Won't Rev past 5k... Just cleaned carbs...

[Jedz123]

Hey Guys
I Had to yank the carbs of my GS750L the other day for one of the needle flow valves got stuck open and caused fuel to pour out of my carbs. Well I took them out and decided to clean them out for the hell of it cause they were out. I found my Culprit a small piece of dirt jamming the float pin open on Carb 2. So I religously cleaned the Carbs out making sure to remove the pilot Jet, main jet, slide, boot, fuel mixture screws... the whole nine and clean them out (If dirt jarred open the float needle it could mess with something else). So after removing everything and cleaning it, I reassmebled the carbs and put them back on my bike. I noticed the bike was starting hard so after about 30 minutes of fiddling with the mixture screws I managed to get it to turn over and idle(not perfect but runnable). SO I hopped on it to see how it ran after the cleaning... I noticed that it was very smooth until 5K rpm, I shift think nothing of it accelerate up slowly to 5K rpm again and notice she won't go past that band. So at The next intersection I pulled out and gave it 3/4 throttle just to see what it would do... It had it's usual low end grunt but as soon as the motor hit 5k rpm she fell on herself and woulden't go any faster. I did a quick loop around the block and pulled into my garage smelling a hot fiberglassy kind of smell. I looked at the headers and noticed that the heat had changed the color of the metal a bit... So in a panic I planted my butt in front of my computer to ask what is going ON!?!?!?!
Any Ideas on what this is and how to fix???
Thanks Jedz!

P.S> I'm going to pull the plugs and read them to see what cylinders are lean or not... I'll post the pics, just got to let her cool down a bit.
Thanks!

[ryonker]

What year bike do you have?

How did you clean your carbs? Did you soak them in carb cleaner or just spray them?

When I clean my carbs I soak them overnight; then I blast carb cleaner spray through all the holes, and I blast air from a compressor through everything. You might even want to use a small wire to push through the jet holes.

Sounds like you still have stuff in your carbs.

You also need to replace o-rings on the carbs and the intake o-rings that are in front of the intake boots.

When your done, you need to bench sync the carbs and then sync them using a manometer.

Rick

[kparkfan]

I second what ryonker said. If you do this and do a good sync on the carbs you will be amazed at how good she will run. While your at it go ahead and adjust your vaves too.

[Jedz123]

Sorry it's an 81...

Here's the readings:

Plug Reading for Cyl 1
Lean...

Plug Reading for Cyl 2
Really Lean...

Plug Reading for Cyl 3
Really Lean...

Plug reading for Cyl 4
Slightly Lean but Ball park...

When I cleaned the Carbs I soaked the jets and screws in the bowl with carb cleaner while I cleaned out the carb passage ways with the spray and a tiny wire thin punch...

How do you bench sync??? What is a manometer... Sorry I'm a total noob with carburetors much more knowledgeable with Fuel Injection... I must have done somthing wrong when I "cleaned it out"... Fail for me!

Do the vavles eh? Guyess I can run down to the parts store and buy some feeler gauges...

[81gs1100]

Airbox and filter?

Did you happen to take this test ride without the airbox or filter fitted?

Without the airbox and filter attached the bike would run super lean and not rev.

[Jedz123]

Yup Air box is secure and filter is installed...
Guess I'm off to clean... again...
Find it weird it worked ok before I cleaned it...

[81gs1100]

Yup Air box is secure and filter is installed...
Guess I'm off to clean... again...
Find it weird it worked ok before I cleaned it...

When you cleaned the carbs did you also take apart the slides and jet needle?

Did you put the needle in the slide the same way, putting the spring or spacer on the wrong side would have a nasty effect on your jetting.

Also, you messed with the floats and such, did you measure the float hieghts? If the floats are set too low the bike would run lean as well.

Is the fuel line kinked?

[Jedz123]

Yes I took the slide out with the boot and spring and all that jazz... But didn't take apart the slide and the needle but just kept that stuff together... cleaned the boot, slide needle and sprayed into the little hole on the slide to clean all that crap out... Your saying if the spring is up side down it can effect the fuel being jetted? I also noticed after I cleaned the carbs out that on of the slides would drop back into position allot faster then the rest of them... It would snap back into place. I didn't measure the floats... Honestly didn't know I had too... wow Total crash course on Carbs right now!
Thanks!

[81gs1100]

Not the springs that hold the diaphram down... Those can be installed either way on most models.

I was talking the needles, the springs are to be installed between the slide and the needle holding the needle up, at first I put the spring on top in which held the needle down as much as an 1/8". Which really leaned it out.

As far as the slide movement... They should slide evenly with some slight differences but all in all pretty darn close.

You are saying they snap back down? They should slide down rather quickly but controlled, they are regulated by air restriction.

When you put the slides back in and replaced the caps did you notice a tab on the rubber diaphrams? Did you place the rubber tabs in the cut outs in the carb base? If there is an air leak from your slide not allowing them to rise the bike would run lean.

[Jedz123]

Yeah i put the tabs back in but I think I know where my mistake is... I'm going to check those seals on the top of the 2 slides that snap back down... The other slides make a whoosh noise when you push them up the other 2... not so much... Figures the slides that snap are to 2 and 3... the 2 cylinders running really lean.
Thanks 81 GS!



P.S.
Really curious... how does an 1100 ride compared to a 750?

[81gs1100]

Yeah i put the tabs back in but I think I know where my mistake is... I'm going to check those seals on the top of the 2 slides that snap back down... The other slides make a whoosh noise when you push them up the other 2... not so much... Figures the slides that snap are to 2 and 3... the 2 cylinders running really lean.
Thanks 81 GS!



P.S.
Really curious... how does an 1100 ride compared to a 750?

Yeah the their are tabs on the rubber diaphrams that has a spot to go into to make sure they are the right way and make a good seal.

[Jedz123]

Checked them and they seem to be set in place still runs like crap... looks like the Carbs are coming back off tomorrow... been working on this bike for 6 hours now...

[Jedz123]

I'm going to take apart, clean and soak the carbs tomorrow... What do I soak these suckers in??? Can I soak the rubber diaphragms?
Thanks for all you help guys!
-Jedz

[mike_of_bbg]

What do I soak these suckers in???

The carb dips of choice around here are Berryman's and Gunk. I can get them at my local Auto Zone or Advance Auto Parts for about $20/ea in one-gallon type paint cans - the dipping basket is included. Ignore the instructions on the side that say 30 minutes and soak the parts for at least 24 hours.

In some states and countries these products are restricted due to environmental concerns. Your profile doesn't show where you are (hint, hint), so we have no way of knowing if those are applicable to you. If you can't find the above products, just search the forums for some alternatives.

A couple more tips: the dip will last longer (as in, not get a bunch of dirt floating in it) if you clean off the outside of the carbs first. Furthermore, the outer two float bowls may have some sort of coating on them to keep them shiny. If you want to protect that, don't dip them. Just spray them out and make sure the passages are clear.

Can I soak the rubber diaphragms?

NOOOOOOOOOOOOOOOO!

Nothing but metal goes in the dip. Remove all plastic, rubber, nitrile, cork, whatever parts. The SOP is to spray the slides off with spray carb/choke cleaner. Make sure to check the diaphragms for any pinhole leaks. Those things are rather expensive to replace so be careful with them.

[tkent02]

Make sure to check the diaphragms for any pinhole leaks. Those things are rather expensive to replace so be careful with them.

Good possibility this may be your problem, no woosh may mean there is an air leak through the diaphragms on 2 and 3.