Poor performance puzzling me..

[TheBigRed]

The Drop in K&N is out of the equation now. Not coming back in either, at least not anytime soon.

When I went to clean it I noticed the seal between the metal used to secure it and the rubber that actually holds the filter is broken/ripped, thus allowing for air to freely enter without filtration.

I'm not going to say this was the cause of the issue, as stated in the first post the symptoms were the same with it and the stock with uni foam installed.

BTW, how oiled should the foam be? I thought it was oil it then squeeze it with a paper towel to get excess oil out (not wring, but press). But maybe this caused there to be not enough oil on the foam??

Amos

[TheBigRed]

I'd suggest, for these trials, sticking with the UNI filter, as you are correct, its CLOSEST to factory flow. Starting at the airbox, what can we look at?
1) are you running the lid on the box?
2) if so, is the airbox SEALED properly?
3) are the airbox boots seated and sealing well? (ive had them LOOK as if they are, but move the box and Ta Da! they slip right off the carbs.. which is the same as running NO filter restriction, and will do exactly what you are talking about. If they are hard, they've usually shrunken back toward the box, and really arent doing their job)

Going to go off of your message for a bit here CafeKid to rule things out.

.5 (before your list of questions on the uni foam) After thinking about this more (see other post) I'm thinking I did not Oil the foam correctly. A) I used K&N spray oil to oil it. B) I used paper towel when "sqeezing" excess oil out. C) The manual says to use motor oil and pictures the squeezing without anything to draw excess out.

1) Yes, the airbox lid is in place.
2) Already answered, but airbox lid has fresh weather stripping around it.
3) I'm not sure on the seal here, they look sealed, and don't come loose when wiggling/moving the box, but I have ordered replacements. Specifically when re-assembling the carbs onto the bike I backed them into the airbox boots first, tightened down the straps to hold them in place then moved the carbs forward into the intake boots and there was no loss of connection or visual movement on the airbox side.


So, tonight I'm going to re-oil the Uni foam with motor oil, and squeeze it out by hand and try to get out for a ride and see if properly oiling that makes a difference by restricting air intake any.

I'll report back when I can.

Amos

[Edit] By the way, for others. Last time I took the bike out (Saturday afternoon) I was able to get the RPM's to around 6k but to get there the throttle could not be open past the 1/2. (just noticed I noted that above oops) But anyway, I think that rules out anything electrical/timing related as it was able to get there all be it SLOWLY[/Edit]

[TheBigRed]

Well, that didn't work, in fact it seems to have made it worse.


I'm done for a few days till the parts show up that I ordered..

Amos

[TheBigRed]

Motors only need three thing to run, air, fuel, and fire. Its not getting enough of one of those up top...

Rinse yours out, dry it as best you can and give it a short test run without oil. A short run won't hurt it without oil.

I'm done for a few days till the parts show up that I ordered..

Amos

I LIED, I'm sorry. I just couldn't let it alone tonight. Soo...

I cut another piece of the UNI foam and placed it in the filter holder WITHOUT any oil.

The results, somewhat the same, but the change in the engine feel wasn't near as dramatic as it had been before, let alone with the super oiled UNI foam.

So, I'm thinking I need more air flow in/through the carbs.

That being said.. here are the jet/carb specs for the 550T, and what is in mine (the only exception being possibly the Jet Needle, but I'm 85% sure it is the right one).

GS550 (80-82) the specs are for the CV's

idle r/min 1100-+/-100r/min
carb mik bs32ss (4 seprate carbs)
id no 47070
bore size 32 (1.26)
float height 22.4.+/-1.0 (0.88 +/-0.04)
fuel level 5.0+/-1.0 (0.20 +/-0.04)
main jet #92.5
main air jet 1.6
jet needle 4bel2
needle jet x-6
pilot jet #40
throttle valve #140
by pass 0.9, 0.7, 0.7
pilot outlet 0.7
valve seat 2.0
starter jet #35
pilot screw 3.5 turns back (mixture screw)
pilot air jet #150

I may have been wrong earlier when I stated that I kept the OEM 650 jets, as the markings on the Main Jet is a different type of imprint. I haven't been able to find any charts that compare what K&L kit sizes correspond to Mikuni sizes, but here is the factor specs for the 650E's jets (I'll get to the point after).

GS650EZ (82 model) the specs are for the CV's

idle r/min 1100-+/-50r/min
carb mik bs32ss (4 seprate carbs)
id no 34260
bore size 32 (1.26)
float height 22.4.+/-1.0 (0.88 +/-0.04)
fuel level 5.0+/-1.0 (0.20 +/-0.04)
main jet #97.5
main air jet 2.0
jet needle 5c45
needle jet Y-7
pilot jet #42.5
throttle valve #125
by pass 0.8, 0.7, 0.8
pilot outlet 0.7
valve seat 2.0
starter jet #47.5
pilot screw 3.5 turns back (mixture screw)
pilot air jet #175

So, stock jetting isn't as HUGE of a jump as it would seem, assuming I have the K&L kit and their jet's are in fact the proper size for the 650 would it be worth trying them out at least to see what affect they have? If so, which jets would I change, the main and main air jet?

Amos

[TheBigRed]

That being said.. here are the jet/carb specs for the 550T, and what is in mine (the only exception being possibly the Jet Needle, but I'm 85% sure it is the right one).

Ok, for those that may still be following this thread here is the latest.

Duane (the builder) said that it sounded like I was lean on the needle jets etc. and has generously shipped a spare set of carb bodies to me (they haven't arrived yet).

So, today I did some research to work on fully understanding the carbs etc. Another forum member suggested checking where the spacer for the jet needle was in relation to the circlip. so, tonight I tore into that (doesn't require pulling the carbs.

I can say for 100% certainty that the jet needles are the correct ones for the 550T!!

Also, I found that the spacer was on top of the clip, which would cause a lean mixture when on the needle. So, I went through and swapped them all to below the clip to richen things up there. It's too late to take it for a ride tonight, but I think I'll take it to work tomorrow to see how it's acting.

Just more FYI, and talking to myself.

Amos

[TheBigRed]

Also, I found that the spacer was on top of the clip, which would cause a lean mixture when on the needle. So, I went through and swapped them all to below the clip to richen things up there. It's too late to take it for a ride tonight, but I think I'll take it to work tomorrow to see how it's acting.

Here are the results..

The issue is now sitting around 4k instead of 5k, so I don't know what to think. I did manage to get beyond that though by holding full throttle for like 30 seconds it would move beyond, at one point surging, then took off like crazy with a little bit of surging.

Amos

[rustybronco]

try lowering the needles.

dunno if it will help any but its nice reading.

http://scootrs.com/tech.cfm?tip=tunecarb

[TheBigRed]

try lowering the needles.

dunno if it will help any but its nice reading.

http://scootrs.com/tech.cfm?tip=tunecarb

I've heard of swapping the spacer out for the washers but with a stock needle can I add more washers to the spacer? Or do I need to start looking for a set of adjustable needles? (did some searching yesterday and didn't find any straight needles, just jet kits, but nothing available for the 550T, and the closest was a stage3 kit for the 550M, but I don't think I need a stage3.)

Amos

[chef1366]

Surging is a lean condition. I'd raise the main jet first and then mess with the jet needle.

[TheBigRed]

Surging is a lean condition. I'd raise the main jet first and then mess with the jet needle.

Ok, I'm still waiting on my co-worker to get me the contact information for a guy he knows that is about an hour away with "cabinets full of jets." I'm hoping he'll work with me in that I can purchase a set of jets and just trade even up till I find what exactly I need.

It would be nice to get some hint as to where I should go from the 92.5's that are in there. Do you think I should go up to 97.5's or just go one step to the 95's?

I guess this will be more important if I'm having to buy complete sets each time, where if this guy will work with me then it may not be so critical to get it right the first time (except to save me some frustration).

Amos

[rustybronco]

The color down appears (as best I can see it) to be a light tan, but it is hard to see all the way down in there..

looks like the jetting is close.

he raised the needle and the stuttering moved lower, that's why I suggested lowering it to see what changes, if any, it makes.

We know the bike has the correct needle, but does the bike have the correct needle jet?

http://www.alpha-sports.com/spst/1981%20GS550T/05.gif (#40 jet,needle)

[TheBigRed]

looks like the jetting is close.

he raised the needle and the stuttering moved lower, that's why I suggested lowering it to see what changes, if any, it makes.

We know the bike has the correct needle, but does the bike have the correct needle jet?

http://www.alpha-sports.com/spst/1981%20GS550T/05.gif (#40 jet,needle)

Yes, the needle jet is correct, I verified this a week or two ago due to PM's with another forum member.

As for raising or lowering the needle from here, I'm not sure that will help any as at it's highest (with the spacer below the circlip) the dead spot comes on at 4k (and about half throttle) and it's lowest (spacer on top of the circlip) the dead spot comes on at 5k. By logic anywhere in between (ie using radioshack washers) will just vary where the dead spot appears.

I actually have another local shop that I want to see if they'll work with me on the jet purchases. They have been reasonable to work with in the past ($40 to rebuild forks that had the clips rusted in place!!). The question is whether they have the jets on hand to try out or not.

Duane's Carbs should also be here today or tomorrow to swap my jets etc into to see if it's a problem with the carb's themselves.

Amos

[TheBigRed]

I'm thinking a re-jet shouldn't be needed as the exhaust had these holes in it before I started the project, oh almost 8 years ago, and I did not have any issues with the performance of the bike then, except for the transmission problem.

I have a set of 110 mains (the 550T uses 92.5 mains) and 160 Pilot Air Jets (the 550T uses 150 and most other 550's use 120)

So, is that too much of a jump to try out?

Amos

Ok, THIS info is good..

110 main is pretty big jump.. that what 7? 8? sizes there? Thats drowning probably. What do your plugs look like?

Never let it be said that I was afraid to admit I was wrong.

At the behest of Duaneage I pulled the carbs tonight and dropped the 110 main's in.

Long story short my issue at 1/2 throttle is gone.

I still have some surging at above about 3/4 throttle, so I may have to go up another size or two, if adding a little bit of oil to the filter doesn't help (I've been wringing it out a bit off and on so it wouldn't be too oiled)

Anyway, just wanted to post an update.

Amos

[TheBigRed]

Ok, just wanted to follow up one LAST time!!!

WooHoo!!

Called a local tuner to see what his suggestions would be for jetting the way it was set up, and he said the 110s were too big. Said I should go up one, maybe two sizes, which would put me at 97.5's.

Ordered some on ebay from nichesupply (3.65/jet6 with $1.88 flat shipping for however many your order). Should have followed up with them sooner to get them sooner. (Ordered Friday afternoon, sent a message Tuesday morning asking if they had processed my order yet got two emails within an hour saying they processed my order and it was shipping.) All that to say, if you order from them you may want to follow up with a message so they get on it, other than that the price isn't too bad.

Anyway, put the jets in Sunday (finally) and got to ride in to work this morning. It's pulling strong the whole way through, and beyond where I was able to go (I was on back roads and through towns, didn't have a chance to get on the highway, but the one straight stretch I did have her up to beyond highway speeds)..


Amos

[Nessism]

In your first post you said the jetting was stock. How did you get to 110 mains?