Trouble after re-jetting

[justin415]

Hello, this is my first post but I've been reading a lot.  Tons of useful info here, thanks much to everyone who makes it what it is!

So, my wifes bike ('91 GS500E) was having some problems with loss of power at 80 mph or so, sputtering and what not until backing down to 65-70.  I did some looking and found out the previous owner had installed a K&N drop-in.  From reading here and the wiki, it sounds like that requires a rejet unless you have the restrictor in place.  There is no restrictor and I couldn't find one so I said what the hell might as well rejet.

I got 127.5 mains and 40 pilots and 2 washers as the wiki suggests.  Cleaned the carbs, checked float levels (although the manual is a little hard to understand, maybe I'm doing it wrong, more on that later), cleaned and oiled air filter, changed plugs, set pilot screw 3 turns out (played around with settings from 1 to 5 turns out, no difference).  After all that, the bike runs way worse than before.  Seems to be running rich as it improves some when I take off the air filter.  It won't idle above 1k and thats with the idle screw turned up the max and the choke on.  When I blip the throttle, it lags for a second then revs but sounds really horrible, missing and stuttering.

I checked the float levels using the tube trick and they seem about right, maybe a little high on one side and little low on the other.  I check the float heights using a ruler and following the manual but I wasn't too sure what it meant by 'lift the float till it just contacts the needle valve'.  I was measuring the height from the lip of the carb to the highest point on the float when the metal tongue just touches the metal clip on the needle valve.  I bent the tongue until it was about 15mm high.  Does that sound right?

I've taken the carbs apart 3 times to verify installation, check gaskets and o rings, check jets, needles, floats etc.  I've checked all hoses, fuel lines are run right, vaccum hose is hooked up.  Checked all intake boots.  Everything looks solid as far as I can tell.  Granted this is my first time working on carbs.

Anyone have any ideas?  I'm pretty close to just scrapping it and going back to stock jets.

Thanks in advance.

[The Buddha]

You cannot have high on one side and low on other ... that is sorta ... I dunno ... bad.
I dunno what else, except send it to me and I'll have it running like a swiss watch (if it was the carbs in the first place) ... or atleast like a swiss vacuum cleaner. I am out of town for 10 more days ... so I guess send it so I get it ~18th.
Cool.
Buddha.

[justin415]

Thanks for the reply.  Did you read the part about how i check the float heights?  Did that sound right?  I appreciate the offer, but I want to try and get it going myself so I learn something

[The Buddha]

Yea U tube method. Its fine. But you cant have one higher by any real amount than the other. 1-2 mm max. I never managed to learn to measure it this or that method. I do it eyeball with a template I cut based on a U tube check. If I am not sure, I do U tube.
Cool.
Buddha.

[justin415]

Actually, I was referring to the adjustment of the float itself and checking the height using a ruler.  The manual isnt very clear about what parts need to be touching what when you take the measurement. 

[justin415]

Wanted to add a few things.  I've re-checked the float height using the tube method and it looks fine.  Also, checked the plugs which are brand new and they are black and sooty which would confirm the running rich hypothesis.

So, my questions is, has anyone had trouble with a 127.5 main, 40 pilot and 2 washers and a K&N drop-in running too rich?  Should the air mixture screw be able to solve this?  It doesnt seem to make a difference what I set it to.

Also, do fouled plugs mean I need new ones?  Even if they are brand new?

Thanks much.

[The Buddha]

2 #4 washers, OK I guess take one out and try it. If it improves, get both out and try it. If it gets worse, put #2 in it.
Cool.
Buddha.

[justin415]

Update:

Removed one washer, that helped some but still runs really rough, skips combustion cycles and starts hard.  Removed all washers, now it won't start at all.  Guess I'm going back to stock jets and getting a stock air filter.  I don't know how you guys got your bikes to work with 127.5 mains and 40 pilots, made my bike run WAY worse.

[The Buddha]

I'll bet some sheite is screwed up. Floats are off maybe, you got somehting letting in too much gas - like bad O rings maybe, or something. I will further bet, you switching back to stock will not help 1 bit.
Why rejetting is not a cure all for an inherent problem. Rejetting is to be done on an otherwise well running bike. Now when you have 1 problem in the carbs, and are getting  in there, you can fix it and rejet while you are working on it ... but its not to replace actual thinking and fuguring out the problem.
I see these all the time, stuff is right in front of people's eyes and they dont see it. I can look at it for you, but I am out of town for 10 days atleast.
Cool.
Buddha.

[justin415]

Yeah, I ordered new gaskets and o-rings because I suspected that too.  Float heights are fine, I even bought a caliper gauge to check the height and they are both at 14mm as the manual suggests.  The bike was running fine before except for having an intermittent lack of power at high speed which I attributed to it running a bit lean with the k&n in there with no restrictor.  Now it won't even idle normally or stay running.  Perhaps just disassembling the carbs tore one of the rubber bits.  I also ordered a new stock pilot jet because i had to use a screw extractor to get out one of the stock ones.

Would it be correct to assume that the needle valve o-ring is the most likely culprit since it's running rich?  Seems if it were the diaphragm o-ring, it would be the opposite since air would be coming in. 

Thanks again for the advice, much appreciated.

[justin415]

Update:

Replaced the needle valve o-ring as well as the needles themselves, switched to mikuni jets (had bought RD's by mistake) and still no change.  Bike was running way too rich, fouled plugs and black smoke. hard starting, rough idle, skipping strokes etc. 

Went back to stock jets and things got better, for a while.  Now, it runs normally except when you blip the throttle it stays at a high rpm and takes 3-4 seconds to fall back to idle.  Any ideas on that problem?

[wildbill]

Did you get a carb rebuild kit? If you did i hope you got two, one for each carb. If not i would so you know all the little bits were replaced with new ones. Your still running rich, maybe the o-ring isn't seated properly when you put the carb back together. I would also make sure the air mixture screws are set to three turns out, maybe 2.5, check the jetting matrix to be sure for your setup.

[justin415]

I didn't get a kit, just bought parts individually.  I now believe my problem is that I'm using the bleeding type pilot jets with holes on the shaft.  The local mechanic I talked to said that wouldn't make a difference, but I found a post by Buddha from 2004 that says it does matter.  Since I can't find any of the non-bleeding type pilots around here, I'm going to try 37.5 bleeding with the 127.5's and the k&n with 3 turns out and 2 washer.  Will report back on the results.

[justin415]

I'm going to try 37.5 bleeding with the 127.5's and the k&n with 3 turns out and 2 washers

This worked great!  Bike fires right up, idles normally, and runs great.  A lot more pull in the lower gears now and feels stronger up high too. 

I'm no expert, but I can say for sure that 40 pilots with bleed holes definitely do not work, at least for my bike.