Author Topic: Super Rocket valve timing (etc)  (Read 2594 times)

Offline Lord Flashheart

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Super Rocket valve timing (etc)
« on: 06.09. 2013 22:22 »
Hi all,  Apologies in advance for this potentially  rambling post, - quite a lot to cram in.
My 'mixed bag' '59 Flash with A10SR engine (DA10R.163 - HC) is still giving me grief.  'Sparks' now sorted thanks to Boyer B replacing dead twin coil.
To recap, bike now has;- *SRM ignition conversion (using some BB bits).        *Dyn. belt drive & DVR2.        *SRM Oil pump.

I've reset/checked ignition timing and tappets. (can anyone improve on the hit & miss 'red dot-through hole' guesswork (pre-strobing) ?

With all set correctly, the engine only wants to spit back (every 2nd /3rd kick.)    When looking at valve timing figures it occurs to me this may be the 'wasted spark'
igniting a 'wet' cylinder while the inlet is opening.    ( nonsense ?)
The valve timing issue caused me to wonder if there may be a 'dot misalignment', but not wishing to rush into stripping the 'chest', thought i'd check timing angles since tappet covers and primary were off I refitted the timing disc and got to measuring opening / closing points.
Results initially surprised me (comparing to Haynes R.R.figs.(SR not listed) ). All valves open earlier and close later, but also vary LHS to RHS. as follows;-
*In.O 75 BTDC.LHS, 67 RHS.  *In.C 87 ABDC LHS, 105 RHS.     *Ex.O 77 BBDC. LHS, 72 RHS.    *Ex.C 52 ATDC.LHS,  55 RHS.
There is a 'click' from the valves as they make/break there seats.   Compression testing indicated 120/130 psi. with no added oil.

Q's arising are;-  1, Is excessive wear indicated ?    2, Is a 357 cam indicated ?   3, Is 35 deg. ignition appropriate ?     4. What comp.ratio would be expected in DA10R 163 (assuming home mkt.)      4, Is any of the above independently or in combination  going to make for difficult starting.  5. What is the common reason for spit-back?

The bike is a recent purchase, not run for years,but was hoping to get some 'running' in before embarking 'blind' on any rebuild work.
Phew !
Happy head scratching guys
Pete      
Flash'

Live for today, but don't regret it tomorrow !

'59 G.Flash-S.Rocket Motor; '88 Honda Hawk 650 (Project); BMW1100RT; '04 HondaVFR800.

Offline bikerboy

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Re: Super Rocket valve timing (etc)
« Reply #1 on: 07.09. 2013 00:33 »
For the 20 minutes it takes I would check the valve timing I think it lines up once every 96 turns or something  ;)

I don't like the "click" when the valves open are you sure they are not clipping the top of the piston ?

Online bsa-bill

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Re: Super Rocket valve timing (etc)
« Reply #2 on: 07.09. 2013 11:34 »
Biker boy makes a good point re valves clipping pistons, I've had this due to a sticking valve, bit of work involved but worth having the head off you will see a mark if the valve is touching a piston.
and while the head is off you can check/retime the valves, just take of the timing covers and pull the idler pinion off and line up the dots as you have said.
I'm not familiar with the SRM ignition but Pazon (offshoot of Boyer I believe) have two holes in the circuit board for lining up the red dot you need to make sure you are using the correct hole.
the two holes are one for clockwise driven system and the other for anti clock wise, from memory I think the rotation is the rotation looking from the circuit board end not the magneto drive end as we are used to.
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Lord Flashheart

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Re: Super Rocket valve timing (etc)
« Reply #3 on: 07.09. 2013 19:49 »
Thanks for your replies bikerboy and bsa Bill , If I can expand a little on the 'clicking' you may conclude that it can't be piston contact ( But I can always be wrong. - and and often am :-) )
The 'click' occurs on all four valves at the very instant that the valve is making contact with the seat. I am turning the engine via the rear wheel,in minute increments, and as the load is transferred off the rocker and the spring pulls the valve onto its seat, that is the moment of the click, when all else is vertualy static.My own feeling was that it might be worn guides allowing the valve head to 'float' a little.   But for all I know it may be quite normal.
As for piston contact, at the time valves move to/from thier seats, the piston by my estimation should be some 10-12 mm off TDC.   Were the click occurring AT TDC when both valves are open I would be in full agreement. ( Unless I have 4 very sticky valves - which does not ring true.)

I'm beginning to think my path of run- evaluate- THEN strip may need to be re-thought.
Happy Days !
Pete

A second thought just occurred, anyone ever known of movement at the collets ?
Flash'

Live for today, but don't regret it tomorrow !

'59 G.Flash-S.Rocket Motor; '88 Honda Hawk 650 (Project); BMW1100RT; '04 HondaVFR800.

Offline chaterlea25

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Re: Super Rocket valve timing (etc)
« Reply #4 on: 07.09. 2013 20:29 »
Hi,
A quick check on the valve timing can be done by  watching the exhaust valve as it closes and the inlet opening on one cylinder while the other is at top of the compression stroke
the inlet should open a little before top dead centre and the exhaust should close a little after tdc
This is the valve overlap period,
The anomalies you measured on the valve timing opening closing can usually be traced to a little  wear on the cam or follower profile
Most makers use a wider valve clearance for checking the timing to avoid the opening & closing quietening ramps.
The most accurate way to check the timing is to calculate the lobe centre (full open) position and use a dial gauge on the valve adjuster tip, checking at 5 and 10 degrees either side of the theoretical full open position
This method ignores any small variances at initial opening or closing

HTH
John
1961 Super Rocket
1963 RGS (ongoing)

Offline Lord Flashheart

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Re: Super Rocket valve timing (etc)
« Reply #5 on: 07.09. 2013 23:16 »
Thanks John,
Am I to interpret from your comments that the important aspect and the easiest to check absolutely are the lobe tips ( angles not normally quoted )
and that the anomalies around the base of the ramps need not be cause for concern . ?
I'm thinking the dial indicator (which i've had in mind for a while) would be a very good indicator of which cam I have fitted, purely from the peak lift.

Pete
Flash'

Live for today, but don't regret it tomorrow !

'59 G.Flash-S.Rocket Motor; '88 Honda Hawk 650 (Project); BMW1100RT; '04 HondaVFR800.

Online bsa-bill

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Re: Super Rocket valve timing (etc)
« Reply #6 on: 08.09. 2013 11:03 »
I have a 357 cam, to be honest it's a bit of Techy bling unless your going to flog it a big revs lots of the time (if your going trackside well yes fit one)
there is a big difference in lift between the 357 and 356 if someone can measure and tell then you could just mark a pushrod and note travel.
the base of the cam may not be trustworthy to measure as it's a known method of cam repair to take metal off the bottom to regain lift, probably not a good way but I believe it is done.
Another random thought - clicking could be the cam follower or pushrod fallling back in contact with the cam.
Whatever it is I would say putting in some ZX1 or equivalent and running it for a few miles would be worth a try, it's eay enough to drain out if no change
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline chaterlea25

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Re: Super Rocket valve timing (etc)
« Reply #7 on: 08.09. 2013 16:55 »
HI Pete,
To get the engine running just check the overlap period at tdc, if this is ok move on and look at other possibilities
I set up a little 250 J.A.P. engine the other week, and didnt even have the cylinder on, pulled the rod to tdc and set the valves "on the rock", the J.A.P. crank pinion has three keyways to choose the best position,
When the engine was complete I checked again and it was spot on  *smile*

I read somewhere that all A10's after ???? number all had the 357 cam

HTH
John
1961 Super Rocket
1963 RGS (ongoing)

Online bsa-bill

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Re: Super Rocket valve timing (etc)
« Reply #8 on: 08.09. 2013 18:41 »
Quote
I read somewhere that all A10's after ???? number all had the 357 cam

Not sure about that one John, I may well be wrong but think it came in about 61 for Super Rockets, think it may also be the same as "Spitfire Cam" (Spitfire Scrambler).
Bet somebody here knows tho  *smiley4*
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online muskrat

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Re: Super Rocket valve timing (etc)
« Reply #9 on: 08.09. 2013 21:09 »
G'day all
357 = 60-63 Spitfire, 61-63 SR, 62-63 RGS (and my '51 A7, '57 A10 Cafe) io 51 btdc, ic 68 abdc, eo 78 bbdc, ec 37 atdc. Cam lift ex = 0.340" in = 0.345"
366 = 51-62 A7ST/SS, 59-62 A7, 59-63 A10, 53-61 A10SF/RR/SR, io 42, ic 62, eo 67, ec 37, cam lift 0.305"
Valve timing measured with 0.020" tappet clearance.
So it looks like Pete has a worn 357. 33-35 degrees timing OK. 8 to 8.25:1 comp. Spit back = advanced timing and/or lean fuel mix.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7