Bike wont fire up

[Robotnik]

Are your carb diaphragms OK?

[willandrip]

Right; Have you had a gauge on to check compression ?

Good is often not good enough on these motors..it has to be right.

I would suspect valve clearances and DEFINITELY pilot circuit if it has stood that long AND the P.O. could not start it.

I now recommend original pilot jets to be discarded and replaced with new items if easily available....they simply are not worth the time cleaning and are never 100% once having been blocked with scale.

Evil is bang on with his advice as per....

[Morespeedvicar]

Yeah I'd maybe take the plugs out and warm them up with a blow torch just incase there wet. Get a small pipett or syringe and squirt some fuel down the card intakes. If it doesn't fire deffo check the valve clearances and or the compression. Maybe worth sticking strobe on to check the ignition timings not gone crazy.
Good luck.
Ian

[Shane54]

Hi guys. Thanks for the replies.

Yes the carb diaphragms are good.
There's definitely compression.
Had all 4 plugs out and grounded then cranked the motor (to eliminate the chance of checking spark on one coil and assuming all 4 coils are working) Definitely spark on all 4 plugs. It defies logic...fuel+air+spark=combustion ???
Dribbled fuel down the throats a few days ago and had zero effect...all things being equal there should've been SOME reaction.
What are the chances the timing is inexplicably a mile out ? I'm not ruling ANYTHING out at this stage and will definitely check it.

If the reserve sensor in the fuel tank is faulty...would it be in a normally open or normally closed state ? What are the consequences ?

[Morespeedvicar]

Are you sure the coils are going to the right plugs, or even if the tci is connected to the right coil?

I had engines running without the carbs an on just squirting fuel down the intakes, so if theres fuel theres either no spark at the right time or not enough compression.

I'd prob have a strobe on it see were it's firing.

[Evilchicken0]

Reserve sensor ... it transmits to the cdi which cuts / interferes with a coil, I'd guess it fails to the non-interfering.

So it has a reserve sensor ... so it's a 3TJ ??? - Do you get a sound from the exup (Exhaust Valve) servo when you turn the ignition on ??? Have a look at the exup valve by taking off the chrome cover down on the side stand side of the exhaust. Flick the ignition and see if it cycles towards the rear of the bike then back to the front.

If this doesn't help .... check the valve tollerances

[Shane54]

Yes EC it's a 3TJ1. The power valve does it's thing when the ignition is turned on.
I'm gonna check valve clearances

[Evilchicken0]

The inlet cam should be at 1 o'clock tdc and the exhaust at 12 o'clock. If you lift the cams the exhaust goes in first

[Shane54]

Ok so....after actually checking the compression with a gauge (not just a thumb over the plug hole) I'm only getting 60 PSI which is of course RUBBISH when it's supposed to be 156 PSI
Swung the motor down in the frame, checked valve clearances....exhausts are good...ALL THE INLETS are riding the lobes so whoever did the shims on that head needs to be taken into a field and SHOT in front of his family

Assumptions are the mother of all horse-ups I know but why should anyone have to check that a job has been "done right"

[willandrip]

Ok so....after actually checking the compression with a gauge (not just a thumb over the plug hole) I'm only getting 60 PSI which is of course RUBBISH when it's supposed to be 156 PSI
Swung the motor down in the frame, checked valve clearances....exhausts are good...ALL THE INLETS are riding the lobes so whoever did the shims on that head needs to be taken into a field and SHOT in front of his family

Assumptions are the mother of all horse-ups I know but why should anyone have to check that a job has been "done right"

You were told...lol.