The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: agonda1 on 26.11. 2015 15:02

Title: valve setting procedure a10
Post by: agonda1 on 26.11. 2015 15:02
Not sure I have used the correct procedure for setting tappets.Right hand exhaust pipe glows RED !Used clearances of 0.010" and 0.016"with alternative pistons at TDC
Any ideas
Jim
Title: Re: valve setting procedure a10
Post by: Greybeard on 26.11. 2015 16:14
The valves are adjusted when the piston, (for those valves) is at top dead centre on the compression stroke; i.e. both valves fully closed; check by putting a finger in the plug hole as the piston is coming up to feel the compression. At the same time the other piston will be at TDC on the exhaust to inlet phase; i.e. the valves will rock as the piston is moved slightly back and forth.
Those clearances sound ok to me.

Overheating may be caused by ignition timing being too far advanced, (or do I mean retarded?) or a weak a fuel mixture, (possibly an air leak on the inlet manifold). What colour are the sparkies?
Title: Re: valve setting procedure a10
Post by: Topdad on 26.11. 2015 16:28
Jim, as per GB's post  but whats the compression like , how easily does it start and what is it like when running .I haven't seen an A10 with pipes as described so unless you get to the bottom of this I don't think it'll be long before it goes bang.   I 'd recheck everything ,timing , plugs to confirm mixture etc bob
Title: Re: valve setting procedure a10
Post by: Klaus on 26.11. 2015 17:15
For check valveclearence have a look at both inlet or exhaust valves. Turn engine till one valve is full pressed, for example exhaust, this is the time to check the opposite side.

Glowing one pipe may cause in a worn camring from the magnet. So one spark fired up the right timing  and the other one is too soon.


Cheers Klaus
Title: Re: valve setting procedure a10
Post by: agonda1 on 26.11. 2015 19:03
Checked everythig - v/v timing - ign. timing - comp good - tappets set correct - point gap correct ( plus mag re-conditioned ) carb set up correct
Observations :- plugs are always black / starts ok from cold but not always easy to start when warmed up ( after being left for 20 mins or so.)
Some time ago I fitted noise reduction baffles in ex. pipes ( could this be the problem ie restricted exhaust gases )
Bike seems to run ok once going and out on road
Problem has been going on for 2 years !
Title: Re: valve setting procedure a10
Post by: chaterlea25 on 26.11. 2015 19:52
Hi agonda1
The valve clearances depend on the year and model / + which cam is fitted

Klaus posted the correct proceedure,

Have you checked the timing on both cylinders?  Reconditioned mags need checking too  *sad2* *problem* *angry* *work*

What non standard exhausts are fitted?
Have you removed the baffles and tried the bike?

Either a very lean mixture on the rh cyl ?? doubtful by black plugs??
retarded timing on that side?
or unburned fuel igniting in the exhaust??
Air leak  due to loose valve guide ??
Is there any obstruction in the inlet tract?? gasket or drip tray??

HTH
John
Title: Re: valve setting procedure a10
Post by: morris on 26.11. 2015 19:54
The way I see it is that the exhaust valve isn't closing properly at speed which makes the flamefront blow out in the exhaust. (bent valve, sticky guide, not well lapped in?)
A good investment may be an infra-red thermometer. They are fairly cheap and can tell you much about the conditions in the combustion chambers by measuring the head and exhaust temperatures.
Title: Re: valve setting procedure a10
Post by: Greybeard on 26.11. 2015 19:56
valve clearances: Klaus posted the correct procedure,
Is my method considered incorrect?
Title: Re: valve setting procedure a10
Post by: muskrat on 26.11. 2015 20:14
"Is my method considered incorrect?" Not really Greybeard, it's good enough. But the way to get the follower over the cam at 180 to the lobe is as Klaus posted.
Cheers
Title: Re: valve setting procedure a10
Post by: chaterlea25 on 26.11. 2015 20:17
Hi GB,
The BSA instructions are in the books
When one valve is fully open the opposite is on the centre of the base circle
BSA cams have silencing ramps, the way to avoid them is as above,
that is why a large tappet clearance is specified when checking the valve timing

HTH
John
Title: Re: valve setting procedure a10
Post by: Greybeard on 26.11. 2015 22:48
When one valve is fully open the opposite is on the centre of the base circle

Eh? I happen to have a new soft tune camshaft here. Studying the layout and lining up a lobe peak with its adjacent cam surface, that cam is just about on the edge of its slope. Easy to get it wrong I'd say. The alternative; both lobes in the same section of arc, (i.e. exhaust/inlet phase) the other cam pair are entirely safe. Am I missing something?


Title: Re: valve setting procedure a10
Post by: chaterlea25 on 26.11. 2015 23:04
Hi GB
Quote
Am I missing something?

Yes ! (maybe)
Maybe I should have explained better,  for example

RH exh valve fully open (down) then  adjust LH exh tappet !!  rotate 360 degrees and do the opposite

John
Title: Re: valve setting procedure a10
Post by: duTch on 26.11. 2015 23:38
 
Quote
Quote

    Am I missing something?


Yes ! (maybe)
Maybe I should have explained better,  for example

RH exh valve fully open (down) then  adjust LH exh tappet !!  rotate 360 degrees and do the opposite

Quote
Studying the layout and lining up a lobe peak with its adjacent cam surface, that cam is just about on the edge of its slope. Easy to get it wrong I'd say.


 The only relevant 'adjacent lobes' are the two inner ones (Exhaust?), which oppose each other- the two outer ones (Inlets?) also oppose each other; I do it as Klaus says, and surprisingly it even works on the Gutzzi *eek*

Title: Re: valve setting procedure a10
Post by: Butch (cb) on 27.11. 2015 04:44
Some time ago I fitted noise reduction baffles in ex. pipes ...

Huh?
Title: Re: valve setting procedure a10
Post by: Greybeard on 27.11. 2015 09:32
Am I missing something?
Quote
The only relevant 'adjacent lobes' are the two inner ones (Exhaust?), which oppose each other- the two outer ones (Inlets?)

Duh, yeh, that's what I was missing!! Thanks duTch
Title: Re: valve setting procedure a10
Post by: Peter in Aus on 27.11. 2015 13:18
I agree with Klaus cant go wrong that way
Title: Re: valve setting procedure a10
Post by: Klaus on 27.11. 2015 13:59
Discussion about the right valve setting dont solve agonda 1 problem about his hot pipe *whistle*

He wrote that all has checked, but fit reduktion buffles.

I guess this will show a fault in ignition timing for one cylinder.
Most K2F have a diffent timing with 1 till 4 degrees by the camring, this will be in addition to the crank showing 2 till 8 degrees.
So it is strongly recommented to set the ignition by a strobe and check both cylinders.

As l build up my scrambler with a megacycle cam and open high level pipes form Armours, I also ordered the recomented silencers.
For testing in the garden I had fit only the pipes, and it was gread in power the engine runs phantastic, but horrible loud.
Than I fit the silences and it was all over with good running, the bike drive me crasy.

Than l odered taiwan silencers, straight through ones, a look a like silcencer with  a little rockwool inside......blow off in few seconds *eek*

I spend them a new blanket isulator and now a dream.
This special cam need the open pipe with reduce in diameter.


cheers Klaus