650L Jetting Questions


2 replies to this topic
  • quicksilver

Posted December 13, 2007 - 03:48 PM

#1

I hunted for these answers quite a bit before I started this ...

THANK YOU VERY MUCH FOR ANY HELP YOU CAN LEND WITH THESE.

-=-=-=-=-=-=-=-=-=-
A Honda 650L is Factory lean (I believe this is correct). [I live & ride at 5000ft level and will ride higher at times.] With that said....
How is the determination made for the jetting the bike is supplied with? Could the assemblers of the bike (Dealer) be jetted with appropriate ones for the area in which it was first assembled? And WHY the F*&! is it lean to begin with? (IF indeed the 650L is assembled lean)

Does pulling the smog affect jetting (would alterations be necessary IF the jets are fine as is; if the smog is pulled)?

Is back pressure necessary for better performance? If a bike is altered for better breathing does this limit back pressure to a point where adjustments are required?

Should all mods be done first and jetting last? Would any alteration in breathing & back pressure affect jetting so that pulling smog, exhaust alterations, air filter need to be done and finalized prior to beginning jetting? (This seems logical but is there any reason for this NOT to be true?)

ARE performance exhausts mainly hype in the 650-L application [if the uses are in line with the design of the bike]?

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  • Frank ZX

Posted December 13, 2007 - 05:43 PM

#2

It's lean to pass emmisions,otherwise the US gov wouldn't alow them to come over here.Yes,I think you need some back pressure,but you can get back pressure just by a tight curve in a stright pipe.You should rejet first,then rejet or check spark plug color after every mod.Just removing the smog equipment by itselp wouldn't require a rejet,but it's too lean from the get go,so you need to up the main jet any ways.Most aftermarket pipes flow alot better than stock.No hype!I have done Dave's mods on my carb,sUni filter,Complete FMF exhaust and a Hotcams camshaft,It's soooo much faster.But just rejetting and removing the baffle from the stock muffler did make a big difference.Good luck.

  • martinfan30

Posted December 14, 2007 - 08:35 AM

#3

I hunted for these answers quite a bit before I started this ...

THANK YOU VERY MUCH FOR ANY HELP YOU CAN LEND WITH THESE.

-=-=-=-=-=-=-=-=-=-
A Honda 650L is Factory lean (I believe this is correct). [I live & ride at 5000ft level and will ride higher at times.] With that said....
How is the determination made for the jetting the bike is supplied with? Could the assemblers of the bike (Dealer) be jetted with appropriate ones for the area in which it was first assembled? And WHY the F*&! is it lean to begin with? (IF indeed the 650L is assembled lean)

Does pulling the smog affect jetting (would alterations be necessary IF the jets are fine as is; if the smog is pulled)?

Is back pressure necessary for better performance? If a bike is altered for better breathing does this limit back pressure to a point where adjustments are required?

Should all mods be done first and jetting last? Would any alteration in breathing & back pressure affect jetting so that pulling smog, exhaust alterations, air filter need to be done and finalized prior to beginning jetting? (This seems logical but is there any reason for this NOT to be true?)

ARE performance exhausts mainly hype in the 650-L application [if the uses are in line with the design of the bike]?



i live at 4300 ft and had my stock carb jetted with 160/55 dyno jet kit. ran great but have an FCR carb now. they are made lean at the factory for emissions. removing the smog will not affect your jetting needs. back pressure , like frank said is handled enough by a bend in the header. after market exhaust and intake mods should be done with jetting ALL at once. the bike will feel totally different, really wkes em up. if you just do exhaust and not rejet, it will become even leaner, increasing eng. temp and possibly affect eng. life. definately worth it to put a good after market exhaust, rejet, uni filter and remove the smog and snorkel.





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