all right and then just go.

Cheers
Title: Re: 1952 Plunger Flash
Post by: muskrat on 06.01. 2011 19:21
G'day all,
            my experience with valve clearances on the cafe (alloy head ) was when pushed hard (always) and set at std specs, the ex valves would be propped open. Larger clearances cured this.
 The only zero clearance bikes I know of are ones with hydraulic lifters eg Hardly Drivable.
 Andy could be on the mark with a loose guide. There was a post not long ago with that being the final wash up.
 Time to get the old stethoscope out.
Cheers
Title: Re: 1952 Plunger Flash
Post by: a101960 on 06.01. 2011 19:47
I would tend to agree with A10Boy
Quote
If it only happens when the engine warms up it could be a loose valve guide. Tight when cold but when the head heats up and expands it goes loose and rattles around.
Anji, your description of this rattle is exactly the same as the symptom that I had, when I had a loose valve guide. If you remove the head the guide will appear to be nice and tight. Heat the head up and you will find a loose guide. You will also find evidence of oil burning on the piston crown.
(http://)
I spent quite a bit of time adjusting, and readjusting the tappets before removing the head and finding the problem. The tappet clearances were always correct, and there was no blue smoke visible at the exhaust. You have the classic loose guide indicator. Once the engine has warmed up the tappet noise becomes audible due to the guide being loose.

John
Title: Re: 1952 Plunger Flash
Post by: bsa-bill on 06.01. 2011 20:04
Well I've goggled my way through lots of pages and come to the conclusion that there is no definitive answer to whether tappets close or open, the best reasoning is as has already been stated here is cast head will close the gaps alloy heads will increase them, so to determine for sure measure cold, go for a run don asbestos gloves and check while hot -mmmm

However while in Goolge I found an article of interest, I've mailed elswhere
Title: Re: 1952 Plunger Flash
Post by: Stu55Flash on 06.01. 2011 20:43
Anjy

Nice job on the plunger it looks really good.

My top end sounds a bit louder when warm. I don't hear any rattles as such its just that you can hear the valve operation more. I just put this down to thiner oil and me being hyper sensitive over the engine sound. Due to the weather I've not run mine in yet and not quite convinced myself that something is still going to fall off. Hence many short journeys and lots of checking bolt tightness etc.  If you could put the bike on youtube with the full sound track we could compare and I'm sure others could comment from their experience.

Stu
Title: Re: 1952 Plunger Flash
Post by: anjimehra on 11.01. 2011 07:07
Anji... What a lovely looking restoration that is! congratulations... Now all you need to do is take a nice long ride to run it in and get us a photo of the bike just in front of the Taj Mahal. That would be super! Cheers. LJ.

Thanks LJ Planning on takingher to Ladakh this year along with my Super Rocket. If it does happen, will post photos of the trip
Anji
Title: Re: 1952 Plunger Flash
Post by: anjimehra on 11.01. 2011 07:17
Anji,

Good to hear from you again. Almost a guarantee that you would win Best Picture 2011 with the bike in front of the Taj Mahal, or one of the other exotic locations (from the viewpoint of the American midwest)  to which you tour. Yes, it is a fantistic looking bike, but what exactly did you not like about the pre-resoration version?

Regarding the valve noise, it occurs to me that if it were simply oil starvation, the noise would occur right at startup, having already been starved at the previous shutdown. It would be interesting and important to pinpoint the origin of the noise. Have you tried a noise probe between the engine and your ear? I use a long 3/8" ratchet extension with the male end closing my ear by pressing against the tab of cartilage that you would press if you were closing them with your fingers. The other end is then touched to vaious points on the engine. The ability to discern noise localization this way is amazing versus just pointing your nose in the general direction.

Richard L.

Hi Richard
Thanks for the compliment. The reason the Flash was in this condition pre rest is that my son thrashed the bike for 4 years, then set it on fire & left it out in the Mumbai monsoons for 15 years !!!! So, although we liked seeing her standing around  looking sad, we decided to do something & ended up with her looking kike this !!
I have tried using a screw driver as a stethoscope & pinpointed the sound at the rocker box.Shes very silent for the first 5 mts & then the noise starts. May strip down the rocker box again to check the rocker gap on spindle as both the spindle & rockers are old.
Anji
Title: Re: 1952 Plunger Flash
Post by: anjimehra on 11.01. 2011 07:20
Nice to see you on the forum, happy new yesr, and nice to see the bike, what a good work ! As mentioned, why not try taking a picture of the (great) bike in a great surrounding, and enter it into the best picture contest ?
e

Hi a10gf

Happy new year to you & your family too.Thanks for the appreciation.The bike is running thanks largely to the rocker shaft you so kindly provided. Planning on taking the Flash to Ladakh & if this happens will post some photos .
Anji
Title: Re: 1952 Plunger Flash
Post by: anjimehra on 11.01. 2011 07:23
G'day Anji,
              gee that's a great looking bike.
 I think you will find the tappet clearances close up when hot so don't go any smaller than what is recommended for your model.
 Might be a sticky exhaust valve that grows a little when hot, just enough to give a tappet noise.
 Just another thought.
Cheers

Hi Muskrat
Thanks for the appreciation. Was achieved with lots of help from the forum.
Am planning on dismantling the rocker box & will keep you posted on whats happening. Am reluctant to take the head off just yet
Anji
Title: Re: 1952 Plunger Flash
Post by: anjimehra on 11.01. 2011 07:26
If it only happens when the engine warms up it could be a loose valve guide. Tight when cold but when the head heats up and expands it goes loose and rattles around.

Beautiful resoration BTW, it looks lovely.



Thanks very much A10Boy.
Just wondering if a loose guide would start acting up just 5 mts after start up, especially on a cast Iron head ?
Title: Re: 1952 Plunger Flash
Post by: anjimehra on 11.01. 2011 07:27
The valve stems expand with temperature, so clearance can only become smaller (assuming that the barrels and push rods expand for about the same amount).

Anji, very nice bike, great work indeed.

Hi MG
Thanks for your appreciation
Anji
Title: Re: 1952 Plunger Flash
Post by: anjimehra on 11.01. 2011 07:34
Judging whether or not the clearance opens or closes when hot depends on the bike.  Comparing an iron head A10 with other models to justify a supposition about this is pointless.  The temperatures in the engine are not uniform, so you can't just draw conclusions based on that.  What DOES matter is measurement and conclusions.  The one data point I have is that at the extreme, the exhaust valve clearances close up on an Iron head A10.  When pushed hard (and I mean 100+ mph), my somewhat tuned motor would open up the exhaust clearances and fire into the pipes.  Larger exhaust clearances cured this.

Now, Anji, first of all, what a great looking bike.  And they are a joy to ride, aren't they?  About the noisy valve gear, some of this may be relative.  Be sure to check oil delivery to the top end and your clearances, but it is normal IME for the valve gear to get a bit noisier as the motor warms up.  This is because the oil gets much thinner.  Just how much noisier is hard to say, but all you can do is check and make sure everything is all right and then just go.

Cheers

Hi Alex
Thanks for your remarks on my Flash. And, yes, they are great fun to ride. The low revving engine with the low CR really makes the bike smooth even at high speeds. Will try & blow the oil galleries in the rocker shafts to clear them. I checked with the rocker covers off with motor running, but did find the oil flow minimal. Should the oil be flying around in the rocker box or should it be barely visible?
Anji
Title: Re: 1952 Plunger Flash
Post by: anjimehra on 11.01. 2011 07:37
I would tend to agree with A10Boy
Quote
If it only happens when the engine warms up it could be a loose valve guide. Tight when cold but when the head heats up and expands it goes loose and rattles around.
Anji, your description of this rattle is exactly the same as the symptom that I had, when I had a loose valve guide. If you remove the head the guide will appear to be nice and tight. Heat the head up and you will find a loose guide. You will also find evidence of oil burning on the piston crown.
(http://)
I spent quite a bit of time adjusting, and readjusting the tappets before removing the head and finding the problem. The tappet clearances were always correct, and there was no blue smoke visible at the exhaust. You have the classic loose guide indicator. Once the engine has warmed up the tappet noise becomes audible due to the guide being loose.

John


Thanks John. Going to check oil flow to the rockers over the weekend, before tackling the head.
Anji
Title: Re: 1952 Plunger Flash
Post by: anjimehra on 11.01. 2011 07:40
Anjy

Nice job on the plunger it looks really good.

My top end sounds a bit louder when warm. I don't hear any rattles as such its just that you can hear the valve operation more. I just put this down to thiner oil and me being hyper sensitive over the engine sound. Due to the weather I've not run mine in yet and not quite convinced myself that something is still going to fall off. Hence many short journeys and lots of checking bolt tightness etc.  If you could put the bike on youtube with the full sound track we could compare and I'm sure others could comment from their experience.

Stu

Hi Stu
Thanks for appreciating the Plunger. We enjoyed working on her as a huge challenge. You are right, its more valve operation than a rattle.Will look at it over the weekend
Anji
Title: Re: 1952 Plunger Flash
Post by: nigeldtr on 11.01. 2011 21:15
Hello,

I had something similar but it was down to a worn out timing side bearing. The oil pressure was fine when cold but dropped rapidly when warm.  I suspect the relief valve never opened and the cam and followers never got enough oil so everything wore out rather fast! Please ignore if you have rebuilt the bottom end.

Regards

Nigel