gs450 - still not running right

[bren]

Doesn't that usually indicate an intake air leak?

yes, that's my understanding, or it could indicate a severe imbalance between carbs. but also a leak would lead to a lean condition. the fact that the lean condition switched cylinders leads me to want to rule out any air leaks

 

[dgates1]

Well first mistake I see from the video is the Morgan Carbtune is designed to work when it is hanging straight. You have it hanging straight but it is upside down. Should be hanging from the top side where the hoses connect. That could skew your balance reading.

Second thought after watching is, do the throttle plates stick at all, or perhaps your throttle cable is sticking?

 

[oldGSfan]

I find the water-based Berryman's dip less effective than the original. Now I dunk the carb and parts in the Berryman's basket and put the bucket in my large ultrasonic for 10 minutes. They come out amazing. I have had nothing but carb rebuilding success since I started doing this, and a lot of troubles previously.

Of course, an ultrasonic that's big enough to fit the carb would work, it's just more convenient with the extra large one I got for $80 a few years back. I recently used it to unstick a slide on a Keihin that was gunked up with years-old varnish. It took 20 mins, and fell right out.

 

[bren]

Well first mistake I see from the video is the Morgan Carbtune is designed to work when it is hanging straight. You have it hanging straight but it is upside down. Should be hanging from the top side where the hoses connect. That could skew your balance reading.

Second thought after watching is, do the throttle plates stick at all, or perhaps your throttle cable is sticking?

the booklet it comes with says, if your bike doesn't pull enough vacuum to move the slides with it right side up, you can use it upside down to get the sync right, and just ignore the quantitative reading, to get it in sync without taking measurements. mine wasn't strong enough to lift the slides so i flipped it.

there's actually a hanger on both ends for that zip tie the carbtune comes with, for this purpose.

no, there's nothing sticking. it's perfectly snappy.

 

[bren]

I find the water-based Berryman's dip less effective than the original. Now I dunk the carb and parts in the Berryman's basket and put the bucket in my large ultrasonic for 10 minutes. They come out amazing. I have had nothing but carb rebuilding success since I started doing this, and a lot of troubles previously.

Of course, an ultrasonic that's big enough to fit the carb would work, it's just more convenient with the extra large one I got for $80 a few years back. I recently used it to unstick a slide on a Keihin that was gunked up with years-old varnish. It took 20 mins, and fell right out.

i've heard people say this online. the EPA stuff is really frustrating. my carbs also have non adjustable needles, and jetting that's right on the brink of being too lean. thanks to EPA "eMiSsIoNs StAnDaRdS" :chargrined:

i'm not sure that i can justify buying and ultrasonic cleaner unless I make a hobby of resurrecting a bunch of old bikes. although 90 bucks at Hobo Freight aint too bad. I might think about it. I'm just getting tired of buying a bunch of stuff at this point!

i've even read about people using berryman's sauce inside of an ultrasonic ... that sounds like it would really do the trick!

 

[oldGSfan]

i've heard people say this online. the EPA stuff is really frustrating. my carbs also have non adjustable needles, and jetting that's right on the brink of being too lean. thanks to EPA "eMiSsIoNs StAnDaRdS" :chargrined:

i'm not sure that i can justify buying and ultrasonic cleaner unless I make a hobby of resurrecting a bunch of old bikes. although 90 bucks at Hobo Freight aint too bad. I might think about it. I'm just getting tired of buying a bunch of stuff at this point!

i've even read about people using berryman's sauce inside of an ultrasonic ... that sounds like it would really do the trick!

Yes, you can put the sauce directly in the ultrasonic, I just like the simplicity of putting the bucket in the water. The ultrasonic 'cheapo' ones you find from China appear to all be the same design, based on the controls, and there are huge price variations. I found mine for $75 and saw others were > $200 that were exactly the same. I barely missed getting a medical grade one for cheap, dang. But my cheap one has worked well for a few years.

Given that I fix most everything myself and have amassed a huge array of tools that paid for themselves many times over - vs. being ripped off by some 'pro', I occasionally lash out and splurge on something that will make my life easier.

I'm still scratching my head over your issues. I had a GS1100E behaving strangely/badly depending on load and temperature. It was the aftermarket no-name coils, putting stock ones on fixed the issue. But having the problem move to the other cylinder does point to carbs.

 

[KiwiAlfa156]

Originally posted by bren View Post ...it ran away when i flicked the throttle

Doesn't that usually indicate an intake air leak?

Can do, it's indicative of a lean idle mixture, either due to extra air (leak) or not enough fuel (clogged jet or passages).

 

[bren]

alright, it's a new day.

• [STRIKE]choke plunger[/STRIKE]
• [STRIKE]Pilot jet[/STRIKE]
• pilot screw
• bowl / main jet
• bowl gasket
• emulsifier
• slide

i took the pilots out just now, and looked through them. the orifices look identical, i can't see why one would be different than the other. some Numbskull Previous Owner had grabbed both jets BY THE THREADS with pliers, buggering them up, and i realized one wasn't fully seating, so i chased them through a m5x0.8 die, and now they both seat fully.

Still seemingly not much change.

it still lopes, the idle still hunts around, by the time the RH cyl was up to 350, the LH was closer to 425. still takes like 4-5 seconds to come to idle af​ter a blip.

once it got fully hot, i set the idle to around 1100 - 1200 rpm, and after a throttle blip, it would hang for 4 or 5 seconds, but then it would sag to like 900 before slowly coming back up. talk about mixed signals. idle dropping after a blip is a sign of a rich pilot circuit. hanging after a blip could be a lean condition, but if one carb is richer, it could just be a balance issue ...

the next thought i have, on the subject of things buggered by PO's, is the emulsifier tubes. one of them is pretty badly buggered. it's got pliers scuffs all over it, and it tends to get stuck in the bowl when i pull the bowl off. the part that goes into the carb body, the part with the o-ring on it, has a lot of gouges on it. maybe it's seeping fuel. I don't remember which carb that one's in currently...

anyhow ... the swapification process continues.​

 

[bren]

okay. i got the carbies back on the table. sure enough that really buggered up emulsifier tube was in the right hand one. the o-rings on both are all chewed up, but especially the one that was in the right cyl (the cold one). i'm wondering if the gouges from this screwed up emulsifier cut into the aluminum of the carb and that's causing the o-rings to get ripped all up.

gonna get em back together and on the bike now.

 

[KiwiAlfa156]

Can you post some pics of the damage?

 

[bren]

yea, i will tomorrow when i take it back apart. i took video of it but my video cam refused to focus on it.

here's a video i made of todays carburetor adventure.

engine run starts at around 4 minutes. i ran it from pretty much stone cold until it was fully hot.

 

[bren]

Well I figured it out finally. I took the carbs back off to swap another piece. Only a couple things left to try - the bowls were gonna be next. But I just sat there for like an hour, looking through it with the bowls off and thinking about it. Following the passages. Spraying carb juice through it. And it was totally pristine in there. I couldn't think of a single reason why it shouldn't be working.

So I finally just stopped. And I thought, I have to be missing something. I already went back to step 1 and started over on cleaning the carbs, to no effect. So I went back even further to step zero.

I set the carbs on the table, went back inside, and started doing a bunch of research on how cv carbs work. Trying to understand them in detail, troubleshooting them, tuning them, etc. And slowly, a realization started to dawn on me...

The bike is already fixed. It's already working perfectly, doing exactly what it's supposed to do - given the inputs that I'm giving to it. It wasn't that something was wrong with the bike - it was actually that I was doing something wrong with it.

So this morning before work, I had just enough time to warm the bike up and tweak things a bit with my newly gained knowledge. I've had both mix screws set at 2.5 turns out, which I read on here was more or less standard practice, and just kind of accepted that uncritically. I took the carb that was running hot and turned the screw out some more, and it started running different. Kinda wonky - but different. So - one thing I learned last night is that if you close the mix screws, the bike should shut off. So I did that - and when it kept running - I realized what I'd done. The idle was set too high, because the pilot was set so lean that the butterflies had to hang open and pull fuel from inside the venturi to be able to idle. Now, closing the pilots made it immediately start getting super hot, so I quickly turned both mix screws out maybe 4 or 5 turns and dropped the idle screw much lower. Suddenly the idle sounded a ton better; strong, steady. the vac gauges also started pulling way more vaccuum. And finally when I blipped the throttle, it came right back down, just like it should. I couldn't believe it. Just like that. All this time, and I fixed it just like that.

So the bike was indeed running very lean - but it wasn't her fault, it was my own basic newbie mistake. I simply didn't understand how to set the mixture and idle screws, and didn't understand the carbs in enough detail to really troubleshoot properly.

my mind is really blown by this revelation. I thought it would be some kind of grand eureka moment when I figured out this problem, a moment of elation. But in reality, the truth kinda hurts. And machines don't lie.

While I feel very relieved to be finally past this issue, I also feel pretty sheepish about it. I've done so much tinkering and working on this bike, blood sweat and tears, trying different stuff, changing parts and what not, all on a perfectly running bike that was simply misconfigured. I mean, some of the stuff it's probably good that I changed it out, like the new carb boots that are nice and soft. I don't even regret upgrading the ignition, I've wanted to do that from the start anyway and just needed an excuse to pony up for it. But man. To think that three little screws are what kept me from riding, for months.

But what can you say. I guess it's just the cost of tuition. I can't be mad about it, I just gotta think that the knowledge gained is worth a few months and 500 bucks worth of fixing what ain't broke. That's half of the reason I bought a 40 year old bike in the first place. But now I can finally get started on the other half - actually riding it.

Anyway, the help on this thread has been appreciated.

​

 

[rphillips]

Learning this stuff is always great, no need to see it any other way... Almost as good as getting your bike running right. Congrats.