Can't get my carbs to tune on a Suzuki gs550t 1981 carbs rebuilt and cleaned shimmed valves new head gasket still no joy?

needs full tune-up==fuel delivery problem --carbs need attention timing --incorrect adjustments to valves --filters--

Back fire is either a mechanical or an ignition timing issue. There is always a gasket between the intake and the carb.

You only have three options as to what is wrong. Either the float is stuck, adjusted wrong or trash is not letting the float needle close fully. My bet is trash from the gas tank.

* check the lever attach to the brake drum if its stuck and corruded (try to clean it)

* check the spring insert in a long circular bar if its playing or bouncing.

* put an oil sewer or grasp in some parts of the brake which plays the brake...







hope it helps....

This sounds like an air leak ahead of the carbs. Air that hasn't gone through the carbs is leaning the fuel/air mixture. Cracked rubber fittings, "O" ring seals, gaskets, and clamps between the carbs and the cylinder may not be sealing well enough. Note that a bad head gasket, bad valves or loose spark plug can also let air enter. The problem will get worse as time goes by. Do a compression check to check the valves.. Burned valves and cracked rubber seals are normally the culprits. Usually, all the valves need is to be re-lapped to provide a fresh face on the valve and valve seat. Check the site below for parts. www.babbittsonline.com

Valve clearance ideal setting is 0.10mm however as ideal replacement size shims are not always available use tolerance 0.05 to 0.2mm inlet and exhaust Procedure remove tappet cover rotate motor to tdc compression (inlet valve lobe pointing to rear wheel and exaust lobe to front wheel) measure clearance if no clearance depress cam bucket hold down by wedging a screwdriver or suitable tool (allen key) between cam bucket and cam remove shim measure with micrometer an relace with a shim 0.15 thinner depress valve remove wedge and measure clearance (if any) repeat procedure 4 each cylinder if clearance to large replace shim with a thicker one till clearance is in spec

take your carbs off and clean them concentrating on the slow jets and the slow jet passageway through the carb body.

Chances are you need to do a complete tune up. This means a new spark plug, cleaning the carb, new air filter and new piston rings. I would also re-seat the valves. Any further top end work ( replacing valves, bore cylinder and new piston ) is entirely based on what is found after tearing into the head.

The vacuum comes from the intake manifold and ported vacuum comes from the carb above the throttle plate. You might have a leak at the carb gasket or intake manifold gasket. Spray some car cleaner or WD40 around the gaskets and vacuum lines while the engine is running and when you hear the idle speed up, you've found the leak. You will need to install the rebuilt carb first, and you should tighten any loose intake manifold bolts. Don't overtighten them. Also check the EGR valve because it could cause the engine to stall at idle. A good tune up might be needed too. I've seen some of those engines run real rough when the ignition timing was off.

Have you adjusted the valve lash lately?
With engine COLD....
Valve Clearance Intake: 0.11 - 0.15mm ( = 0.004 - 0.006")
Valve Clearance Exhaust: 0.16 - 0.20mm (= 0.006 - 0.008")
29mm shim kits with a wide range of sizes are available from aftermarket dealers. (motion pro shim tool works great)
Also a weak valve spring will cause the valve to "float" and make a rattle noise...as well as excessive camshaft end play.
Make sure your valve train is getting proper lubrication.
Good luck....i hope this helps