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fcr-mx no leak jet ap timing...

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i hope some of you can help me timing a.p. squirt on my fcr41-mx.

here's the issue: i could tune the squirt (ap screw out) to eliminate any bog at trottle wacking from low rpm but.. low end is rich and slow to get higher rpms.

if i turn the ap screw in the squirt becomes shorter (less duration/volume) but it begins to bog if i whack the threttle from low rpms.

I know that turning in the ap screw means less duration/volume and later squirt and i think that in my case i have a lean bog caused by late timing of the squirt.

i can't turn the screw out because this will eliminate the bog (earlier squirt) but richen too much low end (longer squirt duration/volume)

my fcr-mx does not provide any leak jet.

can you help me? ....Eddie??

p.s. i also tried the ap mod but didn't help the timing.. :excuseme:

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No leak jet on the MX series of carbs.

Did you do the O-Ring mod?

You shoud not have to move the screw back out more than 2 turns. When you adjust, do so in 1/8 turn increments.

Have you tuned the jetting using a wideband? That really must be right to then set the AP accurately.

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yes tried the oring mod.it shortens the squirt but doesn't affect timing.

i have set the squirt to 1 second (wideband) but to do so i had to turn the screw almost all in and that caused a late timing

i make small adjustments at the time (1/8)

any idea on how can i get an earlier squirt and keep it short?

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Screwing it in, causes the squirt to be sooner. You need to screw it out. Put the screw back to where it was from the factory, and back it out an eighth, test, back it out a little more test. I found it needs to go out typically about 1 turn, +/- 1/4

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the screw has little effect on duration.

wideband has nothing to do with timing of the squirt.

you need to actually look at the squirt.

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thanks william and thanks eddie.

for eddie:

i took the carb off eddie and i tried both screw all out and all in. i saw that all screw out gave a squirt of about 4 seconds and all screw in about 0.80 second

i left 1 second and i got a bog and then quick revving. turning the screw out from this position for about half turn cured the bog but the bike didn't revv as quick as before.. low end seemed rich

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The screw does not affect squirt duration, if affects WHEN (Timing) it squirts. By turning it all the way either direction, you are at the extreme and that will not do it.

Is the rest of your jetting correct?

Put the screw back to stock. Put the O-ring on.

Ride the bike. Tweak the screw out 1/8 turn. Ride the bike. You will find the sweet spot. The screw can easily be turned with the carb on the bike.

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as eddie said make sure and time the squirt with the carb off. Also once you have the appropriate timing do the o-ring mod. (i know you said you already did but potentially you did not have the appropriate timing first)

When I first got the FCR was extremely frustrated as the bog was persistent. However after getting the timing correct it fixed problem somewhat. The O-ring mod finished the job.

good luck!

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The o-ring is a big help as Eddie and others say. Adjust your timing screw so the squirt of gas just clears the slide when you open the throttle to full open very quickly. (it's really a lot easier to check this with the carb off the bike)

This will set the timing correctly. Now for the squirt duration, the o-ring mod will help. A better option might be the new billet AP arm pieces from Zip-Ty racing ( http://www.ziptyracing.com/products/product_detail.aspx?id=MTUxOQ== ) which is included in their new carb mod. Ready racing makes a billet replacement AP arm, but one thing I don't like is that it has fixed timing - it makes the timing screw worthless.

The biggest help in sorting out the squirt duration will probably be installing a float bowl with a leak jet. James Dean sells them ( http://www.jdjetting.com/xcart/product.php?productid=38&cat=1&page=1 ), or you could go with the really expensive R&D power bowl.

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ok i did put the o ring back in. turned the screw from all in, by steps, till 1,1/4 turns out. that's the best bike behavior i could obtain. turning out more makes the bike slower to revv..

bog almost disappeared : only at very low rpm (2° gear) it does a bog for let's say 1/4 second and then revvs but not so quick to perform a wheelie. best revving comes from mid to top rpm.

i cant understand if slow revving is due to lean or rich condition..

sh..t ap tuning must be too difficult to me.. i surrender

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what is your complete jetting?

sounds like you are rich on the needle possilby which would be worsed at the initial opneing of the throttle by to much pump squirt.

the o-ring makes the duration shorter.

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needle is emn third clip mj is 155

but eddie if i whack the thottle from 0 to full i thougt needle woudn't matter

..

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it does just a for a moment.

emn is to rich with a 41mm carb.you need a emr.

what are the specs on the rest of the bike?

155 main jet iis way small on a 41 as well.

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it does just a for a moment.

emn is to rich with a 41mm carb.you need a emr.

what are the specs on the rest of the bike?

155 main jet iis way small on a 41 as well.

200 main air jet

155 main jet

EMR needle 3° clip

45 pilot jet

100 pilot air jet

i put on the EMR needle third clip, turned in ap screw 1/4 and turned in 1/2 mixture screw.

no more bog. bike revvs better! you were right eddie:applause: , low end jetting was rich!

the rest of the bike is :

airbox all opened (cut) on top and right side,k&n, full leovince exhaust system and fcr41-mx the rest of the motor is stock. i'm planning a big bore but no $$ for the moment.... till then what mj size

or what else do you suggest to get all i can from this configuration?

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