back to stock

[Guest]

hi,
1981 gs650g owner. had a fuel delivery connector tube with shot O-rings this spring. carbs came off to fix the serious leak. at this time I figured, why not try to rejet and do some pods (foolishly). 3 months later, after many pilot and main jet combos, I went back to the stock airbox, and stock jetting. runs almost perfect, plugs look fine, but at 55 mph in 5th gear she makes no power beyond that. on hills I then have to downshift to 4th to maintain/improve acceleration. i'm gonna blow it apart again, and put the original jets back in (thought shiny new ones would be better). also new uni filter in the airbox (oiled of course). any thoughts on this line of thinking, guys?
thanks a bunch for your input

[tom203]

Welcome back from the dark pod side! Yeah, put in the original 110 mains; did you mess with needle height when you were podding?
Is your airfilter box secure/tight? that unifilter is just lightly oiled?
Will it hit 70mph in 4th?

[81suzi]

yea, +1 on all of that. will post pics of the teardown/rebuild on the site as I do it

[81suzi]

and no I did not mess with the needle height-just replaced one needle jet/main 'holder' that was FUBAR'ED-also stock. gotta be careful with the brass stuff.

[81suzi]

just an update on why i now KNOW she was running poorly. i had ordered 4 mikuni pilot jets (42.5) from a wholesaler, and OEM main jets (many sizes). when i pulled my shiny pilots out to replace with my original pilots (and mains), i noticed 2 of the four pilots to be slightly different. they had indeed given me 2 mikuni pilots, AND 2 OEM ones! OEM's were slightly longer (on the business end, too) and had 2 holes all the way around the barrel (not alternating 2, then 1, etc...). i can't believe i did not notice this putting them in at first, but then again, who would've suspected such a thing? live and learn, i guess-so i thought i'd pass this on for others to be 'real careful' out there, and realize you can't trust a new part (i really should have known better). project is back on hold due to worn out intake manifold boots that finally gave out this time around ripping while removing the carbs for the 10th time this summer. new manifold boots are on the way, but were > $100.00 (bummer)... this baby is gonna howl again soon, though

[tom203]

Yes, carb removal/reinstall is no fun on this model! Try to get back to 100% mikuni carb parts - they usually don't wear out- some aftermarket stuff is poor quality. My bike still runs nicely with original stuff at 43k.

[81suzi]

got her back together, and with new intake rubber! she behaves like a different machine now!

[81suzi]

here is one of the crappy old ones

[81suzi]

even with all the new stuff and the changes back to stock, she wants to flatten out @ 5500 rpm in 5th gear under load. I can make 80 mph in 4th gear-no problem, but although this problem is improving with more miles ridden, it does remain a concern. no clutch/brake/fuel delivery issues... next i'll check the advance unit to ensure no spring/weight issues and use a timing light to see the advance at the higher rpm's. any other thoughts?

[tom203]

So what happens when you are hitting 80mph in 4th and shift to 5th?

[tkent02]

Should go like Hell.

[81suzi]

yea, ok.

if this is the new 'normal', I get it. I have no problems flogging the bike this hard (like the katana it is), but it's a new experience for me. lotta carbon blew out the pipes when I tuned the idle stop screw tonight. road test again tomorrow-runs like a raped ape till 70 mph in 5th now

[tom203]

I'm unclear about the "new normal" stuff and would prefer not to ride a raped ape . My bike has no such hesitation in 5th at 5500 rpm (and I spend alot of time in this area). In a passing situation, I seldom bother to downshift to 4th, I just crank the throttle and I'm gone.
Ride yours some more- maybe you have a sticky carb slide that needs more action.

[81suzi]

thanks tom, I will. and will keep you posted on the hopeful progress. and yes, my previous experience on the bike was no hesitation passing in 5th gear, too. looking to get that back

[81suzi]

still having the same problem. runs good till I hit 50 mph in 5th-then no more power; downshifting to get up hills, etc... I did have to replace the ignitor box (got it off ebay) with a unit off either and 850, or an 1100, can't remember. again, the bike is an 81 650 g. could I be having an advance problem that is the source of all this? airbox is tight, jets are the stock 42.5 pilots, 110 mains, filter is new, plugs are ngk (new)-everything else is correct on the bike. before I go tearing into it again, I guess I need a gameplan. any advise is appreciated.