Jetting and spark plug experts please help

[nestz]

Hi all, I'd appreciate some help with this. I Recently purchased a brand new 2014 xc300 and ran the motor in over a few hours mainly going from low to 3/4 revs with the occasional wot, then checked the plug and it appeared to be on the rich side (bit oily and darker sort of a tan). I put a fresh plug in yesterday and rode sand dunes giving it everything for an hour then checked the plug. See pic attached.

Im no expert but is it looking too lean? If so where should I start?

Thanks in advance for any advice.

 

[gg3]

Dangerously lean.Did it spew a lot of radiator fluid? Have a look at your radiator level. Probably needs 2 sizes bigger on your main jet but post up what jets & needle you currently have,elevation you ride at & temperature.Also what oil ratio are you running?

 

[nestz]

No radiator fluid lost - its still full. There was a burning smell when I was riding it though, I was thinking maybe it was just because it was new.

I ride at sea level, temperature is about 15 degrees Celsius at the moment

Not sure about jetting settings yet, it will be set at whatever it was set at from factory I guess, but I will open it up tomorrow and report back.

The strange thing is that the orginal plug looked almost too rich, what changed?

Also the silencer is leaking out a lot of unburnt oil - seems a weird thing to happen since the plug appears so lean?

Running 50:1

Im a total novice when it comes to this stuff so you're probably going to get asked a bunch of rooky questions as try to figure this jetting stuff out.

 

[gg3]

May not have badly over heated then.
Open the carb & get the sizes,they can vary a bit from bike to bike.
With a bit of jiggering you can rotate the carb & remove the needle & jets.
Difference would have been riding up to half throttle where it sounds too rich & then riding in sand with a lot of full throttle where it is very lean jetted.
Just check also that the rubber boots either side of the carb haven't come loose & started sucking in more air?

 

[nestz]

Do you think I would've done any damage with it running lean?

Also do you mean remove the jets and needles with out removing the carb from the bike? Ive never opened up a carb before so not really sure what im doing.

The rubber boots appear to be on properly. But I noticed a bolt had fully come out (see photo attached, the bolt above the chain) I didnt lose it because it couldnt get past the chain. Couldve that casued use any air leaks or cause any other problems?

 

[hamilton]

If your running in deep sand, I would go for a larger main jet. (better safe then sorry)
I think a good starting point would be 42 pilot NEDW needle clip #3 180 main.
When jetting for deep sand I go one step larger on the main until it starts to sputter at wot then go down one size.
Also be sure you are using the correct plug heat range (br8es)

 

[gg3]

Do you think I would've done any damage with it running lean?

Also do you mean remove the jets and needles with out removing the carb from the bike? Ive never opened up a carb before so not really sure what im doing.

The rubber boots appear to be on properly. But I noticed a bolt had fully come out (see photo attached, the bolt above the chain) I didnt lose it because it couldnt get past the chain. Couldve that casued use any air leaks or cause any other problems?

Running lean in deep sand for long periods can do damage but it's still running.Tough engines.
Hamiltons jetting recommendation is a good place to start.You will be surprised how much better it will be.Opening the carb is easy,just be patient,keep every thing clean & don't brute force it!( no hammer required).Plenty of instruction info on this forum ,but briefly-
Start with a clean,dry bike.
Loosen the rubber boots each side of the carb.
Disconnect the fuel hose.Keep rags handy,there will be fuel leakage.
Rotate the carb top towards you enough to unscrew the top.Jiggle the throttle cable to get enough slack.Carefully pull the carb top off,it will have attached a long spring,a slider & the needle sits in the slider.(tricky bit)Push the spring up to the cap,the cable end sits in a slot in the slider.Push the cable down & sideways to unhook.Slider will now be separate from the spring/cable.Put a socket in the top of the slider (5mm I think?),undo this & tip the slider up for the needle to fall out.Note what numbers/letters are on the needle & which slot the little circlip is in.Tip-take photos as you go.
Put a bit of clean rag in the top of the carb & rotate it away from you.You may need to remove the 17mm bolt at the bottom.Rotate it enough to undo the 4 screws that hold the bottom of the carb (bowl) on & remove.
Remove the main jet gently (brass hexagonal thing with a hole in the middle-6mm socket).
Remove pilot jet (brass screw with a hole through it, set deep in a hole,need a slot/spade screwdriver)make sure it is a good fit as you don't want to damage this & not all screwdriver have a thick enough end with a narrow shaft to fit.
Note numbers on each & post it up.
Have a beer,smell the fuel fumes in your garage -you just earned a new man badge.

 

[Jakobi]

All great advice! I'm with them.

Plus, its a new plug. You could grab a magnifying glass and check down in the base of the insulator and check the fuel ring. There does appear to be some colour forming on the plug, as opposed to white ash. You can also check for any aluminium flecks which will be present if it was pinging hard.

All in all, it's had a lean run. But I very much doubt any damage has been sustained.

 

[Neil E.]

There may be some difference between carbs, but on mine, I can just undo the main jet cap on the bottom of the bowl and then get at the pilot jet and main jet without removing the bowl.

 

[memphis2857]

Yes don't have to remove the bowl or the fuel hose. Just rotate the carb and remove the 17mm plug on the bottom of the carb and both jets are easily accessible


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[nestz]

Wow - great info! Thanks everyone. I will try and attempt this tonight (if I can get the kids to bed early). All going well I'll report back later.

 

[gg3]

My bad,bowl doesn't need to be removed but I struggle to get the pilot jet out,hands are too big.Kept me out of gynecology school as well.

 

[nestz]

Thanks for the step by step guide gg3, it was a massive help and made the job easier than expected. Here's what I found:

Pilot: 42, Needle: N1EF, #3 clip (third slot down from the top), Main:175

According to the manual this set up is pretty much perfect for my temperature and altitude - so why the lean looking plug?

Also how long does it take for a new spark plug take to show colour so you can read it?

The reason I ask is, after I rode in the sand for that hour and discovered the lean spark plug, I wanted to test if it was lean just on the main jet, so I let it warm up for a few mins, then rode 5mins down the road using 1/4 to 3/4 throttle, with maybe a few squirts of WOT. This was on hard pack so not under load like I was in the sand. I checked the plug again and it looked pretty much the same.

Is 5mins enough to read a plug? If so why is it so lean even on hard pack terrain?

Finally does fuel octane have a major effect on jetting? Like is there much of a difference running 91 as opposed to 98.

 

[gg3]

Nice work!
That needle is not great but still wouldn't have expected that white a plug?
But some more informed guys will comment on that.Possibly sucking air in somewhere?
I run 42 pilot NEDW needle clip #3 175 main at similar temp & altitude with no problems.

 

[memphis2857]

If it were me I would put a 180 main in it to start and then go from there.

Plug reads are very deceiving and not a very good way to jet a bike. It gives you an idea but you need to jet more based on performance than how the plug looks. Also making a jetting change and then riding up and down the street or some other no load situation is not a good way to jet. This is not how you normally ride therefore you shouldn't be jetting to those circumstances. I learned all this the hard way.

Also it will be next to impossible to get the jetting dialed in until you get your squish band corrected.

I learned all this the hard way. I chased jetting for months and never could get it right until I fixed the squish and went to a riding area and put my jets and tools in my pack and went for a ride. Had jetting sorted in less than 10 miles and haven't touched it since.


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[nestz]

Squish band? This is getting complicated. Is this what all gasgas owners have to do to get their bikes running right?

I guess for now I just want to ride my new bike and not worry about it melting because its too lean.

If I put a 180 main jet in will it be safe to ride? Should I make any other changes while its open e.g move the clip position or change the needle? People have mentioned the NEDW needle - is this a better needle and what difference will it make?

 

[memphis2857]

The NEDW takes all the "hit" out and makes the power very smooth vs. explosive like it is now with the N1EF needle. The 180 should make it safe to ride just keep your eyes and ears open and listen for a lean bog and smell for a burnt smell from the exhaust. Maybe after about 30 minutes of riding have a look at the plug just for peace of mind.

Squish band is a cheap $75 mod in which you send your head off and they mill it down to make the engine more efficient, responsive, and boost power. Well worth the money


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[nestz]

The NEDW takes all the "hit" out and makes the power very smooth vs. explosive like it is now with the N1EF needle. The 180 should make it safe to ride just keep your eyes and ears open and listen for a lean bog and smell for a burnt smell from the exhaust. Maybe after about 30 minutes of riding have a look at the plug just for peace of mind.

Squish band is a cheap $75 mod in which you send your head off and they mill it down to make the engine more efficient, responsive, and boost power. Well worth the money


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Thanks memphis.

By 'lean bog' do you mean that it struggles to get 'on the pipe' with WOT?

After half an hour should my spark plug look a brown tan colour? If it doesn't should I not ride it?

Also does running it on 91 octane make a difference with jetting?

 

[memphis2857]

Thanks memphis.



By 'lean bog' do you mean that it struggles to get 'on the pipe' with WOT?



After half an hour should my spark plug look a brown tan colour? If it doesn't should I not ride it?



Also does running it on 91 octane make a difference with jetting?

Lean bog = buuwaaaa sound if that makes any sense. If it's rich it will burble and sputter. Not real sure how to explain it any other way.

After 30 minutes the plug should tell you if it's safe or not. Riding it will be your judgement call. I rode a whole race on my bike and it was so bad lean on the main it would just nose over at wot. But i short shifted and tried to stay off the pipe as much as possible. Not a good idea but I did it with no damage in the end. That's your call to make

Octane won't make a huge difference but it will change your jetting some. It's best to pick a fuel (ethanol free if possible) and stick with it all the time. I run VP 110 because I can buy it out of a gas pump 5 miles down the road and it is leaded and no ethanol.


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[nestz]

So I put in the 180 main jet and switched to a NEDW needle on clip #3 and put a new plug in it (br8es), took it for a ride up the beach mostly WOT, Checked the plug and looks like the original pic I posted (white as snow). Then I took it into some firm packed single trails, riding mostly low rpm, checked plug again, still white. Whats up with this bike? So frustrating.