GT750 J/K carbs

[tz375]

I was under the impression that they were the same but that the K had "Hi tops". I'm looking at what I believe to be a J carb so I trolled the internet for pictures and sure as fate I see at least 2 different carbs - low and High tops and I see a set on ebay that look promising, but they have the strangest spigot clamp arrangement that I don't recognize.

Any of you old model experts like to tell me if all 3 J carbs had inspection windows for synching the slides. And do they take large round or large hex main jets (188 or 159 needle jets.

Thx.

[Buffalo-guy]

All the J/K carbs had the inspection ports, and all had the round main jets, 102.5/100/102.5. What the tall slide was accomplishing, is anyone's guess. That, at least, is the case in this market (Canada), and I can only assume the same for yours, Richard. Cheers.
Fred

[Zook-e]

The tall top was to accomodate a longer slide. If you put a short top with the tall slide it will not open completely at full throttle.

I have both types of carbs.

[tz375]

Thanks guys. This one is a low top with teh right slide. It has what I thought was a place to fit a powerjet - only to see it was really just the air vent to the top of the float bowl.

It has a boss for the inspection bolt, but it's not drilled or tapped. Odd.

[tz375]

I feel like Alice in Wonderland. It just gets curiouser and curiouser.

OK, so this carb has low top and tall gold anodized slide. I checked my box of odd slides and there were two Chrome plated brass slides marked as GT750 L &R but they were much shorter than the alloy one. All of them have a dimple in what appears to be the same spot on the slide.

So if the Chrome ones are short and the alloy are long, how come the carb with long slides has a low top? Any ideas?

In the scheme of things I suppose it's not important but I hate not knowing the full story.

[Zook-e]

If you look inside the slides, some have the slot for the cable and a clip. Some have a screwed in piece that holds the cable, this setup causes the slides to be a different heights and thus having to use the tall cap or short cap depending on which slide set you use.

[Suzsmokeyallan]

Also I'm sure the gold anodized slides were for T500s and the brass ones with the chrome plating (both tall and short) were for the 72 and 73 Buffalos.
Richard it would be safe to say with the slide in and the cap screwed on if it can just clear the venturis aperature when topped out its the correct height slide.

[tz375]

Thanks Allan. I thought I was looking at a 750J/K carb. Seems it's a later 500.

Thanks Eric. Now I understand a little more about J/K carbs. Now I need a bigger brain to contain all these new facts...

Funny looking carbs though. I think they would be a pain in the neck to try to get jetting right on a modified motor. And the older 34mm carbs are even more of a museum piece.

If/when I get some time I'll post details and a couple of pics.

[Suzsmokeyallan]

Richard its amazing how ONE of those old carbs weighs about the same as three new TMX version carbs.

[tz375]

1165 grams or 2.6 pounds is a lot of weight for a carb alright. I didn't weigh a TMX but an aluminum bodied VM32 weighs in at 692 grams or 1.5 pounds. That's a huge difference. And the old carbs are not very good.

[Suzukidave]

I have lost track of the picture but i am fairly sure there are really 3 different types of the early J,K carbs .. short body flat cap , short body tall cap and tall body flat cap .

[tz375]

Dave,

This was one of those situations where I thought I was looking at a 750 carb and it turned out to be from a GT500. Very similar carb and I suspect it may even have been the same casting but machined slightly differently.

I'm just about to ship it back to Terry Grogan who kindly supplied me with a few different carbs to compare OEM with aftermarket. Turns out that OEM heavy carbs are OK but I'd hate to use one on a modified bike. I'd rather buy a set of new carbs or snowmobile carbs and re-jet them than use these clunkers.

[Suzukidave]

I had followed the specs to mod a set of stock carbs for the Yellow GTX-R bike from the performance GT book http://www.smokeriders.com/Technical/Su ... t/p33.html" onclick="window.open(this.href);return false; but i bet the stock carbs were only used so they could comply with racing rules . I have wondered what it would do to replace those modded stock carbs with a set of modern 34 flats ?

[Suzsmokeyallan]

Dave the modern carbs would atomise the charge better with the flat slides, I'd suspect you would easily notice faster pick up in the higher gears, better low end throttle response, and overall improved rideability.
Why am i telling you all of this?, you know you need to go to ebay and put yourself out of your misery by getting a set