Gt750K carbs

[Salmanz8]

Recently acquired a gt750k
Hadnt been run in 5 years

Took the airbox off, sprayed some starter fluid to see any signs of life, and it did sputter, good enough for me

Carbs are off, the original vm’s.

Last guy who worked on em, i have no clue what he was doing.
Center and right carb was switched, one slide was sticking, which i found after that there was a screw put in, in place of the alignment pin .. huh go figure

He apparently couldnt set the floats right so stuck ( yes again ) a screw in the over flow hole

Needless to say, all apart, all cleaned, everything nice.
Couple passages were clogged and bodies had alot of mineral deposits, aka corrosion lol

Got all cleaned up. Tallied up the parts, everything is there.
Needle valves looked to nice to be original, so i am a little confused. It has mikuni 2.0 valve seats across all three.
Needle has no markings, is there anyway to identify ?

Should this have a 2.0 valve seat, or 2.5 ?

This bike needs other things as well, throttle cable, choke cable, handle bars, grips etc but i am trying to keep it original unrestored. Nice everyday rider kinda bike. But thats for later

Would appreciate if someone can chime in

[Salmanz8]

I guess the question is do i have to replace the needle valve seats to 2.5 ? Or would they be ok ?
Other than that complexity, i am ready to put everything back together and set float height.
I guess with the unknown needle valve, i will go with fuel lever in bowl rather than float height.

[Salmanz8]

Anyone ?

[Alan H]

I guess with the unknown needle valve, i will go with fuel lever in bowl rather than float height.

I'm not aware of any lever in a float bowl.
Just send the carbs to Baz and he will strip, clean, polish and service them properly. He's done several sets for me and I'm well chuffed with his work.

[asco58]

Should this have a 2.0 valve seat, or 2.5 ?

This Suzuki 1972/1973 service data book and the shop manual carb page indicate a 2.5 valve seat for a GT750 J/K:
https://www.oldjapanesebikes.com/mraxl_ ... ice/page-2
https://www.oldjapanesebikes.com/mraxl_ ... /index.php

[teazer]

#2.0 are a little small. See if you can get some 2.5s. I don't think they had a 3.0 in that series, but I can't get to my notes to confirm that.

1.5 are what are fitted with an old style fuel pump, that's why I said that 2.0 is a little small.

And YES to setting the fuel level. Float level data is only there because it's easier for most people to check but it represents a certain fuel level and that's what you want to get right.

Take the time to blow carb cleaner or WD40 through one hole in one carb and repeat on the other pair before moving to the next circuit. That way you can see that they all flow more or less the same. And don't forget the starter jet which lives in the base of the float bowl where it is easily clogged.

[Salmanz8]

I guess with the unknown needle valve, i will go with fuel lever in bowl rather than float height.

I'm not aware of any lever in a float bowl.
Just send the carbs to Baz and he will strip, clean, polish and service them properly. He's done several sets for me and I'm well chuffed with his work.

Thanks for the reply alan. Meant fuel level, not lever lol

[Salmanz8]

#2.0 are a little small. See if you can get some 2.5s. I don't think they had a 3.0 in that series, but I can't get to my notes to confirm that.

1.5 are what are fitted with an old style fuel pump, that's why I said that 2.0 is a little small.

And YES to setting the fuel level. Float level data is only there because it's easier for most people to check but it represents a certain fuel level and that's what you want to get right.

Take the time to blow carb cleaner or WD40 through one hole in one carb and repeat on the other pair before moving to the next circuit. That way you can see that they all flow more or less the same. And don't forget the starter jet which lives in the base of the float bowl where it is easily clogged.

Hey, thanks for the reply.
Appreciate the input, i will look if suzuki has any.

I am pretty confident about the carbs being clean now. Lets see how it goes.

Thanks fella

[Salmanz8]

Was thinking about trying as is, but decided against it.
0.5 gph can be significant.
2.5 needle valve sets are on their way.
Will post more info as i have it.

[teazer]

I think that the size is in mm, so a 3.0 is twice the diameter of a 1.5 and will flow roughly 4 times as much.