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jetting question

S

sickd

Joined Dec 2009
149 Posts | 12+
melbourne victoria australia
ok ok i have read all the owner docs on here and its is super informing.

just like a answer to this

bike runs great as is, but has lately been a bit hard to start on the kick, takes 10- 15 kicks, and once starts one the choke it idles away and then ramps up high in revs say 300 rpm higher then norma idle, (i have a taco)

so i was just wondering what i do change in carbi?

bike is as follows

07 fe 550
tappets fine
has modified muffler straight through
carbi jetting is stock as below FCR

main 182
needle obdvr 5th clip from top
idle jet 40
starting jet 85
mixture screw 2 turns
main air 200
idle air 100

thanks mike.
 
My 2007 FE650 acted similarly, the pilot jet was too small.

So when the choke was on, it would start, but was hard to start. To get it to idle at all, the idle stop was set very high. All this added up to a very high idle speed with choke on.

With choke off after warm up, the idle was unstable and speed would creep up on me. I usually wouldn't notice until I wanted to go slowly through a section.

Another thing - with the idle stop holding the slide open just to keep it running in such a lean condition, when I cracked the throttle and the accel pump put in fuel, the response was explosive, violent, scary, and dangerous!

I ended up with a 60 pilot jet. Now it starts easily, idles fine, response is predictable and it just runs great anywhere in the rpm range.

My needle was in the center position, if I remember right.
 
Looks to me like pilot /needle poition are too lean and you main might also be too big also. The pilot is to small for a open exhaust in my 650 i have a 50 pilot same needle as you but on clip 3 from top and a 165 main normally starts first kick, Now its winter it makes it harder to start given you have such a small pilot in yours.
 
thanks guys that helps me a lot i will get to finding a 45? pilot and putting my needle to say 4th from top and see how that goes??
or should i leave the needle
 
there's nothing wrong with that pilot! I put it in all my 650 jetting kits along with a smaller pilot air jet. the reason these lads are stuck with high PJs is because they don't change the PAJ.

bikes can reach high revs on choke when the jetting is such. your MJ is very, very rich, this alone when reduced would also get rid of the effect.

put it this way, Keihin make MJs between 140 and 188 I believe and you have a 182.... 8O 8O

regards

Taffy
 
Taffy might be correct but he is in a location where air temp are cooler but saying that Melbourne has all the seasons in one day anyway lol. Every motor and every place is different all you can do is try them all. :D
 
In the good old days.... we used to do a plug chop to set the main jet size via colour of plug..... get that set right then move on down though the needle position followed by the pilot jet then finally mess around with the air screw to get idle and transition nice..... but that was the old days and apparently carburation is different nowadays!

There is something to be said for the old ways........
 
Who said leaded fuel was all bad lol. Allways remember moto gp bikes doing plug chop on the mighty two strokes at the end main straight. But that was main jet checks primarily.
 
thanks heaps guys appreciate it and taff thanks heaps too I'm am very much confused, i do realise from reading owners doc that it is very rich, but we do get crazy different weather all the time hot hot like 38 down to 10 degrees Celsius, I'm happy with how it runs but just lately its been a bugger to kick start just takes a fair few kicks, and the bike has only done 25 hours since full rebuild from orangeberg and i put taffs dvsk kit and new followers in and new valves, t?chain hole thing runs a dream but just lately hard to initially start off the kicker, has been very cold this year, and i have put a shorai battery in it, (don't think that make 2 tenths on f all lol)

so just curious on a carbi change to make it start a little easier
 
ok ok put a 42 pilot in,

kicked over 3rd kick awesome and revs did not shoot through the roof on the choke, and once off choke it was perfect, on quick twist of the throttle it snaps its GREAT!!!!

thanks for the help everyone
 
that 42 isn't an improvement sorry. whatever else it has done it means the bottom end will be wooly and react slowly and also when it cuts out hot it'll just take longer than ever to start. the answer was to drop both the pilot jet and the pilot air jet.

regards

Taffy
 
Birdwood

Imagine you've seen this so many times you're tired of the argument.

I found all this out in 2000 :shock:

It was myself that put together the PJ to PAJ ratios after hours of work. even sparks agrees with them although he found the pilot air screw to work differently to the factory's very own figures.

fact is, while you run a 100PAJ you must run a large PJ. so yes, you do make the bike run better with a 42/45 and a 100PAJ but that is NOT better than a 75PA/40PJ or better still a 60/38 ratio.

try it mate, the info is as usual; free! :D :D

regards

Taffy
 
Thanks for all the help guys It did start easier but as taffy said it was an absolute pig to start when hot, so I will try dropping the pilot air to 75 and put the 40 back in, and see how that goes,

Can I do that without changing needle positions taffy?

Thanks guys
 
Taffy said:
at last - someone who listens! :D :D

yes you should be OK

regards

Taffy
Click to expand...

Either I wasn't privvy to this info when I was going through my ordeal, or read it and didn't understand it.

At any rate, a huge advantage I'm thinking, if the PAJ can be replaced without removing the carb, that would save a lot of time and work. Supposedly the PJ can be, but I'm sure I can't do it. Does the PAJ come right out the back?
 
Replaced the paj with said 75 and, you need to remove starter remove carb remove rear plastic mouth off carb with 2 Allan keys and then install, no drama to do 15 min job,

THE BEST PART

The bike started 1st kick with the exhaust bung in hahaha,
Unreal thanks heaps taff much appreciated the work you have done to
Put the info in the user docs wich now makes sense once I read it over and over

Immpressed cherrs
 

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