carb set up

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Monkey man
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Suzuki 2-Strokes: T 250 t500 gt 550

carb set up

Post by Monkey man »

Can
Anyone point me in the right direction to balance/set up the carbs on my gt 750 j
i have just had them ultra sonically cleaned and have fitted new rubbers but havent attached the air box yet

any help or guidance would be much appreciated
thanks
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tz375
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Re: carb set up

Post by tz375 »

There are a few possible ways, but I usually start with what is generally called bench synch. That means getting all three slides to lift at the same time.

The simple way to do that is to take a wire coat hanger and cut 3 equal length pieces about 6-8" long.

Slip one into each carb so it rest under the slide. Adjust the cables so they have the same amount of slack first and then crack open the throttle as you look at the coat hanger synch rods. As the throttle is cracked open you will see the ends of the rods dip and eventually fall out, so don't go that far. watch carefully to see which move first and which one is last.

Adjust cable slack to get them all to move together.

Then remove the rods and fit the airbox and ride it.
GTandcbr
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Re: carb set up

Post by GTandcbr »

Same principal as above look here
https://youtu.be/jJGl_hab3Bg" onclick="window.open(this.href);return false;
98 carb Blackbird and GT550j
Monkey man
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Re: carb set up

Post by Monkey man »

Thanks guys - simple really lets hope its as easy in practice
Monkey man
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Re: carb set up

Post by Monkey man »

What went wrong?

Hi guys what a nightmare - put carbs back on after having them ultra sonically cleaned , set them up as advised put fuel in the tank and disaster - fuel pours out of the back of the carbs and the bike does not fire up .
it appears fuel is running or leaking down and from the two couplers linking the front pipes - cant tell whether its internally or externally.

Some pointers to go on

took the tank off and emptied the fuel out - full of crap
petrol cock might not be 100%
bike was initially running before carbs were sent for cleaning but this similar problem occurred which led me to have the carbs cleaned in the first place

any ideas where to start ?
GTandcbr
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Re: carb set up

Post by GTandcbr »

Hi. If the petrol tank is full of rust it could be causing loads of problems. Any rust in the tank will end up in the carbs. This can prevent the float needle valves from closing therefore overfilling will occur. One answer to this is to fit in line filters. The next problem is that your petcock is also not working. The tap is constructed with a diaphragm so that petrol flows through only when it is running. Unless you have it in the prime position?
To clean the petcock this is the same tap https://youtu.be/qWNyvjaWfz8" onclick="window.open(this.href);return false;
98 carb Blackbird and GT550j
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tz375
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Re: carb set up

Post by tz375 »

+1

Empty the fuel tank and get all of the rust out first
Remove the fuel tap and clean out the filters on top (inside the tank) and clean out the tap itself
Remove the carbs again and clean out any rust or debris from every nook and cranny and then check the float levels with carbs tilted (not upside down). You could also wet check the fuel level with the carbs off the bike and set them more accurately that way.

And any time you have petrol sloshing about, make sure you have good ventilation and a fire extinguisher and no one smoking.
Monkey man
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Re: carb set up

Post by Monkey man »

Thanks for the advice - have viewed the link on the fuel tap maintenance and opened mine up - found the hole in the diagfham didnt line up with the vent hole in the tap itself so some progress there - Read advice (by les howard-RealClassic.co.uk) on internet on how to de-rust tank so have bought caustic soda etc to do it myself - will take carbs off at the weekend and will update thanks
Monkey man
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Re: carb set up

Post by Monkey man »

Update and sucess ! A friend came up to help -we took the carbs off and they were spotless with no obvious issues so we put them back together and on the bike . After swilling the tank out with fuel we put it back on and tried again . The bike still wouldnt fire up but at least there was no leakage from the carbs . We then checked for a spark at each plug by placing against the engine casing and all was ok here but the bike still wouldn't start . The spark plugs were wet and there was still some fluid leaking from the exhaust couplers.

My pal concluded the cylinders were flooded and then decided to run the bike with the spark plugs out and this had the effect of spurting all excessive fuel out of the barrels and over the garage floor- it looked quite alarming but when no more came out we put the plugs back in after drying and heating them on the gas stove . The bike eventually fired up and once all the smoke cleared sounded great - after a while it settled down to an even tickover - i have since been out on it today and it is fab, a little clutch grab but otherwise superb - i intend to leave the tank cleaning until the winter and enjoy the rest of the summer as it is for now - thanks for all the advice and i wouldnt have got it going without the help of my mate Bob - owner of 'dustdevils' - an off road motorbike business in Costa del Sol Spain.
GTandcbr
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Re: carb set up

Post by GTandcbr »

Great news! Just a gentle reminder if you dont fit in line filters it will not be long until your carb problems return......
98 carb Blackbird and GT550j
Monkey man
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Re: carb set up

Post by Monkey man »

Thanks - will get them and fit them asap!
Monkey man
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Re: carb set up

Post by Monkey man »

Hi guys - still having problems with the Petcock - looking at the video for the gt550 on the attached link there is a spring at the rear of the diaphragm - mine is missing - does the Petcock for the gt 750j supposed to have one ?
GTandcbr
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Re: carb set up

Post by GTandcbr »

Yes its the same tap. Not surprised its leaking if you dont have a spring pushing it back! You wont be able to get a guenuine one. Best thing go to a hardware store try a selection of springs. Remember it is quite a weak spring because it is pulled back by the carb vacuum only.
I have measured the spring for you 13mm long 8mm diameter.
98 carb Blackbird and GT550j
Monkey man
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Suzuki 2-Strokes: T 250 t500 gt 550

Re: carb set up

Post by Monkey man »

Lucky me - i had an old petcock off my t500 so opened that up and took the spring out and fitted it to the 750 petcock - have also fitted the inline fuel filters so im ready to go
will upload pics when i can figure out how to do so
CBWELLS
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Re: carb set up

Post by CBWELLS »

Just an anecdotal story as related to the "spurting all excessive fuel out of the barrels and over the garage floor..."
I once had a similar situation on a B&S V-twin lawn tractor & I did a similar action, ie. I removed the plugs & cranked the engine over to push the fuel out of the cylinders. Well, that was successful, but a surprising by product was a spark from the plug-wire jumped to the engine & ignited the fuel. I had a very effective home-made flame thrower that shot fire about 10' across the yard. Fortunately I was outside & my car was far enough away that it was all just very exciting & funny at the time, but had I been in my garage, it would have gotten really ugly REALLY FAST! Fortunately, the fire went out & nothing but the grass was toasted.

Just sayin'...Be really careful when gas is given free rain (spelling pun intended)!
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