Sticking valve ??

[Freak]

I can't work out the cause of a missfire on my Evo
It fires up from cold without a problem
A few minutes warming up and all's fine
I'll ride off and after a mile or so she'll start to bog down on choke
This is when the battle starts as there is no happy medium between choke and no choke. The motor coughs and splutters for about five minutes until it slowly calms down again. Then it's fine for the rest of the day.
The difficulty I'm having is tracing the fault while it's actually happening.
I'm leaning towards something odd like a valve sticking while the head warms but it's really only a guess.
Any ideas?.. I've done the usual plug change, HT leads & carb clean.

[John Hopkins]

Is it possible that you have a mucky petrol tank....maybe you took it to the pressure washer and got some water in it...John

[Freak]

I must admit John, I haven't checked the fuel :o
There's a chance I've broken my own golden rule of always starting with the simple possibilities. :rolleyes:

[lowrider]

I must admit John, I haven't checked the fuel :o
There's a chance I've broken my own golden rule of always starting with the simple possibilities. :rolleyes:
And the cheapest
;)

[Taff]

Might be just the cold weather, checked me plug leads aint loose a few times on mine as i trundle thru the village, and turned to reserve just in case, same as you though, once it's warmed up it's fine.

[Freak]

Might be just the cold weather, checked me plug leads aint loose a few times on mine as i trundle thru the village, and turned to reserve just in case, same as you though, once it's warmed up it's fine.
Ya get some right wierd looks sat in traffic with the bloody thing coughing and wheezing like an asthmatic fat kid on a cross country run though.

[RobK]

Ya get some right wierd looks sat in traffic with the bloody thing coughing and wheezing like an asthmatic fat kid on a cross country run though.

Heh, my Shovel does it as well. Choke is an on/off affair and in this cold weather it's not keen at all.

Needs a good few minutes to get properly warm before it starts to behave.

[Freak]

I'll not worry so much then although I'm gonna drop the fuel just to make sure it's not drawing moisture.
Thanks all.

[Grav]

Worrit needs is a damn good thrashing. :)

[gurnE]

Has it started recently since it's got cold?

Sounds like carb icing.

My twin cam does the same.
You can buy a winter fuel treatment from your HD dealer, there may be a cheaper non-HD option but I've not looked since I get it cheap anyway.

[RobK]

Ya get some right wierd looks sat in traffic with the bloody thing coughing and wheezing like an asthmatic fat kid on a cross country run though.

What carb has it got on it?

[Freak]

Standard CV although it has had the 'Official Harley Tune Up' for more open pipes which by all accounts means they've just drilled out the jet a bit bigger :rolleyes:

[Taff]

Them Dynojet kits are good, cant remember what's in 'em, cos it's years since i ran one, but it were alright.

[John Hopkins]

Worrit needs is a damn good thrashing. :)

Mine likes that.. :D John