Author Topic: smoking super rocket  (Read 6363 times)

Offline duTch

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Re: smoking super rocket
« Reply #30 on: 30.06. 2012 16:37 »
I'm trying real hard to not be side-tracked from topic, but at least this one's Mikes'.. Maybe I didn't do history to have a chance of a mark??
  Julian- I've reluctantly started looking at the instructions of things..But the writings gotten too small to read!!

And we still haven't got Mikes smoke issue sorted, and only have 9 days minus 2 to sort it....=7  (scraped through maths)
 Cheers fer now
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Offline mfhutchins

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Re: smoking super rocket
« Reply #31 on: 01.07. 2012 19:22 »
ok so i just started to look at things before i pull the head.  since i dint really know what to look for, i wanted to post a picture of what it looked like when i pulled off the left header pipe.
there was some oil on the valve stem.  normal?  there is a grey powdery coating on the guide.  normal?  also there was uncombusted fuel in the header pipe hole. normal?

any advice as i continue to remove the rocker box assembly?

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Re: smoking super rocket
« Reply #32 on: 01.07. 2012 20:49 »
 G'day Mike,
                that looks pretty much normal. I would think if it was a guide/valve problem it would be inlet, allowing oil into the comp chamber.
Did it smoke like Lorenzo's bike  *eek* ?
Hay BobH, I only said to the wife the other day that when I ride I feel like a 21 year old. She said I'm lucky to have the +50 year old I've got. *smile*
Cheers
               
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Offline mfhutchins

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Re: smoking super rocket
« Reply #33 on: 01.07. 2012 20:59 »
ok, inspection covers off and noticed that there is zero tappet clearance on the left side.  i must not have screwed that nut in tight enough.  maybe i messed up the valve adjustment.  its only my second time doing one.
i will keep dismantling, but could this cause the smoking ie. allowing valve to not close sufficiently?
there is clearance on the other side but i have not put a feeler gauge to it yet.

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Re: smoking super rocket
« Reply #34 on: 01.07. 2012 21:22 »
 Doubt that would cause the smoke. Would not take long to burn a valve and run like poo. Keep diggin'.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Online Clive54bsa

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Re: smoking super rocket
« Reply #35 on: 02.07. 2012 01:37 »
I feel your pain mfhutchins, When I got my '61 Super Rocket I sent the motor to SRM for numerous improvements and after assembling the bike very carefully, after 500 miles I noticed a knock in the top end, turned out to be a spun little end bearing, done by SRM, they fixed the rod after I removed it and sent it to them, after reassembly one again the performance went bad after another 500 miles, turned out to be SRM's 357 cam had worn flat, "we had a bad batch, send it back to us and we'll replace it"....another dissassembly and reassembly. After 11,000 miles SRM's special timing side conversion bearing went bad, I sent it back well out of warranty with a curt note saying I had expected this bearing to last longer than 11 K, and they sent me a new bearing, and yes one more dissassemble and reassemble. All this wouldn't be too bad if I lived in Aberystwyth Wales, I live in California USA. All that being said I have gotten quite adept at tearing down and reassembling A10 motors.
Bottom line is you probably should start by compression testing, then removing the rockerbox, make sure there are no broken valve springs etc, if all looks good then remove the head and finally the barrels, you could do it in an afternoon, and in my opinion it's worth it for the peace of mind. I know full well the P'd off feeling you have, have a pint, put on your favourite tunes and go for it.
Good luck mate
Clive


'54 GF,  '61 SR,  '71 B50MX

Offline mfhutchins

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Re: smoking super rocket
« Reply #36 on: 02.07. 2012 15:31 »
found: bent exhaust pushrod & fine, hairlike metal stuck to left valve spring.

still digging...

Offline Topdad

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Re: smoking super rocket
« Reply #37 on: 02.07. 2012 17:04 »
Hi mfhutchins, so zero, tappet clearance ,coupled to bent pushrod on the same valve , doe's that valve move at all ?  I had a similar experience when I'd just rebuilt mine despite completely renewing everything via SRM including the sludge trap and throughly cleaning system some debris managed to find it's way to the rockerbox and blocked the oil feed ,when I stripped the valve it had kissed the piston no visible sign of damage  until I pulled it out very tight but only really visible when place on a flat surface with the old valve  next to it ,it was well bent so thats what's my money's on, whizz the head off and check everything but start with that valve .Best wishes BobH, ... Musky ,from the sounds of things your wife and mine would get on ,thank god you're in Oz I'd hate 'em to compare notes , cheers bob. 
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Offline mfhutchins

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Re: smoking super rocket
« Reply #38 on: 02.07. 2012 21:22 »
ok, so the piston rings look fine. 

since i dont have a valve spring compressor, how am i supposed to check the valves/guides?  i did the simple test where you pour fuel into ports and watch for leaking through the valves and there was none.
in fact, everything ive taken apart so far looks fine except for the bent pushrod and the mystery fine metal shavings.

one final thing i can think to do is check the ring end gap.  any good methods for doing this?

could the smoke have been caused by just the bent pushrod and zero valve clearance?

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Re: smoking super rocket
« Reply #39 on: 02.07. 2012 22:04 »
G'day Mike,
               The only way to check the valves is to remove them. A spark plug socket over the keeper and a sharp blow with a knockometer usually dislodges the collets. You will need a vs compressor to assemble. A quick lap with fine grinding paste will tell if it's bent. Should end up with a nice even 1-2mm mark on the valve and seat. Check the top of the guide and underside of the keeper for evidence of contact.
 Look for marks in the bores. If any the barrels off and rings off. Keep them in order. 10 -012thou gap.
Sorry for being short, off to work.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
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Online beezermacc

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Re: smoking super rocket
« Reply #40 on: 02.07. 2012 22:08 »
Bent push rod..... sounds like this was not properly fitted into the rocker cup as the rocker cover was mounted onto the head. Use the special BSA comb upon reassembly or be very careful that everything is sitting properly. Shine a torch in the tappet covers when everything is assembled as you turn the engine over and make sure the tappet cups and push rod tips are properly fitted. Check all the tappet clearances a couple of times during two or three rotations of the engine. Set the tappets by the 'one down - one up' method; i.e when one exhaust tappet is down, the other is up; same for inlets. If your rings are new I wouldn't worry too much about the end gap, people measure the end gap to give an indication of wear. I've seen engines run perfectly well with large end gaps, in excess of 0.025". If you really want to check you'll have to remove a ring and put it square in the bore using a piston to push it down. In old bores you would check the end gap at various positions down the bore to measure bore wear rather than ring wear.

Look very carefully for shadows in the bore i.e areas where the rings are not making contact with the bore surface. This would indicate poorly bored cylinders but should also show up on a compression test.

Valve guide wear.... buy a spring compressor! There's no way round it and now you have the head off it would be daft not to check this before reassembly. Also, as stated in Topdad's post you need to be sure that all the valves slide freely in their guides. At this stage it would be wise to check all the oilways are clear by blowing through the rocker feed pipe.
Just seen that others are posting at the same time, sorry if i've repeated anything.
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Offline mfhutchins

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Re: smoking super rocket
« Reply #41 on: 02.07. 2012 23:26 »
a friend of mine has a valve spring compressor that i will be borrowing tomorrow.
i definitely did not use that method to set tappet clearances.  i will going forward.
should i bother with the ring end gap?  my thought is that one or more rings may be too long??? how likely is that?
no shadows in the bore.
should i throw the valves/guides in the oven to check for free movement when hot? i am assuming when i check them cold they will move freely.

if the valves are fine tomorrow, am i to assume that i should reassemble the engine and hope that (1.) a ring doesnt break this time around (2.) i need to ride the bike with the 30 weight oil and let the rings bed into the cylinders and see if that alleviates the smoke issue?  ...or was the zero valve clearance/bend rod the issue?

Offline duTch

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Re: smoking super rocket
« Reply #42 on: 03.07. 2012 09:00 »
Hiya Mike,
            You're doing well, there's a lot of info there, 'zero gap' in my mind means half way between 1thou gap, and 1 thou over tight, and if it was more than that for some reason like the push rod has been misplaced, maybe there's a chance that the 'spring collar' is pounding into the top of the guide? That'd maybe produce swarf like that, and a bent rod??
    Your own spring compressor is a good investment, and don't lend it, I did and it ain't the same.

  Cheers for now, one thought at atime, and do as the others suggest
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

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Re: smoking super rocket
« Reply #43 on: 03.07. 2012 10:39 »
G'day Mike,
               do I read right in that the barrels are off?  "(1.) a ring doesnt break this time around" Check the gaps. As Beezermacc said a large gap will still work but no gap won't.
 If the valves slide good cold they will hot as the head & guide expand more than the valve stem. Were there any marks on the top of the valve guide? When they are loose they ride up and get clouted by the underside of the keeper. To check if any are loose (they won't feel loose cold) place head in oven (wait till wife is out) *smile* at 100c for 1/2 hour. Place upside down on blocks and give the guides a light tap with a timber dowel/file handle/curtain rod and mallet. If it moves replace it with a 1 thou oversize guide. At 250c they will almost fall out. If you need to replace one the valve seat will need to be cut and naturally all valves lapped in.
 You'll be an expert in no time.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline mfhutchins

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Re: smoking super rocket
« Reply #44 on: 03.07. 2012 16:12 »
ok.  now that ive removed the valves from the guides, how much excess play should there be?