can anyone tell me why my rear cylinder head is colder to the touch than the front one on my 2003 roadking even at the exhuast tips the rear is colder than the front i do have cobra true dual exhaust, and have installed the cobra fi2000 fuel processor. any info on this issue would be greatly appreciated thank you. keep the rubber down and the shiny side up.

 

You have to start the bike so it can warm up.

Really?

Colder? get a temp gun and get back to us with some facts.

I'm not even sure if it's possible for the rear cyl to run colder than the front, anybody?

 

The only way I can see a rear cyl being colder than the front is the cyl is not firing.

 

All the time or just when idling in traffic? That's normal...


edit - maybe not on a 2003...

 

Welcome to the forum !

 

almost always cold but it does seem to work at high speeds, i mean like it seems to kick in at high speeds

 

gtk,i tried a coil off of one of my buddys softail and it got a little hotter and seemed to start up quicker so i have ordered a new ignition coil.

 

sounds like you are on the right track, good luck

 

1st is since you didnt say the motors not running well in your initial question / post and that the rear cyl doesnt seem to be firing at all and bike cant get out of its own way on 1 cyl i have to assume its running decent and that your saying both ex pipes are hot but one is cooler then the other which is what i have to assume is the case.

But if rear cyl is in fact not firing and your not telling us thats a totally diff story that could be a bad plug or plug wire and or bad coil for the avg normal things that could cause non firing , extreme case thats not as likely but possible could be a bad valve and or cam / lifter going bad.

So with that said assuming all the baobe is ok does the aftermarket rear cyl exp pipe on your bike still cross over under the bike from right side under the bike to left side then exit to the rear?

If yes it could be the that the rear ex pipe from head to end of ex pipe is longer then the right side is so ex has more time in the longer ex pipe to cool down a bit more before exiting the rear ex tip which could explain a slightly lower ex tip temp.

Also,has the bike been custom tuned in such a way that richened up the rear cly a tad on purpose to make rear cyl run cooler which could also effect / cause rear ex temp to be a bit cooler too.

How do the plugs look , approx the same (very light to med tan color?)

If the motors running well i would not worry about it , but if the rear cyl is in fact not firing at times then go after the 1st things i rec like other people rec too.

Scott

 

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Since coil may be an issue have you also thought about replacing the plug wire-s since they may need replacement too? (are plugs fresh?)

In general an ign coil last longer then the plug wires do so keep that in mind.

Could also be a partially clogged injector causing the rear cyl to not fire at idle and or low engine speed but then work better was rpm & pulse rate from ECM increases.

So if new coil etc doesnt fully fix it try a healthly dose of chevron techron ( concentrated version as stated no label) of 2oz techron per gal fuel to see if that helps.

Many people overlook doing any kind of maint on EFI systems in their cars/trucks/bikes and its not uncommon to have an injector that partially gummed up causing misfiring or a completely dead cyl in an extreme case.

Scott