Will 1100 carbs fit 650?

[Guest]

Just rebuilding my second gs650gt and I'm servicing the carbs when I find that the air fuel mixture screws are all completely seized in......spent nearly a week now trying to find a replacement carb set but no luck. A mate has got a set from his old gsx1100 which from a quick glance look pretty much the same as the 650g( sure the Jets would need changing etc) but can anyone tell me if this swap over is feasible?
would really appreciate some help as this is the last part of a build that has taken me 6 months and the sun is finally coming out!!!!😝

[Steve]

The throats are larger (34mm vs 32mm) and the spacing between the carbs is different.

There are measures that can be taken to remove the mixture screws, don't give up on your carbs yet.

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[JTGS850GL]

The GS650's are a little unique. Yes, they are BS32 carbs but they have an unusual size main air jet. That's the press fit jet that's on the right side when looking at the front of the carburetor. The side that faces the air filter. Most BS32 use a 1.7mm main air jet, but the GS650 uses a 2.0mm jet and the GS550 uses a 1.6mm. Just make sure you get a spare set from a GS650 and you should be OK with all the other jets. It is possible to drill the main air jet out to the correct size but you need the right drill bit and a stable drill press.

In order to get those pesky mixture screws out you'll first need to put a few drops of penetrating oil in the hole and then heat the hell out of it using a propane torch. Heat it up, add more oil, heat some more until you can see the oil boil. Be careful about flame ups. I use PB Blaster as the lubricant of choice. Then try to screw it out SLOWLY. You'll need to go back and fourth screwing it out then back in some and then back out some. If it gets too hard then add lubricant and heat it some more before you try again.

If there's not enough slot in the screw head to have the screw driver bite, then one choice that I've used is to use a dermal tool or hack saw and cut a slot down the tower into the screw head. It's not pretty but will give you a new slot to use will usually get the mixture screw out. It wont hurt the operation of the carburetor.

Heat is the key to getting these bad boys out the first time. I don't even try to remove them until I've heated them up good with lots of PB Blaster lubricant. Haven't had one defeat me yet and only had to slot one because the PO destroyed the screw slot.

[Steve]

If there's not enough slot in the screw head to have the screw driver bite, then one choice that I've used is to use a dermal tool or hack saw and cut a slot down the tower into the screw head. It's not pretty but will give you a new slot to use will usually get the mixture screw out. It wont hurt the operation of the carburetor.

Here is what that looks like when you are done:



Not going to win a Concours competition, but they are not "ugly", either.

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[JTGS850GL]

Actually it's not even visible if it's on the inside carbs. The hard part is trying to get those slots as nice and straight as Steve did on those.

[Steve]

The hard part is trying to get those slots as nice and straight as Steve did on those.

A steady hand on the Dremel is ll it takes.

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[Chubbaracing]

My air fuel screws are deeply recessed so cutting a groove down the sides will not work.....at a complete loss now

[tom203]

How about a pic to help us visualize your problem?

[Chubbaracing]

I've just spotted a set of carbs off a gs550 katana for sale in the states which look identical?!?!? Could these be adjusted to suit? Tried drilling the mixture screws on mine and started promisingly on the drill press but the consult bit snapped right at the bottom so it's now FUBAR.....

[JTGS850GL]

550 carbs have different sized main air jets then your 650. The pressed in air jets can't be replaced but in your case can be drilled out to the correct size. The correct size for a 650 is 2mm. Use a drill press and drill straight down. The size of the main air jet effects all circuits.