Bowl levels are the same, sooooo.....

[frosty5011]

If you can't tell from riding the bike, whether all 4 cylinders are firing, a quick way to check to see if the cylinders are actually firing is to put a drop or two of water about halfway down the header pipe. I use a little plastic syringe - it helps prevent me from getting burnt. Put it up close to the header, after the bike has warmed up - squeeze out a drop of water onto the pipe, and when that water drop touches the header, it should sizzle/boil away. If not, that cylinder is not running right. (Yes, it may still be extremely hot from the heat transfer, too hot to touch/hold, but if it doesn't sizzle away right away, you don't have proper combustion).

In fact, you can even tell if the bike is running too lean. If that drop or two of water don't even want to boil away, but "bounce" off of the header, chances are you're running too lean. Takes a while to know exactly where on the pipe to do this, and see the different effects, but it is an excellent indicator.

[Scud]

Bert,

Thanks for the info on the needles, while carbs are apart I will note them.

Frosty,

I will indeed try that also, I just cannot imagine that it is radiating heat from cylinder #2??? I mean it is just as warm as the others after five minutes and it seems to me that IS firing.

Thanks guys,

Scud

[Scud]

Fellas,

Here is a picture of #1 after a one-hundred miler.

Should I just ride and take the carbs apart when the weather is too bad to ride.

http://i20.photobucket.com/albums/b226/scottjm/1Plug.jpg

Scud[/url]

[KEITH KRAUSE]

Looks more "normal" now. Shows combustion.
The insulator is telling you it's very lean though.
Could be a bunch of reasons for it.
I don't ever recommend running on a cylinder lean. I do know what you're asking (and hoping to hear) though about putting it off 'til winter. All I'll say is that I've seen others ride around on a LIMITED basis, and have no apparent problems. Mostly short rides to work, that kind of stuff. I wouldn't take it on longer rides though, I'd find out what's wrong and fix it.

[Scud]

Keith,

I appreciate your patience, knowledge, expertise and insight. I will only take short rides and maybe, just maybe get to the carbs before the snow flies.

The bike is very clean and in GREAT condition, cosmetically and sound so I do not want to mess her up obviously.

I will take everything to heart and get to those carbs when I can.

Again, many thanks for all the posts and I will get back to all whn I have some answers.

Scud (Scott)

[Hoomgar]

No one touched on the holes in his exhaust? Scud, you mentioned rotted exhaust pipes. Was it the pipe in question that has the holes? Exhaust leaks can also have an affect on combustion. You could be having a combination problem. Please give more details on the condition of your exhaust buddy.

[Scud]

Sorry for the long delay....I am in Montana and away from internet for the most part until this Wednesday.

Holes in the exhaust....well, both sides have holes (1/8 inch) and gashes up to one inch in length by 1/8 inch along the bottom side of both pipes. In fact, last week I had a short of some sort that made the engine stop for a second or two and then start, this led to a backfire that blew a one inch by two inch piece (torn on three sides and hanging from the attached piece) on the number three and four cylinder side (right), I was able to fold it back into place without it breaking off.

I checked my harness and found a suspect wire that I fixed and the problem went away.

Question, do you think this has something to do with my problem even though it is on the right side exhaust pipe??

Which leads me to another question....anyone have stock exhaust pipes for sale that will fit my 1980 GS 750E...I am in the market now. :?

Thanks,

Scud

[Hoomgar]

I am not the expert but I know enough to know that major exhaust leaks like your describing can have a serious impact on how the bike runs. I am surprised that none of the guru's picked up on that when you posted it last month.

What affects exactly it would have is what I don't know but I am guessing that yes it could be related to your problem or at a minimum could be compounding it.

[Scud]

Thanks Hoomgar, I thought that a while back but since I had not heard back I figured that it may be alright to leave it as such since it was on the bottom and not cosmetically visible unless you looked underneath the pipes.

I guess it is time to look for a set of pipes. I really like the stock set even though they are hard to find.

Scud

[gsBert]

well, seems like the new plus picture is indeed leaner than you'd want it.
i don't think it's too dangerous but it might just be because i haven't holed a piston yet.

so the concensus seems to be: fix it.

i feel like a noob for not picking up on the exhaust bit, that could indeed be it (me being a noob, and your lean being exhaust)

1100 pipes should fit your 750, that's what i have on mine.

i find it better to put a 4:1 system on there it's lighter and won't leak as easily. you might want to look into that. shouldnt require rejetting if you're still using a stock airbox if you buy a street legal 4:1...

[Scud]

I have saddle bags (actually suitcases) that ride near the OEM exhaust. Aftermarket pipes have a tendency to ride higher and I think would interfere with my suitcases (samsonites!).

I have not ridden her since the last few posts and will more then likely not until I pull the carbs....good incentive....

Scud

[Scud]

I'm back.. GSBert, Hoomgar, Keith and all, I took the carbs off last night..do not know what got into me..maybe it was all the rain outside ...anyway here are the specs on the jets in my carbs, all have the same jets installed.

Mains 112.5
Air 170
Pilot 42.5

I live at 6,200' and have all the floats set at 22.4 mm.

I looked at the carb in question (#1) and it looks fine...hmmmm... I cleaned all jets and re-installed.

Also, I ordered a Vance and Hines 4 into 1 so I will pull the pipes off today and get ready to install those as well, should be here next week.

Anymore thoughts or ideas?

Scud

[KEITH KRAUSE]

Well at least you know the jets are the same, at least the ones you looked at. I suppose #1 could have a leaner needle jet or something else going on. Who knows the carbs history? I'm not reading back to see what's been done but I know we've tried to cover everything.
The pipe will require some re-jetting anyway, at least the main jet. And now you won't have any negative effects from the bad exhaust. I do suggest new exhaust gaskets though.
Obviously, somethings causing that cylinder to run leaner than the others, but who knows what?
After you get the pipe on, I would double check the vacuum synch. At least hook up the tool and read the levels to see if they're still as you set them. I suggest this because many times the synch "changes". Most of us have set a level, tightened the adjuster screw, but lo and behold after exercising the throttle a few times to verify, the level changes a bit. Maybe you'll find the level off a bit (lower) if you re-check?
If it still runs leaner than the others, maybe we can all get together and make a check-list of every possible lean condition, regardless of how remote the chances.
By the way, taking plug reads at different throttle positions can possibly narrow the cause down too. You may find the plug starts burning more similar to the others at a certain throttle position. For example, it may burn similar to the others a full throttle, but quickly lean out at 1/3 throttle or vice-versa. It may be lean at minimum throttle, etc. Marking the throttle and taking various reads has always been a good way to trouble shoot. If I remember, you haven't tested in this way. And I mean at a solid 1/3 throttle, chop off and read, then full throttle for the main, then mimimum throttle for the pilot circuit. Might tell you something.
But I'd first triple check the vacuum synch.

[gsBert]

congrats on the carb teardown scud.

as keith mentioned: did you look at your needle jets (the tube the needle under the diaphragm slides in and out of)?

the different throttle opening plug chop will indeed narrow the lean condition down to the range. if it's all across, blame vacuum leaks or compression, else you got one weird jet or somethign else wrong (hope its not something else cuz its gonna be a female dog to track down)

you kow how to do the plug chop right?

this sounds dumb, but you did make sure none of your diaphragms had holes in them right? (it's too obvious, i'm sure you checked)
my carbs also have vacuum nipples on the diaphragm cover. they should all be plugged except for the one going to the petcock. tripple check that too.
let us know. good to see this thread progress.

[Scud]

Keith - I will take out the needle and remove the jet that has all the holes in it that the main jet threads into and the needle slides in and out of...what is that called anyway (thanks gsBert)??...and make sure that all holes are clear. Also, Keith you mention exhaust gaskets, the originals consisted of two half moons only on cylinder exhasut ports one and four...does this sound right?? The fellow I purchased the bike from was the original owner and very detail oriented, I knew him personally before he shed the wing of his Maule aircraft at 100 feet AGL and he died as the result.

Hmmmm...diaphragms...I looked closely at all and did not see any tears...those things freak me out...they seem thin to begin with and I do not want to F#$K them up if possible.....so I have been REAL gentle with them. gsBert, my carbs do not have anything on the diaphragm cover, just a solid aluminum cap.

I will also do a plug chop and kill the engine at high, medium and low rpm's ( I have the perfect, untravelled road for that test) and let you know what I find wtih regards to plug color.

As mentioned, my new pipes and larger main jets arrive next week...then the fun begins again. I have performed a few synch's and own a Morgan carbtune..love that thing..

I also am waitning for a new valve cover and breather gasket alon with the end plugs.

I am off on a business trip tomorrow and will return on Sunday night to check this post.

As usual, thanks for all the information and ideas, we will figure this out I know that for sure!

Scud