Alright I've read through the posts for the last week, read all the how to's and still have a problem here.
Rejetted per the formula given 125/40/1 3 turns. Synched the carbs. adjusted the air/ fuel mix screws per instructions.
Problem.....
It runs like a raped ape till I hit 5th gear then it bogs badly in 5th and 6th. I've narrowed it down to the 1/2 to 3/4 throttle range. I can twist past this point to wot and it does not bog as bad as though its trying, twist back into the bad range and its like there is a switch closing the fuel lines. Keeps running but really bogging. I've installed a clear inline filter and it remains full of gas when it is acting up in this range.
Other noticable difference after rejet. It starts hard, cannot touch the choke. Can start it easily if I turn the idle screw in about 15 turns it will start ok then I wait till the idle picks up to 3k, adjust it down, wait, 3k, adjust it down...... It restarts great when warm. My suspicion is the needles, can see nothing wrong there, any suggestions?
I've checked and rechecked the float levels and did replace 1 float seat that would not close. All seems well in this are right at the gasket levels.
By the way, fish aquarium air tubing works great to check float levels..
Love this forum and enjoy the info.
what happens when you run on prime
It has no effect whatsoever
Still bogs.
I'll also mention when its bogging and I roll the thottle back abouyt 1/4 it lurches and revs, gets to bucking when at the edge of the 1/2 to 3/4 postion.
stock filter and exhaust? stock jetting is 122.5 if im not mistaken. so 125 is still in stock parts range. if your running differnt airfilter then think it needs to be bumped to 130, 140 an 1 washer with slipon, and 145-150ish with 2 washers for aftermarket filter and full exhaust system. belive thats what Srinath claimed
OK my first guess is ... air filter is dirty. Take it and slosh around in gas ... dry and re install. If you did that already ... next question will be ...
OK when it bogs does it seem to start sounding dry and like hissing ... that means slides are comming up too fast. I'd like more symptoms and specifics.
Cool.
Srinath.
Thanks for the replies so far guys... I have stock air filter and exhaust. Thinking bad air flow, I took the filter out to check the response and its the same. Should run with this configuration of jets and settings but its got the dead spot.
When it bogs the only sound i"m hearings is the baooooooooo. No specific hissing noises.
It bucks like crazy as though its trying.
Quote from: terry1013Thanks for the replies so far guys... I have stock air filter and exhaust. Thinking bad air flow, I took the filter out to check the response and its the same. Should run with this configuration of jets and settings but its got the dead spot.
in that case, is the restrictor (ring around air filter) on?
No restrictor ring.
OK real jetting issues come up in 5th and 6th only so dont worry ...
OK try this ... open throttle fully in 5th and 6th from 1/2 to 3/4 ... see what it does.
Then open fast and see if it bogs ... fast bogging, slow not bogging = slide comming up too fast. How did it run before you touched it ...
Cool.
Srinath.
It did not run before I touched it. Tank was full of rust and I've cleaned and cleaned. Both carbs varnished VERY bad. As I took the carbs apart wanted to go ahead and rejet after reading much of this forum.
As I ease into 5th, initially, its fine. Then it begins to buck. When I try to accelerate though the bucking it bogs bad till I'm very near wot. In the meantime if I ease into 5th and it starts bucking I can back off of the throttle to 1/4 and it picks back up. Very disturbing, takes off like a bat outta hell till it reaches that point again and bucks and bogs.
Gonna ride down the road, shall return.....
Ok I had a friend that had an old GSXR 750 ... his bike would bog and nearly die as he opened the throttle, and as he closed the throttle in disappointment ... the thing would wheelie ... The triple Hit him in the temple one time ... floats were too high ... You sure you're are fine ...
Cool.
Srinath.
Cold today, learning the charcteristics of the bike. About 6 turns in on the idle screw, no choke fires right up.
After warm up, good country road here. Down 1 mile & back. First pass seems almost normal. little bucking in 5th accelerate through to wot & it picks up slowly. 6th gear better but same tendency to bog. When I flick to wot from 1/2 and 3/4 position it just goes to the wot slowly picking up speed mode. It seems to get worse as the bike gets warmer. fast flick to wot & slow flick no difference. It feels as though theres a dead spot from 1/2 to 3/4 & its bucking while in that zone.
Slow street right in front of the house on way back saw at 30mph get up to 6th gear & it's kinda backfiring sputter when I try to goose it in 6th while going that speed.
I did replace the plugs.
Floats have been checked , checked, rechecked and double checked.....
Wearing the phillips head off the drain screw..
I can run this thing all over the place through 4th gear, no problems whatsoever, when I hit 5th the show starts....
Also took carbs apart 3 times and double checked the 14 mm heigth. All ok and level check right at the gasket, always.
It don't wheelie, when I back out of the throttle but it does lunge really well, again, very disturbing feeling.
I was thinking the retaining washer is underneath the needle circlip, allowing the needle to 'float'.
Getting more specific: what rpm in 5th gear does it begin to bog?
What rpm in 6th?
What about the same rpm in 4th?
Do the floats float?
I noticed 4000 rpm in 5th it was bogging. 4th gear unaffected. 6th I don't know...
That's low in the rpm band. Like 1/4 throttle. Not a whole lotta pickup down there, in that high a gear.
Do your floats float?
Scratch, the floats seem to work fine through 4 gears and at idle. No leaky when the bike is off, level is even with the gasket.
ok, runs fund in lower gears up the rpms? had this issue once before and it didnt go away till i changed every damn Oring and ran Fine wires and compressed air through every damn port. the one that gave me the most trouble was the O-ring right under the Slide guide (plastic part the slide sits in) that O-Ring was about turned to gooo. changed it, re synced them as i tore them both down to nothing. and ran fine, the other thing is that damn choke. i believe it tends to "flutter" for lack of a better term and screw up the mixture in topend. you shouldnt need to keep adjusting the idle stop screw, once warmed up, set it and leave it. you will drive yourself mad as you keep turning it up and down.
Thanks Blue, I was looking hard at the slide glides when I had it apart the last time. The plastic didn't seem to come up outta there so I left it. Is it just a press fit or is it held in place by something? I ran the fine wire through and used air compressor pressure through all small ports. I also made sure the carb cleaner exited elsewhere when sprayed into the ports all ok. The orings under those glides are an unknown so I reckon thats my next step. At least so I know.
On a GS carb set ... if any of the vital O rings are bad ... it will leak gas. The only O ring that will affect performance is that one under the top. Its got O rings under the plastic insert the emulsion tubes go into etc, but they all dont do anything. Float and T fitting O rings keep them from leaking, and the one on the Air screw does that and possibly from sucking air ... though I dont think air in any significant quantity can get in that way at all.
Cool.
Srinath.
Alright guys. This is starting to wear me down here. I work on lift trucks everyday. Fuel injection systems on modern stuff and 25 years ago cut my teeth on old carbs but this is kicking my arse. I think my next step is to reclean the carbs.. again and add another washer under the needle to get a richer mix at high demand. Since it starts ok, even without the choke and runs fine up through 4th gear I have to surmise that either its starving for air or fuel when in that needle jet fully up and main jet supplying fuel. With the air filter laying in the garage it still bogs.
Its gotta be in the needle. I know my diaphrgms are ok, small orings are in place. Nothing acts like its vacuum leak, no revving. Can someone tell me otherwise?
I appreciate all the comebacks and will look closely at any tips provided as I tear these things down again.
Send it to me ... trouble shooting is free ... Yea you'd pay for 2 way shipping ... but I have seen many people get stumped by these carbs ... Yea they are simple, they dont have too many delicate parts or very tricky anyhting ... Frankly I have seen people that tear apart engines and fully rebuild them ... get stumped by these ...
FWIW - Your problem sounds like rich not lean ... so choke staying open or some weird screw up in the fule supply ...
Cool.
Srinath.
remove all the top stuff and the slide and needle assembly (mind that tiny ass oring when you first pop the top off)
Pull the float bowl, Float/Idle circut plumbing, and unscrew the Main jet acouple turns only, Now with screw driver handle or something plastic that wont deform Brass, SMACK the main jet like your trying to hammer it back in, it will shift the emultion tube out the top (its what is holding the slide guide into the carb) back the jet out a few more threads squirting some WD or PB Blaster helps this along. keep working it till you can get the emultion tube all the way out, then the slide guide, You will now see that Hiden but oh so critical PAIN IN THE ASS Oring. Make sure all your orings Fit Nice and snug when you reassemble it.
Hey bluknyt ... that emulsion tube O ring ... what exactly does it prevent or allow to happen ... I didn't think it did anything ... its entirely encased in metal and plastic ... no passages to or out and OK it being there will maybe prevent a tiny bit of fuel bleed out at high intake velocities ... I didn't make much of its usefulness ... its usually crushed and crumpled by the time you get it out ...
Cool.
Srinath.
Thanks again Seshandri and Blue.
The weather is gonna be sh+tty here this weekend so I'm gonna take em apart one more time and go at those o'rings under the glides. I'd really like to fix this myself if I can. If after this they still bog I'll be sending them to you Seshandri.
yeah Its often goo, and the emultion tube is often locked in with corosion. the emultion tube has little ports on the side, kinda like a Bleed type jet and i think helps to smooth flow abit when needle shifts up and down.
now,when i first got my GS, i had running issues that had no end. cleaned, and recleaned, changed orings but still gave me hassles. once i changed that Oring it went away. look at it this way, what does an Oring do? why machine a groove in metal and mold inner support in plastic if its not sealing? i dont know if it keeps from sucking air while fuel sloshes, or if it keeps from sucking Fuel when it sloshes. biggest issue i remember, is when i would come to a stop, it would Die. fire rigt back up and idle like nothing happened. so im inclined to think its fuel slosh related from front to back, as leaning while sitting still did nothing.
Ok, tore the carbs completely down again. Blueknyt, thank you very much on your help with the slide glide orings. They were junk. Seshadri, I saw where the orings were mushed apart under the glides and there was a very distinct trail of gunk/residue from the main jet port to the edge of the carb intake hole under the glides indicating an open trail of fuel. Also this was the first time I've had the emulsion tube out and found the left carb that had the worst oring had a thick black build up of corrosion on the outside of the tube blocking up 2 of the 4 holes for fuel to exit. I had run carb cleaner through this passage many times and was surprised to fing that much in there. I say corrosion because nothing short of emery cloth would cut this black crusted mess. I really had to work to reopen the emul tube holes. I replaced those orings and recleaned the carbs while apart. I went ahead and added a 2nd #4 washer under each needle. I reinstalled back on the bike. I also kreemed the tank while I had it off. Thanks to Seshadri's great info on treating the tank I was able to clean a lot of rust out of this tank ,"slosh it this side that side upside down, more rust do it again". As I reassembled the bike I installed 5/16 clear vinyl tubing ".20 a foot at Lowes" as fuel line and installed a new filter inline from the pitcock to the carbs.
The results.... :thumb:
Bike starts when using 1/4 choke. It runs a lot better. I can run through all the gears 5th and 6th included and there is no bogging/ starving going on. I installed the filter in a manner that I can glance down and watch it while riding and see what is going on. When you start the bike, the filter level doesn't move in idle, rev it up and the level starts to go down and eventually empties. Still runs ok though. When I hold 65 mph for longer than 5 minutes or so it gives a slight indication that its starting to lean miss. Clear filter empties as soon as I get out of the driveway. I suspect that this is strictly from the vacuum pitcock supply not keeping up with demand. IMO this is not a problem for me at this time. I will spend the whole summer on the backroads of Ohio and don't want to mix it up :guns: with highway cagers with my experience or lack there of. Posting another thread for some thanks to you guys and others.
ok next time your on the Highway or running 65mph, switch over to PRI on your petcock. see if this doesnt cure your issues, forsome reason when at Highway speeds, there isnt enough vacume at that port to properly open the petcock diaphram, and it will drain your bowls. my diaphram started leaking to the point the port was suckin fuel, so i blocked it off and just run on prim and switch to run or Res to stop fuel flow. My res doesnt work anyway, prev owner Cut the stand pipe for tank valve so it will drain the tank from full to empty without switching.
Woot, Go blueknyt, whos the carb guru :mrgreen:
Fought with the little bastard twin fuel suckers for a weeks straight to figure out that issue. also didnt know that i wsnt running stock needles at te time too.
Not familiar w/ gs carbs yet, but I'd say check for a tiny crack in the diaphragm. Are they moving up freely?
my .02 cent
Jonah
carb diaphragms will kill its runnig above 5-6K ... even the tiniest rip ... Petcock Diaphragm will make it not run in anything other than prime ...
Cool.
Srinath.
Well I held the carb diaphragms up to strong light and really checked'm but saw no cracks or anything. They slide up nice & free together under a high rev as I watch them. Not worried about it at this point, its just a slight feel of starve at 65 or so and I'm just wanting to ride back roads for a while.
Rode tonight to W Milton & back 40 miles round trip and it ran great. I put a little gas treatment in the tank and will run it for a while and get some miles on it. It almost seems as though 1. The carbs might need 1 more washer, might try that. Or 2. The fuel system is restricted just enough from the tank petcock that it takes a while in high RPM under load to start depleting. But I still say, I can roll though that spot when I start to feel it and I get power. Gotta be needles folks.
Again I'll run it awhile before I do anything else.
Srinath have you ever had to use 3 washers per carb?