slight exhaust pop on start up

[steven61467]

Had my bud sync my carbs this weekend,and for sometime ive had a slight "backfire" exhaust pop when i first start the bike up for the day,once its warmed up,it goes away,he noticed the vacuum on one cylinder was slightly lower during warm up,and got better once it got hot,,,and ive notice if you are sitting on the bike the left rear cylinder takes a tad longer to get as warm as the other three,we seem to think its a valve sticking slightly?


Bike has 31k mileage and has never had a valve adjustment,could that be part of it?
once the bikes up to temp,it goes like a ***** ape,and sounds normal

 

[naughtyG]

I'd say make sure you warm it up always before you gas it hard. A valve check/adjustment may be a good idea, but have you had a good look in your carbs lately? Done the shotgun? Ran any SeaFoam at all? It may just be a slightly clogged passage - the pilot jets circuits are prone to gumming. Also do take all four slides out to inspect the diaphragms carefully and make sure the slides run freely when cold.

 

[The Beekeeper]

Might be a good idea to do a compression test and guage the results between a cold and warm test...........At this point I'm thinking carb too.................Tom.

 

[steven61467]

I'd say make sure you warm it up always before you gas it hard. A valve check/adjustment may be a good idea, but have you had a good look in your carbs lately? Done the shotgun? Ran any SeaFoam at all? It may just be a slightly clogged passage - the pilot jets circuits are prone to gumming. Also do take all four slides out to inspect the diaphragms carefully and make sure the slides run freely when cold.

Carbs were off the bike last year,and they were all cleaned,and looked ok,seaform many times as well,i can take the diaphrams out and dbl check again. I might add,i just changed the plugs 2 weeks ago,and the four that came out all looked perfect,and identacle

 

[VMike]

Check for vacuum leaks with some starting fluid and inspect your rubber connectors and caps on the carbs.
Mike

 

[sdt354]

31k is overdue for the valve adjustment. Not that it has to be the problem. Mine runs quirky for a few seconds when very cold, with the choke on. Always has.

 

[bazwell]

Could be all sorts of things.
Higher float level on that carb would do it. Maybe do a quick wet check of the float level.

 

[ouchez]

My 05 "farts" when started cold until warmed up several minutes, then all is great.

O

 

[grimmie]

31k is overdue for the valve adjustment. Not that it has to be the problem. Mine runs quirky for a few seconds when very cold, with the choke on. Always has.

+1