Differing exhaust pressures...?

[JFISHSOLEVIBE]

So as I work my way trough the kinks on my GT380, there is one that I can not nail down yet and need some guidance.

I mentioned this in a separate post, but when I hold my hand over each exhaust pipe while the bike is running, the pressure exiting the pipe feels hearty and strong from the left cylinder, the center although split into two feels the same, the right however feels more like a continuous hot breathe and smokes a bit more than the others.

Compression is consistent between all 3 cylinders, and the carbs are synced and equal.

It is the stock exhaust which I did replace the baffles in about a year ago (6-7000 miles ago).

The ignition is the Newtronic electronic ignition which of course I recently timed to spec.

I heard it suggested that the right pipe may be deteriorating inside, but could there be any other causes of this? The bike seems to be running good, but my guess is that whatever the issue is, is in fact having some type of effect on performance, it would have to right?

Could it be spark energy? Coil? I'm stumped!

[tz375]

It could be almost anything but I'd start with that muffler. Remove the muffler and baffle and see if one of the baffle plates has collapsed and partially blocking flow. It's also possible that you have rodent nests up the front section of the silencer.

See what you can see of feel in there- use a length of stiff wire or similar to probe it from both ends like and upper and lower GI tract inspection....

[Alan H]

Turn the tickover up a tad on the right carb.
I reckon it's not set correctly so 'only just' firing on tickover.

[yeadon_m]

+1 what Alan says, provided the sound the two outers make when you rev it up are the same. If they're not, back to what TZ suggested as well.
Mike

[Coyote]

From cold, start the bike and run it for 20 - 30 seconds. Kill it and feel the pipes. The cylinder that's not keeping up will be markedly cooler. I suspect in your case that would be the right. Had a very similar issue with my 550 cafe. Finally after trying everything else multiple times, I shucked the stock resistor caps and replaced them with the non resistor type. Instantly cured.
NGK only makes one. Their part LZFH It's a right angle cap. It looks small due to the absence of a resistor. Available at any auto parts store. Seems like the price for all three was about $8.
OR: http://www.ebay.com/itm/like/131252105911?lpid=82" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

[JFISHSOLEVIBE]

Coyote, believe it or not I did this! I also used the b8ex iridium plugs. Definitely helped overall performance but didn't remedy that right pressure :-/

Are you still using the regular plugs or did you go to the iridium style?

[Coyote]

I sold that bike. My GS1000 uses standard NGK B8ES

[pearljam724]

Timing being slightly out of adjustment compared to other cylinders is a common cause of different exhaust pressures. I found not relying on static timing finally corrected that on my 750. But, as stated previously. It can also be caused by a few other things. Long story short, had an ignition gremlin on RZ 350 for about a month before I tracked down the problem. An ignition ground being pulled from it's solder inside the ignition switch also caused varying exhaust pressure on it while the bike was idling. Once I fixed the ignition, it never had that exhaust behavior again. Which was very evident before I fixed it. Before, I fixed it. I was leaning toward the cylinders needing rebored. I was wrong. Keep in mind, that ignition / timing and spark are all related to this behavior. So, I would focus on those three things.

[JFISHSOLEVIBE]

I was thinking the same, too. Timing or spark. I did just recently set timing with a dial gauge, so as far as that tells me, timing is dead on. Plugs all show a perfect burn on each cylinder, no indication on the plugs of any funny business. My ignition is the Newtronic electronic kit, so no points. I will check all of the connections to make sure nothing is lifted or jumping just in case.

Are you using the electronic ignition as well? What am I missing that I should be looking for considering the above?

[tz375]

Did you take the pipe off yet to check it?

[JFISHSOLEVIBE]

Not yet. I'm thinking that that's gonna be the problem. I'm going install the set of chambers I have this weekend and see what comes of it. Hope that closes the book on the problem!

[pearljam724]

Not yet. I'm thinking that that's gonna be the problem. I'm going install the set of chambers I have this weekend and see what comes of it. Hope that closes the book on the problem!

Could be the exhaust baffles like Richard said. You'll find that varying the timing a degree or two. Will change each cylinders exhaust pressure. Depending on the adjustments. I would triple check electrical connections and grounds related to ignition and spark. I would also change the coil lead boots. The metal piece inside the boots that hold the boot to the plug have 2 wired clips that hold the boots onto the plugs on some designs. Those clips often get bent out of shape and no longer hold the connection firmly to the threaded end of the plug or resistor cap. That causes a bad ignition and spark connection. Check to see if there is slop in the boot when it is attached to the plug. The boots simply twist off the lead wires. Make sure there is a good clean connection with the leads wires attaching to the boots. Could have a bad resistor inside your boot as well. If your boots have them. Which most do. Could have a leaking exhaust around the exhaust gasket. That can be observed by oil leaking down the headers. Put some heat resistant RV silicone around the collars and let it dry. Or properly adjust the collars to prevent leaking. Could be early signs of bad crank seals. Prior to my seals giving up the ghost. That cylinders plug always read leaner than the others. Regardless, of any air fuel adjustments I made. Then it started puking crank oil out the breather when it was toast. Check engine cavity often for crank oil.

[Glyn.G]

Hi,
Exact same thing happening on my 380. Left and Middle cylinders are producing a steady blast of exhaust pressure, but the Right exhaust is producing less than an asthmatic gnats cough ! I took off the offending silencer and found it had a definite rattle inside, probably a baffle plate floating around in there. Got a full set of Higgspeed expansion chambers due at the end of this month so hope it cures it.
I also checked the timing and points gap but all seems fine. Nice colour on the plugs too.