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Post by wildcard on Jul 30, 2012 23:27:13 GMT -5
i am going to build a 2 into 1 pipe for my 1980 xs650. i am doing it to get a power gain. any idea on how much of a gain i will get and will i need to rejet the carbs or change anything else? everything is bone stock right now. Attachments:
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Post by XS Rod on Aug 1, 2012 8:45:01 GMT -5
Gain? news flash bro... you could lose power. Pipe diameter and length are contributing factors as well as each bend and radius... it's a bit of a science... suggest some reading on the subject.
You need to do more than exhaust to get these engines to "open up"... gotta work on the inhale as well as the exhale.
Good luck... keep reading... you'll get there.
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Post by wildcard on Aug 1, 2012 17:19:04 GMT -5
my plan is to blow a hole in the right pipe with a torch then turn the left pipe into the right one and weld em up. just gotta make shure i can still unbolt and pull em off as 1 unit.
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Post by XS Rod on Aug 2, 2012 14:15:40 GMT -5
K...
Just my opinion here and assuming some aspects of your intended confiuration... if you take the stock exhaust and weld one header into the other header with no collector and use one of the two mufflers... I think you will see a decrease in performance.
Fellas, my experience with stock exhausts is limited to the standards... are these pipes twin walled on the Specials? Since I've never seen a pair of them turned blue I'm assuming they are... if so that's gonna impact your weld process bro...
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Post by headcase on Aug 2, 2012 20:03:41 GMT -5
My '79 has the factory originals on it, and yeppers, double wall. You're gonna have to get pretty creative with the hot wrench to get it all to stick together. You'd have to open up the chrome outer tube wide enough to get whatever welder you're using far enough inside to weld the inner pipe, then patch the outer back up. The aftermarket 2-1 headpipes are at least equal length before they merge. Chances are good that wherever the cut pipe hits the other one, they're not going to be equal length. If not, then you're talking a different setting for each carb. My guess is you'd kill power, if not more. Then again, it may run like a scalded cat with a lit cherry bomb up it's wazoo.  |
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Post by wildcard on Aug 2, 2012 22:58:04 GMT -5
thanks for the input guys. as soon as i get a chance im gonna pull the pipes off and see what i can come up with. i already have a bike for loudness and flash.(2002 750 honda shadow ace bobber project) so the paln behind the yamaha is to keep her mostly stock but get some power out of her to. its already a fast stock bike for the year and cc but i want more power.i did 90mph in 4th gear at 3500rpm shiftin at around 4000rpm. i wanted to push it more but she started to wobble bad.
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Post by XS Rod on Aug 3, 2012 9:07:44 GMT -5
Headcase... well put bro... i like the creative with the hot wrench...  Wildcard... these motors with the right mods and in a well state of tune... will pull like a freaking freight train, in my loving opinion this middleweight will punch out anything in it's class and quite aways up the food chain. Yo... the right mods and the right combination of them. Tons of good info right here and all over the net... read and ask bro read and ask... We see em all the time... poor wretched machines all cut up with wires twisted together, scarred frames, neglected suspension. Machines that even if it did fire up i'd be way to smart to go blasting off on... rat bikes... don't turn that nearly complete machine into a rat bike bro... we'll hiss and boo all the way. |
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Post by headcase on Feb 22, 2013 0:34:52 GMT -5
we'll hiss and boo all the way. Probably a good thing forums don't have audio and video, right? Can you imagine how many expletives and one finger salutes would escape? And I'm still waiting for the courage to bring up the custom flex-tube exhaust idea that refuses to leave my brain. I hang my head in shame every time I think of it. |
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Post by grizld1 on Feb 22, 2013 10:00:51 GMT -5
If you're after performance with minimal mods, forget about making a 2-1 out of the stock head pipes. For one thing collector dimensions are critical, and you don't have a clue about how to design the collector. The tried and true best system for street performance on these machines is simple--1-1/2" OD headpipes between 34" and 38" long and free-flowing mufflers. And yes, you'll have to tune the carburetors with appropriate jets after any exhaust modification that produces more power (or even, in many cases, less).
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Post by headcase on Mar 25, 2013 17:20:52 GMT -5
Griz - How important is the exhaust crossover on these bikes? (Twin exhaust, obviously) I know on cars it helps with low rpm torque and keeps the machine gun rattle coming out the back to a dull roar, but does it make a noticable difference either way on the 650?
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Post by grizld1 on Mar 31, 2013 9:34:35 GMT -5
Sorry, headcase, I missed your post for awhile. IMO a crossover in a 2-2 system is nothing to fret about. You won't see it on a racing set for these machines or even on the very high priced Bub 2-2 pipes. If you use your ear at all when tuning, you're better off without the crossover.
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Post by headcase on Apr 22, 2013 19:55:27 GMT -5
Ears are the most important tool in the box most times.
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