Carb adjustment: new air filters and exhaust

[andrewraffaele]

Dear all,

My bike is a completely stock 78 XS1100 standard. I would like to yank the air box and replace it with individual filters (velocity stakes or pods). I'd also like to pull the baffles out of my pipes (4 to 2). How will I need to adjust my carbs? Are there any other pitfalls I'll run into with such big changes to my intake and exhaust?

This is my second XS, my first is in LA. The LA bike earned 6,000 miles in a month last summer. Took it from Chicago to northern Michigan, to Chicago to LA. Sadly, it's in poor shape now. I love these bikes, and don't want to destroy my low mileage bike that's here in Chicago with me.

Gentlemen, your thoughts are greatly appreciated, any body know some body in the Chicago area willing to do Carb work?

Thanks kindly,
Andrew

[motoman]

Are there any other pitfalls I'll run into with such big changes to my intake and exhaust?///
Guess it's alright if you don't mind the power loss and tuning nightmare. You'll only be able to tune it to run correctly at one end of the power curve or the other. Those engineers across the west pond were way better at gettin' the most out of these scoots. Not gonna inprove on that and guttin' a perfectly good stock exhaust or any other one for that matter WILL result in a major power loss and will NOT be tunable. Know that may be not what you wanna hear, but it IS the facts.

[CatatonicBug]

My thoughts?? Don't do it!!

You're just asking for trouble. If you have the stock exhaust, you have the very best-tuned pipes available for the bike. Removing baffles will not only destroy performance (the engine needs the back-pressure to run correctly), but it would also destroy a perfectly good set of very valuable pipes.

The airbox thing is debatable, but replacing a good airbox with pods usually leads to more frustration than anything else. I'm a bit of a purist, so I admit I am biased, but if you have all the stock components, keep them. Trying to swap them out for other items will just cause you headaches.

[XS1100_OEM4ME]

+1

+1 Motoman, unless you are planning a top end only drag bike, you will not get a better all around better preformance then the stock pipes IMHO I know looking at those two little holes on the ends, it seems like they would be slowing you down, but these bike work best with the "tuned" back presure that they designed into the whole package The pods will make R/I of carbs easyer, but you won't notice much gain in HP IMO

Are there any other pitfalls I'll run into with such big changes to my intake and exhaust?///
Guess it's alright if you don't mind the power loss and tuning nightmare. You'll only be able to tune it to run correctly at one end of the power curve or the other. Those engineers across the west pond were way better at gettin' the most out of these scoots. Not gonna inprove on that and guttin' a perfectly good stock exhaust or any other one for that matter WILL result in a major power loss and will NOT be tunable. Know that may be not what you wanna hear, but it IS the facts.

[bikerphil]

Jetting guide...

http://www.xs11.com/forum/showthread.php?t=382

[andrewraffaele]

Dear all,

My bike on the west coast runs pods and a 4 into 1 straight pipe. Ya might think I'm full of it, but that bike feels like its got a hell of a lot more torque. Maybe it's tuned for the bottom end, it does loose a bit of power around 70mph in 5th gear, I always have to give it a bit more gas to push through.

Also, I swear the LA bike is better on gas than the bike I have with me in Chicago. Last week I burnt through a half tank going the 52 miles between the previous owner's place and my house... The west coast bike gets better mpg than 20.

Thanks for all the thoughts, and I'd like to offer my apologies. I know it kills all you purists to hear about stock bikes getting altered.

Andrew

[natemoen]

I will trade you a set of headpipes for your stock exhaust. Then you can weld on any muffler you want.

[cywelchjr]

Dear all,

My bike on the west coast runs pods and a 4 into 1 straight pipe. Ya might think I'm full of it, but that bike feels like its got a hell of a lot more torque. Maybe it's tuned for the bottom end, it does loose a bit of power around 70mph in 5th gear, I always have to give it a bit more gas to push through.

Also, I swear the LA bike is better on gas than the bike I have with me in Chicago. Last week I burnt through a half tank going the 52 miles between the previous owner's place and my house... The west coast bike gets better mpg than 20.

Thanks for all the thoughts, and I'd like to offer my apologies. I know it kills all you purists to hear about stock bikes getting altered.

Andrew

That points to something wrong with the Chicago bike, cause it should get good low end torque and do well mid range and really wake up at the top end, and should get a LOT better than 20 MPG, my basically stock (at least as far as air box with unmodified aftermarket exhaust considered to be one of the closest to the stock OEM system) gets about 29 on short hops around town (where it just gets fully warmed up on runs regularly) and road runs have generally run between 37 and 40 MPG (the road run mileage is pre FD swap, the around town is post) I've not gotten on the road measures since swapping the FD as all the road runs I've had planned have ALL fallen through and I've not gotten a full tank on the road, but the FD swap seems to have given a good 2 or 3 MPG boost on the road, that is if I don't go pushing the speed hard and overcome the plus of the FD.

[cywelchjr]

Dear all,

My bike on the west coast runs pods and a 4 into 1 straight pipe. Ya might think I'm full of it, but that bike feels like its got a hell of a lot more torque. Maybe it's tuned for the bottom end, it does loose a bit of power around 70mph in 5th gear, I always have to give it a bit more gas to push through.

Also, I swear the LA bike is better on gas than the bike I have with me in Chicago. Last week I burnt through a half tank going the 52 miles between the previous owner's place and my house... The west coast bike gets better mpg than 20.

Thanks for all the thoughts, and I'd like to offer my apologies. I know it kills all you purists to hear about stock bikes getting altered.

Andrew

Oh, another point, give me a bike the same year as mine with about the same level of dress, with mine essentially stock and that bike with nothing done performance wise but pods and straight pipes, and overall performance wise, I'll wipe the road with him. His might work better at the bottom end or the top end, but given a riding course that needs to use the full power band of the bike, the bike with the stock exhaust and intake will win every time.

[BA80]

Cy is right. Sounds like the carbs aren't right, valves are out of adjustment, or the brakes are hanging up.....or all of the above.

Of course that is assuming it's hitting on all 4 cylinders.

[andrewraffaele]

All four hammers are hitting, the bike had no troubles accelerating quickly on the highway. Also, the brakes are properly adjusted. I've had no problem wheeling the bike around with just the power of my legs.

That said,

Carbs probably need a bit a tunin'? Once more, Anyone know an XS guy in Chicago who does carb work? I'm not looking for a handout, I just don't want to take it to a shop.


Andrew

[bikerphil]

Andrew, do whatever you want, it's your bike. I used to run pods and 4-1 exhaust and it ran fine. Just a little low end loss. You'll probably pick up a little low end with 4-2. Need to be a bit more patient when tuning, you can find the information here.

[crazy steve]

There's no 'right' answer here, but there are a bunch of wrong ones....

With very careful, painstaking tuning you can eke a bit more power out of these with pods and a 4-1, but as Phil said, with a low-end loss. For most, you'll stay the same or even lose some. Unrestricted exhaust is a real no-no if you expect any sort of decent street performance though. You will have a bit more latitude with a 4-1 over a 4-2 setup, but you still need some backpressure.

Fuel economy? Yes, you should be getting much better than 20 mpg unless you're beating the holy hell out of the bike. Even in traffic, you should see something around 30 mpg give or take a bit. As far as doing the carbs, this is something that can be tackled at home, even if you've never done it. There's been plenty of horror stories from owners who paid to have their carbs rebuilt, and after shelling out big money, more often than not ended up redoing them themselves to get them right.

[XS1100_OEM4ME]

Andrew

Hey, +1 on Phill's "its your bike" you can go stock, mod, rad or even trike and we will still try and give any advice we can. I had 4 into 2 Mac's on mine when I got it and it sounded great I just had pop's and stuff that I couldn't tune out, switched to stock and big improvment, not as loud, but runs much better and way easer to tune. If you like something else, that is cool, whatever puts a smile on your face

Dear all,

My bike on the west coast runs pods and a 4 into 1 straight pipe. Ya might think I'm full of it, but that bike feels like its got a hell of a lot more torque. Maybe it's tuned for the bottom end, it does loose a bit of power around 70mph in 5th gear, I always have to give it a bit more gas to push through.

Also, I swear the LA bike is better on gas than the bike I have with me in Chicago. Last week I burnt through a half tank going the 52 miles between the previous owner's place and my house... The west coast bike gets better mpg than 20.

Thanks for all the thoughts, and I'd like to offer my apologies. I know it kills all you purists to hear about stock bikes getting altered.

Andrew

[DiverRay]

First, check to make sure you still have the '78 carbs! The '80 up have an "O" ring on the seat for fuel inlet, and they WILL leak and cause poor mileage.
Second, go to ebay and geargefix. Tell him what year you have, and follow the table for the mods and he can set you up with a GOOD rebuild kit for about $85 for all four carbs. This will have the jets and pilot jets you need, and THEY WORK!.
Third, look at the card rebuild section on this site, and spend about three hours going through the carbs yourself. It's NOT rocket science, I know, I worked with NASA and JPL people! The jetting chart will get you very close, and the rebuild will keep the fuel flow correct.
IF the "new" bike is NOT a '78,, DO NOT EXPECT the same bike! They have been de-tuned to meet "smog" since '78, and do NOT run quite as well. At the same time, I've ONLY gotten 20MPG when the carbs were pouring fuel into the engine.