2001 EC 300 Mid Range Problems

[Jamie195]

Hello,

Recently purchased a GG EC 300. The bike starts easy and idles fine etc. However it has a huge flat spot mid range where it stutters and doesn't feel like it wants to even go through the power band in lower gears. Once past it gets better. It had BR8EG (Very black and wet) so I have changed to BR10EIX as was recommended by the local motocross shop. Carb has been cleaned and has slide #7 and needle on leanest setting. Main Jet is 178 and pilot jet is 38, I live in the UK so elevation is 0-500ft. Reeds look fine and powevalve looks fine. This is my first enduro and 2 stroke so would really appreciate some help and advice, even someone can tell me what size jets to try etc

Thanks very much

 

[mjtursky]

If I'm not mistaken, a BR10 is a colder plug and would foul easier then the 8. If you are running the factory JN, I would recommend the next leaner OEM JN. In most Keihin PWK carburetors, the straight diameter can influnece up to 1/4 throttle. So very little would change by moving the clip position. That would influence 1/4~3/4 opening.

 

[Jamie195]

If I'm not mistaken, a BR10 is a colder plug and would foul easier then the 8. If you are running the factory JN, I would recommend the next leaner OEM JN. In most Keihin PWK carburetors, the straight diameter can influnece up to 1/4 throttle. So very little would change by moving the clip position. That would influence 1/4~3/4 opening.

Thanks for the reply... Stuck with the BR8 and I'm just going to try a 172 main jet and leave the pilot jet as a 38. Or do you have any more advice?

Cheers

 

[Jamie195]

Also does anyone reccomend the RM250 NEDJ needle, I imagine I can try this with my current jetting as its a leaner needle? Although I've only seen people on the forum using this needle on much newer bikes.

(Not familiar with jetting etc)

Cheers

 

[Jakobi]

An older model won't like a diameter that lean.

 

[wrench]

Are you getting a lot of smoke from the exhaust when the power drops off?

 

[Jamie195]

An older model won't like a diameter that lean.

Ok is there any you would reccomend? Or would you downjet first

 

[Jamie195]

Are you getting a lot of smoke from the exhaust when the power drops off?

Not really, it just stutters but once it's through to the powerband she's fine

 

[Jakobi]

What needle is in it? What state is the engine? Reeds? Exhaust packing? Are you certain its a jetting issue? You really need to know the state of the engine is good before you try to jet it up or you'll just go around in circles. The older the bike, the more important.

 

[Jamie195]

Ill find out what needle at the weekend but I'm certain it's a standard needle, the engine seems fine although I'm no mechanic. Checked the reeds and powervalve all seems fine. I know what you mean about jetting around the problem but I'm not sure what else the problem could be.

Cheers

 

[Jamie195]

Jakobi... The silencer is one thing I have not checked. How important could this be for a the mid range problems as now I think about it, it is way too loud. I have ordered some more packing

Cheers

 

[nambo-trev]

Does it have a spark arrestor? If so is it bunged up or free flowing??

 

[Jamie195]

Does it have a spark arrestor? If so is it bunged up or free flowing??

I took apart the DEP end can and repacked it. Not sure what a spark arrestor is but I would guess it doesn't have one? Still midrange bog and running rich

Cheers

 

[Hawkeye]

Does the needle and/or slide show a lot of wear? With a bike that age, that could be a factor. Also, the orifice where the needle seats into could be worn larger?
You probably checked this, but is the main jet tight in the carb body? The reason I ask is that I've seen a KDX 200 run even after the main jet came loose and fell out! She didn't like any throttle openings more that 1/4 turn, but it still ran and made it back to the pits. A loose main could mess up the midrange, but I'd think it would blubber like crazy on top as well.
Well, I just wanted the opportunity to tell a cool, weird story that had us stumped out on the trail that day with the KDX.

 

[KTMAndy]

Jamie I've had similar issues with my 250 gasser. I found Jakobi to offer great advice.

For about 18 months I thought it was just a 2 stroke characteristic until I rode my friends 300.

However, since then I've been chasing the smooth torqy power.

I've replaced the stator which was looking fried. Then started re jetting which didn't do much at all....

However somewhere along the process I managed to snap the standard needle. N1EF so I've ordered a few more, but in the mean time Diggs gave me a CEK needle.

It's totally changed the characteristics of my bike. Far more than anything else I have tried.

I'm away to try it properly tomorrow but just riding on the tarmac I have no flat spot like before, bags of low end power. However the cut into the power band it's a little severe.

Current set up

Low jet #42
Main jet #175
#7 slide
CEK needle clip #3

Running 50/1 fuel also with Dep can and from the uk.

 

[mjtursky]

I agree with KTMAndy.

My EC250 runs well with the same MJ & SJ. But I use a slightly leaner CEL (straight dia) JN. That's because I use a 6.0 slide which gives a better signal to the nozzle to get the main circuit going.

 

[KTMAndy]

I struggled to find needles that I needed both from local dealers and from eBay. However I found gear4moto in the us and the needles arrived within 4 days. Apprx ?6 each.