What now??

[t4tiger]

Hi,

I've turned in the pilot screws to just below 2 and the revs are dropping quickly now so thanks Mustang .  Still got the backfire.  It will have to wait for me to strip it down again.  Sick of it at the mo.  I'll report back in due course.  Many thanks for all the various  input. 

[Mustang]

by backfire , do you mean popping of the exhaust on the overrun when you shut the throttle down ?
if so it is generally caused by an air leak in the exhaust pipe system , a leaking joint at connection points .

otherwise a backfire can be caused by anything :
a bad coil , water in the gas , bad sparkplug ,
intake valve going tight .
needle valve flooding the carb/carbs,
dirty air filter
bad plug wires and on and on .............................

[JayDub]

by backfire , do you mean popping of the exhaust on the overrun when you shut the throttle down ?
if so it is generally caused by an air leak in the exhaust pipe system , a leaking joint at connection points .

otherwise a backfire can be caused by anything :
a bad coil , water in the gas , bad sparkplug ,
intake valve going tight .
needle valve flooding the carb/carbs,
dirty air filter
bad plug wires and on and on .............................

AND silencers which have been messed about with by the PO 

HEY MUSTANG... does turning the fuel/air mix screws IN make for a richer mix or leaner? (Mikuni's)

[t4tiger]

I'll try and get a video of it and post in due course...

[t4tiger]

http://s1379.photobucket.com/user/t4tiger1/library/

Hi,

New coils, air filter and sparkplugs fitted.  Just putting back together and will see if this works.  Hopefully I have added link to pics of old spark plugs.  There are differences.  Can anyone interpret them for me please??
(http://s1379.photobucket.com/user/t4tiger1/media/DSCF6119_zpsbqaq2wbz.jpg.html)

[Sin_Tiger]

One on the right is good, middle one might have been suffering pre - ignition, left has been running rich.

[Mustang]

how many miles on those plugs ?
the left while being on the verge of too rich actually has a nice brown color to it . just a bit much though the other two look too lean to me
#3 is not too far from being spot on
so I tend to agree with the

[t4tiger]

I can't remember when I changed them, less than 10000.  So....what do I need to do to get them all spot on?  Also, having changed the plugs , the backfire is still there and when I left the bike to run for a while the revs started to climb to about 2500 and then came down again.  After a few minutes it would do it again...and then nothing for several minutes and then repeat.  Any ideas? Is it haunted....  Arghhhh

[Mustang]

how are the carb rubber manifolds ?...........air leak between engine and carbs can do that

[t4tiger]

All a few months old.  Feeling like a visit to the dealer 

[GavD]

I had a brand new rubber carb/head manifold split on me after only a couple of carb in/out's. I hadn't overtightened the clamps or anything, it just went on me. Have a check.

[Sin_Tiger]

  you have far too much free time on your hands.

with Gav, the carb rubbers can be damaged by enthusiastic or frustrated man handling and a crack will be difficult to spot. One way to identify a leak is to smear vaseline over suspect areas which will get sucked in. It's also useful stuff when assembling 

[Mustang]

  smear vaseline over suspect areas which will get sucked in. It's also useful stuff when assembling 

is that Scottish slang for something I don't even want to ask about 

[ssevy]

I believe he is talking about piece work

[nickjtc]

We're deviating a little from the topic at hand, but KY is the lubricant of choice.  :icon_wink: