Gs heating up

[Fadi09]

Hi everyone.I m a new on this site.i have recently bought a used gs500 2003 Spanish model.the problem i m facing is that my bike is heating up and back firing while decelerating.also there is black smoke residue on the silencer.before this bike i had a honda 125 so i have zero knowledge regarding big machines.can any one guide me whats the reason for all this.Your help will be greatly appreciated.regards

[qcbaker]

Sounds to me like the bike is running too rich. There are a lot of things that could cause that, but the first thing I would check is to see if there's anything clogging the air filter.

[herennow]

High Fadio, and welcome. Thanks for calling our bikes a "big machine" Makes me think of the TT big bikes that today shattered the lap record for an AVERAGE 135 mph lap of about 16.5 minutes!!!!!!!

as for your problem, I'll take the first stab.

Your bike may well be fine, we like to worry about them but generally, they are quite robust. I for one have wasted money on problems I was convinced were there, but were not.

How do you know it is hot?  Have you measured it? (Infrared/laser type temp gun on the head?) Or does it just "Seem" hot. Is it affecting the running?  The factory lean jetting does not help this but I found when rejetting richer that temperature did not change much,

A merry exhaust popping on deceleration is normal as bike is jetted lean from the factory. (not a big bang, that is not normal).

Can you post a photo of the black residue? if inside the exhaust that is also probably normal.  is bike using much oil?

how many km on bike?

[herennow]

snap! ok, second stab...

[Fadi09]

I will upload the pic in just a moment.as far as the heating issue is as how i assumed its heating up is the bike shut down and is not happy while starting.i ve given it a rest for about 10 mins and after that it started normally.also while starting it gives a misfire like there is residue on spark plug.i ve converted it in to a cafe racer so the silencer is not factory fitted one.one thing more.i ve noted it is given me an average of 10 km per liter or approx 35 to 38 mpg.its bad for a 500cc as my 1300 cc car gives me an average of 18 km per liter.(1 us gallon=approx 4 liter).Also the place i live all people have either a 70 cc or max125cc bikes.so this thing is a freaking monster as compared to those.so its a monster for me.as for km ,ive no idea as the speedo meter is not working.oil consumption is ok i think.at the moment i m searching for a good mechanic to get it checked for the peace of mind

[user11235813]

you should not be getting less than 20km/L

[ajensen]

Buddha is the jetting wizard. I'd take the carbs off and carefully take them apart. Check the jetting, the float level, the mixture screws, all the o-rings, etc. If you send the jet sizes to Buddha, he can help you dial your carbs in. Do not be afraid of the carbs. Just take your time and remember where everything goes. BTW, my totally stock GS500f gets about 56 mpg (24 kpl ).