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rossi 04-17-2017 02:59 AM

Jetting advice
 
Hi

Can some one start me in the right direction with jetting. As a recent 4 stroke convert, I have limited experience with 2 stroke jetting, other than getting my son's RM85 to run properly.

Bike: 2010 EC300 6 days, Gnarly pipe, just replaced the stock piston with Wossner kit, and cleaned out the top end which was a bit coked up. Left the base gaskets at 1.1mm to match the exhaust port height. I didn't have the correct thickness of solder so I haven't checked the squish yet, but I know that this bike has been maintained as stock rather than modified so it would probably benefit from being reduced.

Jetting is currently stock
38mm AS2
N1EF clip 1
MJ 165
PJ 35
#7 slide

Riding - Based in Cyprus. Anything from fire trails to real gnarly single track and dried river beds
Winter 15-20 deg C, 0-1000m
Summer 20-30+ deg C, 0-2000m
Humidity typically around 65%

I haven't ridden it since blowing the dents from the pipe and replacing the piston so the symptoms may have improved, but it was bogging at the bottom end, not pulling cleanly until PV opening. At 50:1 it was blowing unburnt oil out of the exhaust and smoking lots. I was advised to swap to 60:1 which cleaned up the exhaust but I would feel happier running 50:1 for a bit more engine protection. Plug was black and a bit oily.

I'm not looking for jetting perfection at the expense of regular adjustments due to temperature and altitude changes. Instead a good working setting that can cope with temperature and altitude changes, improve running and also fuel range.

Parts availability in Cyprus is a bit patchy so I will probably have to order in from UK or mainland Europe. So far I have tracked down suppliers who can send me standard Keihin needles and the Yamaha needles; I have drawn a blank on the Suzuki needles.

So can someone start me off with advice for a minimum order - a needle, couple of mains and pilots that will get me sorted.

Thanks in advance.

Jakobi 04-17-2017 03:32 AM

The needle is the problem.

Order Suzuki RM250 needle: NEDJ
Part: NEEDLE, JET (NEDJ) (13383-37FM0)

42 NEDJ#2 (second from top), and 172 main jet.

You might want to grab a 168, and 170 main jet as well to test with, but start richer.

That will get you much closer to where you want to be.

rossi 04-17-2017 04:06 AM

Quote:

Originally Posted by Jakobi (Post 176134)
The needle is the problem.

Order Suzuki RM250 needle: NEDJ
Part: NEEDLE, JET (NEDJ) (13383-37FM0)

42 NEDJ#2 (second from top), and 172 main jet.

You might want to grab a 168, and 170 main jet as well to test with, but start richer.

That will get you much closer to where you want to be.

Thanks Jakobi. The Suzi part number made the difference and I have managed to track down a supplier.
Will the pilot be ok at 35?

Edit - I'm assuming the 42 is pilot?

JP4 04-17-2017 10:08 AM

Yes, Jakobi is recommending a 42 pilot jet. The 35 you currently have will be too lean with the NEDJ needle.

Jakobi 04-17-2017 12:34 PM

Quote:

Originally Posted by JP4 (Post 176145)
Yes, Jakobi is recommending a 42 pilot jet. The 35 you currently have will be too lean with the NEDJ needle.

As above :D

rossi 04-18-2017 07:01 AM

Thanks for the advice guys. New needle and jets ordered and on their way to me.

Jim_C 04-21-2017 03:03 PM

https://www.jdjetting.com/xcart/home.php?cat=15

Maybe just trying to keep it simple, but I have used the above with no problems. Gives you needles, pilots and mains with chart. Has worked spot on for me in Arizona.

rossi 05-14-2017 01:25 PM

Thanks to the joys of international postage I am still waiting for the NEDJ to arrive but I do have the jets. I am hoping the needle arrives this week as I have a race next weekend and I need to get rid of the off idle blubbering, excessive fuel use and almost non-existent idle.

My other alternative is a N3CH which i was given today. Any recommendations for jet sizes and clip position with this needle?

The other problem is that while I can spare some time to swap them over any testing is going to be very limited, especially since I will also need to clean the filter, change tyres and attempt to straighten the side stand after another rider attempted to park his bike on top of mine today - strangely enough the stand does not support the weight of two bikes plus a rider :(

Jakobi 05-14-2017 05:50 PM

40 N3CH#3 178 main.

rossi 05-14-2017 09:43 PM

Quote:

Originally Posted by Jakobi (Post 176863)
40 N3CH#3 178 main.

Thanks. I might have to hope that the NEDJ turns up because I haven't got a 178. I will be able to get hold of a 175 though - close but I don't want to run lean.


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