[geezer]

Hi Guys, I'm based in Norfolk UK, have a MC19 1989, runs well ,until now, has suddenly decided not to start, turns over ,try's to run but just backfires, any clues for me before i start taking bike to bits, thanks

 

[Dannoxyz]

Greetings & Salutations!

What happened between when it was working to now?
Did it sit for a while without running?
How long?

 

[geezer]

Greetings & Salutations!

What happened between when it was working to now?
Did it sit for a while without running?
How long?

yes sat for only 2-3 weeks but the weather hear is cold and damp, all the bike does is backfire perhaps should leave till weather warms up

 

[Dannoxyz]

does it start OK with full-choke?

 

[geezer]

does it start OK with full-choke?

tried on half choke,& full choke, will fire but not run

 

[Dannoxyz]

let's do quick test

• get small squirt bottle
• fill it halfway with petrol
• squirt 2cc into airbox
• wait 30s
• start bike

Did that work?

 

[geezer]

tried that, no it didn't work, guy i bought it from has offered to get his mechanic to give it a thorough check over, ie, fuel, electrics, etc.

 

[NotANiceName]

Spark, fuel, air, compression. These bikes are known for their electrical components failing. I mean the bikes almost 40 years old! Try checking the stator, regular/rec, had to replace my regulator, Put thermal paste on the new one to the frame for better thermal dissipation, that usually goes on these. As well as check spark strength, might not be igniting properly. Check spark plugs, ignition coils, these bikes have 2 with each one powering 2 plugs. Might need to clean air box while your at it. Give carbies a deep clean and recalibration with proper equipment, 4 vac. Hopefully compression is all good, if not, good luck finding a new motor. Maybe put a cb400sf engine in it, unlock the rev limiter a bit, stiffer valve springs.

Hopefully it’s all good now and your riding it to the redline .