XR650L Exhaust Studs aka "Can'o'worms!


37 replies to this topic
  • Brtp4

Posted December 10, 2007 - 11:48 AM

#21

Got it. But please re-read my post, when I was at a 45 and you at a 52, and since our altitudes were somewhat close, I could not understand such a difference. I asked Burned and he explained:


you see the bigger pilot jets on the other bikes because they run the pilot air jet bigger/farther out.the pilot jet and pilot air jet are a direct realtionship.

There is no difference between a 45/100 combo vs a 52/125. Its the same ratio of fuel to air
[/I]

His pilot size depends on his pilot air setup.

BP

  • martinfan30

Posted December 10, 2007 - 01:16 PM

#22

ok, my appologies.

  • XR650L_Dave

Posted December 10, 2007 - 02:47 PM

#23

Got it. But please re-read my post, when I was at a 45 and you at a 52, and since our altitudes were somewhat close, I could not understand such a difference. I asked Burned and he explained:


you see the bigger pilot jets on the other bikes because they run the pilot air jet bigger/farther out.the pilot jet and pilot air jet are a direct realtionship.

There is no difference between a 45/100 combo vs a 52/125. Its the same ratio of fuel to air
[/I]

His pilot size depends on his pilot air setup.

BP




pilot air jet- I assume you're talking about the FCR carb, not the stock CV?


Dave

  • Brtp4

Posted December 10, 2007 - 05:57 PM

#24

Ayep.

pilot air jet- I assume you're talking about the FCR carb, not the stock CV?


Dave



  • August West

Posted December 10, 2007 - 06:08 PM

#25

Love all the technical discussion regarding jetting the FCR!:banghead:

The FCR-41 that I got from Sudco was sent with the slow air screw backed out (from fully seated) 10/12ths of a rotation...there doesn't seem to be any identifying alphanumerics on this jet. The pilot jet they sent was a 50.

Thanks for your words, Brtp4! Since you and martinfan30 live up at higher altitudes, I'm left wondering if when you guys recommend, say a 52 or a 55 pilot jet, do I need to be considering my altitude adjust accordingly? Do your settings work when you're down from sea level on up to 3400 feet? I'm mostly in the 500-2000 feet elevation range.

The main air is a 200. I've seen people talk about having a 100 or a 200...is this a drastic difference in set-up?

My engine was ready today, so I went and picked it up, took it home, and put it back in (2 hours). Tomorrow, I'm fitting the pipe, can and carburetor. The weather's supposed to hold out for the next few days so if I'm lucky, I'll be riding maybe tomorrow afternoon!:busted:

Thanks guys for all your inputs. Since I don't have the jets I've ordered yet I'm going to install tomorrow with the 170 main jet, 200 main air, 50 slow jet, and the slow air screw 10/12ths out. I'll keep you posted.

  • martinfan30

Posted December 10, 2007 - 07:25 PM

#26

personally, i havent ridden below say 2500 ft. but ive been up to 10,600 and it still ran ok, a bit rich but ok. i would like to see how she does down low.

its well worth the shot to try the factory jetting at your ele. let us know.:banghead:

  • Brtp4

Posted December 10, 2007 - 07:36 PM

#27

AW,

The thing is, Martinfan and I are at similar altitudes, but have way different slow-speed jets, because the pilot air circuit factors in. If I understand Burned correctly, this is a ratio, so different pilot jet sizes can result in the same low-speed mixture.

It seems most of the newer FCRs have the adjustable pilot air screw as opposed to the jet, so yours probably does also. When I was looking for mine, here is the quote from Burned:

Quote:
Originally Posted by Eddie Sisneros
it actually has the 100 pilto air jet or does it have the pilot air screw conversion in its place?

Quote:
Originally Posted by Brtp4

OK , how do you tell?


Quote:
Originally Posted by Eddie Sisneros
under the intake bell,left jet.

if its a actuall 100 pilto air jet it will be stamped 100.if its the conversion it will have a screw and a spring.


Originally Posted by Brtp4
Pulled it off and checked again.

No markings, and has a spring under it so I assume it is the conversion.

BP


My guess is that the 50 is OK as a starting point, if you get the pilot air screw at the right baseline. If I have a 45, and MF30 has a 52, and we both have somewhat similar altitudes, there seems a lot of overall circuit adjustment in this screw, so you should be OK.

Regarding altitude, so far this is an unanswered question for me. I have gone up about 800 feet and it was OK, but the real test is putting on some miles and seeing how it works on the trail. It may seem fine but when you try it in varied conditions you may find a weak spot. I hear that the FCR is too sensitive, don't know yet.

FWIW, Burned is an underrated resource on here. He knows the topic really well, and is extraordinarily helpful. To put it in reference, Sudco sends their stuff out to us buyers jetted WAAAAYYY off, not even close. If I had to find the right setup starting from their baseline I would be lost - and out a ton of cash for jets.

Oh yeah, my bet is that the 170 is way too rich.

BP


Love all the technical discussion regarding jetting the FCR!:banghead:

The FCR-41 that I got from Sudco was sent with the slow air screw backed out (from fully seated) 10/12ths of a rotation...there doesn't seem to be any identifying alphanumerics on this jet. The pilot jet they sent was a 50.

Thanks for your words, Brtp4! Since you and martinfan30 live up at higher altitudes, I'm left wondering if when you guys recommend, say a 52 or a 55 pilot jet, do I need to be considering my altitude adjust accordingly? Do your settings work when you're down from sea level on up to 3400 feet? I'm mostly in the 500-2000 feet elevation range.

The main air is a 200. I've seen people talk about having a 100 or a 200...is this a drastic difference in set-up?

My engine was ready today, so I went and picked it up, took it home, and put it back in (2 hours). Tomorrow, I'm fitting the pipe, can and carburetor. The weather's supposed to hold out for the next few days so if I'm lucky, I'll be riding maybe tomorrow afternoon!:busted:

Thanks guys for all your inputs. Since I don't have the jets I've ordered yet I'm going to install tomorrow with the 170 main jet, 200 main air, 50 slow jet, and the slow air screw 10/12ths out. I'll keep you posted.



  • August West

Posted December 10, 2007 - 08:43 PM

#28

It occured to me that I've got the conversion air screw because of the spring and no numbering on the screw. Checking out the parts diagram in the Sudco catalog confirms this, too.

As soon as you mentioned ratios, it occured to me that the screwing in and out of the slow air screw is effecting sweeps in the ratios and you then tune the engine accordingly. I'm new to all this so any enlightenment along the way is a good thing:thumbsup:

  • martinfan30

Posted December 10, 2007 - 09:10 PM

#29

brtp4, good conversation here! i have zero experience with the conversion. i have asked about getting it for my fcr but have been told by a few not to waste my cash on it. i dont know exactly why, but i assume the cost is not worth it as you can compensate with the pilot.

50 is prob a good pilot to start with, just didnt fit my needs with the new hotcam installed. you can make a 45 or 52 or even 55 work with the conversion kit(if i understand it correctly). you are also right the 170 WILL be too rich

ya eddie s helped a bunch with my setup after going fcr, pod filter and now hotcam... very knowledgeable guy. good stuff here!

Rich.

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  • August West

Posted December 11, 2007 - 05:37 PM

#30

Today I put the FCR-41 on, the FMF Powerbomb, and the Q2 can on the bike and proceeded to start the bike. Finagling with the conversion screw, and seemingly having to back it out quite a ways, the bike came to idle! The idle set screw was pretty much maxed out as well (full CW). It was hard to ascertain how many turns I did on the conversion screw because the bend in my flexible XRonlys fuel screw handle made it difficult to tell when the screw was all the way in and hence, how many turns out I did...felt like a lot though...

First impressions: The throttle response is better and it seems like the powerband is better too, although I was expecting a bit more. It seems like the engine spools up a bit faster and smoother. The exhaust sounds good and the fit was superb...FMF did a great job in the design department. I only got to ride it for 10 minutes or so before it got dark. I managed to burn my Olympia overpants on the exposed midpipe:banghead: so I'll need to install a heat shield or at least wrap the pipe for the duration.

I ended up using the stock push-pull throttle cables because there's a difference in the thread-ins on the throttle assembly at the handlebar and the two cables that came as part of the kit have the same size thread-ins on all ends. Not sure if Sudco screwed up or what but it all works with the stock cables...I'll be contacting them to get the story.

So now the question is, how do I know if I'm running rich or lean at full throttle? The bike runs good but honestly I thought I'd get more top end...is this where playing with the main jet is called for?

I think I'm going to ride up to my Honda guy who does all the tricking out for the guys around here. I'll let him ride it and see what he thinks.

  • quicksilver

Posted December 11, 2007 - 07:30 PM

#31

I am starting to get all set up to do some basic mods and have been following this thread with some interest. Some items are simply too hard to find for the "L".

I have actually spent 2 hours searching for yoshimura slip on for my 650L and could not find ANYTHING. Does ANYONE know ANYWHERE (I tried eBay - big-time) that sells a Yoshimura exhaust for a 650L ??? I'll buy used: Hell at this point I may just switch, but I want to give it everything I can to find one.

  • Brtp4

Posted December 11, 2007 - 08:33 PM

#32

Today I put the FCR-41 on, the FMF Powerbomb, and the Q2 can on the bike and proceeded to start the bike. Finagling with the conversion screw, and seemingly having to back it out quite a ways, the bike came to idle!

Seems it should only be out 2 or 3 turns.

The idle set screw was pretty much maxed out as well (full CW).

Mine too.

It was hard to ascertain how many turns I did on the conversion screw because the bend in my flexible XRonlys fuel screw handle made it difficult to tell when the screw was all the way in and hence, how many turns out I did...felt like a lot though...

AW, take a small piece of colored electrical or duct tape and put it around the screw, flag-style. You can use this to count.

First impressions: The throttle response is better and it seems like the powerband is better too, although I was expecting a bit more. It seems like the engine spools up a bit faster and smoother. The exhaust sounds good and the fit was superb...FMF did a great job in the design department. I only got to ride it for 10 minutes or so before it got dark. I managed to burn my Olympia overpants on the exposed midpipe:banghead: so I'll need to install a heat shield or at least wrap the pipe for the duration.

I ended up using the stock push-pull throttle cables because there's a difference in the thread-ins on the throttle assembly at the handlebar and the two cables that came as part of the kit have the same size thread-ins on all ends. Not sure if Sudco screwed up or what but it all works with the stock cables...I'll be contacting them to get the story.

You sure you are getting full throttle linkage movement?

So now the question is, how do I know if I'm running rich or lean at full throttle? The bike runs good but honestly I thought I'd get more top end...is this where playing with the main jet is called for?

Try a smaller main and see if it runs better.

I think I'm going to ride up to my Honda guy who does all the tricking out for the guys around here. I'll let him ride it and see what he thinks.


AW, the power is better, but they are still slow.

BP

  • August West

Posted December 14, 2007 - 04:46 PM

#33

WooHoo!:ride: The bike rides way better now! The powerband keeps on strong...all that mushiness on top is gone and all that popping/gurgling on deceleration is gone too! It's definitely on its way towards an XR650R as far as my ass dyno goes.

Update: I put a 160 main jet and a 55 slow jet (carb came with 170/50) and whereas the idle circuit still needs tweaking, the power up top is definitely better...second gear roll-on wheelies are easy now:applause: . Now I'll try my 165 main, then my 158 main to tweak the top end and I'll try a 45 slow jet to get the idle worked out...as it stands my idle speed screw is maxed CW and it seems my conversion screw is just about all the way out and then it idles fine. I'll see if the 45 will bring the number of turns down on my conversion screw and if it'll bring my idle speed screw back towards the middle of the adjustment range.

:banghead: :busted: :D
So, I haven't tried it yet, but can you change out the main/slow jet without taking out the carburetor? By just dropping the float bowl? I know it's not that difficult but taking the throttle cables on and off is a bit bearish. Anyone have thoughts on this?
:D :busted: :ride:

  • Brtp4

Posted December 14, 2007 - 05:17 PM

#34

Great news AW!! BTW, you may know this, but next size up from the 160 should be a 162. Don't know about the float bowl question though.

BP

WooHoo!:ride: The bike rides way better now! The powerband keeps on strong...all that mushiness on top is gone and all that popping/gurgling on deceleration is gone too! It's definitely on its way towards an XR650R as far as my ass dyno goes.

Update: I put a 160 main jet and a 55 slow jet (carb came with 170/50) and whereas the idle circuit still needs tweaking, the power up top is definitely better...second gear roll-on wheelies are easy now:applause: . Now I'll try my 165 main, then my 158 main to tweak the top end and I'll try a 45 slow jet to get the idle worked out...as it stands my idle speed screw is maxed CW and it seems my conversion screw is just about all the way out and then it idles fine. I'll see if the 45 will bring the number of turns down on my conversion screw and if it'll bring my idle speed screw back towards the middle of the adjustment range.

:banghead: :busted: :D
So, I haven't tried it yet, but can you change out the main/slow jet without taking out the carburetor? By just dropping the float bowl? I know it's not that difficult but taking the throttle cables on and off is a bit bearish. Anyone have thoughts on this?
:D :busted: :ride:



  • xr650l bum

Posted December 14, 2007 - 06:46 PM

#35

loosen the airbox and intake boot, then just rotate the carb to the exhaust side. Take off the brake resevoir. Be careful when taking the bowl off. The pin that holds the float likes to fall out when carb is tilted like that. I use to put a towel or paper towel to catch something incase it fell and I did not see. I am sure this will be the first of many times. Good luck!

Oh ya. If you can change the bolts to allen head instead of phillip. Better, and easier to tighten/ loosen with the right allen wrench.

  • August West

Posted December 15, 2007 - 08:56 AM

#36

Thanks guys! I only have on hand a 165 and a 158 to go to...I'm going to go ahead and order the whole series since they're cheap enough...should have ordered them all when I got the carburetor from Sudco.

Also will try bum's suggestion re: jet replacement w/o carb removal. All bolts are allen on the carb already!

Rainy weekend, might not get to the bike 'til Monday.

Have a great weekend y'all!

  • xr650l bum

Posted December 15, 2007 - 09:06 AM

#37

Sorry. I reread the posts and see you are talking about the fcr carb. I thought you were talking about stock. I only have experience with stock and eddie.

  • martinfan30

Posted December 15, 2007 - 03:26 PM

#38

yes you can loosen and rotate the carb (FCR) enough to get the bowl off.





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