post carb cleaning, trouble

[emzdogz]

hi folks, I just re-cleaned my '80's BS 34 carbs again after they'd gotten gummed up months ago. Replaced the float needles and the part they sit in, rubber caps over (under?) pilot jets and also float bowl gaskets.

Put them back on today, and the bike doesn't want to start easily.
Finally got it to run just now and it feels as though it's running only on one cyl. Very slow idle, even with choke pulled out. I also replaced the mixture screws and set them identically before putting the carbs back on.

For now I have those "clear" plug caps so you can see when it's firing. Even when running at that very slow, no-good rate, both sides are firing ( i see spark at the cap). Could it be a dead cylinder even if the plugs are firing on both sides (at least at the caps)? (is that possible)

It tried at one point to go ahead and run on both sides, I think, but I went ahead and shut it down thinking it just wouldn't be good for it to run that rough way and wanted to avoid a backfire situation, as the neighbors have a baby, etc.

Was just reading the carb guide and it says if you replace the float bowl gaskets that you must punch out all the little circles in the gasket, or the enrichener circuit won't work.

Question: when it's running with choke pulled out, is that simply adding additional fuel? or does it also block out the regular fuel flow and run JUST on the enrichener circuit, until you push the lever back in?

I'm almost thinking it's just not getting "enrichened" on one side.
Tomorrow I will pull the float bowls and see if I neglected to punch out one of those little circles in the new float bowl gaskets.

thx

 

[5twins]

While you're in the bowls, check the choke feed jets as well. They're one of the 1st things to get plugged when the bowls gum up because they're near the bowl bottom. Use the choke and it sucks crap right into those jets, plugging them. Then the chokes don't get their required gas and don't work .....

 

[emzdogz]

thanks 5Twins. Will do. Great photo, by the way.

 

[5twins]

Thanks, it took a few tries to get this shot. Your bowl won't look exactly like this on the flange part because this is from a Virago carb set I did last summer. The choke jet and fuel inlet will be the same though.

 

[emzdogz]

went to go ahead and take the carbs off again and as I had them loose from the boots and getting ready to pull out, I looked into the intake of the left side and saw...... wtf is that? anyway, I don't see very well these days - once I got my glasses I saw it was that the gasket between rubber boot and head had slipped and swiveled while installing it, so it was only attached at one point, and the rest of it was blocking the intake.
That's what happens when I try and work without my glasses.

So I removed that boot, placed the gasket correctly and popped the carbs back in, hooked them up, etc....and vroooooom, starts right up - but running way too fast, even without choke. So anyway, eventually, I got it running so it sounded ok HOWEVER I still have problems to address.

a. it's puking oil from the clutch pushrod seal - makes me wonder if the pressure relief outlet is clogged and it's only option is to blow oil out that seal. Or the seal is just bad. Either way it has to be addressed.

b. Also the right side isn't firing right. There is some gas at the end of the pipe and that pipe - at its end is cold. Not totally cold, but not hot like the other one. The plug was also gassy.
(not oil) So that side isn't completely burning its fuel. Something else I notice - the Mikes replacement air mixture screws don't need to be turned out very far.

c. Another thing, on that right side, turning the air mixture screw has no result. On the left side, i can alter the idle speed or even kill the engine by turning that screw in or out. On the right side I turn it all the way in and it has no effect. Doesn't alter run speed at all, either way.

So either those passages are again clogged, despite a good cleaning - OR the enrichener circuit on that side isn't closing off completely and is feeding additional fuel in on that side only.

So next, I will do (again) a valve adjustment to see if that might be the cause of the fuel not burning off on the right side.

Anyway, just thought I'd mention that the initial problem was that gasket having slipped and blocking the intake. Now, ironically, that's the side that runs correctly.

 

[emzdogz]

re-re-studying the carb guide. I already see something I did wrong setting float height.

 

[grizld1]

You replaced the float valves; now you need to check to be sure that the right side float valve is sealing, that float level is correctly set, and that you don't have a float with a hole in it. Fuel in the float chamber vent line and failure to respond to fuel screw changes are the "tells" on float and float valve issues.

 

[emzdogz]

You replaced the float valves; now you need to check to be sure that the right side float valve is sealing, that float level is correctly set, and that you don't have a float with a hole in it. Fuel in the float chamber vent line and failure to respond to fuel screw changes are the "tells" on float and float valve issues.

thanks!
Looking forward to getting it straightened out.

 

[emzdogz]

so, I'm having a heck of a time getting the existing brass floats adjusted just right. Seems they are twisted/tweaked a bit, so the left one or the right one is always higher or lower.

A question for those of you who ordered new floats: were the new floats' "tangs" already in about the correct position? or did you have to bend them right away upon first installation?
thx

Am thinking of just ordering new ones, as I'm kind of tired of messing with these old ones. Can't seem to get them straight.

I know my float valves do seal off ok (they are new, so they should). What I did was put a long tube on the "t" inlet and with the carbs upside down on bench with bowls off (so floats closed off valves by gravity) I put some gas in that line and blew on the end of it, to see if gas forced itself through. It didn't. They stayed shut and allowed no gas. Then I tried it again, slightly lifting the floats and gas blew easily through.

 

[5twins]

Just keep twisting the floats until you get them straight. If you must buy new ones, I don't recommend the ones from Mike's. They're mostly junk. Originals from Yamaha are your best bet but they are expensive. No, they're not pre-set and may be twisted as well. That's why I don't think you should replace your originals unless they're totally shot, like have holes in them or something.

 

[emzdogz]

ok, will do then. They don't have holes. I tried like heck to drown them and they wouldn't be drowned.

 

[emzdogz]

haven't put the carbs back on, due to time constraints. They are sitting upside down on work bench, wrapped up in rags.

Anyway, I've measured the float position several times and if I set them and then leave them sitting on the bench upside down and come back out in a couple of days and measure again - dang! there is clearance where there was not clearance before. (between float and slidey thing on ruler)
So, over time, they "settle" downward.
Of course on the bike gravity won't be an issue. But i do believe this lets me know that setting the position on these things can't be absolute.
or?
Be nice if the kit came with a plastic tool, like a u-shaped thing that you could position on the inside of the lip of the carb body and it would be just the right height allt he way across.

anyhoo...just thought I'd mention that.

 

[emzdogz]

pertains to a Honda, but interesting:
http://www.salocal.com/sohc/tech/carb/asmpg_mgs/flthgt.htm

 

[jayel]

Be nice if the kit came with a plastic tool, like a u-shaped thing that you could position on the inside of the lip of the carb body and it would be just the right height allt he way across.

anyhoo...just thought I'd mention that.

measure what you need and cut out of a old credit card

 

[emzdogz]

Re-assembled this today. Started and ran much smoother, with no visible smoke. However, right side exhaust still had gas in it and right pipe cold and mixture screw modulation in or out has no effect on that (R) side. But it sure sounded smoother.

Seems like if float needle wasn't closing off, that gas would overflow out that carb throat, but it's not doing that.

So gas is going into combustion chamber, spark is happening but the fuel isn't being burned.

So next, I will check valves.

I was really encouraged when I turned the petcocks on and fuel flowed into bowls but no overflow like last time - and then further encouraged when it sounded so smooth. But alas, right cyl is still not burning mixture.

I have this strange feeling though, that if I went ahead and rode it, it might kick in. Too much standing un-ridden for this bike.

 

[emzdogz]

pulled (R) float bowl with carbs still on bike and pulled the floats downward a bit, real carefully, so hopefully they will cause the float needle to cut off fuel flow sooner. Of course NOW the damn battery won't crank it anymore...so it's sitting on the Tender now.

 

[bbillington]

Have you checked that plug to see if it's fouled? Even if it were, they usually start firing once the bike has warmed up a bit, but worth a look.

 

[emzdogz]

Yes, it was gas fouled (wet/flooded). I did clean it off and dry it. I think what I'll do is actually take it down the road for a real ride (at least around my neighborhood) and see what is does in real world running - and in higher RPM ranges than what I can do in my carport.
thx.

 

[emzdogz]

Yesterday I saw on Youtube a video which I think was by someone on here - so whoever that is, thanks for the videos! that's wonderful.

I see from that video, one thing I was not paying attention to in setting float height.

I was taking the measurement with the carbs upside down but with floats just loose - not paying attention to whether the tang was contacting the tiny plunger on float needle. To be honest, I didn't even know that was a "moving part" - the plunger.
So I re-did the adjustment (with my third hand, and wearing 2 pair of reading glasses, lol) so that I'm taking the measurement with floats touched a bit so the tang is just beginning to contact the plunger.

Let' see what that does for me.

Another thing: I re-checked the pilot jet, just to be double-sure it's not plugged. It is the stock 42.5 jet as spec'ed for the BS34's. I also see in the listings of pilot jets that could be used for that carb, that 42.5 is one of the richer ones available - i.e. there are much smaller ones of the same type available.

Question: why would anyone ever need to put a SMALLER size pilot jet? Normally any mods involve opening up exhaust, as well as using supposedly freer flowing air filters (pods or unifilters). So it just makes me wonder under what circumstances you'd want to use a smaller size than stock pilot jet. (I always read that the bikes came jetted really lean from the factory).

Thanks again to whoever took the trouble to make those videos.

Much appreciated!

 

[XSLeo]

Sounds like your getting good carb advice, so I'll put in my two cents on your clutch pushrod seal leak.
Oil under pressure from the oil pump is sent to the transmission shaft bearings. Guess what's behind the clutch rod oil seal, That's right, a tranny bearing. Oil under pressure there leaks out the seal if it is bad. Good thing is that changing that seal is easy.
Pull the seal in any way you see fit as long as you don't hurt the hole it's in. Remove the sharp edge around the hole. With the clutch push rod in place can you feel much movement as you wiggle the rod up/down, left right. If it has much play the bushing in there is worn. A worn bushing wears seal out fast.
Mike's has an excellent "How To" on replacing the bushing.
Now to install the new seal I like to use a #3 Phillips head screwdriver. To us the screw driver, slide a fender washer on the screwdriver. Needs to be bigger than the oil seal, Slide it on the screwdriver. Now slide the seal on the screwdriver. Oil the screwdriver.
A bit of Yamabond on the outer edge of the seal will help it slide in and seal the seal to the cases.
Slide the screwdriver in the hole where the pushrod goes. This will guide the seal in straight, With a gentle push the seal should pop right in place. The washer will keep the seal from being pushed to far. Now remove the screwdriver.
If you got the sharp edge of the hole removed properly then you will have a good seal installed, if the hole had even a small sharp edge it will cut the seal and leak.
Get an extra, maybe two, just in case.
Leo