Non starting Lightweight

Hi... I need a of some help if I may. I have finally got around to getting a 1976 Lightweight back on the road, it has been in the garage for 14 years unused.

It is an FFR 24v converted to 12v, so all the components are now 12v and I have recently replaced all the below:
Battery
Starter
New pistons
Valve sills
Head gasket
Crank Bearings
Leads
Plugs
Dizzy cap
Rota arm
Points
Condensor
Fuel pump
Carb
Fuel lines.

So after all that, I have a spark, around 145psi on all 4 pistons, fuel coming out of the fuel pipe at the carb end. Valve timing checked, tappets adjusted as per manual and made sure spark 1 is firing on compression stroke. With this setup I would expect at least some sort of pop from the exhaust, but all I get is every now and again back fire through the carb, but this doesn't seem to be lighting, just atomised fuel. I have checked the spark with the Laser spark plug testers and also removed the plug to make sure there is a spark from the plug.

I have checked to make sure I can see the timing marks on the crank puller whilst at tdc with piston 1 compressing..

So I am at a lose to why it will not fire.

Any help would be great, I have read lots over the last couple of weeks, but nothing explaining to issue I have.

Jason..

JKJGood said:

Hi... I need a of some help if I may. I have finally got around to getting a 1976 Lightweight back on the road, it has been in the garage for 14 years unused.

It is an FFR 24v converted to 12v, so all the components are now 12v and I have recently replaced all the below:
Battery
Starter
New pistons
Valve sills
Head gasket
Crank Bearings
Leads
Plugs
Dizzy cap
Rota arm
Points
Condensor
Fuel pump
Carb
Fuel lines.

So after all that, I have a spark, around 145psi on all 4 pistons, fuel coming out of the fuel pipe at the carb end. Valve timing checked, tappets adjusted as per manual and made sure spark 1 is firing on compression stroke. With this setup I would expect at least some sort of pop from the exhaust, but all I get is every now and again back fire through the carb, but this doesn't seem to be lighting, just atomised fuel. I have checked the spark with the Laser spark plug testers and also removed the plug to make sure there is a spark from the plug.

I have checked to make sure I can see the timing marks on the crank puller whilst at tdc with piston 1 compressing..

So I am at a lose to why it will not fire.

Any help would be great, I have read lots over the last couple of weeks, but nothing explaining to issue I have.

Jason..

Click to expand...

how do you no its no1 compressing are you watching the valves

Hi... Correct, checking to make sure both valves are closed.

JKJGood said:

Hi... Correct, checking to make sure both valves are closed.

Click to expand...

and no4 are both rocking?

On checking again, seems 4 is not rocking when the rota arm is firing 1. I now have a feeling the Dizzy is 180 degees off. When 1 inlet valve opens the piston is travelling down, when it is travelling back up the dizzy is firing number 4. So the rota arm is at 2 o'clock postition, where I thought it should be at 7 o'clock..

JKJGood said:

On checking again, seems 4 is not rocking when the rota arm is firing 1. I now have a feeling the Dizzy is 180 degees off. When 1 inlet valve opens the piston is travelling down, when it is travelling back up the dizzy is firing number 4. So the rota arm is at 2 o'clock postition, where I thought it should be at 7 o'clock..

Click to expand...

sounds like 180 out

Thought as much, will try in the morning...
Thank you..

Happened to me once on a Triumph Herald, never did work out how. Came to the conclusion it might have been cos previous owner somehow managed to fit the cap on 180 out and I put it back on properly. Ought to have been impossible but then again!
Best of luck!
Nowadays, if in doubt, I remove the plug to number one and hold my thumb over the plug hole while turning the crank with a spanner to make absolutely sure it is on compression.

I purchased the engine a few years back and assumed the Dizzy was the correct way round, as I never removed it whilst working on the other bits.. Let's see if turning 180 helps...

So good news, switch 180 degrees and it fired up, just need to tune it now.. Thanks for the confirmation.

Will post shortly on how it looks.