GT750 with CV carb Needle Jet available

[Vintageman]

The 1974 and up GT750 with CV carbs, is the need jet still available?

Does anyone know the series of the Needle Jet?

Thanks

[jabcb]

The 1974 and up GT750 with CV carbs, is the need jet still available?

Does anyone know the series of the Needle Jet?

Thanks

Per the online parts diagram its still available:
http://www.partzilla.com/parts/search/S ... parts.html

[pearljam724]

Out of curiosity, why would you want to replace them ? They will last forever if you clean them and replace the o-ring. Unless, you maybe lost one ?

[Suzukidave]

Out of curiosity, why would you want to replace them ? They will last forever if you clean them and replace the o-ring. Unless, you maybe lost one ?

They can need replacing as the needle will wear the metering hole into a egg shape that will mess with the mixture .

[tz375]

That's true. They can wear but it's not as common as one might expect. It would be interesting to know if those OEM needle jets are still available.

Certainly if a bike has worn needle jets, the mixture will be richer than stock and that may be enough on a particular bike to make it less pleasant to ride.

[Suzukidave]

That's true. They can wear but it's not as common as one might expect..

I have really picked up this problem on the " Oil Cooled " GSXR site . On there many complain the needle jets in the CV carbs wearing oval in as few as 20,000 miles and it takes the needle right along with it . After market companys have responded with chrome plated or exotic materials needles to slow the wear .

[Vintageman]

Does anyone know the series of the Needle Jet. If available aftermarket it’s available (Mr. Obvious).

When I rebuilt my bike, I don't think I checked them out. For I could swear I contacted Dillon Power Sports at the time and they said NA even when listed so did not remove. They were in tight so I did not want to try to remove unless I had new ones (or more like I just did want to look and get discouraged since I had no replacement)
I'll try partzilla

The Needle jet pushes out towards the bowl opposite of the VM carb which pushes out towards slide correct?

For me old "vintage stuff" it’s usually not wear due to miles of use. Instead I have found that the needle jet is the most sensitive item to corrosion based of where it is.

For 40 years my bike has a needle going through the needle jet 99.99% of the time, with a gap between them so small you can't slide a hair in between. As the days warmed the cold metal of the slide caused moisture in the air to condense, run down needle, and filled the tiny gap with water.


I’m getting ready for the Bike riding season (still a lot of snow here, but snowmobile season just about over). I need to change my oil line on GT750 since the check valves leaks (smokes first starting if bike sets a spell). I bought a complete spider where the gent in UK changed all the check valves with the ones he had made. Since I have to take off carb I'd figure I check the needle jet if I can get only. My gas mileage is not as good as it should be maybe. Also I usually always change them unless very shinny inside where metering barrel area is. I would like to take a look see this time

And maybe my Oring is dried out and some fuel leaking by there

[tz375]

Pop them out and replace the O rings - still available from Suzuki and ask you local dealer for a price on three new jets.

Yes. They come out downwards. the bowl retains them - opposite of a VM series.

There are many variants of the BS series carbs but only one that I know of used that series jets and not in our size. They are OEM fitment only and not available as a "series" in the way that a 172 or 159 is.

[GT750Battleship]

Hi,good idea to fit new O rings,found mine were on the way out...made a big difference to how the bike runs
Cheers,
Roger

[Suzukidave]

Deleted idea

[tz375]

Dave,

You are spending too much time with normal carbs. On the BS40 the main jet screws into the float bowl below the needle jet. Odd arrangement.

The only way to get them out is with an appropriately sized two step punch - or use a disposable chop stick.

[Suzukidave]

Thanx Richard .. deleted my idea

[Vintageman]

Partzilla, said ~6 Needle Jets in USA inventory. I bought 3

Also 3 orings -plenty of those around

The Jet Needle is back ordered and said that could mean anything even NA. I did not drive an order on those.

I think the needle jet is Z-0 and read least night Yam XS650 (years? uses same but Z-6 from MikeXS... too rich). Well I see in UK some new and looks to be aftermarket versions.

[tz375]

How do you know that a Z-6 is too rich for your bike? Did you try them and it ran rich or speculation?

A Z-6 will be richer across the board and proportionately richer at low to mid revs but maybe that's what your motor needs to compensate for ethanol. Try a set versus old OEM vs New OEM just to see what works on your bike.

[Vintageman]

How do you know that a Z-6 is too rich for your bike? Did you try them and it ran rich or speculation?

Speculation/Experience doing similar changes with other engines. I assumed the numbers size is analogous to VM Needle jet series numbers. e.g. P-0 to P-6 step may not be so rich it won't run but MPG will surely be affected.

ON my 73 GT550 I had new O-9 since my original O-5 were junk. Last year i found shiny new ones O-6 and went from low 30s mpg to high 30s. Also cleaned up small throttle- idle heavy fumes: intown, warm day, riding it felt like it would foul a plug (never did though) that's gone now too. With chambers and the way I like to rev up with small throttle, O-5 maybe too lean O-6 just right for 73 GT550


My GT750 may be too rich now- heavy low throttle fumes 30ish MPG. I put the pilot air jet-still bucks some when let of throttle cruising: maybe more clutch dampener slack? I think it was 0.7 air jet... the smaller one noted in Suz bulletin). I may go couple step leaner (0.9).
I hate to change two things at once but, like to clean the the GT750 up and improve cruising MPG and fumes... if possible

Now I can check the Z-0 needle jet to see if it has any wear or pitting now I have new ones coming (given don't get lost in the mail). I bought Keyster (did I just say a bad word?). kit back when and used float valve and bowl gasket. Did come with jet needle. Well I did not use for my OEM needle were OK, but would if I needed them