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Old 04-26-2009, 07:58 PM
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Question 2001 cr250 jetting

well I have put on a vforce3 reed valve, fmf gnarley pipe with turbine core 2 sparky, went 400 main 25 slow 2nd clip s-7 nozzle bike now has improved on bottom alot but my fear is that I am too lean with the 25 slow jet, anyone out there running that small of a slow jet on same bike? my plug is dry, and white, my fear is i will blow up my bike
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Old 04-28-2009, 02:50 PM
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dissapointed with the lack of response on here about my issues with the 01 cr250, so I took the plunge and bought a jd jet kit, will let all you know if it is the godsend people say it is.
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Old 04-28-2009, 05:20 PM
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Sorry about the late response but sometimes allot of people start threads at the same time and the first one gets buried. You just need to bump once in a while and youíll get your answers. I have the same bike and almost the same set up. I am at sea level and run the JD red needle with the clip 4 from the top, 380 main, 4s nozzle and a 25 pilot.

You can read all about my trials at 01 CR250 cutting throttle slide
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Old 04-29-2009, 07:35 AM
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so jd's 32.5 pilot is still too rich for your bike? I have a 25 in now bike runs good but that lean scares me
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Old 04-29-2009, 09:00 AM
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As long as your plug reads tan or brown, your good to go.

The 32 pilot, supplied by JD, made my bike a bit sluggish on the bottom end.
I even went to the 20 pilot and found when I let off the gas, the bike would surge, so the 25 turned out to be the ticket.

You said your plug was dry and white, dry is OK but white isnt. If you are checking your plug right after a high speed run, (Plug Chop) then I would richen the main.

What ratio are you runing in your premix?

Last edited by VAL; 04-29-2009 at 09:25 AM.
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Old 04-29-2009, 03:00 PM
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got the kit today will install tomorrow and let you know, at a 25 pilot and 380 main you should be real lean at sea level, the 380 main should be for high altitude like real high, I am going to try the 32.5 with his needle and see how it goes, all i am trying to do is get rid of my low end bog, I hope I didnt just pay 88.00 for a tapered needle I already have the 400 main in now and a 25 pilot and my bike still had slow low end response gonna try red needle 2nd clip with his 32.5 and the 400 main 1st
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Old 05-01-2009, 09:18 PM
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VAL from what you are saying on your bike, you have the clip at the 4rth position which makes ir run richer, but you have a 25 pilot which makes it run lean, you also have a 380 main which again is very lean for sea level, the 380 is for high elevation, although your bike might run good, it just seems you are off setting a rich needle by using a lean pilot, I installed jd kit like they suggest, I am at 3rd clip tried the 32.5 seemed better and now will try the 27.5 tomorrow at capital forest poker run, will advise.
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Old 05-08-2009, 02:42 PM
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JD KIT IS A WSTE CARB STILL THE SAME AS B4 GOING WITH A KEIHIN NOW 2001 MIKUNI FOR SALE WORKS GREAT
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Old 05-09-2009, 07:25 AM
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Originally Posted by 1motoman69 View Post
JD KIT IS A WSTE CARB STILL THE SAME AS B4 GOING WITH A KEIHIN NOW 2001 MIKUNI FOR SALE WORKS GREAT
I think there's a satisfaction guarantee, did you talk to JD about it? Which Keihin are you going to try?
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Old 05-09-2009, 10:35 AM
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I am going with the keihin off a 2000 cr250 from what i have heard this carb will be heaven on my bike will try to send back jd kit they are local to me 5 miles away
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Old 05-10-2009, 02:11 PM
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Originally Posted by 1motoman69 View Post
VAL from what you are saying on your bike, you have the clip at the 4rth position which makes ir run richer, but you have a 25 pilot which makes it run lean, you also have a 380 main which again is very lean for sea level, the 380 is for high elevation, although your bike might run good, it just seems you are off setting a rich needle by using a lean pilot, I installed jd kit like they suggest, I am at 3rd clip tried the 32.5 seemed better and now will try the 27.5 tomorrow at capital forest poker run, will advise.
Yes I know but remember, we are talking about different circuits. The air screw and idel stop for idle, the pilot which is at the bottom of the carbs range, the needle for mid and the main for top to open. I dont know how much of my thread you have read (I know its long) but you will see the progression of my selections. I was on the track last friday, about 90 degrees and 80% RH. The bke ran great except for the very bottom end which I fixed with a turn of the air screw. I wasnt riding very fast, so when I pulled the plug, it looked like I expected,a little dark. That evening I went out to the river and opened her up for about two miles, did the plug chop and she was coffee brown with a little cream.

Last edited by VAL; 05-10-2009 at 02:19 PM.
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Old 05-10-2009, 07:34 PM
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hey as long as you are happy is what I say, of ocourse now that I have ordered a new keihin I took my bike out today with the jd kit in the mikuni 2nd clip with a 27.5 pilot and 400 main, oh man!! talk about a beast almost flipped it 3 times it would seem that I have found the magic scenerio with this mikuni, dilema now is do i send back the keihin or put it in?
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Old 05-11-2009, 12:22 AM
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Originally Posted by 1motoman69 View Post
hey as long as you are happy is what I say, of ocourse now that I have ordered a new keihin I took my bike out today with the jd kit in the mikuni 2nd clip with a 27.5 pilot and 400 main, oh man!! talk about a beast almost flipped it 3 times it would seem that I have found the magic scenerio with this mikuni, dilema now is do i send back the keihin or put it in?
1motoman69 which needle do you have in clip #2, red or blue? What is your elevation and temps?? I wonder why Honda switched to the Mikuni in 01' instead of staying with the Keihin??? It seems by then most of the other 250's were using the Keihin and continued to do so.
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Old 05-11-2009, 08:24 PM
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I have red needle 2nd down form top, sea level temps now 65 near seattle wa, i have been playing with this mikuni for a while now was running a 25 pilot like val, but that scares me, wnet with the 27.5 which gives me piece of mind I guess stock was 35 which is way too rich i also have fmf gnarley pipe and vforce3 reeds bike is insane and now have alot more bottom
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Old 05-12-2009, 08:17 AM
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Guys, everyone keeps saying that they are scared to run leaner.

You have to remember that when the factory puts these together, they know that everything is tight and needs to break in. They, of course donít want to have a bunch of complaints from new owners who have burned up a brand new motor on the first day out. Stock jetting is great for break in, you are guaranteed a ton of top and bottom end lubrication. But after the bike has a few hours on it and everything is within working tolerances, then stock jetting is generally way too rich.

It also has allot to do with your riding style as well. If you are a desert racer with a ton of long range, wide open, sandy runs, then by all means jet her rich enough to keep her happy. If you are like me who only goes out to the track, with this bike, and who isnít Ricky Carmichael, pinned the entire way, then jet her accordingly.

I have gone all the way down to a 20 pilot. It took just one ride out and after warming up the bike, going full throttle for about 10 seconds and then letting off the throttle, the bike surged, telling me I was too lean on the bottom end. Went back to the 25 and everything was fine.

Use the jet numbers as reference, use the plug color as verification.
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Old 05-12-2009, 07:54 PM
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Val I agree with your assesment of bikes generally being rich from the factory, yet I do understand the concerns of others about being too lean. I'm probably not as experienced as you, but have done some jetting over the years and must say that I've never had to go this many steps leaner (@ 5 sizes) with a pilot jet. Have you? 2 sizes generally gets the job done, even at my higher altitudes. Also I'm not too comfortable with the whole plug reading thing, especially areas other than the mainjet and wide open throttle, seems to be different schools of thought on the subject. I have at times gone lean enough to feel the decel surge you described, and once felt an off idle bog that I thought was also a lean indication. Do you know of some other indicators of a lean condition in regards to the pilot jet?
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Old 05-13-2009, 08:29 AM
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Quote:
Originally Posted by YZhallsme View Post
Val I agree with your assesment of bikes generally being rich from the factory, yet I do understand the concerns of others about being too lean. I'm probably not as experienced as you, but have done some jetting over the years and must say that I've never had to go this many steps leaner (@ 5 sizes) with a pilot jet. Have you? 2 sizes generally gets the job done, even at my higher altitudes. Also I'm not too comfortable with the whole plug reading thing, especially areas other than the mainjet and wide open throttle, seems to be different schools of thought on the subject. I have at times gone lean enough to feel the decel surge you described, and once felt an off idle bog that I thought was also a lean indication. Do you know of some other indicators of a lean condition in regards to the pilot jet?
If you go too lean on the pilot, and I mean tooooooo lean, the bike will race when you start it. Have you ever run a two stroke and turn off the fuel? You know that revving it does just before it dies.

I may be over simplifying things but, IMO, the pilot will not get you into trouble with seizing the engine. The pilot will tell you if its too lean, by surging and if its too rich by blubbering and not idleing. The one that is the killer is the main and to some extent the needle. When you are going full bore, the inertia of the engine will mask some lean tendencies, so thatís why I am a plug reader after a high speed run. I have never seen a bike seize at low speeds. It has, in my experience, been after a high speed (engine speed) run like you would experience going through a sandy wash or crossing a dry lake, or that long straight at the track.



Oh and I am not that experienced with the jetting issues. If you read my post on cutting the throttle slide01 CR250 cutting throttle slide you will see I am new to the two strokes and have learned through this, my first smoker. In all my years of riding (41), I have never had a bike that was this much of a challenge to jet properly. But on the other hand, I have never owned a bike that was this snappy.
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Old 05-15-2009, 11:42 AM
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If you go too lean on the pilot, and I mean tooooooo lean, the bike will race when you start it. Have you ever run a two stroke and turn off the fuel? You know that revving it does just before it dies.
As odd as it seems, I experienced my bike reving up on cold starts with the choke on, when the pilot was what I considered to be way too rich (32.5). Now after working my way down to and settling on a 22.5 pilot, I noticed it no longer rev's up on cold starts with the choke.

Quote:
I may be over simplifying things but, IMO, the pilot will not get you into trouble with seizing the engine. The pilot will tell you if its too lean, by surging and if its too rich by blubbering and not idleing. The one that is the killer is the main and to some extent the needle. When you are going full bore, the inertia of the engine will mask some lean tendencies, so thatís why I am a plug reader after a high speed run. I have never seen a bike seize at low speeds. It has, in my experience, been after a high speed (engine speed) run like you would experience going through a sandy wash or crossing a dry lake, or that long straight at the track.



Oh and I am not that experienced with the jetting issues. If you read my post on cutting the throttle slide01 CR250 cutting throttle slide you will see I am new to the two strokes and have learned through this, my first smoker. In all my years of riding (41), I have never had a bike that was this much of a challenge to jet properly. But on the other hand, I have never owned a bike that was this snappy.
I'm the opposite I guess as I've been riding 2 strokes most of my time. Unfortunately I didn't pay much attention to tunning them for the majority of that time.
I wonder if plug reading varies between 2 stroke and 4 stroke??
Here's a link to a 2 stroke plug reading thread with pic's, I think most would say these plugs look way lean but supposedly they aren't. [Only registered and activated users can see links. ]

And here's a link to what is said to be a better way to check your 2 stroke jetting, in all throttle ranges. [Only registered and activated users can see links. ]
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