GT550 carb woes

[kawonda750]

Same problem, different day.
Left cylinder does not fire at idle. After about 1/8 throttle , it kicks in and the bike runs nicely. Timing is right on. Since it does not work below 1/8 throttle this points to the idle circuit/ pilot jet. I have removed, sprayed with carb cleaner and blown out the pilot jet and its channel 7 times now with my compressor with no results. I replaced the pilot jet with another , new one last time with no cure. BTW, I am using genuine Mikuni jets.

I am mainly a Kawasaki man and have a whole box of VM28s for Kaw triples. The channel for the pilot jet on these is a straight hole into the carb. I have looked into the Gt carb and see a raised part at the bottom and my welding cleaner pins do not go through. I checked one of the carbs that are working fine on the GT and found the same thing..The same raised part with no clear way into the carb body so assume this is how they should be.

So, any ideas. It is becoming very frustrating. It must be plugged somehow.but ?????

Thanks Dave

[karl pa]

Did you look into ignition or plugs? I have had this issue with ignition/plug problems.

[kawonda750]

I cleaned and changed the plug on that cylinder Karl. Checked timing and it is right on. As it happens , I had ordered an Accent ignition which will be delivered on Monday so I will see what difference that will make.

We'll see whay happens Monday.

Thanks for your input again Karl.

[karl pa]

I would put in new plugs when changing ignition, I had plugs that acted weak even after cleaning them.

[kawonda750]

Thanks Karl. I ordered them yesterday too.

[kawonda750]

I am at a loss to explain this. I have installed the Accent ignition and the left cylinder problem continues. I removed the carbs for about the 8th time yesterday. I took the left one apart pilot jet out, float needle out and air screw out. I sprayed carb cleaner 3 times and blew out every hole with my compressor 3 times. I exchanged the pilot jet for another brand new one before also. jets are all genuine Mikuni too.
The left cylinder does not idle but as soon as it gets past 1/8 open it fires and the bike runs perfectly. I exchanged the right plug with the left and the left still does not change so it is not the plug. I find it hard to believe that it could be the carb because I have done thie same cleaning so many times with no change.. The slides all move at the same time so the synch seems right.

It idled on all cylinders with the initial start up this spring. The vacuum gauge showed the centre cylinder was stronger so I reset the slides and they all register the same on the gauge now. The only thing I have not changed is the coils. Could it be that? Although it runs fine above the idle.

[kawonda750]

I guess I have found the problem. The base gasket on the left cylinder is broken. I was feeling the exhaust to see if it was firing and felt a breeze. I had to order the special gasket from the UK because I used their 1 mm longer rods. Besides having to wait, I hope this is the root of the problem.

On the bright side, I have very clean carbs......

[kawonda750]

Can anyone tell me the thickness of a gt550 head gasket. I am looking at getting copper gaskets

Also, can I reuse a standard head gasket since the head will come off to replace the left base gasket

[kawonda750]

I have the cylinder apart now waiting for the gaskets. The copper guy does not have the right thickness stock so I went with the stock Suzuki ones. I would prefer the copper, reusable ones that I can anneal and use again but , no such luck right now.

FYI, I get the compressed stock head gaskets to be 1.18 to 1.21 mm thick with my Chinese vernier.