Author Topic: What goes in this hole then?  (Read 18015 times)

Offline Mosin

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What goes in this hole then?
« on: 09.08. 2009 21:27 »
I was out for a lovely ride on the A7SS this afternoon and all seemed to be going very well. A bit too well as it happens...

After about 45 miles I started to ascend a very steep incline (Hartside in Cumbria for those of you who know it) As I was going up with the engine working hard and running a bit hot, I noticed the power seeming to fail. It almost felt like dirty petrol or the points not being set quite right. I ended up in first gear really revving the engine hard just to prevent it from stalling. Then all of a sudden it cleared and I made it up to the cafe at the top. My friend who had been following me said that as I had been struggling he had noticed a bit of blue smoke coming out of the left hand tail pipe, but this had cleared when the power returned.

We had our cup of tea and toasted sandwitch and I decided to check the plugs and points before continuing. All seemes fine and the A7SS fired up first kick and off we went. After about 20 more miles exactly the same thing happened again, but this time I could not make any power in any gear and we were forced to stop at a very nice pub. I noticed that once again the bike appeared hot and seemed to be leaking a bit of oil from what looked like the rocker cover gasket, but this stopped as she cooled down and off we went again, this time on a big main road where I was able to maintain a constant speed which seemed to keep the engine cool and she performed faultlessly for a further 15 or so miles with no visible sign of any oil leaking at all. Unfortunately, I had to slow down to go through Carlisle and as I left the city the problems returned. This time much worse with no power and oil gushing out all around the rocker cover and possibly also the cylinder head. At this point I phoned the RAC and got recovered home.

This evening I cleaned things up as best I could and pulled the tank off to see if I could see where the leak was coming from. It was then that I discovered this hole (picture) in the top of the rocker box. It is about an inch across and threaded on the inside. Looking in Haynes, there is no mention of it or what should be filling it. So, if anyone can help me, I Could do with knowing:
  • What should go in here?
  • Would loosing it have caused the problems which I have experienced?
  • Why would these problems seem to dissapear when the engine was running cooler?
  • Is loosing it likely to have caused any other problems with valves/cams ect?
  • Am I barking up the wrong tree entirely and should I be looking at something else altogether?

The engine still seems to have good compression, and all the oil seems to have come from the region of the rocker box, but I have never experienced a failure such as this to result in such a drastic lack of power before. Any help anyone can give me would be most welcome.

Simon
1960 A7 Shooting Star
1959 D3 Bantam
1994 Triumph Trident 900

North West England

Offline a10gf

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Re: What goes in this hole then?
« Reply #1 on: 09.08. 2009 21:47 »
Some previous owner made his own breather system ? By itself this cannot have any influence on engine power afaik, but you'll get some oil spraying out. I suppose you still have enough oil left in the tank, or did it run low, and thus got engine overheating ? But low oil cannot explain this:
Quote
Then all of a sudden it cleared and I made it up to the cafe
unless it was close to seizing.

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Offline rocket man

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Re: What goes in this hole then?
« Reply #2 on: 09.08. 2009 22:46 »
that doesint look good youd be best off removing the rocker box  id get another
one you could always put a breather on the rear rocker box inspection cover
thats the best place for one but that hole shouldent be there

Offline trevinoz

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Re: What goes in this hole then?
« Reply #3 on: 09.08. 2009 23:03 »
It looks like someone has modified the rocker box to be similar to the Ariel Huntmaster which has a threaded plug in the top to aid the fitting of the pushrods when fitting the rocker box.
Trev.

Offline alanp

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Re: What goes in this hole then?
« Reply #4 on: 10.08. 2009 08:53 »
Ummm, is it possible that whatever was in the hole fell inside and jammed a valve or rocker temporarily? I'd take the rocker cover off to check.
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Offline LJ.

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Re: What goes in this hole then?
« Reply #5 on: 10.08. 2009 09:06 »
Quote
Ummm, is it possible that whatever was in the hole fell inside and jammed a valve or rocker temporarily? I'd take the rocker cover off to check.

Good idea Alan, I think I'd also want to take off the rocker box cover, chuck it away too and fit one with no modifications. If your engine is correctly fettled then you should not need any sort of breather up there. Neither of my A10s have any top end breathers and both run fine.

Sort that top end, fill up with plenty of oil and do the route again and lets see how she performs again. Then we can sort out the other problems if they reoccur.

Give us a shout if your stuck for a cover I may be able to help.
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Offline cus

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Re: What goes in this hole then?
« Reply #6 on: 10.08. 2009 11:00 »
Mosin,
I agree with the others about that hole, but that power lose going up the hill (under load) sounds to me like
the engine nipping up, (partial seizing), if you are loading up the bike fully advanced, try retarding it a bit &
see if it improves, thats if you have a manual R/A lever, otherwise you might want to check the timing etc.
I had a similar problem on a bike with a Boyer & a wiring short, it would alter the timing, when the bike cools
down the piston frees up.

regards, Cus
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Online RichardL

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Re: What goes in this hole then?
« Reply #7 on: 10.08. 2009 14:11 »
Well, rocker-covers don't, now, seem to be scarce, but someday they will be. I don't like the idea of discarding still-useful and no-longer-made parts. The hole is evidently threaded, if original appearance is not an issue, why not plug it with a nicely fit and decent appearing threaded plug and move on? One could also use it as the breather port if one chose to do so. Otherwise put it on eBay to see if someone can get use out of it. Even if it ends up on a rat rod it's better than the scrap pile.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Offline a10gf

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Re: What goes in this hole then?
« Reply #8 on: 10.08. 2009 14:30 »
Richard wrote:
Quote
why not plug it with a nicely fit and decent appearing threaded plug
Yes, make something nice and rounded, then polish it all.

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Offline LJ.

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Re: What goes in this hole then?
« Reply #9 on: 10.08. 2009 15:21 »
With hindsight to what your saying Richard, I think your correct! The hole is threaded as you do say, I'm wondering if the thread is the same as the clutch spring adjusting hole on the primary chain case in which fitting the appropriate plug would still serve as the push rod fiddling hole, if that is what the hole was put there for in the first place.
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Offline rocket man

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Re: What goes in this hole then?
« Reply #10 on: 10.08. 2009 20:59 »
you could make it into an ashtray if you do deside to plug the hole up
make sure its well sealed id be worried about it vibrating lose again
get another one then its one less hole to worry about there are plenty about at the moment
try ebay

Online RichardL

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Re: What goes in this hole then?
« Reply #11 on: 10.08. 2009 21:08 »
Not to get religious, or nothin', but that's why God made Loctite.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Offline Mosin

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Re: What goes in this hole then?
« Reply #12 on: 10.08. 2009 21:32 »
Not to get religious, or nothin', but that's why God made Loctite.

Hmm, maybe that's where I have been going wrong then. My Loctite is made by a company called "Henkel". Just my luck, God obviously invented the stuff, but despite his divine wisdom, lacked the sense to patent his design and I end up with some cheap copy...


Anyway, to get back to the subject of my hole. I have found and purchased a new 'unholy' rocker cover on ebay and also bought some oil and a new set of gaskets, so as soon as they arrive I will get them fitted and see where I go from there. This evening I have removed the old 'holy' cover in readiness. I also took the liberty of removing the sump plug and on doing so, the entire tank of oil poured straight out of the sump. The anti-wet sump valve had previously been working fine, but it would appear not to be working at all now. Could this in some way have contributed to my woes?

Thanks for all your help so far guys. I was feeling really down about the hole thing yesterday, but your collective wisdom and support has left me feeling a bit more upbeat about it today. One day this hole thing will be just a bad memory...



Simon
1960 A7 Shooting Star
1959 D3 Bantam
1994 Triumph Trident 900

North West England

Offline a10gf

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Re: What goes in this hole then?
« Reply #13 on: 10.08. 2009 21:36 »
Heads up, quite often "Problems are sources of knowledge".

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Offline LJ.

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Re: What goes in this hole then?
« Reply #14 on: 10.08. 2009 21:40 »
Chin up Simon, its not all bad, you only have to fit it now! Do you have the special comb? can be done without... just.

Do make sure the tappets are undone so they are completely loose, dont make the mistake of tightening the cover down against the springs as your likely to damage the corner studs. There is a lot of spring pressure there. Give us a shout if your unsure of anything.

Good luck! You'll be riding in no time.  *smile*
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red