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Rapide backfires when starting

danno

Well Known and Active Forum Website User
VOC Member
Hi
Is there anyway of avoiding loud backfires when starting the twins?
My series C Rapide has always done it and my father could never sort it out.
It's a bit of a worry in town centres when people aren't expecting it!

It must be fuel vapour igniting in the exhaust. I have electric start as well as kick.
Any help appreciated.
Dan
 

John Appleton

Well Known and Active Forum Website User
VOC Member
Hi
Is there anyway of avoiding loud backfires when starting the twins?

It's a bit of a worry in town centres when people aren't expecting it!

Dan

You should experience it in an East-European border control building where they all carry guns!!! Russ will confirm the atmosphere when that happens!

John
 

ossie

Well Known and Active Forum Website User
VOC Member
mine done that a lot in the sixties when i used it for work every day ??
none of me neighbours was late for work///:)
 

danno

Well Known and Active Forum Website User
VOC Member
Also, what kind of ignition system?

All I know is that's it's a Lucas electronic ignition system.

For starting I hold down the tickler on the front carb and sometimes the rear until fuel appears.
Kick over a few times without ignition.
Turn on ignition and choke,position kickstart just past compression then kick.
I find that choke isn't always needed and can turn it off as soon as engine starts.

Doesn't always start on the electric start from cold and can sometimes take a while on kick.
Good exercise though.
 

Bill Thomas

Well Known and Active Forum Website User
VOC Member
Hello Danno, Does it do it when you switch on ? Mine did it from new and i rang Rita, He told me it should only bang when you switch off !, He thought I had a bad switch but it was a bad front mini coil, Cheers Bill.
 

Howard

Well Known and Active Forum Website User
VOC Member
All I know is that's it's a Lucas electronic ignition system.

For starting I hold down the tickler on the front carb and sometimes the rear until fuel appears.
Kick over a few times without ignition.
Turn on ignition and choke,position kickstart just past compression then kick.
I find that choke isn't always needed and can turn it off as soon as engine starts.

Doesn't always start on the electric start from cold and can sometimes take a while on kick.
Good exercise though.

So........? You flood the carbs. Kick it over to pump petrol through the engine into the exhaust. Then when you start it with sparks and hot gas something goes bang ?????? :)

I think a few less kicks, or don't tickle it till it's ready for starting might help.

H

No offence meant Danno. I suspect you're not very familliar with old engines - the only engine management computer you've got is under your helmet!!

H
 
Last edited:

Albervin

Well Known and Active Forum Website User
VOC Member
Assuming you are using quality fuel I would only depress one tickler for a count of 3, use full choke on both carbs, kick through one cycle then stick the boot in (on the rear cylinder). I can
usually fire up 2nd kick using this technique even if the bike has been standing for over a month. Chokes are opened 2/3 immediately on start then fully opened before I set off.
 
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