Anyone using JD Jetting kit in UK ?

[DaveH]

Hi,
am new to the forum...have recently bought GG EC300 - 2004 model but with very little use. Bl**dy awesome bike compared to the heavy 4T bikes I have been used to.

Have just taken delivery of a JD jetting kit from the US.

UK GG importers recommend as standard a 38 Pilot, 178 Main and N1EF needle on clip position 2 or 3.

JD jetting recommend Blue needle, CP 3, 185 main jet if running below 55 degrees F (!!) 182 main above 55 degrees, pilot 42 or 45.
Wondered if anyone else was running the kit in the Uk and if so what settings they use.

Likely to be running the bike to 2500 feet elevation max and over winter so below 55 degrees seems about right. Having looked in the jetting database there are very few people running jet sizes as large as 185, but then no one has listed a JD needle either.

Dave H

 

[GMP]

Do a search in the jetting database. I've been running the JD Blue needle (generic PWK 38 kit) in my 250 since it was new with outstanding results. I have no experience jetting a 300 with it though. Those #s sound rich to me. Since I'm running a 180 main and 48 pilot in a 250 with a #7 slide @ 1000' I would start with a 175 - 178 in a 300 with a smaller pilot.

 

[Gasgasogeros]

my 300 use jdjetting with very good results . With main 182 blue needle at 4 clip of the top pilot 42 air screw 1,5 turn out

 

[DaveH]

Those #s sound rich to me.

Yep...did to me too. Thats the main reason for the post....seems a hell of a jump up over stock but I have no experience of the JD needles.

Jet settings in the instructions are also the same for all models from 200 - 300cc ??.

Seems odd though for JD to put R&D time into a kit and market it with hooky instructions ...do I go with them or not, thats the question.

Think I may try the #182 main first (as per Gasgasogeros post) and go with the rest of the recommended settings

DH

 

[iancp5]

FWIW
There seems to be an unusual amount of variation between succesful jetting especially between US and UK. There are various theories why. I suspect that the majority in UK need tight, technical settings where the majority in US need more open, fast setups. But that is both a generalisation and theory not fact. There may also be issues with fuel differences between our countries. I tried the LTR setup and it made my 300 run like a dog in the woods. My best setup was using a CCK needle, 42P & 180M. May have some of that wrong but it was definitely CCK needle - smoothest power delivery. You can jet them to be more explosive if you want.

 

[DaveH]

FWIW
There seems to be an unusual amount of variation between succesful jetting especially between US and UK. There are various theories why. I suspect that the majority in UK need tight, technical settings where the majority in US need more open, fast setups. But that is both a generalisation and theory not fact. There may also be issues with fuel differences between our countries. I tried the LTR setup and it made my 300 run like a dog in the woods. My best setup was using a CCK needle, 42P & 180M. May have some of that wrong but it was definitely CCK needle - smoothest power delivery. You can jet them to be more explosive if you want.

Thanks for that....I have a spare cck needle and the carb is now jetted 182m/42p with the JD blue needle...quick job to swap needles for comparison

 

[GMP]

Another thing to consider is the "JD Blue" needle definition itself. There are many different JD Blue needles. I'm going through this now with my brother's Husky 250 with a PWK 38 swap. The needle I use is from a kit that used to be called the "PWK38-39 MX/Enduro generic kit". Now it is specified for a KTM 144SX. I told him to contact JD and have him clarify it is the same needle. From my experience JD has always suggested that you start rich and work leaner which is a good conservative plan. Sometimes the starting points are a lot farther off than others. That said, the jump over stock main size is primarily due to the fact that the JD needle, like the D and C series single tapers, has a much wider tip and obstructs the nozzle more at full throttle. Standard practice is one or two sizes up over stock. Countering that, 300s have a bigger signature, so compared to a 250 in the same conditions running the same needle I would expect the results to be one to two main sizes leaner.

FWIW here in the north east USA we ride very tight and technical terrain, and for the most part use very little of a 250s power. Our bikes have to be jetted clean off the bottom as well.

 

[DaveH]

Thanks Glen...bit new to this 2 stroke tuning lark so not quite sure what you mean by 'bigger signature'. Seems illogical that a bigger engine should need a smaller main but I bow to your experience...

A lot of nadgery technical stuff round here too so I need the low down grunt !

 

[iancp5]

Thanks Glen...bit new to this 2 stroke tuning lark so not quite sure what you mean by 'bigger signature'. Seems illogical that a bigger engine should need a smaller main but I bow to your experience...

A lot of nadgery technical stuff round here too so I need the low down grunt !

He means a 300 sucks harder than a 250 if they have the same carb/intake size, which they do. So it will pull more fuel through the same size jet but apparently it would pull too much all things being equal so you jet down a little from a 250. See that's logical too.

 

[DaveH]

He means a 300 sucks harder than a 250 if they have the same carb/intake size, which they do. So it will pull more fuel through the same size jet but apparently it would pull too much all things being equal so you jet down a little from a 250. See that's logical too.

Thanks Ian...all makes sense ...sorry for being a bit dim

 

[splint]

Is the fuel the same in the U.S. and U.k.? I know from my experience that it seems that U.S. fuel and Australian fuel is not the same.

 

[iancp5]

Is the fuel the same in the U.S. and U.k.? I know from my experience that it seems that U.S. fuel and Australian fuel is not the same.

I think it's different. I "think" (just hearsay) that the US has more bio alcohol mixed in and due to harsher winters in some areas has special winter mixes. I also think we can get higher octane at the pump in the UK. That doesn't mean higher calorific (energy) value is necessarily different but it could all effect jetting especially the alcohol.

 

[Todd5774]

Ive just installed a JD jetting kit in my 300 and followed the instructions/recommendations using the blue needle and the bike is better in the open much more power however it now has significant bog off idle, so some tuning is needed. it is definitely not a fit and forget upgrade, you do need to fiddle..

 

[GMP]

Nothing to do with jetting is a fit and forget upgrade. What description/part# is your kit?