Hey all,
Just bringing the list in on this and passing what John has found out over the past 2 years of tinking to get his carbs working "just right"...
At 11:01 AM 4/19/02 -0400, John P Vitamvas wrote:
>As for the X, here is what I found, you can forward it to the list.
>
>On my X my off idle response was poor in cold weather, the exhaust stunk very badly and the power was down. I used my eyes, ears and nose to determine the bike was running a tad lean. Seems these bikes are very sensitive to tuning, moreso than my dad's XJ750.
>
>Over the winter I found that a .75mm shim under the needle clip raised the needle enough to "fatten" the midrange nicely. This isn't the case in the summer - it kills the midrange. The afterburner at 7500 doesn't exist anymore, but the spread of torque is nicely improved. Gas mileage actually went down a little, but that may be because I rode it harder. After
>noticing that at WOT at high revs the bike seemed to bog worse, I actually stepped down the main jet by one step. If the factory is a 105, I went to a 102.5. I don't remember if those are the exact numbers, but I have the original jets at home. Possibly the old jet was just enlarged after 30k miles of riding and cleaning! Regardless, this eliminated the bog up top.
>
>Additionally, as bikes age the vacuum diaphragms weaken and leak, causing richness at WOT because the piston doesn't retract, limiting airflow. Just another thought. I couldn't find diaphragms at a reasonable cost, so I dropped the main a size.
(Just had an idea of seeing how the slides react when you use a vacuum
cleaner. A flowmeter used for cylinder head testing might work, but don't
have or have access to one. Next time mine are off or anyone else that has
them off can try the vacuum trick, just make sure there is no fuel in the
bowls. Don't want any vapors around an electric motor.)
>I found that when the weather warmed up the shim was a little much and the bike would bog a little (note I am very anal about the tuning, someone else probably wouldn't notice the power decrease but I did). I removed the .75mm
>shim and resynched (it is CRITICAL to get a good synch, it will kill the throttle reponse off idle if it is not spot on). Using my Carbtune II I adjusted the synch so all carbs were equal with equal pilot screw settings. The pilot screws can be used to set the exact idle mixture, which I have done. I tuned it by ear, adjusting each screw leaner and leaner until the idle decreased.
>
>I run a 1150RPM idle.
>
>Bottom line: For winter, a shim under the needles and a 102.5 main. For summer, no shim, and a 102.5 main.
>
>The result is a bike that you can barely smell when idling or on the throttle. Lightning quick throttle response (i.e. NO delay when you hit WOT even from idle), good gas mileage (38 when being flogged, 45 under more reasonable use), and incredible power. The surge at 7500 is back now with the shim gone... it's strange that it's perfect for winter riding but too
>much gas for summer riding. Air density, anyone??
(The slide moves different in the cold? Roughly when does the transition
from needing the shim to happen? Seems odd. Could be the slides are
stiffer in the cold.
Have gone from 75F to 15F in the space of 2 days riding and didn't notice
any major difference, so it might just be a function of age. Suppose you
could check for the slide action being the reason by parking in a meat
locker overnight and then riding in the warmer air. LOL )
>At some point in its life this bike is getting fuel injection...
Long time thought I've, but the cost among other things... Yami finally
went FI on some of the sporties, so perhaps a re-mapped setup might
work. Pretty much gave up on the idea. Would rather spend large amounts
on a gearing change or another ride. ;)
>Feel free to distribute this...
Done!
Jeff "The Mountin Man" - '86 MaximX