FZRSupport: the FZROnline Archive

I painted the exhaust a few days ago, expected some wearout and discoloration but #4 has signs of hotter conditions. Looks like the paint wore off further than the rest. Kind of works like the spraybottle mist on the headers. At this point should i open up the moisture screw a half turn to see if it helps? any thoughts? Thanks in advance.

I would not advise touching or even adding a moisture screw!
If you mean ,the mixture screws;then that would be a possibility, but paint burning off header pipes is not an accurate method of determining mixture settings which only apply at idle.
Even with a laser thermometer;multiple readings must be taken to determine an average.
The water spray method is only used to help diagnose which cylinder to concentrate on when an engine runs very roughly.
Carbs that are syncronised (balanced) with the correct air screw settings may still need adjustment from standard to run smoothly; each engine is individual,depending on components.
Hard to tell from that pic,but has the no.4 header a more severe bend than no.1.(constriction will cause heat build up)
If the carbs have been stripped in the past,perhaps no. 4 jets are transposed from an inner cylinder.
Has this been ONLY run at idle since painting;if not; paint discolouration is irrelevent to mixture settings.

I would certainly use a IR Temp gun about 2" down each header just to check. It may be hotter, it may not be. Might be a thinner section of steel there - could be several reasons why. A IR Temp gun can help you at least understand what is going on.

As wilandrip stated, the IMS or Idle Mixture Screws are to control the A/F at idle.

If you find that the temp is higher on that exhaust at idle, then you can certainly back off the IMS for that cylinder a turn and re-check with the IR gun. Results are fairly quick.

just need to get my hands on a IR gun, thanks guys ill let you know how it turns out.

Do you have a crayon or a candle?

Warm up your Bike & touch each of the primary tubes with the wax. Start towards the tail-pipe end & work your way forward till you find the spot where it begins to melt. Make sure you have a rag to wipe it off right away. The wax should melt at approximately the same place on each primary tube. If one melts much further back than the others, you have a lean cylinder.

There are special "Crayons" that are designed to melt at different heat ranges. I think you can find them at a welding supply store, but you can make do with just regular old crayola or candle wax.

~JM~

Sounds like a good idea, thanks ~JM~.