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Enduro Intake/Carburetion - 2 stroke Jetting, Reeds, Air Filters, etc.


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Old 10-04-2018, 09:46 PM
Wypipo Wypipo is offline
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Default Need help. Where to start

Had the carb apart for the first time today to see what wa in there.
N1EF on leanest clip.
170 main
42 pilot

Looking at my plug and amount of Spooge I am running rich. After 8 hours of a good mix of all throttle positions I pulled the plug and it was just a little rich, not too excessive and some small Spooge dripping.

Put an RK Tek head on, didn?t change jetting at all, gapped brand new plug to 0.018 and went for a 20 minute ride. There was the most Spooge I?ve ever seen. Not just a trail dripping but also looking at the pipe straight on was just a giant black circle all the way around the hole. I pulled the plug but the whole thing was still silver with just a drop of oil on the tip.

The bike won?t start cold without the choke
Doesn?t seem to be hanging idle (from the other thread I posted)

Riding in 3rd with the throttle barely cracked it sputters and cracks a bit and seems to try to chug along but it stays going. It doesn?t try to bog at all but it definitely doesn?t have that smooth electric feel. And this is barely cracked like just enough to make a difference past idle. Any more open and it smooths out.

Same throttle position in 3rd. And then opening the throttle wide it hesitated just barely and then gets on the pipe. I can?t get the front wheel off the ground when trying this.

I?m riding between 3-5,000 feet

I have an N3CH, NECJ and NEDW needles on the way.

Not sure where exactly to start first...main? Pilot? Needle? And what increments should I be going when changing jet sizes?
Not sure why so much Spooge with the RK Tek head and same jetting?

Thanks!


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Old 10-04-2018, 10:22 PM
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dANbOT dANbOT is offline
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I'm not an engine expert, but in my experience: when you change something that increases power (such as porting, big bore, shaved or high compression head) your basically making a stronger air pump out of the engine, and it can draw a stronger signal on the carburetor making the jetting too rich. I have found that i needed to lean out the jetting to compensate for this effect.... a wild guess at 2 steps leaner on the main and pilot

But... that pesky stock needle would never tune very well for me or many others, I always had some small lean or rich spot that was bothering me somewhere lol. Your likely to have to jet from scratch with your new needles anyways. I have had a great experience with the suzuki NExx needles, a huge improvement over stock.
This is all assuming you don't have a leak, or mechanical problem of course.

Others may be able to help you with setup for your specific needles, but for what its worth here's my setup for 3000 to 7000 feet at 10 to 30 Celsius:

S3 Stars head with highest compression insert/ and thin base gasket to correct squish gap
NEDW #2 clip for warmer temp / #3 for spring and fall
35 pilot
air screw 1 out + or - for large temp swings
165 main
*

I get moderate spooge with a Qstealth muffler, smokes a little but I like a slightly rich mid-range for torque. Idles forever and barely loads up.
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Old 10-05-2018, 03:23 AM
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Jakobi Jakobi is offline
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The N1EF is probably too lean on that clip position, and the clip will have been lifted to try and compensate for the overly rich small throttle response, which you probably won't be able to jet out with that needle.

The problems with the bolt on heads are that you still have a load of variables in terms of piston to head clearance (squish) and compression ratio, unless if you took the time to spec them up.

When your needles arrive you'll have something to work with.

I'd use the NEDW#3 with the jets you have. Make sure you drop the idle speed right down nice and low.
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Old 10-05-2018, 08:11 AM
Wypipo Wypipo is offline
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Thanks I?ll wait for the needles to come and start over
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Old 10-05-2018, 05:11 PM
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Davehuge Davehuge is offline
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Hi Wypipo

Is the bike new to you? I guess it is as it sounds like the first time you've opened the carb to see what's in there.

Before you start tuning the jetting, check the basics...

Clean air filter.
Check exhaust silencer is clear and not blocked (may sound daft but worth checking).
Check float height and operation of float valve.
Strip and clean carb, check all jets and orifices are clear.

All the best, Dave.
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Old 10-07-2018, 07:47 AM
Wypipo Wypipo is offline
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Thanks Dave yes the bike is brand new. The only thing I have not done yet is check the float height and clean the carb but it is a brand new carb. Is there an easy trick to getting the carb off of these bikes without having to loosen the subframe?
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Old 10-07-2018, 09:03 AM
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Davehuge Davehuge is offline
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Hi Wypipo

As it's a new bike then you could assume that all jets and orifices are clean, float height is good and float valve is sealing correctly, but there's no harm in checking to be sure.

I guess your bike is just jetted too rich, I've heard many people complain about the same with new bikes. I suppose the factory just send them out like that to be on the safe side.

As far as I know that's the easiest way to remove the carb, by loosening the rear sub frame. Of course, if you're only changing the needle, pilot jet or main jet then there's no need to remove the carb. The rubbers can be loosened, the top removed, then the carb rotated. At least that's what I can do on my old 2004 model!

To start with I would stick with the 170 main, maybe you could go leaner but for the moment try and get the pilot jet, needle and clip position sorted. As Jakobi said, try the NEDW needle with clip at mid position. Depending on how that goes you could try going leaner on the pilot jet, one step at a time, so from 42 to 40 to 38. After fitting a different pilot jet set the Air Screw to 1.25 turns out then adjust in/out to suit.

I found the MOST IMPORTANT thing was to only make ONE CHANGE AT A TIME, then get the engine up to temperature and test it. This ensures you know if you're moving in the right direction and also helps you understand which component effects which throttle position. I also kept notes on what I changed and how it felt, but that's just me!

Have you found the Jetting Database on this forum, it's interesting to see other people's setups...

http://www.gasgasrider.org/forum/showthread.php?t=2162


I found this chart helped me understand which components effect which throttle position...

calibration_chart.jpg

Are you using a good quality, full synthetic 2 stroke oil? I mix mine at 50:1 (200ml oil to 10 litres fuel) which seems to be the standard and I've never had any problems.

When I bought my bike it started fine and ran, but there was no power, it felt flat as a fart, in fact that's why the previous owner sold it. I thought there was something seriously wrong with the engine but I was pleasantly surprised when I discovered it was just jetting!

Before sorting the jetting it wouldn't lift the front wheel at all, now I have trouble keeping it down...honestly!

Be patient and stick with it, it's very rewarding and well worth the effort when you have it running correctly.

All the best, Dave.

Last edited by Davehuge; 10-08-2018 at 04:31 AM.
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Old 10-08-2018, 06:54 PM
Wypipo Wypipo is offline
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I?m using motul 710 at 50:1. I dropped the pilot down to a 40 and went for about a 3 hour ride. Still lots of Spooge. This the plug afterwards, not sure how telling it is. Also when backing the air screw out to 2 turns it was a super fast idle, almost seemed too fast. Turned it back in to 1 turn out and it sounded proper again.
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Old 10-09-2018, 05:28 AM
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Davehuge Davehuge is offline
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Hi, I'm sure Motul 710 at 50:1 is fine.

So you dropped to a 40 Pilot Jet, that will only really effect the mixture at idle and the initial throttle opening. So if that's all you've changed you probably haven't noticed much difference when riding.

Have you been able to change the needle yet or are you still on the N1EF? From my experience and what the majority of others say, the N1EF is always too rich.

Once you try a leaner/fatter needle you'll feel a change and the amount of spooge will decrease.

The plug looks black and oily so definitely not dangerously lean.

To be honest, plug readings are more useful for checking the Main Jet size by completing a 'Plug Chop' procedure - involves cutting the ignition whilst running at Wide Open Throttle, at high RPM, under load. Needs a long straight road/track. Google it you need precise instructions.

All the best, Dave.
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Old 10-16-2018, 04:03 PM
Wypipo Wypipo is offline
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Another question - when I start my bike with the choke on the idle is very high. When I shut the choke off it settles back down. Is this normal?
It happens any time I pull the choke up not just after starting. The bike could be warm and sitting there idling. If I pull the choke up it starts idling way faster.
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