Been afraid to ask..
 

My bike seems to favor the left exhaust. At idle the left exhaust puts out scalding heat and the right one blows out tepid air. There is no rag in the pipe or anything like that. Is that just a product of the headpipe design? When you wing the throttle it is different.

Totally normal and nothing to worry or be concerned about.... ;)

have you synced the carbs.
if not,than i would suggest to do the sync.i had simular problem.once i re-synced,it was fine.the rear will run hotter.
it wasnt perfect,cant tell in the cold,but when its correct,the rear head will be a little hotter anyway due to its lack of air flow to the head.

I don't think it has too much to do with the sync or the rear running hotter (actually at idle it should run cooler in the rear so that when the front is air cooled they are both pretty equal).

This confused me for awhile too... try touching the header right where it comes out of the engine block though, both sides will singe your prints right off!

I am working up to a carb sync. I have the gauges and an extra "boost joint" and some t fittings. Looks like I have to pull the air box to set it up. Pain in the dick.
And yeah the headers are hotter than hell so I know they both fire.

I would think its because the front cylinder exhaust fumes have to travel through a greater distance of exhaust pipe, and that pipe is more open to cool easier as it is not curved around the rest of it like the rear is.

That was the best guess that I could come up with as well.

Ok guys..... the exhaust is 2-1-2 so both pipes "see" both exhausts.

Without getting into too much theory or technical stuff, this is what is going on.

At idle and low RPMs most of the exhaust gasses flow through the left pipe (from behind the bike) then as the RPMs (and exhaust pressure) rise the right pipe starts flowing more.

This is common and normal for this bike. Doesn't matter if you have the stock cans or slip-ons (Full systems can work different and would need to be discussed on a case by case basis).

Anyone on here can try it out, while the bike is idling, put your hand over each exhaust outlet, the left will be noticeably hotter than the right.

Haha, we could have kept going with our guesses... you should have let us chase that goose around a little longer ;). I was almost sure that it was when your muffler bearings wear out.

Yeah it looks like the main exhaust flow would mostly go right by.

That's one of the first things I did after adjusting the Johnson rod.

Yeah and a lot of folks went on and on about poor build quality and how could Honda do something like that and many recommended to remove the "restriction"..... and yes I did remove the one in mine..... around a week before Dan Kyle posted his dyno runs where he showed in back to back runs with the only change being the "restriction" removed and guess which one made more power??

Yep, the stock set up with the "restriction" in place.

The restriction
 

So, as I have read on here in the past, that some grind out that restriction where the pipes go 2 into 1.
Did the factory then leave that extra pipe overlapping the hole in there for a reason? Assuming that as pressure rises in the pipes, the gas flow evens out as 8541Hawk suggests. Where as if the restriction were not there, would it effect the gas flow adversely?
Just curious, Thanks.

Well at idle the flow is still mainly through the left pipe at idle with the restriction removed.

As for if it was there for a reason, I did answer that in the post before yours and the answer is yes it is there for a reason.

As I am really trying not to make this to technical I'll try to keep it as simple as I can.

It has to do with back pressure and the large exhaust pulses a v-twin generates.

The easiest way to understand the exhaust system on these bikes is think of it as a 2-1 system with a relief valve.

The gas flow is designed to exit the left exhaust until the pressure rises above a set point and then it makes the turn and exits the right side so the exhaust gas pressure doesn't rise above that point.

This is the reason why 2-1 systems really don't work that well on this bike.
They are fine down low but at higher RPMs you end up with way too much back pressure because of the 270-450 firing order and the large gas pulses.

And, unfortunately, once again I did not see your reply while I was writing up mine, even though yours posted 12 minutes earlier. I obviously need to think and type faster.
Thanks much for your previous reply to mine.

Well I'm glad now that I did ask.



I'm thinking I have a great bike for the miles. Like that 50y old chick at the bar that still looks pretty good. And not even smoking.

But I bet you she has a few hidden leaks :D