Another Header Performance Thread

[Nessism]

How do you explain the 165 Mikuni Mains on a stock motor?

I don't know Jim but the test uses CO monitoring equipment as well as specific fuel consumption testing, and the test shows that the engine was not overly rich during the dyno pulls.

One thing I know is that CV carbs can be funny some times regarding jetting. Years ago I attempted to get an XS400 to run with pods but nothing I could do would make that bike rich enough up top. I even drilled out some jets to ridicules proportions yet the plugs still showed lean. Bottom line is that I'm sure those 165 jets were no doubt too large, but for some reason the engine wasn't pulling as much fuel though them as one would expect by looking at the number.

 

[posplayr]

I don't know Jim but the test uses CO monitoring equipment as well as specific fuel consumption testing, and the test shows that the engine was not overly rich during the dyno pulls.

Another thing I know is that CV carbs can be funny some times regarding jetting. Years ago I attempted to get an XS400 to run with pods but nothing I could do would make that bike rich enough up top. I even drilled out some jets to ridicules proportions yet the plugs still showed lean. Bottom line is that I'm sure those 165 jets were no doubt too large, but for some reason the engine wasn't pulling as much fuel though them as one would expect by looking at the number.

Too bad they did not have Bill to help sort the CV's out :-\\\

 

[49er]

Too bad they did not have Bill to help sort the CV's out :-\\\

Hey, that's a low blow, but very true!

 

[jimb12]

If they used the stock needles, that may have restricted flow, and explain why they put such oversized main jets in it.
Using an actual jet kit gave much better results if you'd read the info I posted. Looks like about 15% increase for the pipe/jet kit/pods combo. I don't have dyno charts for it, but performance on the dragstrip is a known quantity. Meaning it is known how much power it takes to move a given weight in the 1/4 mile in a given time and resulting trap speed. Also, this bike with the jet kit had the best carbureting CV's that I've ridden in fact. It was a win-win, better on the track and great to ride on the street too.

Nessism, keep in mind that this test that you're quoting, is just one test, and is certainly not the final word on GS exhaust systems and carburetion. Not saying my info is the final word either, but it was real, I saw it.

 

[Nessism]

If they used the stock needles, that may have restricted flow, and explain why they put such oversized main jets in it.
Using an actual jet kit gave much better results if you'd read the info I posted. Looks like about 15% increase for the pipe/jet kit/pods combo. I don't have dyno charts for it, but performance on the dragstrip is a known quantity. Meaning it is known how much power it takes to move a given weight in the 1/4 mile in a given time and resulting trap speed. Also, this bike with the jet kit had the best carbureting CV's that I've ridden in fact. It was a win-win, better on the track and great to ride on the street too.

Nessism, keep in mind that this test that you're quoting, is just one test, and is certainly not the final word on GS exhaust systems and carburetion. Not saying my info is the final word either, but it was real, I saw it.

The first article I referenced show a gain of about 2 hp (2.5%) with header/airbox lid off and this article shows about 5 hp (6.2%) with header/pods. Getting up to 15% is very find work indeed.

 

[Guest]

Great thread, Ed. And great posts, too.

So my Beast with 1085, ported head, degreed aftermarket cams and VM33's should run pretty good, eh? I need to get'er done!! And as luck would have it, I just met up with a guy in Reno that has a bike dyno. I am going to barter some work with him and he's going to help me dial in my carbs.

 

[49er]

Wanna bet?!!!! I have built them to run "coast to coast" reliable! Ray.

We are talking GS1150's, right? Are you stroking and boring, or just boring?

At 1400, just boring would not leave much support around the base gasket/crankcase mounts. Not saying you can't beef this area up too, but you're looking at combating serious distortion. What maximum CR would you consider reliable on one of your 1400 road engines?

 

[rapidray]

1100 or 1150, it doesn't matter. There is PLENTY of gasket surface for the base gasket & I consider about 11 to 1 the max compression, for the street, with the CORRECT set up followed. I rode a champagne colored 82 1100/1400 on the street, EVERY day for over 2 years in Hawaii! Not a single problem or leak! There are things you HAVE to do to make it work but it is DEFINITELY doable! Ray.

 

[49er]

1100 or 1150, it doesn't matter. There is PLENTY of gasket surface for the base gasket & I consider about 11 to 1 the max compression, for the street, with the CORRECT set up followed. I rode a champagne colored 82 1100/1400 on the street, EVERY day for over 2 years in Hawaii! Not a single problem or leak! There are things you HAVE to do to make it work but it is DEFINITELY doable! Ray.

Thanks Ray. Is that a no to you stroking them then?

 

[jimb12]

You don't need to stroke an 1100/1150 to get 1400+ cc as the stock stroke at 66mm is fairly long already, and the bore spacing is wide.
A friend had a 1327 flat top (10.25:1 advertised) in a resleeved stock block. It was a riot on the street, 3500rpm grab some throttle and up she'd come.

 

[posplayr]

I found that Matchless had uploaded the subject document.

http://www.mediafire.com/download.php?7malviyy2z3

 

[woodman]

Thanks for putting that article up, Ive been looking for it forever