Yes the long needle carb will tune quite differently to the shorter needle carb on your 7 port.
The trick is make sure you have the HSN set rich enough. Then you just tune with the LSN only. Set the HSN to .25 in from flush and leave it there. Now tune with the LSN until you have it running good. If it is a little rich at the very top of the rev range (say the last 20%), then tweak the HSN in a little, like 1/16 to 1/8 of a turn to get that last 20% of the rev range perfect.
Now you are tuned in, any changes due to weather etc you make with the LSN only.
Because the longer LSN stays in the spray bar throughout the entire rev range, it is neccessary to have the HSN set rich enough to pass enough fuel past the LSN needle tip (especially at full throttle). Unlike other carbs where the LSN works up to say 1/2 throttle then the HSN works after this up to full throttle, in the long needle carb the LSN regulates the fuel from idle right up to full revs. All the HSN is doing is acting like a tap, to ensure there is enough fuel available, no matter where the LSN is situated.
If you get any lean bogging (especially as the tank level gets down) it's a sure bet that the HSN is too lean on this sort of carb. Depending on fuel and pipe types, you may need to run the HSN flush or above flush to get it working spot on. I found that around .25 turns in worked for me with the 0801 or 2047 pipe. I have changed both my motors to the shorter needle and am loving it. I don't find any negative effects on performance or economy, but they are easier to tune in general.

Thanks Grizz
I feel like I should take on the challenge of tuning the long LSD:eek:
From what I have seen of the guys that run the long LSD at our track,the biggest mistake is the idle gap being too big and compensting with the LSD screwing with the tune:(I am running the 2072 pipe.
If I don`t have any joy,I will shorten the needle.:sneaky:

Got it thanks for the info!

The Gen 5.5 carbs have the short lsn, they may have changed the length a little but it is still a short needle.

Rex

what i have noticed from these carbies is they are very sensitive to adjustment and a liy=ttle bit of a turn makes a huge differancs

Yep, that is a common mistake. Big idle gap, covering up a very rich bottom and lean top. Recipe for disaster, especially with the long needle carb as it will run real lean at the top end - not nice :(

I haven't got my hands on a Gen 5.5 yet, but I was led to believe they had the long needle. Thanks for clearing that up Rex :)
Man - they sure do chop and change the needle length in different models, and even in some batches of the same model (the intermediate needle that came out in some Gen 4's). That's the beauty of shortening the LSN yourself. At least you know exactly what you have in there, and how it's going to tune :cool:

Carb O-rings
 

Help, I need to have (2) GOTOR-0023 o-rings. A-Main and others sold out or on back order. Any ideas where to get some? I had 4 go out with in a week on my sons and my engines. They just crumbled apart.

Contact Mark at Massive Mods. He had them last time I checked.

Is he from Austraila? I need them ASAP. Thanks for the fast reply

Yes, Massivemods.com. He ships really fast! I'm in the US and I got stuff in 3 days!

While you waiting for new O rings, just make some out of fuel tubing. I have been running the fuel tubing O rings for a year now (because of the crumbling brown factory ones) and they work fantastic.
Just cut a slice of fuel tubing a fraction wider then the groove in the needle. Fit the tubing over the end (with a pair of long nose pliers and slip it into the groove. Sit it so the front end (needle point end) is in the groove and the other is sitting proud of the groove. Now gently screw the needle in until the tubing is completely out of sight. You will notice the excess tubing from the rear of the needle peel off as it is forced into the needle seat or tube. Now screw the needle back out and you will see you have a perfectly fitting fuel tubing O ring. The tubing is fuel resistant, slippery enough to allow easy adjustment but still hold the needles in place, won't dry and flake and is soft enough to keep a perfect air tight seal. Easy and very cheap :)
Hope this solves your problem and gets you racing :cool:

I just noticed you are in WI. You should get them in a few days too I would think.

Yes this works well also. I did this until I got my new o-rings from Mark. Thanks Grizz.

Correction , the US ones have short LSN. every distributor has specified which ones they want for their region.

The chopping and changing comes from people putting misinformation about what they assume. if anyone wants to confirm anything in the Go Engine range and are not sure please contact me and ill be happy to give you the 10.4 on whats in there.

[email protected]

Each distributor can tailor basic things to suit for their region. EG we want the Long LSN needle so thats what we get here. US wants the short taper needle as that suits their needs.

Hope this helps

:batman: