My M2 has started backfiring on a closed throttle which is getting a bit annoying now
Checked all the exhaust connections and seems o.k. but i still have the dreaded sidestand switch fitted Could this be anything ?
If you trail the throttle a bit on deceleration it won't bang with a whiff of throttle but shut tight it bangs like a good'n.

I fitted the exhaust before the winter lay up and it has only started doing this since i got it back on the road,i haven't touched anything

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Should Have Stuck To making Tubers

http://www.mikuni.com/tg_backfires_in_exhaust.html

Found this but i could understand the backfiring when i first put the shortened end can back on.
It has farted back a few more times in the intake too

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Should Have Stuck To making Tubers

Hello it's me again
Just been on Bad Weather Bimbos and got a list of possible causes

Check exhaust seals

weak battery

worn sparkplugs

faulty ground wire at regulator

sidestand switch

wire from CPS worn on harness ??

pink wire ignition coil

clean check diodes/fuses

master circuit breaker

broken positive battery cable

cam position sensor

So what is the CPS wire ? and from above what would be worth checking first ?

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Should Have Stuck To making Tubers

Just keep talking to yourself, I'm sure you'll get there eventually

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Wear the fox hat

Not sure I agree with many of the BWB ideas you listed.

I would be starting with looking for leaks in the exhaust system, which you have done. Then I would check the intake seals for leaks. I would check the ignition timing to ensure there was sufficient advance. Then I would try an extra half turn on the air screw to see what difference that made...

The shorter exhaust is not going to help cos at throttled conditions some of the exhaust gas is sucked back in to the cylinder during valve overlap, and in doing this, air is sucked into the exhaust which is similar to having an air leak.

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08 Specialized Langster

One more thing is the tacho needle is doing a bit of jumping around at a steady throttle

I have some of those James blue intake seals fitted as i couldn't get the originals to seal and that showed up as a flat spot/splutter when you whacked the throttle

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Should Have Stuck To making Tubers

But it runs OK under load?

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08 Specialized Langster

All runs o.k. apart from the backfiring,it does it hot or cold,no difference really.
I always feel the engine runs nice under load

What you said about the exhaust being shortened,i got it all together about last september and was out on it for a short while and i had no backfiring then,it's only after the lay up
I did strip the carb and clean it but that was last sept again

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Should Have Stuck To making Tubers

.....and that there is your biggest clue

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Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR

Electrical ? Sidestand ?

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Should Have Stuck To making Tubers

Well done Sherlock ........snot like you to ignore standard wisdom on such matters is it ?

If the tacho is bouncing around then the ignition is compromised and this is normally down to stand/clutch switch/diode issues = unburnt fuel in the zorst etc.......

Of course, your problem could also/ equally be a badly set up Mikuni......

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Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR

So is it time to remove my 10 year old clutch/sidestand switches and see first if that is the prob

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Should Have Stuck To making Tubers

What is the best, neatest way to do the clutch and sidestand switches then ?
Can you remove them altogether ?

Will these diodes now be redundant?

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Should Have Stuck To making Tubers

Cut them out, solder the wires and heatshrink.

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If your dreams don't scare you, they are not big enough.

The popping back thru the intake, especially if its just on a wiff of throttle can be tweaked out by reducing the gap on the pump actuator needle to 0.2 - 0.5mm instead of the manuals sugested 2mm

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Buelling is exhillarating
But downhill bike racing is so terrifying it makes your arse grow teeth