stock carb question...

6fidi · Full Member Joined: Oct 19, 2008 Posts: 21

Does anyone one know the best set up for the stock carbs when running straight pipes.
Will straight pipes make enough difference to require a jet change?

Thanks.

oldskoolcool · Full Member Joined: Sep 08, 2007 Posts: 372

depends on elevation etc. I had to go up on the Mains one size on my 78. and thats it. i tried upping the needles 1 and it was super boggy. stock pilots too.

Romer · Posted: January 23, 2009, 11:36 pm Post subject: Re: stock carb question...

Check out the "Carb guide" on "xs650 garage". They have a good jetting section. But don't ask those guys too many questions.....they are kinda testy.

xsleo · Posted: January 24, 2009, 1:48 am Post subject: Re: stock carb question...

most of the guys on 650garage are good folks, just a few are testy.

xs1961 · Posted: January 24, 2009, 9:40 pm Post subject: Re: stock carb question...

No such thing as a 'best' set-up...All motors are individual & can be affected by the state of the internals rings/compression/ignition etc. as well as sea level/ temperature ..blah blah... Start rich (safe) and work down from there... Best to junk stock carbs if running open or unrerstricted pipes and/or non standard airfilters .. Wink

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

I'll admit, I get testy, especially when people want to run straight pipes. An engine really needs some back pressure in the exhaust to run best. These bikes are hard enough to jet right with aftermarket mufflers and filters. If you want tips for straight pipes my only advice would be to ask on some Harley list. The bottom line is straight pipes don't work very well no matter how you jet. If they did, we'd all be running them. In my opinion, the best exhaust set up for a twin is a 2 into 2 with long tapered megaphones ...... Conti's come to mind ..... probably the best sounding and most beautiful muffler ever made. And if you have to ask "What's a Conti?", well then run those straight pipes. Google Conti Mufflers, you'll see what I mean.

xsleo · Posted: January 25, 2009, 3:25 am Post subject: Re: stock carb question...

i agee 5twins. i have seen many bikes that ran great with a stock or slightly less restiction system. then someone screws them up with drag pipes. all the owners do is adjust the carbs and never get them right. but loud pipes save lives, or so they say. i have found that a good exhaust system can increase the low to mid range running and even help the top end some. and having a good low range throttle responce has gotten me out of more situations than loud pipes. i do like the looks of a drag pipe and there are systems for other bikes that look like drag pipes but have the right design to give good all over performance. so i think some one can build a good performing drag pipe looking system if they wanted to.

cpotts454 · Posted: January 25, 2009, 8:14 am Post subject: Re: stock carb question...

hey 5twins, I will agree to run Conti Mufflers when you agree to buy them for me. Wink

xs1961 · Posted: January 25, 2009, 8:50 am Post subject: Re: stock carb question...

I had Contis on my 1000S Guzzi once...Luverly...& pricey..

kyle1911 · Posted: January 25, 2009, 1:31 pm Post subject: Re: stock carb question...

Yeah...Rode a friends 1980? 79? Can't recall the year Hailwood Replica Ducati. Had Conti pipes on it, and some other performance goodies. I am not a big Ducati fan, but that thing was all about mechanical music. Back on topic... I wonder how much the shape of the muffler matters. Unless you are running with no baffles, it seems like it should not matter much. Megaphone, cone, reverse cone, etc. If they are all running the same baffle core, how does the engine know the difference? My STILL unfinished streetracker will put this to the test. 1 3/4" headers, reduced to 1 1/2" at both ends. The megaphones are straight, with only a couple of inches of steel wool at the end. "See, Officer, there is packing in these mufflers!" I agree that backpressure is required on some engines, sometimes, in some ranges. If megaphones are unbaffled, I can visualize some expansion chamber effect, with length being critical... I never pursued math, but I do enjoy studying this stuff. A large bucket of compromise, all the time. Check out the King's exhaust in this old pic. Almost every pic I have of his old bikles, the pipes are radically different. Yamaha must have been really pulling out the stops on pipe research. These almost look like servo controlled valves...??? Maybe i am seeing things, maybe some of the "Old hands" on here know? I am curious!Kyle

Romer · Posted: January 25, 2009, 4:22 pm Post subject: Re: stock carb question...

5twins, what do you think about JC whitney cheapies and stock jetting? Do you think that would give enough back pressure?

6fidi · Full Member Joined: Oct 19, 2008 Posts: 21

5twins wrote:

I'll admit, I get testy, especially when people want to run straight pipes. An engine really needs some back pressure in the exhaust to run best. These bikes are hard enough to jet right with aftermarket mufflers and filters. If you want tips for straight pipes my only advice would be to ask on some Harley list. The bottom line is straight pipes don't work very well no matter how you jet. If they did, we'd all be running them. In my opinion, the best exhaust set up for a twin is a 2 into 2 with long tapered megaphones ...... Conti's come to mind ..... probably the best sounding and most beautiful muffler ever made. And if you have to ask "What's a Conti?", well then run those straight pipes. Google Conti Mufflers, you'll see what I mean.

I'll admit I get testy with selfrightcious angry little men who have to lend an air of attitude. If you want to express your opinion do it like an adult and not like an angry little boy. get a personality. And if you have to ask.."Whats a personality?...well then run that mouth cuz nobody gives a bleedin f***.
Thanks to all of you who answered with tact and respect, it is greatly appreciated.

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

6fidi .... I may be angry and I may be little ..... but 19 posts and now you're an expert on 650s or forums in general? I don't recall using the "F" word in my post but I think I saw it in yours. Good luck jetting your carbs, you're gonna need it. I stand by what I said. Straight pipes are a racing thing and have no business being on the street. If you're so offended I would think you might consider the offense your pipes might have to the general public. Motorcyclists have a bad enough image as it is without guys running straight pipes on purpose.

650skull · Support Staff Joined: Jul 19, 2007 Posts: 1186

[quote 6fidi] I'll admit I get testy with selfrightcious angry little men who have to lend an air of attitude. If you want to express your opinion do it like an adult and not like an angry little boy. get a personality. And if you have to ask.."Whats a personality?...well then run that mouth cuz nobody gives a bleedin f***.
Thanks to all of you who answered with tact and respect, it is greatly appreciated.

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