Author Topic: My smokey super rocket  (Read 815 times)

Offline RogerB

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My smokey super rocket
« on: 02.01. 2021 15:48 »
I'm in confusion over the A10 crankcase breather, which I think may need attention. and I'm hoping you guys can give me a steer. Here's the story .

The bike was fully restored between 2010-2011, has done just 3,000 miles since and I've done 2,000 of them. In the restoration it was rebored +20 and had new valves and guides. Toward the end of last summer I noticed it was smoking a bit from one cylinder. Thinking the only way oil would get into the cylinder to be burnt was either down through the valve guides (new!) or up through worrn/broken rings (new!), I took the top end down expecting to find a broken ring. The bores, pistons and rings are pristine. I haven't taken the valves out as my cheap spring compressor fell over and died and I really don't want to have to buy a new one just to see that these are as good as I'm sure they will be. I will if I must.
 
So I got to thinking about the breather. I have the work sheets from the restoration and an early entry is 'Breather blocked. Drill and clean up parts'. I've read ALPH!'s thread from 2019 and I'm thinking it looks as if I've got to delve about behind the timing covers, which was really not part of the winter maintenance plan!. But before I do, can anyone out there explain to me how the breather works? And, is the little ball mentioned in ALPH1's thread  an anti-wet-sump valve? I ask because the bike does wet-sump, the oil level in the tank does seem to drop while I'm riding (though I've always thought the oil-return looks good), and I was amazed at how much oil came out of the primary chain case when I took that off to sort the clutch this winter. I'm thinking that I may have a sticky little ball, a blocked breather, or both. But I have no real idea how to tackle either. Before I go into yet another session of blindly groping and hair-tearing-out, can/would anyone out there give me some clues, please?

And thanks.
Happily rolling along

Online chaterlea25

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Re: My smokey super rocket
« Reply #1 on: 02.01. 2021 19:30 »
Hi Roger,
So many variables to contend with?
Shine a torch down the inlet tract an look for oil on the smokey side
If guides are fitted carelessly the guide bore in the head can get scored or its not unknown for guides to come loose in the head

If you are losing oil into the primary case it could be the seal is bad, excess crankcase pressure or the bike being started with a lot of oil in the crankcase

To check the breather, ?
did you check that there was air puffing out the outlet, below the cam trough on the primary side when the engine was running ?
The breather is timed being driven from the camshaft gear by a peg. the top hat shaped breather sleeve is cross drilled so the breather outlet is opened every rotation of the crank as the pistons fall
To make the rotating valve airtight a cork washer is positioned between the cam gear and the rotating sleeve
This washer needs to be under compression to some degree to accomplish the sealing ( they come in a variety of thicknesses)
If you remove the outer timing cover the end of the breather sleeve can be seen, grip the end of the sleeve and try to rotate it back and forward as there is some slack on the driving peg. then try and move it inwards and outwards? it should not move in /out but should have some resistance when turned to and fro against the peg
I set them so that the sleeve is too tight to turn with fingers but easily with some pliers

While the timing cover is off, wash the oil from around the oil pump with some solvent and blow it dry
then watch for leakage between the pump components and also the the crankcase
Very often the wet sumping oil is coming from the pump more so than the ball valve in the crankcase

What brand are the pistons? A while ago the rings that were supplied with "wassel" or no name pistons were useless, (since rebranded Hepolite)
JP rings are also known for not "running in"

Enough for you to go on with for now

John

1961 Super Rocket
1963 RGS (ongoing)

Online KiwiGF

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Re: My smokey super rocket
« Reply #2 on: 02.01. 2021 20:38 »
Hi Roger, a cheap DIY spring compressor can be made from a short piece of pipe of roughly the spring diameter and a cheap wood clamp, you need to angle grind a “window” out of each side side of the pipe to be able to flick the collets out.

The spring pressure is not high, just remember to tap the collar to unstick it when you get a little pressure on it, otherwise you may bend the clamp.

Many std spring compressors do not fit bike cylinder heads, which is why I “bodge” my own.
New Zealand

1956 A10 Golden Flash (1st finished project)
1949 B31 rigid “400cc” (2nd finished project)
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Offline Peter in Aus

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Re: My smokey super rocket
« Reply #3 on: 03.01. 2021 00:04 »
Hi Roger and  *welcome*
Do you drain the sump before starting as it seems you don't do much riding, I have to drain my sump if I left it longer than one week without riding it, the way you are talking it sounds as if it is wet sumping.
Peter

Busselton West Australia
49 A7 longstroke
58 A10  SA

Offline RogerB

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Re: My smokey super rocket
« Reply #4 on: 03.01. 2021 10:10 »
Many thanks for your thoughts guys. Looks like I have to bite the bullet and get the timing cover off. Maybe I'll do that later today. Since I'm kind of learning on the job - or, more accurately, teaching myself on the job - it all gets very scary. Couple of answers for you:
I have no idea what brand the pistons/rings are. I'd be surprised if the guides are poorly fitted because of who the restorer was - but I'll keep an open mind.
I have looked down the exhaust opening and the valve looks fine - but with it in place and closed that's only a superficial look.  And thanks for the picture KiwiGF - I had seen a suggestion that it can be done with a G-clamp, but didn't want to risk it. Maybe I will now!
Like I say, it does wet-sump. I had reconciled myself to simply draining the sump after any long period of inactivity! Sure, it hasn't had a lot of riding, partly because of mechanical issues (like the carb top detaching very scarily a few times - now replaced with new carb) and partly because I've been focussed on my two Velocettes, both of which have had many issues but both now sorted and clocking up some miles. Time now to focus on the SR.
My main reason for taking the top down was because I thought it was clattering a bit and down on power - so I thought I'd look at the smoke at the same time. Oh what cans of worms these machines can turn into! Good job I love them!
All this will not be quick - especially as I will have to order and wait for delivery of items such as the timing gasket - but when I have progress I'll report back.
Many thanks.

Happily rolling along

Offline Swarfcut

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Re: My smokey super rocket
« Reply #5 on: 04.01. 2021 12:18 »
 I'm wondering why the tank oil level drops while riding. It is either accumulating in the sump (and thence to the primary case) or simply being burnt and giving the smoke.

 My first thought would be to make sure the pump is scavenging as it should, and there is no restriction in the return to the tank and no easier return exists to the sump via the rocker feeds. This latter less restricted path means more oil in the sump, rather than the tank and the resultant smoke. More oil will return to the engine, rather than being returned to the tank, hence a possible explanation for the drop in level in the tank. This is well reported in previous posts on the Forum.

  Testing the scavenge side is an entire subject in its own right, witchcraft, magic or some secret dark art according to how you approach it. It is a simple system, but known to defeat the hardiest soul.  The ball valve on the pick up pipe needs to be free, and unable to restrict return flow. 

 The other ball valve is on the feed side and is designed to prevent flow gravity from the tank to the sump via the pump and bearings while the bike is standing. They all wet sump to a degree, but daily use back in the day meant this was hardly an inconvenience. Not so now where the tank will empty quite happily in a short time in bad cases.  As a start, the sump needs to be drained and the smoke on start up observed, and if the oil level drops drained again to see if oil is accumulating when the smoking starts. This would indicate the problem is in the scavenge side,  (rather than bores/pistons/guides) and an imbalance in supply and return.

 The breather runs  internally across the back of the engine to exit just above the gearbox sprocket. To physically clean the  cross drilling will require the inner timing cover to be removed. but an airflow test to detect a blockage can be done by lining up a hole in the breather sleeve with the corresponding hole in the inner timing cover (it's about the 2 o'clock position) and applying air or a paraffin gun to the  face of the breather sleeve. A free flow will exit onto the sprocket.

 Swarfy.

Online RDfella

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Re: My smokey super rocket
« Reply #6 on: 04.01. 2021 16:35 »
Quick rough & ready way to check valve guide condition is to get someone to follow you and note if there's any blue smoke on the overrun - preferably for several seconds downhill with throttle closed.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Offline RogerB

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Re: My smokey super rocket
« Reply #7 on: 04.01. 2021 23:26 »
Many thanks Swarfcut - clear and helpful.

As for the scavenging - I’ll have to plan to examine that later, when the engine is rebuilt and running. All I know so far is that at the start of every day’s riding I take off the oil cap and check that oil is returning. I have no idea whether the amount is as it should be - but it ran with no smoke for over 1,000 miles. And the smoke I was investigating isn’t nearly enough to suggest the engine is burning very much. But I’ll keep it top of mind because the more I read and the more other things seem OK, the more likely it seems that this might be the issue.

But here’s a question for you: You say the ball valve on the pick-up side needs to be free. Is the is the one on the scavenge pipe from the sump? Because if it is, then I can’t get at it to check it. I have taken the sump off and cleaned the gauze filter (it didn’t need it). I can see the end of the pipe inside the sump, but I can’t reach it. I had been expecting this to come out attached to the sump - or is it held by the other end being plugged in somewhere inside?

Today I’ve taken off the timing cover, so now I’ve seen how the breather timing works. The breather gasket was rather second-hand and there was one thirty-second of end float. Also, the oilway was somewhat compromised by a blob of instant gasket which had about half-blocked it. Oil/air would have got past, but not as easily as it should. I’ve cleaned that and blown air through the crankcase and it seems fine.

I’ll be cleaning off the pump and checking it as Chaterlea25 suggests and I’ve removed and cleaned out the anti-wet-sumping valve.

And I took one of the exhaust valves off - to my inexperienced eye it looks fine : the seat is good, the valve is straight and moves freely. There is just the absolute tiniest bit of play between the valve stem and the guide. Tomorrow I’ll compare it to the other one.

Frustratingly, I haven’t actually identified anything that is clearly a problem, but it’s getting to the stage where I’ll just have to rebuild it and see if anything has changed. I'll replace the breather gasket and I guess I might as well put in new rings, as I’ve got it apart, on a  ‘just in case’ basis.

Thanks to everyone for their feedback it’s been a help and a confidence booster.
Happily rolling along

Online berger

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Re: My smokey super rocket
« Reply #8 on: 04.01. 2021 23:41 »
roger the scavenge pipe should sit below the filter in the sump plate and is easily seen but the breather cork and obstruction sounds promising there shouldn't be any slop when the cork is fitted, it should be slightly compressed

Offline Slymo

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Re: My smokey super rocket
« Reply #9 on: 05.01. 2021 07:00 »
I might be tempted to check the seating of the oil pump. When I first put my SR together it made big smoke out of the righthand muffler. Turned out that there was a large amount of oil weeping out the back of the pump which in typical mazac style had gone out of shape. It meant there was a lot of oil in the timing cover which I sorted by resurfacing the pump on glass and emery paper. Been good since. If there is a poor fit that might explain poor scavenging too.
NZ

Offline Swarfcut

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Re: My smokey super rocket
« Reply #10 on: 05.01. 2021 09:40 »
 A little more about the two ball valves.

      As bergs says, the scavenge pipe non return valve should be in view, pointing downwards, when the sump plate is removed. It extends below the face of the crankcase, and as such is often bent upwards when cases are stored without the sump plate to protect the pipe and valve. If it's not there, there is something seriously amiss. A correctly operating valve consists of a cylindrical housing for a loose ball bearing which can be pushed up and move freely upwards to allow oil flow back to the scavenge side of the pump, yet not obstruct the flow when fully open, and drop down and seal when the engine is not running.  Without the pipe, which runs almost horizontally into a drilling in the crankcase on a Swinging Arm engine, the scavenge will work to a degree, but with a higher sump oil level, and if I understand correctly this could be an explanation. The valve should be easy to identify and prominent with the sump plate off.  Earlier Plunger engines are slightly different in pipe design, but the principle is the same.

 The other valve, the so called " anti wet sumping valve"  is a spring loaded ball in the oilway from the output port of the pump to the timing bush.  This is only accessible for cleaning or replacement from inside the crankcase, and the blanking plug behind the spring and ball can only be reached by splitting the cases.  The operation of the valve can be crudely checked with a matchstick down the oilway, pushing the ball and feeling it return under spring pressure. A loose or missing blanking plug means poor oil pressure (loose and leaky) or no oil pressure (missing) and the oil tank contents pumped directly into the sump.

 To endorse Slymo's excellent and often overlooked observation, the pump to crankcase mating face has to be well oiltight, as it experiences both pressure and vacuum in very close proximity. Leakage means a tendency to wet sump when standing and low oil pressure at the bearings when running, and a lack of suction on the scavenge side as air rather than oil can be drawn up.

  Pump gaskets are notoriously variable in accuracy of manufacture and quality of material. Whatever you have, try it in different positions to get  the best match of oil holes and gasket holes.

 From experience, oil return on start up, at tickover, is a strong continuous stream into the tank as the oilpump scavenges oil from the sump. This lessens to gulps of oil and air, still on tickover, as the scavenge successfully drains the sump. Under power, the return oil stream is strong and continuous.

 Swarfy

Offline RogerB

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Re: My smokey super rocket
« Reply #11 on: 05.01. 2021 11:41 »
I'm feeling a bit humble, because this morning before I went on line I read my Haynes manual a bit more thoroughly- and there was the scavenge pipe in one of the pictures. I just looked at mine and it sits as it should: I think I may be able get a line on it and blow through to check it's clear. So, I need to order some gaskets  and while I wait for them attention turns to the oil pump (gasket to be ordered!). This has turned into quite a job, given that when I started I expected just to lift the barrels and replace a broken ring! And I haven't even mentioned the issue with studs in the rocker cover which need re-setting!
There will follow a long silence while I wait for parts and re-assemble. I'll add a post when I can report progress.
Many thanks again.
Roger
Happily rolling along

Online JulianS

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Re: My smokey super rocket
« Reply #12 on: 05.01. 2021 11:57 »
I would use an SRM gasket, the best on the market at the moment.

The photo shows SRM on left, BSA NOS top right and nasty cheap pattern item with oil holes too small and stud holes too large bottom right. This last one  only fit for the bin.

Offline Swarfcut

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Re: My smokey super rocket
« Reply #13 on: 05.01. 2021 12:50 »
      Well that puts my hopes of an easy fix (bits missing) in the trash.  If the pump is coming off, check the tightness of the thro' bolts, and give it a good looky look for cracks, swelling, flaking if it is an original pot metal body. It should be free to turn with firm finger or thumb pressure on the drive spindle. If a tacho type, avoid turning by the tangs, they break off easily.  Dismantling is easy, reassembly a bit more difficult to get right, keep the gears meshed as found and twisting the three parts checking to avoid binding as you tighten the bolts, so from experience leave well alone if it turns OK.

 The original design uses a small fibre washer on the single front stud to match the thickness of the gasket. Without it the pump will bind when tightened down. Using  the one piece gasket as in Julian's picture will require it to be cut centrally to shorten. That gasket is from the later A65 engine, which has a longer pump and also has the anti wet sump valve redesigned to be serviced without major dismantling. You can see the larger hole in the gasket to clear the ball, which now seats against the back of the pump on the A50/65/75

 Original threads into alloy are Whitworth, rocker studs are 1/4 BSW to the rockerbox, Cycle Thread at the other end for the nuts. Same threads as on oilpump studs.

 Swarfy.

Online JulianS

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Re: My smokey super rocket
« Reply #14 on: 05.01. 2021 14:18 »
No it is not an A65 gasket it is SRM A10 item, large hole allows it to be used with the both the standard set up and the modified oil feed on the end feed A10 and avoids the use of a fibre washer, which are seldom the same thickness as the gasket material.

The upper gasket in the photo is SRM A10 to compare with A65 gasket below which is the longer.