My checklist, anything I'm missing?

[maparker]

First off: 1981 GS450TX 12900 miles. Just replaced the stator, has the Honda R/R upgrade and is finally charging on its own.

I just replaced the intake O-rings...who knew they weren't supposed to be flat! Thanks to Robert Barr of course:-D.

I've cleaned the carbs by dipping in Berryman's and have run Seafoam through the tank. I bench-synced the carbs before reinstalling but I still have one cylinder that is rich because the plug is wet with gas and its constantly surging and hesitating when you hold a constant throttle position.

My next thought is that I may have a valve that's way off. Would this cause enough difference in vacuum that a bench sync would still let one carb run much richer?

After checking the valves what's next? I'll also try and borrow a carb-tune which may tell me something about my vacuum as well, but I guess I need advice on where to go next.

Thanks as always,
Parker

[Steve]

I've cleaned the carbs by dipping in Berryman's and have run Seafoam through the tank.

When you dipped the carbs, can we presume that they were completely stripped?
How long did you leave them in the "dip"? One carb at a time, overnight, is best.
How much SeaFoam did you run through the tank? For cleaning purposes, it's best to add about half the can to a full tank of gas, then run that tank out, at least until you get to reserve, then fill the tank before parking for the night. Not sure about the effects of a strong solution left in the carbs overnight, but it certainly helps for the few hours it takes to run through the tank.

My next thought is that I may have a valve that's way off. Would this cause enough difference in vacuum that a bench sync would still let one carb run much richer?

Yes, it's possible that valve (mis)adjustment will affect the mixture.

I had that problem on a previous (non-GS) bike. The valves were tight, amost to the point of not closing at all. This means the valves closed later than they should, and the piston was considerably into the compression stroke by the time they closed. This pushed some of the intake mixture back into the intake tubes. When the valve opened again, it went through the passages again, getting more fuel added. The bike was fuel injected, so it controlled mixture based on water and air temps. Cold starts were a royal pain. If I could get it started, subsequent warm starts were very easy for the rest of the day.

Don't rely on the sound of the valves to determine whether they need adjusting. Valves on these engines tend to tighten up, which makes less noise, not more.

Carb sync is the last item in a good tune-up.
1. Valve adjustment
2. Compression check
3. Ignition timing (more necessary if you have points)
4. Idle mixture adjustment
5. Carb sync

.

[maparker]

Thanks for the quick reply Steve. I left each carb in at least 2 hours...maybe I should pull them and do each overnight again.

I put half a can of Seafoam in a full tank, rode for ~45 min then let it sit overnight and then rode the rest of the tank to reserve and filled it.

I'm trying to track down someone in CO who has the right feeler gauges and a source for shims. I'll do that next, then look at ignition timing...I've never checked it or compression. Of course in the past a quick carb clean always had me running right, though.

Thanks,
Parker

[Steve]

A couple of hours in the dip might be OK if they weren't too dirty to start with. The half can of SeaFoam might have finished cleaning them out OK. It might be OK to leave a strong concentration of SeaFoam in overnight, I am just not sure how the stuff affects the o-rings and other non-metallic parts in the carbs, so I just leave it in for a few hours, while riding.

Any auto parts store or Sears will have feeler gauges that will work. Metric ones are easiest as there will be no conversion to worry about, but standard feeler gauges will work, too. Send me an e-mail and I will send you a copy of my Excel spreadsheet to help keep track of your valve adjustments.

Z1 Enterprises has the shim removal tool and shims at very reasonable prices. Keep in mind that you can sometimes move existing shims around to adjust your clearances, you don't have to replace them all.


.

[snowbeard]

hey Mark, thought I'd post here instead of the ride thread, so which carb is it that's coming up gassy?

one thought, of course, if it's old #2 then you've likely got a petcock diaphram ripped.

if it's another one, but always that one, could it be the plug wire or cap? you might pull it and check it for spark grounded to the engine (after the proper amount of time for the gas to evaporate :shock or swap the wires 1&4 or 2&3 (I don't know if you can swap just a pair, or if it has to be all of them...) see if it follows the wire or the carb. if it's gassy I'd bet somehow there's no spark??

I need to check my valves someday this fall, and I don't have any tool or kits of shims, but maybe between the both of us we could get one together? otherwise the best offer I've had was scott way down south, which would require either a trailer or an overnighter.

[maparker]

My parents are selling the family farm after 42 years (...yeah I know a little sad) and Dad just sent me a box of old ignition tools, engine testers, etc that he had. Turns out there is a set of feeler gauges in it that go all the way down to .001 inches so I'm going to pull the cover this weekend and check all the valve clearances. I'm don't think that'll be too much of a problem, I'm more concerned about sourcing the shims. Once I get mine figured out I'd be glad to help you...maybe it'll give us an excuse for another ride later on!

My next problem is figuring out how to set the ignition timing. My manual says something along the lines of "YOU cant adjust it, so don't mess with it!" I need to search somemore, but what I've found here is a little conflicting. Some descibe 18 pins and others 20...what the..?! Anyone out there who can give a detailed explanation of what I need to do on an '81 with electronic ignition?

I'm pretty sure I may have some airbox issues too. I bought new boots and that seemed to help, but there is a bolt broken off and I'm not convinced that there is ever a good seal between the airbox and the carbs....maybe I should try sourcing another or God forbid try PODS!:shock:


Any help as always is greatly appreciated!

Mark

[snowbeard]

good luck!! \\/

I assume it's not cylinder#2 then...

[maparker]

I don't actually know how the cylinders are numbered? The 450 is a twin and its the one on the left side of the bike...although the plug on the other one is exactly the toasty look I like either...now that I think about it more (I read your post pretty early this morning!) that might be the case. The gas line runs into a T that is evenly spaced between the two carbs so I would think they would flood equally no? I guess maybe I need to add tearing apart me petcock to the list. Thanks for the idea.

It is rideable, and even if it sputters and bucks I'm still planning on trying to ride with you guys on the 29th!

[snowbeard]

D'oh! forgot you were a twin. so whichever carb your petcock vacuum line goes to from the petcock might be the culprit? there should be two lines on the petcock, a big one for fuel out, and a smaller one for vacuum to be applied to the diaphram. if the diaphram is ripped, you'll get super rich on that carb, since it can pull gas instead of a vacuum!

I once thought I had burned a hole in a valve, but later found this to be the case. I know a really good ebay guy who sells diaphrams? siriusinc I think it was?

[maparker]

So theoretically if this was my problem unhooking the vacuum line and running the bike on "prime" might help pinpoint it since it would no longer be pulling gas in the vacuum line? Or am I not thinking about the internals on the petcock correctly?

[snowbeard]

sorry, that would be right, it should bypass the vacuum line, which I would clamp off while testing this. hope that's the full of it!!

A friend of mine just reminded me he has a Suzuki valve puller that he's going to give me, maybe next week sometime I can get it from him!!

[kb9lae]

My 88 450l had a similar problem. My left plug was rich, turns out it was a bad plug. The iginition timing if it is like mine should not be adjustable. If I remember correctly you can only set it out of alignment 180 deg. But that would be hard to do if you payed attention to how you put it back together. I also had problems when the running rich symptom switched sides. Turns out an air filter helped alot.

[maparker]

I should probably try switching plugs too and see if the problem switches sides. I hopefully will have a little time this weekend to devote to getting it right.

[snowbeard]

just swap the plug wires, that way you can tell if it's the wire or a bad plug. if it follows the wire you know it's your coil, wire or plug cap. If it stays where it was, you know it's either the plug or the carb, or possibly the valve.

I would bet money on the petcock, have you ever had it off and fully apart? doesn't take much to rip, and it happens unexpectedly, with no interference from us. just repetitive mechanical motion.

you could even check it without disconnecting it at all, just clamp a vice grip on the smaller hose and put it on prime? I'd start there, as it is the easiest test, then try the wire swap. then the actual plug swap if it doesn't follow the wire to eliminate the plug itself.

if none of these fix it, then I'd say it's worth using up a seal on the valve cover...

I'm gone til tuesday, but I'll try to check up on ya on the road! \\/

[maparker]

Snowbeard, you my friend are indeed a genius... or at least very helpful. I was doubtful that the petcock was the problem, but I was also troubleshooting from more of a car, tractor, etc. background. I think your previous experience colors your outlook. Anyway my wife got called to the hospital and I though "Maybe I'll just go play around with the bike for a while since my sons asleep." Fired it up in the garage, at 10:30 on a FRIDAY nobody will mind right?

While I was letting it warm up I notice GAS! RUNNING OFF OF THE EXHAUST!:shock: It was leaking right out of the front of the motor and down the pipe! I pulled the vacuum line from the carb to the petcock and gas just poured out...no wonder my mileage has been sucking (Pun intended!).

Now if I can find a diaphram or rebuilt kit or a used petcock. I want it fixed NOW! I gotta be ready for next weeks ride!

Thanks to everyone who gave input, if any body has a source for a rebuild kit cheaper than buying a new petcock please let me know.

Parker