effects of running lean?

[snowbeard]

so I know I'm messin with a good thing, but I can't help myself. At least I've done it in a reversible scenario

So I got an old GS650GL set of pipes, headers and cans, but someone had already hacked off the ends of the cans to make them "open"


this produces a megaphone effect that is f'n loud!!! embarassingly so, really. I did post about it but I think I left it sit too long and it got popped from the forum.

anyway, I have finally cut all the can section off and added on a set of harley aftermarket add-ons (I can only assume they are after market, but they are hardley) they are the ones that open flat off the sides. (top left of pic)


I got it all together, and some makeshift hangers on them. I cut slots in the ends of my header set,

then the inner pipe fit into the hardley pipes, with them then fitting inside of the chromed section of my header set. with the hardley clamp I was able to stuff it all together in a fairly solid fashion.

however I am in no way under the impression I have a solid seal there, it will leak as is, but I will deal with that eventually.

When I ride it sounds good, maybe a little louder than I want still, but in a good way. It does however backfire and pop a lot on deceleration, it does this slightly with the OEM pipes, but much less so and softer of course...

I can only imagine that these pipes will have more air flow, leading to a lean condition in general but ...


here is the big question: what sort of damage will I possibly do to the engine if I run this way for too long?

I've gone to great lengths to protect my baby, being able to fully restore her to original condition. I don't really care if these pipes blue, or really what happens to them, but I don't want to actually damage the engine...

also, if anyone has any suggestions on maybe packing these new pipes to reduce the flow and sound just a little, bring em on!? I'd like to get a volunteer or two to listen to it and tell me if I'm being obnoxious too.

thanks everyone!!!

[wharrah]

initially you'll get bluing of the chrome of your header pipes...the temps of your exhaust will skyrocket due to lean-ness of the mixture... richer the mixture, the cooler the burn.

And, if left that way, over time (anywhere from a few days to weeks) you'll end up burning a hole in a valve, or a piston.

Bad smoke will then happen.

[RobGS850L]

Yeah better a little rich than too lean. Do like Mikuni says. Take it out and give her a full throttle blast and after you get up there in rpm let off and see if she picks up in rpm. Let off slowly and you'll see what I mean. If it feels like it's picking up speed even though you're letting off you have a lean situation. Surging under a cruise situation is also a tell-tale sign of being lean.

[bradleymaynar]

I posted a similar question a ways back. My muffler had fallen off (don't ask me how, it's one of those mysteries) and I was running with an open header. Loud, but the performance definitely suffered. My question here was if I'd be okay to ride it until a suitable replacement had been found. The answer was "NO". By running it open I was taking the chance of holing a piston since it was causing an extreme lean condition.

Now I know you're running with mufflers in place, but if you have a lean condition, you need to richen up the mixture.

As for the popping on deccel, it could be due to the leaks around where the headers and can meet. Another possibility is synchronization. I'd check the synch first, and if it's fine, then work on sealing up the joints.

I'm not sure where to go or what to use for packing material, but I'm sure a search on line will get you some answers.

Brad bt

[Road_Clam]

Exhaust poping on decelleration is from two reasons. Reason #1 is lean pilot jetting. Reason #2 is exhaust header gaskets (or a pipe joint) not sealing properly, and sucking air..

[snowbeard]

well I know it runs pretty well with the OEM exhaust, she could use a synch in real life.

how would raising the needles do for it? how hard is that on our carbs really? could it be done by pulling the tank and accessing the diaphrams from the top, or would the whole carb rack hafta come out? is that even enough or would it need new jets?

I'm pretty sure it runs a bit rich in general, I can often smell almost raw gas at stoplights... but the plugs with the OEM are a dark-ish brown.

[snowbeard]

so I drove it to work today, is-miles with a few on the highway Temp were below freezing on the way there, a bit above going homeIt only backfired after a particularly hard gassing followed by an imediate shut down. No surging at cruising speed, and the pipes are no different (but that could be the wind/ cold)

so the leak in the exhaust, would that mimick the lean condition, or does it induce leanness itself? I know its not well sealed, there's a huge gap right under my heel.

I appreciate the advice even tho I know many of you disagree with the mods route. It's all part of my greater understanding of the combustion engine8-[

[SqDancerLynn1]

Your best bet to get a leak free seal is to completely cut off the old muffler & have a short pipe made to connect to the muffler

[snowbeard]

that's a good point, I could take off the whole connection there where it's dodgy and weld on the right diameter pipe to take the HD end... I did find a whole sportster exhaust system in the recycling bin last week, that's where I got the clamps...

any thoughts out there on increasing the baffling capacity of this set up? maybe packing something into the new can before attaching it? glass wool maybe? what does that actually do? is it supposed to make it louder or is that just if you replace the baffles with it... ( I think of glass packs on a car being louder, but would it reduce the noise if used with the existing baffles?)



so if I'm riding in very cold conditions, could I hole a piston without bluing the pipes?

so many questions...