jetting kit

Taffy · Dec 24, 2013

Hi

I've now sold about 150 of these kits and had little or no feedback from about 140 of them. it is difficult to know what that means BUT I pulled my old Mk1 off my 2002 FE400 about a year ago and just went riding with everything rich in a Mk2 carb. this is the same carb as is fitted standard to a 2004-8.

Just recently I decided to spend a bit of time getting the jetting right. so few people can run a MJ under 165 that I was concerned at my own needle being any good. I used to run low/lean jets on the Mk1 so kept expecting to hit a wall. nothing happened. got to 165 and kept going...

Well, I'm down to a 35PJ and 50PAJ combo with the needle in clip 7, the MJ is a 150 and it is running ..... rich!

so I'm pretty much on the same jetting as the old Mk1 I had. it is possible to get right down. only two petrol heads have done it and that is Sparks and myself.

650s need a 165MJ and a 40PJ tops, and the other lower CC bikes are often in between. I believe sparks had a 450 or a 550.

regards

Taffy

WArdogG · Mar 27, 2014

Hi there Mr Taffmeister!

Bought one of your jet kits with the needle for my 08 FS 650, and I was very happy. Starting was very very easy hot or cold, and I never had to use the choke for cold starting. Though it's not that cold here, even in winter.
I've never had the bike on a dyno, so I cant say much power wise, but she was definately more responsive, especially at midrange and up, where I could actually feel the bike pull when I rolled on the throttle in 5th gear, instead of it just accelerating gently with the stock setup. I hadn't done much fiddling otherwise, as the bike felt fine as is, since she was only used as a commuter.

I believe I am running 162MJ, 40 PJ, and the smaller MAJ you supplied, 1.5 turns PS. Stock pipe
My stock jetting was 42, 165, and I dont recall the needle.

I will order some more jet kits at a later stage for my 470 and 501, when I change the carbs.

Taffy · Mar 27, 2014

cheers fella!

what altitude are you at again?

regards

Taffy

steve · Mar 27, 2014

Mine got setup on a dyno and includes an opened up stock muffler. The tuner removed all evidence of jet sizes, but I had a play with my jet drills to figure out where it ended up. 800 m and been this way for about 200 hrs now and runs fantastic.

41 mm stock FCR on FE650 with Lineaweaver needle
MAJ 190-200
PAJ 3/8 or 55
R&D Flex Screw 1 5/8
main 150-155
pilot 40
start 85
clip from top 6/7
ap mm 0.2

Since you've had your needle available, I've thought about testing it out, but can't imagine how it could be better. The dyno operator was impressed with the needle too, so status quo for me. But, seems 150 mains are fine in the 650 AFAIK. Of course they do suck a bit harder than the 400.

One of my little pleasures in life continues to be people's expressions and comments when they return from a test ride

bushmechanic · Mar 27, 2014

hi Steve maybe try a 155 main air jet with your current setup ?

having the MAJ right makes more difference than the needle taper IMHO

WArdogG · Mar 28, 2014

Hi Taffy

I'm at about 3000ft, and if it matters humidity is noramally very low.

Also, I'm running normal 93 petrol, I rarely noticed any major difference when using 95, but I must admit our fuel is not the best of quality down here in South Africa, and sometimes I wonder if they just put 93 fuel in the 95 pumps anyway...

Taffy · Mar 28, 2014

I supplied a 165,162 and a 160. try the 160 at that altitude. otherwise it looks good.

Taffy

steve · Mar 28, 2014

bushmechanic said:
hi Steve maybe try a 155 main air jet with your current setup ?

having the MAJ right makes more difference than the needle taper IMHO

If I'm bored one day, we always learn from experiments. Right now, I'm playing with 4 FCRs of different types for DR adaption. Been a pain getting all the jets for those. Got to machine up some sleeves and stuff, test a 41, so might have to richen that up a bit vs the 39 used to date etc.

There is no doubt that getting the PAJ to match the PJ is beneficial for 1/4 throttle, and Taffy's table is great for that. Haven't played with MAJs much at all to date.

Taffy · Mar 29, 2014

Steve, it's the

155

Click to expand...

MAJ you want to try....

Taffy

bushmechanic · Mar 29, 2014

Dale lineaweaver suggested I try a different MAJ with his needle in 2007

Lineaweaver said:
Main air bleed has the greatest impact @ very high rpm and initial throttle bursts from closed throttle.

i found that a MAJ of about the same size as the mainjet to be about right for what i was doing at the time

the most useful info I found on its function is here

http://www.factorypro.com/tech/tech_tun ... s,Pat.html

Patric burns said:
This graph is 100% a figment of my fevered imagination, and is only to be used as a general guide, not an absolute definitive end all be all word of truth. That said..

1. air jet way too small
2. air jet a little bit too small
3. air jet just right
4. air jet a little bit too big
5. air jet way too big

there is mention of running a smaller MAJ in the jetting section in the doc but its hard to find and very hard to follow

bushmechanic · Mar 30, 2014

I run a 165 main jet and a 165 MAJ with dales fabulous needle, since Steve has a 150-155 main i suggested a 155 MAJ

schwim · Mar 31, 2014

There, clean as a whistle.

Enjoy your jetting thread, folks!

bushmechanic · Mar 31, 2014

nice work Json

its about time someone started deleting abuse regardless of where it comes from

and with the new whistling clean feel the point of the rest of my post above was to point out that a 155 MAJ is never going to be the "correct" air jet for every situation.

Taffy is right, changing the MAJ in an FCR is not my idea it was first though of by the people who developed the carb

ned37 · Apr 2, 2014

???????????????????????????????

Fe65007 · Apr 9, 2014

Taffy

Brought your kit approx. 6 months ago installed all jet and needle according to your specs.

On first install I had it dynod and at Full throttle produced 52.88hp
Pilot jet was to small 38? (was not getting right fuel air ratio right down around 10)I have not even looked at changing MAJ. Should I need to?

I have now gone up to 52 pilot jet- bad bogging issue.Screw is at 1 3/4 turns.
Needle is in centre clip. With 165 main.
Bike absolutely rockets of the line but I think still it needs to be richer up top.
Your needle is a real smooth power delivery.(from stock needle).
And just has to many clip positions to choose from

Im looking to have bike dynod again in near future will let everyone know result.
When the other guys talk about jet sizes and needles my bike seems very far off I think altitude has a big part.
Riding conditions change day to day how would one tune perfectly?

Oh bike is FE650 07.With open muffler cap and black wheels..

Darren.

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