Jetting and spark plug experts please help

[Jakobi]

Do you have a used spark plug to put in there and check?

What oil, at what ratio are you using? Have you set the float height?? (possibly too low, starving for fuel at extended WOT). Have you checked the intake (carb boot, reed block, and manifold?) Consider inspecting the stator side seal too.

Does it feel lean? Sound tinny? Make the hestitating starving gasping bwaaaah *cough* sound when you whack the throttle open? If you ride with steady throttle and then roll the throttle back does the bike surge forward before the revs drop?

[gg3]

Apart from the plug colour ,how did the bike run?Noticeably different?

[nestz]

Using motul 800, 50:1. Why try a used spark plug? I will have another look for air leaks. Not sure about how to set the float height - is that not set correct from factory? It does feel lean, very very tinny, sounds like a 125. I didnt really notice the other symptoms you mentioned though.

[Jakobi]

Used plug - it's easier to stick an old oily plug in, do a run and inspect it than it is to try and get some clean porcelain to colour up. If it's really lean it'll turn an old oily plug white and ashy.

In saying that, I'd be looking into the things I've mentioned prior.

[nestz]

Originally Posted by gg3

Apart from the plug colour ,how did the bike run?Noticeably different?

Yeh the power was broader - probably from the nedw needle. Its hard to know how its meant to feel. My last bike was a ktm sx250 and this 300 feels so weak compared to that - is that normal, are they quite tame bikes?

[memphis2857]

Ditch the Motul! That oil is lack molasses and the flash point is too high. The flash point on Motul is like 550* where as all other quality synthetic oils is around 200*. This was another issue I went through. What will happen is the oil will load up in the crankcase during slow riding and then when it comes time to WOT the bike will suck all the extra oil out of the crankcase and make it run like crap. That being said I don't think it has anything to do with your lean condition.


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[memphis2857]

Originally Posted by nestz

Yeh the power was broader - probably from the nedw needle. Its hard to know how its meant to feel. My last bike was a ktm sx250 and this 300 feels so weak compared to that - is that normal, are they quite tame bikes?

It's not going to have the big hit of the sx250. But it should still pull nearly as hard. It's just going to explode into the powerband like you are use to.


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[memphis2857]

Just had a thought. Check to make sure your airfilter is installed properly.


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[gg3]

Hi Nestz,this is a mystery?
As memphis said it won't have the hard hit of the sx250. You should be able to easily lift the front using the throttle though?
Does it idle nicely or does the idle hang. ie. after giving it a burst of throttle it idles at high revs & then comes down gradually?
+1 on the air filter.It is easy to not seat it properly at the bottom.
That jetting is near enough to being right for testing purposes so we need to eliminate 2 problems.
Too much air - Check filter.You have checked everything else except crank/case seals ,unlikely on a new bike so work through the easy stuff first.
Not enough fuel- Jetting is ok so check float height (+1 jakobi),plenty of info here on how to do it.While doing it look for a piece of swarf or plastic that may be jamming it or rough aluminium casting that may be contacting the floats & stopping them rising.There will be visible contact marks on the top of the plastic floats.Wrong float height is common on new bikes but usually too high not too low?
Try running it with the choke on & see if it is better.Choke on will make it richer.

[nestz]

Originally Posted by Jakobi

Have you checked the intake (carb boot, reed block, and manifold?) Consider inspecting the stator side seal too.

What am I looking for around the reed block, maniford? Just that the bolts are tight, or am I pulling apart and looking for something? Also what am I looking for on the stator seal?

Is there anyway to have them pressure tested or something? If so how is that done?