On the road and stumped: hesitation/lurching during acceleration (among other things)

[Guest]

It will turn them dark, not a problem. If you leave them in several weeks like a friend of mine did, it makes a slime that sticks everything if you don't scrub it off with WD40 and hot soap and water. I have had good luck with the stuff at NAPPA, supposed to be a little more ECO friendly I think. When you put the carbs in as clean as you might think, you will still see a cloud of crud boiling out when the cleaner is still clear.

 

[eil]

Did you drain the gas from the float bowls and check it for contaminants? This is tricky to do with the carbs on the bike, but I've done it. Easier to remove the carbs if you can.

You can do 80% of a carb cleaning by just removing all of the float bowls, taking out the jets, and inspecting them under good light. Look for grit in the bowls, blockage in the jets, etc. Throw it all back together and test ride. If symptoms persist, it may be time for the more in-depth cleaning or look elsewhere for the problem.

Try adding a little choke the next time it acts up and see whether it runs better or worse.

 

[klylor10]

I don't get it...

Given time constraints, I dipped each carb body and parts for 1.5 hours each, sprayed through all passageways with carb cleaner, and sprayed out with compressed air. The carbs look like they just came out of the factory.

I synchronized the carburetors (which are absolutely spot on now), and adjusted the idle mixture screws using the method for CV carbs where you blip the throttle and observe the response. Screws are now set about 2.75 turns from lightly seated.

I removed the inline filter, and am getting solid gas flow. I dismantled and verified that my fuel cap vent is clear.

Yet: the problem persists, and does not get better when I turn the choke on a bit or turn the petcock to prime.

The problem is intermittent, and I hear some popping when it occurs, maybe backfiring? Also as the engine gets hot my idle climbs to 2-3k and doesn't want to go down. I thought this was a symptom of being too lean, but since the choke doesn't alleviate things I'm beginning to wonder if I've got an air leak somewhere. My intake boots are relatively supple, and I just put in new o-rings for them. I sealed my airbox with new side cover foam and foam where the filter seals to the box. Either there's another place in getting a leak or I didn't do the sealing properly.

Thoughts?

Edit: After a bit of reading I saw someone who discussed replacing gaskets where the exhaust tubes connect to the cylinder head. This reminded me of two small oil seeps I had from those connection points on both cylinder 3 and 4. I tightened down the bolts (a couple of which were not fully loaded right) and the seeps stopped. Maybe that's the problem? Could air sneak into the cylinder through there if they aren't sealing well?

 

[Guest]

There are no constraints, 24hrs or it doesn't work. The brass parts could be in there forever, but the crud lining the passages you are spraying through is tougher than the printing on your carburetor dip can. It all has to be cleaned out 100% or things don't flow correctly. Slides and diaphragms are not cleaned in the dip, it will eat the diaphragms.

 

[SlipperyPete]

I'm having similar symptoms on my 78 750. It was suggested I check out the points. I don't know if you have those, but I thought I'd mention it. The thread is in the carb section. Good luck!

 

[alke46]

I'm having similar symptoms on my 78 750. It was suggested I check out the points. I don't know if you have those, but I thought I'd mention it. The thread is in the carb section. Good luck!

His signature shows his GS is an 82 so no, he doesn't have points.

 

[Guest]

Geez, this isn't getting any better. I can't remember for sure if you replaced the stock ignition with a new dyna or not, I know you've replace the coils, wires and caps already.

 

[Guest]

Refer to post # 23. He admitted he only soaked the carburetor bodies and parts for 1.5 hrs each because of some silly thing he read on the dip can. I haven't ever heard of any MY CARBURETORS MELTED POSTS. It might darken the aluminum some (mine included) but that's all. He needs to actually rebuild his carburetors properly and be amazed when those pristine carburetors go into the dip and crud comes boiling out and it turns the dip too dark to see through. The rest is a waste of time as to what could be wrong without having clean carburetors. 1.5 hours is not even enough to clean the jets.

 

[qcktvr]

Good morning,
I have been reading this thread and feel for you and your bikes problems, unfortunately I do not know the answer; but..
It's sounding to me as if you have been messing with your carbs trying to mask the problems caused by something else; this was/is a common problem with older marine and car motors with carbs.
My experience has been that they (carbs) rarely suddenly give problems, exceptions might be water getting into the float chambers or a cv diaphragm rupturing.
Carb cleaning/rebuilding after storage with old fuel is different.
I have not touched my carbs so cannot talk specifics, but with your high idle speed they are clearly, to me anyway, not adjusted correctly.. surely adjustments must be made on a warmed up motor to give you the correct idle speed and throttle response??
Typically they will not idle cold without choke, which also gives an increased idle speed, as it warms up you reduce choke and idle speed goes down to what you have adjusted it to??
My last problem was a completely dead spark plug, actual plug, there was good spark with spare/test plug..
Optical IR pyrometers are pretty cheap now and useful for monitoring exhaust temps as it warms up..etc..
Guess I'm trying to say, you should not rule out having an ignition problem, HT/plug wires touching/shorting, coils, voltage??
Anyone nearby with a spare igniter to try??
I think it more likely if intermittent and with various cylinders etc. maybe a pity that you got in to those carbs...
Good luck
Trevor

 

[Gorminrider]

if I dip each body and all small parts for 24 hours each that'll be 5 full days at a minimum! Guess the other option is to buy a bunch of cans... You don't think a few hours would be enough?

I have never had any luck merely soaking things to clean them. It doesn't work for my (admittedly!) filthy laundry and it doesn't work for bubble-gummy deposits stuck in tiny holes,IMO. Jets have to come out wherever possible and all the tiny holes cleared-in the carb bodies too. As in laundry, Soaking helps, but it still needs scrubrush, washboard or even agitation (sonic cleaners?) to move the dirt off the surface.
IF it's a carb problem, soaking alone may not fix anything...it might move stuff around, or begin to dilute the gums but as soon as you dry it out, it reconstitutes and gets sucked back into place when you reassemble and start the bike.
No doubt what I say is not exactly true for all solvents in all situations, but where I am, it's easier to dissassemble and completley clean things mechanically or with air than it is to keep buckets of toxicity agitating...

 

[Guest]

Soaking in dip for 24hrs does work from my experience, VM carburetors being a bit trickier than the others. It is sufficient to melt the baked on crud in the tiny passages, but requires additional cleaning methods afterward.

 

[Wingsconsin]

My first thought when reading this was - clogged inline filter being used -
If the carbs have been properly cleaned (I use an ultrasonic cleaner and carb dip when I do them) and synched they should produce fuel flow.
The valves are done creating proper compression and compression numbers check out.
Electrics seem to be refreshed and operating -- ? Stator firing and offering enough juice ?
A bad winding on a stator could cause the intermittent firing at higher speeds I believe ?
Have you confirmed the stator and R &R health ?
An old CX Honda I worked on once for an acquaintance had this issue - it idled fine and ran up to low RPMs fine - but when going beyond 5000 RPMs it did not create enough juice to keep the bike firing on all cylinders (only 2 on that bike) - It was a problem with the 'high speed windings" if I remember correctly (this was years ago) - the idea is that the bike needs more electric at higher RPMs and the stator may not be producing it or the R& R not passing it along..?

Delta connected stators generally produce a higher current flow at RPM's, and are ideal for many three phase battery charging stators. Wye connected stators are capable of producing higher voltage at lower RPM's. Three phase stators overall are much more efficient than their single phase counterparts. They produce more current at lower RPM's, and overall much more across the entire RPM range than a comparable single phase stator, making them ideal for most street motorcycles (and many larger dirt motorcycles with batteries)

[FONT=arial, helvetica, sans-serif]Altitude should not be factor for CV carbs[/FONT]

 

[klylor10]

Wow, this thread is really blowing up. Thanks for the all the suggestions, everyone.

I took the bike to 2 different motorcycle mechanics today in an attempt to have them ride it and tell me what they think is going on. The one who didn't ride it was stumped and thought it to be electrical. The one who did claimed carbs to be the issue (more specifically the pilot air bleed on just one carb, although he couldn't tell which one).

So.... I'll settle in for the long haul and do a 24 hour dip of each like is vehemently recommended. I wish I had an ultrasonic cleaner around, but the dip will have to do.

I spritzed some starter fluid around the intake boots to check for leaks, and they appear to be sealed, so I'm really hoping that the intensive carb cleaning does the trick. The other mechanic spoke of possible faulty wiring in the pickup or starter coil. I really hope I don't have to do any rewiring/replacing of parts.

I could use a bit of advice that should be straightforward: the head of one of my pilot jets is stripped, but it's tight in there. I see two options: get a jet from the dealer and try to extract the one that's in there or leave it in with the dip and hope that it's enough to clear any blockages. What do y'all think?

I'll update more as time goes on.

 

[Guest]

Starting out with everything clean will eliminate a lot of tail chasing and make other problems show up for what they are. Look to posplayr for electrical advise. I would try to extract the jet and replace it or get another carburetor body, they are usually available from someone here. Possibly cut a slot in the jet with a rotary tool if space allows. I had a friend soak the carbs and walk away, forgot them for a week or more. Made a mess to clean up but no real damage to the aluminum I could tell after they were thoroughly cleaned with WD40 and hot sudsy water.

 

[Guest]

Like I said earlier I sure wish I had a good set of carbs to send you. Did you manage to check the voltage that's getting to the coils? as a previous poster said, it may not be the carbs due to the fact that you've ridden the bike for quite a distance and it was running fine...right?

 

[klylor10]

Update:

I pulled the carbs last night, took one apart, and then had a thought: this problem started just after I installed new Dynatek ignition coils (among a couple of other things). To do this, I had to crimp on eyelets for the primary wires. My thought was that perhaps the connection on one of these crimps was not good, so I tracked down a soldering iron to solder each terminal. I wanted to do this before I committed to 3 days of carb soaking, so I put them back together and back on the bike. I finished up the soldering job and everything looked real nice. I buttoned everything back up and went for a test drive. Much to my dismay, things were worse, and problem that I had been having previously (intermittent firing on cylinder 3+4) showed up again. The plug on cylinder #4 fouled with gas (that one was a new issue). I swapped around the wires (1 and 4, 2 and 3) and the problem remained on cylinders 3+4. I checked spark on those cylinders, and it's a nice bright blue one. Compression is good, so that just leaves me with fuel as an explanation. Perhaps in taking the carbs apart and putting them back together something happened, I'm not sure...

I went ahead and dismantled the carbs, the first 2 bodies are soaking right now, and will finish their 24 hour dip later tonight. At that point I can put in the jets and other 2 bodies. It's okay to mix up jets between the carbs, right? I assume they're all the same.

I ordered a replacement pilot jet as recommended by OldVet, but am having a bit of trouble getting the old pilot jet out. There's still a bit of head on it that I can grab, but it's stubborn. I'm hesistant to use a screw extractor but I'm not sure what else I can do if it won't screw out for me. Someone I chatted with out here recommended a left handed thread drill bit.

Like I said earlier I sure wish I had a good set of carbs to send you. Did you manage to check the voltage that's getting to the coils? as a previous poster said, it may not be the carbs due to the fact that you've ridden the bike for quite a distance and it was running fine...right?

I wasn't able to read your post until after I had started the carb dip. I had forgotten about checking that in the fray of all the stuff I've been thinking about. It will have to wait until the carbs are together and back on the bike. I wish you had a good set of carbs to send me, too... The bike was running alright for the first 3,000 miles, I think, but I may have improperly cleaned them in the beginning and through riding dislodged some particle in the carbs.

 

[TxGSrider]

Recently I have become a big believer in the left had drill bit. I used one for the first time on a broke bolt and low and behold it unscrewed the bolt without having to use an extractor. Id think it'd be perfect for pilot jet removal.

 

[jsandidge]

I just had to remove a pilot jet with the head broken off 2 weeks ago. I tried a left hand bit, but it never really grabbed the jet to spin it out like I had hoped. It still worked out fine, though. I just tapped a torx head driver bit into the hole I drilled, and it turned right out.

This is the method I used (toward the end of the video)

 

[bobgroger]

If one cylinder is cold, 99% chance the pilot jet(s) is plugged. There is a VERY small hole in the end that plugs up frequently and for no reason. If that is the case it will generally run OK at full throttle. Plugging is exacerbated greatly with Ethanol. You can clean it out with 30ga wire, or new ones are ~$4. Also be sure there is a rubber plug under it.

 

[klylor10]

Update:

It's a good thing I'm reading Zen and the Art of Motorcycle Maintenance in my down time here, because otherwise I may go insane.

The carbs/jets came out of the 24 hour dip last night. I used carb cleaner to verify that all passageways were clear, and dried them with compressed air. I reassembled them and synced them today. For context: my setup is the rest the tank backwards on the seat so the fuel/vacuum line can reach it but I can also get to the carb screws. The bike sounded great (although there's a bit of unevenness at idle which I can't quite figure out), so I flipped around the tank, reassembled everything, cleaned up and was feeling good.

Get ready....

The petcock would not deliver fuel to the carbs, even in prime. I tried tilting the tank and lifting it up a bit, but that didn't help. To isolate if it was a petcock or carb problem, I hooked up a fuel bottle and tried running it off that: success! The carbs drink the gas, no problems there.

I unhooked the fuel line from the carbs, put that end into a gas tank and turned the petcock to prime: fuel flows freely. The only time it won't flow is when connected to the carbs.

There are 2 things I wonder about, and I'd love input:

1: Something going on with the pressure differential between the gas tank and the floats, where the gas tank is too low to overcome the differential and properly deliver fuel. I've never heard of petcocks failing in this way, but I suppose anything is possible.

2: Float problem in the carbs: I checked the float height and its 21-22 on all carbs. Could a cracked float create this kind of problem?