Running bad when cold... Help please

**XP@** · 16th February 2006, 12:39

Can anyone help point me in the right direction please.

Three days ago I had a wof and new rear tyre, put on my f650.
yesterday in the morning I started as usual (using choke) all ok until i tried to use more than 4000 rpm under power. then all hell broke loose, then didn't break loose... massive missfire pops, coughs, bunny hops and the like.
so i eased off and all was cool.
choke off.
tried to put the throttle on again and the same happens (this time in front of a cop who started to look interested).
shit i thought better crawl up the hill and home. half way home all came right

This morning same again.

I am suspecting one of the carb sliders is sticking open and giving me way too much fuel... any suggestions before I start ripping things apart?

**imdying** · 16th February 2006, 12:56

Wouldn't a slide sticking open give you too much air? That'd give you a lean mixture, which could possibly result in the backfiring you describe.

**Motu** · 16th February 2006, 13:14

Air box lid....something dislodged in the intake somewhere.

**thealmightytaco** · 16th February 2006, 19:08

Originally Posted by Motu

Air box lid....something dislodged in the intake somewhere.

True?! Man, I never woulda picked that. Does it create weird ass flow?

**FlyingDutchMan** · 16th February 2006, 20:53

Possibly slowly leaking float valve? Bowl over fills and bikes run way too rich. After a while the petrol level is back to where it should be and starts running fine again. Leave it over night + excess petrol in the carbies again, etc. Just a threoy though. Dunno what it has todo with changing a tyre.

**Flyingpony** · 16th February 2006, 21:49

Originally Posted by XP@

On my f650. Yesterday in the morning I started as usual (using choke) ...

There's your problem. It's summer so why are you using the choke to start the engine?
On a frosty sub-zero morning one can understand, but on 15deg mornings!

My guess there's something a miss with air or fuel. Is the ignition system and spark plug all okay?

**imdying** · 17th February 2006, 08:14

In theory he should still need the choke. A 15 degree morning won't compensate for the fact the motor isn't warm enough to correctly atomize the fuel. If he needs the choke to start it from dead cold, it sounds like it's correctly tuned.

**XP@** · 17th February 2006, 08:28

Originally Posted by imdying

In theory he should still need the choke. A 15 degree morning won't compensate for the fact the motor isn't warm enough to correctly atomize the fuel. If he needs the choke to start it from dead cold, it sounds like it's correctly tuned.

Tried without choke this morning ... it started ok, but it cut out, so a small amount of choke is probably the best plan

But then we still had the coughing and spluttering, not backfiring though.

I think my best plan is to check the air box, give the filter a clean tonight and leave it to dry. then tomorrow pull the carbs, give them a clean and check the floats and seals.

**imdying** · 17th February 2006, 08:43

Yeah have a poke about. Sounds like air is getting in somewhere, so make sure the bits that bolt to the head are tight, and the carbs are bolted to those correctly. Haven't taken on a bad batch of fuel? The halfway home all came right bit is a problem... maybe something is moving? Give everything a good jiggle, make sure nothing is obviously loose. You could try draining the float bowls into a clean container, check for crap floating around that might be occasionally blocking a jet?

**XP@** · 17th February 2006, 08:56

Originally Posted by imdying

Yeah have a poke about. Sounds like air is getting in somewhere, so make sure the bits that bolt to the head are tight, and the carbs are bolted to those correctly.

Will make sure all is connected and no leaks hope it isn't the inlet manifold again... I'm on my 3rd already and it has only done 117,000 kms.

Originally Posted by imdying

Haven't taken on a bad batch of fuel?

Who knows the crap they put in the gas here... I am probably running on 50% diesel, 25% water, 20% pee and a trace of the real stuff

Originally Posted by imdying

The halfway home all came right bit is a problem...

Over 3 days it has been consistant crap for 2km then fine, so it really seems to be a cold only problem.

**imdying** · 17th February 2006, 09:36

Originally Posted by XP@

Will make sure all is connected and no leaks hope it isn't the inlet manifold again... I'm on my 3rd already and it has only done 117,000 kms.

Ahhhh, the plot thickens! Tell us more...

**heavenly.talker** · 17th February 2006, 10:20

Some bikes are like women

Warm them up before riding them hard.

A little preparation before starting off will give better performance!

**XP@** · 17th February 2006, 14:58

Originally Posted by heavenly.talker

Some bikes are like women

Warm them up before riding them hard.

A little preparation before starting off will give better performance!

Yes but 3000rpm is but a kiss on the cheek! I usually get her rolling (down the hill) before turning her on, and then I wait a while before revving her up. I even give the rubber chance to warm before using it.

And it is not as if I still have the "Other Woman" I sold the CBR last week. Ah, maybe that is it, she was having an affair with the other woman and is now pissed at me.