Questions
 

Hey GO folks,

I got a used GO GX5R recently, and I have a few questions as it didn't come with a manual. It still has really good pinch, and gives good power, but I still have questions because I want the best from my engine.

1) It has been mentioned several times that the base needle settings are flush, and tune from there. Is the assumption that this is without a restrictor venturi installed?

2) I have a 6.5mm restrictor installed (it came with only this one). Is this recommended? I have heard that smaller restrictors cause tuning issues in other engines, but I want to get as much run time as possible.

3) I have my LSN turned in about 2 turns from flush, and the HSN about 1 turn in from flush with the 6.5mm installed. Does this sound about right? It still seems really rich to me, and I only get about 6-7 minutes run time on a 120cc tank.

4) The slide on my carb is pretty rough; and seems to have a catch about 1/3 throttle. How do I improve the slide smoothness? I've had a couple of times where it has stuck open causing me to over shoot corners and jumps.


I have read the tuning guide from the NZ folks, and there's alot of good info there, thanks.

Make sure the throttle arm to the servo is in line with the slide, having it at an angle can cause it to bind.

Are you running a throttle return spring? Recommend, this will also help. I use "hair bands" for this, work great.

I have come across this a few times in the past, and as suggeted, make sure the throttle linkage is at a 90degree angle to the carby body during it's full travel: you may have to adjust the linkage ball on the carby slide to suit. A different brand servo arm with mounting holes in slightly different positions can also help. If the problem persists, remove the carby slide,(remove the idle speed screw so the slide can be slid from the carby body), and check for any small burrs on the slide itself, particuarley along the grove where the idle stop screw runs. the slighest burr will cause problems. If needed,very gently sand the burr off using 800 grade sand paper. Also check the end of the idle speed screw for any burrs. I rub a small amount of Black Powered Graphite Powder into the grove of the carby slide, this also helps to prevent friction on the slide. As for needle setting, they sound a little too far in: Check that you have not over oiled your air cleaner foams? This will play havoc with your tuneing. All your tuneing should be done with the restricter in,( I run a 6.5 myself on a GO GX11 with great success , achieving 11 minute run times), because that is how you race it, but make sure that the engine has had at least a tank full of run time before you try any fine tuneing to get some heat into the chassis.
I Hope this helps.

Anybody tried 3needle carb from Go yet? :D

Hi Bulge,

Set the idle gap to .7 to 1mm with the venturi out.
We normally run the 6.5 venturi in buggy, and most guys use the 7mm in truggy. No tuning issues with the 6.5 venturi at all. If you start going down to 6mm mand smaller the tuning window gets less and it can get a little tricky to get things just right.

Base needle settings (which may vary a little with fuel and pipe) are -
LSN 1.5 to 1.75 turns in from flush
HSN 2 to 3 HOURS in from flush.

Most important with the GX carbs is not to go too lean on the HSN (for the reasons mentioned in our tuning guide). Basically if you start getting lean bog around the half tank mark, you need to riched the HSN and hour at a time until the lean bog goes away.

Only heard about it from a customer this morning !!!
Seems to have been a little break down in comunications to distributors on this one. As far as I know nobody has the new carb in stock anywhere on the planet as yet.
Customer sent me this pic - don't know where he found it, as the new carb doesn't even appear to be on the GO web site as yet.

3 needle carbs are AWESOME!!!!...but is it the same 4 hole design that other companies are using or has GO figured out how to incorporate a tapered needle instead??....with the 4 hole design, if your not lined up with the holes correctly, you'll have some issues tuning....have ran into this problem more than once on OS engines...line the holes up and it's all good, but be in between the holes....:flaming:.....ya....caused alot of headaches for alot of people....either way, as long as there's folks willing to explain how to use the 3rd needle, it will be all gravy baby;)!!!!



another thought....does this mean that the long low speed needle will be a thing of the past?? doesn't make much sense keeping that design with the 3rd needle...i mean the 3rd needle is there to fine tune the midrange transition, kind of like the taper of the long low end needle...idk, idc, i'm tired and rambling..gnite peoples

Sticking Slide and 6.5mm Venturi
 

Thanks so much for the reply Grizz1 and SNOOKS. Great info, and I'll try out your suggestions; but I have a quick followup question...

Do I need to use something to seal up the slide boot when I put it back on? Maybe some thick grease? or should I use a silicon based sealant of some sort?

I guess 2 questions... How is the slide lubricated? Does it get oil from the fuel, or should I periodically pull the boot off and oil the slide directly? (I always wondered about this, but I've never had a sticky slide, so I didn't worry about it much.)

I wouldn't worry about sealing the boot. Never had a problem with leaks. Just check periodically for pin holes etc.

Yes, the slide gets lubricated from the fuel mist in the carb during use. It also gets a bit of lubrication from the after-run oil you drip down the carb throat after every use too - which of course everyone does, eh lads :nod: :D

after run oil:confused::lol::confused: is he putting the motor up till next year???

I found it here - http://rcspecial.com/news/?p=86718
Then asked straightaway. Didn't know that noone else knew about it :D I hoped that it was tested already by someone here :D

Re the new 3 needle carb.
Heard back from GO today, and I have been told all GXII-5RHO's produced from now on will be fitted with this new carb. Seems the performance and economy returns from the new carb are the real deal :)

We will be getting supplies of the new 3 needle for our NZ customers to retro-fit to their existing HO's in the next couple of weeks.
Looking forward to running and testing with the new carb to see how noticible the increases in power and economy are, but I am figuring if the company has committed to fitting this new carb to all new HO's produced from this point forward it must be making a tangible difference or they wouldn't go down that road, seeing as the 2 needle version is performing so well around the world.
Just when you thought it couldn't get any better :D

havent posted here in a while!!!! thats a good thing!!! GXII's are rippin minty!!:D

ohhh MOOOOO-TOOOOO....:D you gotta get some of these things in for next year....if you can get ahold of the H.N.I.C. of distributing here in the U.S.A. that is....

Here you go gents. Expoded parts list for the GXII with the new 3 needle carb :cool:
Seems most of the new parts are designated GR on the parts listing.