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Kirtwell needs help from TTalk

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My CRF450 is missing in the mid to 3/4 throttle position...It idles great and if you crack the throttle open it pulls hard.

This all started suddenly last weekend...so I thought it would be something as simple as a dirty carb..or jetting now that the temperature is now in the 100's....I have the new SS valves in this bike and they were in perfect specs...I checked them while I had the carb off...

I looked in my CRF manual and it recommended the following

168/42/4th clip position..

I was running

170/42/4th clip

So I did a thorough cleaning of the carb and changed the 170 with a 168.

The bike ran great Saturday and I thought everything was great but Sunday morning I fired up the bike and on the way to the practice entrance...I notice the missing came back.....I raced my first race and it was horrible due to the missing at a consistant half throttle......I would hit the face of a jump and it would try to die....so it got too dangerous to ride.

At the track a fellow racer recommended I check for metal shavings on the alternator magnetic sensor....and there was alot of shavings on it..but after doing a good cleaning ..I've still got the problem...

Can you guys give me some ideas to what this could be?

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are you running a aftermarket flywheel, and or any other ignition componuts ?

this stuff will give you fitts like this !

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The only thing aftermarket on this bike is the air filter...and like I said earlier..I did put the SS valves in the head.

I'm hoping someone reads this and say...OHHH...I had the same problem...go check this: :eek:

Keep the ideas coming and I'll check whatever you guys think it could be. :applause:

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I don't have the quick answer you're looking for but I recommend finding a buddy with a 450 that will let you swap parts back and forth. I had a similar problem with a 426 that I finally found by swapping carbs. And I never did find the problem with the carb., it was clean and looked like it should work good but didn't. I replaced it with a used carb.

Good Luck

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Good idea...I have several buddies that have CRF's but most of them are 04's..I'll check and see what parts interchange and try that :applause:

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Even if their bikes are 04s, the carbs will interchange. The jetting will be slightly different, but they'll work. It will at least point you in the right direction.

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I had a similar problem that turned into a no start. Turned out to be the alt not putting out enough voltage. It comes with a pluse generator attached.

I have a 02- it was suppost to put out 50v kicking I was only getting 19-25. This was at the point of no start. Anyways this made the spark plug unable to fire. Comes with a new flywheel :eek: I already had a stock one and a trailtech one, but I think the later ones come seperatly.

You will need a graphing multimeter or something like it to catch the reading.

good luck :applause:

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Kirtwell,

Look for something simple. If the problem started after your rebuild it is probably something you did (or didn't) do. First thing I would look at is the coil, plug wire, and plug cap. It could be as simple as the plug cap not being secure. Trace all the grounds and make sure there is no corrosion also.

Get that thing running right or you will have to ride Howard's KTM at the GMBIV. :applause:

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OK it's fixed.....

After all the research I did on this bike....Ok...all it was ......was jetting...

I was running the following jetting 170/42/4th clip/ 1 1/2 on the air screw.

I played with every combination with the main all the way down to 162 and up to 178....and from 38 to 45 on the pilot...with no change what-so-ever...

so I was getting frustrated to say the least.

Then after talking with some people here on TTalk..I started moving the clip up on the needle....I moved it up (leaner) to the 5th groove..and not any noticable differnce...moved it up one more....just a tad difference...and then all the way up to the 7th clip.....BINGO! ALL THE HESITATION WAS GONE :applause::eek:🙂

AND THE BIKE RAN LIKE A SCALDED APE... 😛😛😛

I decided to NOW play with the main jet....and the 168 gave the bike a pull that almost yanked my arms out of socket..I swear 😛

So I ended up with the following jetting:

168 Main

42 pilot

7th clip (i'm ordering the next bigger needle...JIC)

1 1/4 turns on the fuel screw.

I'm so happy and now I can ride with confindence again...

I thought I'd let you guys know what I found in case you run into the same problem...

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Kirtwell,

Get that thing running right or you will have to ride Howard's KTM at the GMBIV. 😛

LOL Dave...how many laps would it go around the track without blowing 😛😛😛

It's like musical chairs....Just waiting for the music to stop and find all the chairs taken :applause::eek:🙂

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