Hello everyone.

I need help .

I get a used BME .90 (Supertigre 90 converted to gas) which simply wong fire up.

I have already cleaned the carb
I have already change the membranes of the zama carb,
The ignition works and the spark can be clearly seen
Im using a mix of 32:1 gas / Synthetic oil

Whats strange is that I have even pour some gas directly to the carb and event directly to the piston and the engine wont event make a little effort to fire up.

Any suggestion on why this might be happening.

Any recommendation would be of great help.

Regards.
Víctor Arreola.

Doesn't sound like enough oil in that mix to me , but anyhow, have you checked the timing of the spark?.
About 5 degrees before top dead centre should get you started.

Quite possibly a bad spark plug. But, have you spun the engine over without the plug in and with the cylinder pointed downwards to see if the engine is flooded? Too much gas is just as bad as not enough. Also, try a 6 volt battery connected directly to the ignition box; bypassing any switches, etc.

The ignition timing should be set at 28 degrees "antes de punto superior". (BTDC)

I prefer to run 20:1 oil in the .90/15cc engines if using non-sythetic oil. A good synthetic oil should be fine at 32:1.

AV8TOR

prop hub might have slipped or come lose while changing prop, that would change timing. I run my .90 conversions 40:1 synthetic from the start . And all other conversions . Don't believe in wearing out an engine to call it breaking in . It will get there on its own. Don't use a 6v battery if it has the Falcon ign or the older rcexell versiom

I thought even the older RCEXL ignitions were rated 4.8 to 6 volts?? I have had a tired balky ignition perk right up and run right when going to 6 volts. I then retire that ignition because I know something is not "up to snuff" with it. This is all assuming we are testing with a new, good spark plug...

AV8TOR

they are good for 6v but a charged 6v= 7.2 or some where there about , the older and even not so older will work ok , UNLESS it burns out, no guarantee

If the ignition works good on 4.8 volts, use that voltage. A higher voltage will shorten the life of the unit.