Checking valve timing on a GF

[jhg1958]

I read with envy about engine rebuilds that start first kick. Mine will not start at all.  I have only been rewarded with a backfire through the carb.

I have checked the timing three times. It has a Wassel electronic ignition and I get a good spark.  I have removed the new carb and checked that it is filling with petrol by putting a piece of Perspex on the float bowl. I have even tried easy start spray.

 I have compression but not checked as I do not have a tester.  The engine was professionally rebuilt to the cylinder head, but I finished off the rebuild with the timing side.

I am coming sadly to the conclusion that I have buggered up the valve timing.  Is there any way to check without taking the timing side off?

Or any other helpful suggestions?

John

[Swarfcut]

 As a rough check both valves will be closed at the top of the compression stroke. This would indicate the cam timing to be correct, but I'd check the tappet clearances anyway. On a normal magneto bike the pick up to the cylinder on compression will be above the brass segment on the slip ring. With a Wassell unit I don't know how you check for correct spark timing, unless it's with a strobe. There must be someway to check the static timing, I would think, to install the ignition unit timed correctly.

 Common errors are to time up after TDC and on a magneto bike swapping the leads. Is the Wassell a double ended coil? In which case it sparks in both cylinders at the same time.

 So, if simple checks don't solve it, looks like the covers come off and it's back to basics with the dashes and dots.

Swarfy.

[RDfella]

Sounds more like ignition timing than valves

[Triton Thrasher]

You may not be flooding it enough.

[jhg1958]

I agree that it sounds like ignition but I have checked and rechecked. The wassel ignition uses a wasted spark with a single coil.

I will connect the ignition system to the battery to exclude any poor connections and have another go. Then onto the valve timing. I will feel a right chump if it is, as getting it right seems so straight forward.

Is there anything I should do with a new carb?

John

[Triton Thrasher]

As a rough check both valves will be closed at the top of the compression stroke.

 
Swarfy.

And if they’re both open about the same small amount at the top of the exhaust stroke, the valve timing can’t be far wrong.

[RDfella]

Is there anything I should do with a new carb?

Take it apart and check it's functional and in working order (no blocked jets / holes or stuck float etc). If it's a Mikuni it probably won't need that as they're very well made BUT unless it's jetted especially for your engine, begin to despair. People (myself included) have thrown away new Mikunis in desperation of trying to get the engine running on them. Far too many variables jet-wise.

[jhg1958]

I bought an Amal monoblock I have taken it apart. There was a fair bit of oil in it. I suspect this was from the inside of tank as I put oil in when I emptied it as a rust preventer.

I checked the float level with a bit of Perspex on the bowl and it seemed ok. I focused on the carb as I expected the plugs to be very wet as it was not firing but they were not.

I am surprised at your comments on the Mikunis.  I thought they one of the best upgrades you could get and I had missed out on a trick.

I think the engine is very tight. Even with the plugs out I find it hard to turn with the back wheel.  The engine had a rebore and a new cam, but these were GF spec as I was not looking for a performance bike.

[Rex]

I'd strip the carb to make sure that oil (or production swarf) hasn't blocked the pilot jet.
As others have said, I'd avoid Miks too, as there's just too many variable.

[route 66]

Take the plugs out and heat them up with a blow lamp.While theyre out spray a misting of fuel down the plug holes and quickly put plugs back in. Works every time.

[CheeserBeezer]

Plugs should be wet, if not clean carb. Also, when starting a new engine I try to start with the throttle closed and gradually turn the tickover up on each kick until it fires. I have Mikunis on two of my bikes and they work really well.

[chaterlea25]

Hi All
Is there a clockwise and anti clockwise timing marks on the Wassel ignition?
People fitting Boyer ignitions often get this wrong
On a new rebuild another thing to check is that t he pushrods are seated properly
Are all the tappet adjusters at approximately the same position ?
Make sure the petrol is new and fresh and the battery is fully charged with EI


John

PS, I also like Mikuni's

[tomkilde]

You may want to try tightening up the clutch adjustment nuts.  If the clutch is slipping, the force generated by the kickstarter will not transfer to the crankshaft.  Don't ask me how I know this.

[jhg1958]

Rex I have stripped the carb down and cleaned out the oil.  I did not find any debris. I still think the oil came from my tank.

I connected the electronic ignition directly to the battery (with fuse) and I get a spark but it does not start.

I bit the bullet to check the valve timing.  Not sure why I was so reluctant, an easy job really. It looks spot on.  I have included a photo just in case I am missing something.  I assume there is no need to check the position of the pistons when setting the valve timing.

Heating spark plugs takes me back to my youth.  It a great idea once I have reassembled the timing side. I have tried a bit of fuel into the cylinders but that did not help.

Cheeser that is a great tip about the tickover. 

John there is a clockwise and anti clockwise marks on the Wassel ignition.  The manual states anti clockwise for the BSA. I took a photo at the time. The C is clear but the letter A is obscured by the flash reflection. I put 7 litres of premium petrol in the tank. I am not very happy with the taps as they seem very stiff.  They have neoprene seals rather than corks.  I have checked the flow and the level in the float chamber.  When I tickle the carb I get petrol running down the carb.

Tom The clutch suggestion is a good one.  It does not feel like it is slipping but it is a new one from SRM and I suspect I was fairly cautious about over tightening the springs.

This will have to be a job for Sunday as I am busy tomorrow. Many thanks for all your suggestions I have a lot to work on.  I was getting very disheartened at it not starting.  On the plus side with all my kicking I see I have oil retuning into the oil tank.  One thing less to worry about.

John


 

[Angus]

I hope you are not in the same boat as me. On my 1950 T100 the intermediate gear fell of whilst changing the magneto  . I have put it back with all the marks lining up but that gives me suck, blow, squeeze, nothing  . So having found info by a certain ‘Triton Thrasher’ (is that you TT) on a triumph forum I am currently getting a degree wheel to do it all with that  .