FCRMX Pilot Jetting Assistance

[khardee]

Sorry for this long post ... just trying to give plenty of detail.

I put the FCRMX kit in my 400S a week or so ago. I used the alternate needle (emn?) as suggested by the kit. I did not have an extended FS so I had set the stock one at 2 turns out. Overall it was running pretty well, but I had a couple of issues that I noticed a couple of others here having.

1. Surging at a constant low rpm / speed.

2. Slight off-idle bog. Better than the re-jetted Mikuni but still not what I thought it could be.

3. I can't do a stoppie, but if I got on the front brake really hard, the engine would die.

From the searches I read, it seamed a smaller Pilot Jet was in order, and an extended fuel screw so I could do the Pilot Jet test. Maybe check float level as well.

The temperature has dropped about 20 degrees the last few days, and the surging had all but disappeared. Well the smaller PJ's and FS came in Friday so I decided to give them a try anyway.

My only other engine mods are the 3x3, twin air filter, muzzy ss with titanium muffler (no cork or sa).

I now have a 40 PJ and the extended fuel screw in the FCR.

My first issue with the surging did not return, but that may be attributed to the cooler weather as it was better before I made this change.

I think the off-idle bog is worse now. I'm not sure because I did not test it well enough before changing the PJ/FS. I don't think I had tried snapping the trottle from 0 to 1/2 like I did now when doing the PJ size test. If I open the throttle from 0 to 1/2 a bit slower than as fast as I can, it seems fine. But if I snap it, it bogs horribly. Even to the point of stalling the engine. This seemed to happen more often when I was at opposite ends of the FS turns range. 1 turn out seemed the best, but would still stall if I opened the throttle fast enough from 0 or 1/8th.

What concerns me even more is that when attempting to do the PJ sizing test, I could not really tell any difference in the idle of the engine from 3 turns out, all the way to the bottom.

So I slowed the idle down a little and did the test again. I still could not tell a difference in idle from FS all the way in until about 2 turns out, where it started stumbling a little and cut off. From what I read, I thought it should behave just the opposite?

One thing I did not do as instructed was to check all jets for correct size. I will do this next time I take it off. The ones on the bottom seemed right, except I think I remember reading 80 on the short jet to the left of the PJ ?

My float level looked to be between 8 and 9 mm (I couldn't decide exactly when the needle was touching). I have not done the stoppie test again as I don't have every thing bolted on like I should

?

Maybe I got a bad extended FS? I did 'eye-ball' the two next to each other and the tip of the extended FS seemed to be shorter than the stock FS. Maybe I got a bad ext FS and should put the stock back in ... I hate to not be able to adjust it now though ...

If you made it this far ... Thank you very much for reading

Any suggestions?

[Wayward Son]

you are testing while riding the bike right?

[Landslide]

All I can say is good luck!

I'm having my mechanic (refered by TT) install the FCR MX kit on my "S" (3x3 & full Yosh RS-3) and it's running way too rich with what the kit provides! He's been fighting with the jetting for five days and intends to contact TT!

This will be a good learning experience for us all $$$$$$$$$$$$$$$$$$$$ !

I wanna go ride! ?

[Wayward Son]

if he has been fighting for 5 days he has no idea what hes doing.

[Wayward Son]

anyone that thinks they have some impossible fcr jetting issue can bring me the bike.i will fix the bike WHILE YOU WAIT FOR FREE!

i know not everyone lives near me.however i am that confident that these issues are not a severe as being made out.thus my offer.

paying some clueless mechaninc to tinker for 5 days is ridiculous!

on a side note,i dont make one penney from the sales of these carbs.

[Landslide]

Tell that to the guys at TT!

They refered him!

He's using "test equipment" at the tailpipe to "read" the jetting results!

I even shared your (Eddie) jetting recommendations which I've noticed are now different for someone else with the same bike, carb, and elevation.....ie main jet & needle! ?

I understand this is a new conversion, but lets not make us all guinea pigs at our expence! $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

[DR-Z400SM79]

anyone that thinks they have some impossible fcr jetting issue can bring me the bike.i will fix the bike WHILE YOU WAIT FOR FREE!

i know not everyone lives near me.however i am that confident that these issues are not a severe as being made out.thus my offer.

paying some clueless mechaninc to tinker for 5 days is ridiculous!

on a side note,i dont make one penney from the sales of these carbs.

I wish I lived near I definately take you up on that...But I am getting kind of nervious seeing a ton of peolpe with off idle boging and steady cruising surging....I will be doing this mod some time next month and am still trying to figure where to start with my jet settings...

So should I start with a 40,38,or 35 pj? 158, or 160 main

I'm at 1000ft

yosh ti

3x3

[Wayward Son]

show me which suggestions changed.inlcude elevation,pipe and type of riding.no one here is guinea pig.

your now accusing me of wronging people here by trying to help them.that isnt going to fly!

[Landslide]

Driving from Las Vegas To Colorado = MORE BIG $$$$$$$$$ in GAS!

[Wayward Son]

I wish I lived near I definately take you up on that...But I am getting kind of nervious seeing a ton of peolpe with off idle boging and steady cruising surging....I will be doing this mod some time next month and am still trying to figure where to start with my jet settings...

So should I start with a 40,38,or 35 pj? 158, or 160 main

I'm at 1000ft

yosh ti

3x3

with no insert the jetting supllied with the kit is correct starting point.

you have handfull of guys out of the hundreds of carb kits sold that have issues.

these carbs sell out as soon as they are in stock.

[DR-Z400SM79]

with no insert the jetting supllied with the kit is correct starting point.

you have handfull of guys out of the hundreds of carb kits sold that have issues.

these carbs sell out as soon as they are in stock.

So do you think I would be making a mistake by starting with a 40 pilot jet?...

[khardee]

Testing on and off the bike.

Tried the PJ test off the bike

-> did not notice a difference in idle speed with FS changes.

-> 0 to 1/2 throttle snaps could make the engine die (poof)

Test riding the bike mirrored the off the bike tests but to a lesser extent. It felt pretty good except for trying to slam the throttle open from an 'idle' speed. e.g. - When coasting at slowest speed in 1st or 2nd gear and quickly snapping to > 1/2 throttle. This killed the engine a couple of times. Had it happen at 1 turn and 2.5 turns. If I open the throttle a little slower, it seems to take the gas well and pull hard. I don't know that I ever tried slamming the throttle open like this before from an 'idle' speed so I may have had that all along.

I'm still bothered that I can't seem to peform the Pilot Jet sizing test described by Eddie in the jetting forum. I can't detect a difference in idle as expected while turning the FS. I also thought it should stumble when turning the FS in ... the only way I could get it to stumble from FS changes was by turning the idle low, then it would cut off when I got to about 2.5 turns out (from fully in).

Thanks for quick responses, wouldn't you know my internet went out Friday afternoon and Time Warner will not send someone out until Monday ... I'm at my parents house across town now. Will check back tomorrow.

?

[Landslide]

I apologise Eddie for any negative insinuation, I'm just frustrated! My bad!

For the record I do not believe you or anyone else is doing anything wrong. ?

[Wayward Son]

So do you think I would be making a mistake by starting with a 40 pilot jet?...

start your own thread in the jetting forum.you didnt make a mistake persay.40 pilot may required with a aftermarket fuel screw.

[Wayward Son]

Testing on and off the bike.

Tried the PJ test off the bike

-> did not notice a difference in idle speed with FS changes.

-> 0 to 1/2 throttle snaps could make the engine die (poof)

Test riding the bike mirrored the off the bike tests but to a lesser extent. It felt pretty good except for trying to slam the throttle open from an 'idle' speed. e.g. - When coasting at slowest speed in 1st or 2nd gear and quickly snapping to > 1/2 throttle. This killed the engine a couple of times. Had it happen at 1 turn and 2.5 turns. If I open the throttle a little slower, it seems to take the gas well and pull hard. I don't know that I ever tried slamming the throttle open like this before from an 'idle' speed so I may have had that all along.

I'm still bothered that I can't seem to peform the Pilot Jet sizing test described by Eddie in the jetting forum. I can't detect a difference in idle as expected while turning the FS. I also thought it should stumble when turning the FS in ... the only way I could get it to stumble from FS changes was by turning the idle low, then it would cut off when I got to about 2.5 turns out (from fully in).

Thanks for quick responses, wouldn't you know my internet went out Friday afternoon and Time Warner will not send someone out until Monday ... I'm at my parents house across town now. Will check back tomorrow.

?

you have to do all testing riding the bike fully warm.test in nuetral in the garage is irrelevant.i can make any bike with a fcr bog and stall in nuetral regardless of jetting.

just for sake of reference,what fuel screw are you running?

your findings indicate you need a smaller pilot jet yet.your pilot circuit is still rich.

im not sure what going on with these recent fcr's.something has changed in the carbs.

does your carb have a air cut valve?

did you visually confirm it has a 100 pilot air jet?

[khardee]

I hate being such a noob with this ... I don't know about the air cut valve. How can I verify it's existence?

I will visually confirm all jet sizes and post back.

I am using the ZipTY? from the TT store (FS01 I believe).

Thanks!

[mickeydee]

burned got mine right with just 1 post.since then i have experimented and have found that his way was really the best.i've only had to play with the pj to get it right down low with the ZipTy fuel screw.one thing i had to change with my fcr was to do the BK mod to be able to get the squirt duration down to 1 sec

[Wayward Son]

I hate being such a noob with this ... I don't know about the air cut valve. How can I verify it's existence?

I will visually confirm all jet sizes and post back.

I am using the ZipTY? from the TT store (FS01 I believe).

Thanks!

can you shoot me a pic of the right side of the carb?

make sur enone of the vent lines are pinched as well.

[dano99]

Just a thought Eddie, what about explaining to us what all these diferrent jets do (i.e. Pilot jet, main jet, air jet, needles, etc) Maybe then we could trouble-shoot a little easier. It just might cut down on the million questions your getting! ?

[bumtarder]

For the basics;

http://www.dansmc.com/carbs2.htm

http://www.keihin-us.com/tune1.htm