Backfiring

[Ernst]

Hi,

finally I have my '99 Sv 650S.
The shop fixed the regulator problem (On the same day of the purchase it stopped working after 120 km)
Now they have installed a honda regulator.

But.... the bike doesnt run smoothly now and again: after 30 km motorway when I release the throttle it goes down, on one cilinder maybe and it does backfire, or in a tunnel or when descending from tibidabo ( a mountain in barcelona). It feels like a very cold machine without choke. Also I smell gasoline, The exhaust is not standard but a loud nameless titanium pipe. I took out on eplug ( the other one I couldnt reach now) and there was a CRE9 which had a coffee with milk color. The air filter seems clean, I will blow it out tomorrow. I used ron95 gasoline.
Most likely the carbs are dirty.
any other suggestions?
(hwat strikes me the most is that the shop have done 250 km on it to test the regulator...and they did not notice the probs? Here in spain reliability has a different perspective then where I am from: Holland)

[Biker Biggles]

Lots of things there,but you do need to learn how to get both plugs out as these will tell you if one or other cylinder is too rich or too lean.As a matter of routine I would check that both choke plungers are free and fully moving,and that there is no water in the fuel.It may be that your aftermarket pipe will make it run a bit rough anyway.

[Ernst]

Lots of things there,but you do need to learn how to get both plugs out as these will tell you if one or other cylinder is too rich or too lean.As a matter of routine I would check that both choke plungers are free and fully moving,and that there is no water in the fuel.It may be that your aftermarket pipe will make it run a bit rough anyway.

Thank you, I checked one choke plunge, which worked correctly.
Tomorrow I will do the other one, and I'll take out the other plug.

I have to get used to work on a Suzuki, after 6 guzzi's I am spoiled when it comes to work in your backt=yard on your bike :)

btw 20 years ago I stayed regularly in Barnet, near Church hill road, or was it Cat hill road... Cant remember

[Typhoon]

Correct me if i'm wrong but the SV Spark Plug Code from NGK should be CRE8.

[Ernst]

Correct me if i'm wrong but the SV Spark Plug Code from NGK should be CRE8.

You are right, therefore I mentioned it :)
Maybe here in spain because of the heat the use colder plugs?
I will call the shop to ask if there is a psecial reason for this.

[hongman]

My new office is in barnet. Wrotham Park ;)

[Biker Biggles]

Small world with Barnet briefly at its centre?
Wrotham Park?Didnt Admiral Byng live there?

[embee]

No need to use a colder plug for road use, it's more likely to cause problems than cure anything.

I'd second checking the choke plungers, you really need to take the carbs off to get at the front one especially if the screw hasn't been removed recently.

Otherwise generally check all electrical connectors, take apart any you can get at and lube the terminals with dielectric grease or contact cleaner.

The other thing to check on the curvey is wiring harness chafing, the well documented points are behind both the rider's seat fixings (they are slightly long and hit the harness behind the bracket), and also remove the pillion seat and check on the left side towards the back where the harness bends round a frame bracket. You can get problems generally around the steering headstock where the wiring flexes.

[hongman]

Small world with Barnet briefly at its centre?
Wrotham Park?Didnt Admiral Byng live there?

Yep ;)

I'll stop derailing now but it is such a small world lol.

[andrewsmith]

i would say new plugs as a precaution
Vasaline the electrics
Check the cables and oil accordingly
balance the carbs also
Also if you think it needs it a new oil and filter. be a shame to do most of a service and have to go back later on

[boot]

Also worth checking for possible air leaks.