backfiring blade engine

[stupott901]

hi there
why would my blade engine start backfiring

i went to start it up tonight and it would not start it turned over but not fire up so i cleaned the plugs (as that worked last week) and put them back in now it still turns over but wont fire up and backfires and smoke comes out the carb trumpet ahhhhhh
any suggestions ?

[Mark G]

Sometimes if mine has been sat for a week or so it doesn't like to start unless you give it a tickle of choke...

[Bulldog Bri]

don't know much about bike engines, but could the timing be slightly out?

Had a similar prob with my crossflow!

['The Gaffer']

hi there
why would my blade engine start backfiring

i went to start it up tonight and it would not start it turned over but not fire up so i cleaned the plugs (as that worked last week) and put them back in now it still turns over but wont fire up and backfires and smoke comes out the carb trumpet ahhhhhh
any suggestions ?

You could try changing the plugs.

Check that plugs are wet indicating fuel.

If dry, no fuel, try stripping and cleaning carbs and jets. (Carb cleaner and low pressure compressed air)

Check you have a spark on all plugs, if not possible ignition fault, wire off somewhere?

Is air filter clean?

Check you have good clean fuel coming from the tank, is fuel filter blocked?

Try starting with tank cap off, possible tank vent problem?

Is battery good?

If you have tinkered with anything recently, backtrack and see if anything has been disturbed.

Look out for air leaks, is everything tight?

Good luck and let us know how you get on.

[stupott901]

hi there

ok the plugs were wet with fuel and a bit of oil?

what the best way way to check spark?

yes i have clean fuel getting to the engine and filter is okay

there is fuel getting to the carbs

i have put the battery on charge for an bit then ill try again

cheers
stu

[Richard]

First clean carb.
Likely to be old fuel or dirt.

If not then;
timing issue,
over fueled
open jet
and finally ecu.

Best of luck

['The Gaffer']

what the best way way to check spark?

Take all plugs out and hold the screw threded part of each plug in turn to a earthed metal part of the engine and see if you can see a spark between the electrodes at the end of the plug.

Try to hold the rubber plug cap when doing this as you may get a nasty electic shock if not. Wont kill you but very painful.

[stupott901]

ok cheers will give it a go tonight

[stupott901]

ok found out what the problem was it was the plugs i have replaced them with new ones strange as the ones in there were new but it has been standing for an while

thanks for the help guys
stu

[Richard]

Excellent news !

Off to clear the filters now 

['The Gaffer']

ok found out what the problem was it was the plugs i have replaced them with new ones strange as the ones in there were new but it has been standing for an while

thanks for the help guys
stu

Good news. 

[gingerpaul]

The bike engine in our old single seater was eating plugs and it turned out that it was massively rich. Do you know whether your set up is right?

[stupott901]

nope not sure if its set up right but plan to get it tuned and checked over once i have sva'd it