Exhaust/carb jetting question

[Lucien Harpress]

My bike has been sitting in the shop for the past two weeks waiting for the guy to look at it, so of course I haven't been able to do anything with it. In the meantime, however, I wondered if it's possible to consider a thing or two.

Now, I've been having low-end issues ever since I bought the thing, and I'm wondering on the off-chance that jetting may be an issue. Here's a photos to help explain what I'm getting at.



As you can see, the exhaust isn't stock. Problem is, I don't know WHAT it is. From what little I know about these bikes, I know that the exhaust and the carb jetting is inter-related. I'm just wondering if the PO switched the exhaust and never re-jetted the carb. Or if you even have to with these types of exhausts.

So, my question is two-fold.

-Can anyone here tell what kind of exhausts I have (it's a 4 into 2 setup) just from this photo?

-If so, what kind of jets should I be looking at using for that setup?

I probably won't be able to do anything until I get my bike back, but when I do I'm 90% positive I'm going to be going back through the carbs again. When I'm in there I can see exactly what kind of jets I have (I'm not sure what they are right now) and see if they're the right ones.

Really this is just something to do while waiting to get my bike back (although I'm GOING to call the guy at the end of the week if he doesn't call me). Thanks in advance.

[psycoreefer]

Sure jetting "could" be an issue, problem is its impossible to say without knowing what jets are in the bike now... Do you know if its got the stock air filter or a KN washable type?

Usually you wouldn't need to re-jet swapping out the stock exhaust for a different 4 to 2, but that doesn't mean a PO didn't do it anyways....

[jmnjrpa]

Like the bike! Not sure how much help I can be though. The pipes look like they were a conglomerate or off one of the newer touring bikes (read large like HD or Honda). Yeah I know, that sucks in the help department. If the pipes have no baffles or restrictions it will be difficult to tune well. I believe the low RPM will be rich and high will be lean. I hope I have that right as I am delivering this from this site. There are far more competent people here than I profess to be.

[Lucien Harpress]

As I said, I'm not an expert on these bikes. I'm just learning as much as I can to stay one step ahead of my problems.

My engine issues are more than likely due to crap in the carbs, or crap from the gas tank getting into the carbs. I'm just trying to figure out (when I get into the carbs again) what jets I'm "supposed" to have in relation to my exhaust setup, and was curious if this was possible via photos.

As far as I can tell, my airbox setup is completely stock, along with the filter. It seems to be an older style (if that helps any).

[Larrym]

Exhausted?

Lucien,

Pic really helps to ID the pipes.

Looks like the standard header pipes with the original mufflers cut off, a set off chrome "glass packs" welded on, and a set of "resonators" welded to the back of the glass packs.

The glass packs are a straight flow through with no baffles. This means way less restriction and back pressure when compared to the stock set up. Better air flow through the exhaust but with a tendency to "pop" in deceleration and and "bellow" under acceleration.

The resonators are a nice touch! They extend the exhaust past the bottoms of those bags and direct the hot gasses down where your hard bags won't get cooked while you're sitting at those stoplights. The resonators take those pops and bellows from the glass packs and give them a lower "hollow" sound. I bet it sounds very nice.

Performance wise, with this set up you're gonna be running a tad lean on the middle/top end of the RPM range. At the lower RPMs this set up isn't going to require changing idle jets but the idle mixture screw adjustment will be different from stock.

Going one size up from the stock mains will likely Appease the Gods of Combustion. As a bonus of your set up, you can get a read on your "Lean vs Rich" situation by looking inside the ends of those pipes: grey/white=lean, tan=perfect, brown=rich, black=over-rich.

Compare the spark plug readings with what your pipes are telling you and you'll see no major difference. I mean, what color are the insides of those resonators right at this moment?

Does your set up still use the crossover between the two sides? (Usually runs under the bike near the center stand...)

[Korr]

I was about to say that those pipes are a home made custom job attached to the stock pipes, but Larrym beat me to it and he used way more smarts and know how to boot

[Larrym]

FlashBack.

My years at Meineke Discount Mufflers coming back to haunt me.

[Silent]

To my eyes that really resembles a Dayna muffler I just put on my bike, except with the added resonator at the end of course. The shape is about right on the center section.

[Larrym]

I'm Baffled. Are you??

There's no way to tell from the pics if the mufflers you have are the "glass pack" type or the type which uses baffles. If the mufflers were off and you looked inside a set of glass packs you could see straight through to the other side. If they were the baffle type then you would not be able to see all the way through as usually the design calls for a pipe inside of another pipe.

This could be important as the mufflers with baffles come a lot closer to providing enough backpressure and make changing the jet size unnecessary most times. My set up uses slip on mufflers with baffles so I didn't have to fuss with the jets.

The disadvantage of the muffler with baffles is that these types can actually become plugged with carbon and/or oil. This adds to the backpressure and can really cause a loss of performance.

Is there a make/model ID on those mufflers somewhere?

[oseaghdha]

Whatever they are.......

With that much pipe, stock jetting would probably work fine.

Jets are not going to affect the low end much at all. You would see a difference at speed, not idle.

You ran the thing, then it went crap on you.
Look elsewhere, like the pickups/coils/plug wires.

[Lucien Harpress]

Thanks for the info, guys. As I said, it's really tough to check exactly what all the components are because the bike isn't in my posession at the moment. Which reminds me, I need to call the shop that's holding it....

My brother thought it had glasspacks when I brought it home. Unfortunatly, checking them is going to be difficult- the PO welded everything together. Not just that, but he WIRE welded it. It looks like $#!%, but I don't have the time or money to do anything about it right now.

The sound isn't bad once you get up to speed. At the low RMPs it sounds a bit like a boat, but that's minor. If I do any changes to the exhaust, I'd like to see what four individual exhaust pipes would sound and look like. I know a guy who can do custom exhausts, and has before, so if I ever decide to do that, I'll have options available.

Well, it's good to hear that there's one less thing I have to worry about. Now, I just have to get the bike fixed (maybe), back to my house (definitley), and back on the road again ASAP (goes without saying)!

[Larrym]

Missing Bike?

When you get the bike back from the shop you'll be able to look at the insides of the resonators.

I have a set of glass packs on my truck and with the standard jetting I see the inside of my pipes aren't grey/white. Light tan so I left the jetting alone.

I agree with oseaghdha about the low end performance cause/fix. That is if there's a genuine problem there. My bike doesn't raise the front end off the ground when I crack the throttle at below 3k rpms. But it doesn't bog down like I put on the brakes when I twist the grip either.