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02 Honda Crf450r jetting recommendation.

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My crf feels like it’s missing on acceleration and I think it’s a possible lean condition. Stock jets are in and wondering if you guys have any recommendations on sizes you run? I’m a sea level. Turned the screw out about 2 two turns and still an issue. Starts real good but same problem on accel. Any thoughts thanks.

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Your fuel mixture screw effects idle, not open throttle. What makes you suspect you are lean? What does the plug look like?

Any idea what type needle you have and what clip position you are on?

Is this a recent development or a new to you bike?

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Your fuel mixture screw effects idle, not open throttle. What makes you suspect you are lean? What does the plug look like?
Any idea what type needle you have and what clip position you are on?
Is this a recent development or a new to you bike?

The stock jets are installed cause I did rebuild the carb with kit. Looked up jet sizes #175 main and #45 pilot and that’s what’s in the carb. In repair manual it says if you have a hesitation in acceleration it might be cause of lean conditions. It does feel like it’s a lack of enough fuel on accel. I will look at what clip position it’s in as I just put it in the same position as it was in the old needle. I bought the bike without running and rebuilt carb/adjusted valves/ and now starts and runs but when test drove it accells but feels like it cuts out and then picks up quickly and repeats the faster you go.

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The stock jets are installed cause I did rebuild the carb with kit. Looked up jet sizes #175 main and #45 pilot and that’s what’s in the carb. In repair manual it says if you have a hesitation in acceleration it might be cause of lean conditions. It does feel like it’s a lack of enough fuel on accel. I will look at what clip position it’s in as I just put it in the same position as it was in the old needle. I bought the bike without running and rebuilt carb/adjusted valves/ and now starts and runs but when test drove it accells but feels like it cuts out and then picks up quickly and repeats the faster you go.

Forget to respond to plug. What plug are you referring too? I did install a mixture lean/rich needle that I can adjust easily. Now understanding it’s for idle makes sense.

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He means spark plug.

New plug. Ran for about 10 min and pulled slightly white but I would say lean by not much.

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The condition of the spark plug can often give you some insight as to running condition. Take a whiff of the exhaust as well to get an idea of rich/lean.

When you say it is missing, what does it sound like? Popping out of the exhaust at any point or bogging on acceleration? Any popping on deceleration? Considering taking a short video and posting it here.

Are you sure you cleaned the carb completely including all fuel passages?

How far into the carb did you go? Did you remove the slide and vacuum plate?

Is your float bowl set properly?

After market exhaust?

Any chance the intake boots around the carb are loose, specifically the one after the carb and before the head? How about the hot start plunger? Ensure it is not leaking air. A good technique for finding an air leak is to introduce a little butane or mapp gas around the carb while idling and see if the idle increases. Excessive air will lean out the mixture.

 

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Edited by Augoose
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On 2/11/2019 at 2:51 AM, GD10 said:

 

My crf feels like it’s missing on acceleration and I think it’s a possible lean condition. Stock jets are in and wondering if you guys have any recommendations on sizes you run? I’m a sea level. Turned the screw out about 2 two turns and still an issue. Starts real good but same problem on accel. Any thoughts thanks.

 

i dont think 175 is stock jet just fyi (pretty sure 165 is) also check your plug gap it should be .039-.043

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i dont think 175 is stock jet just fyi (pretty sure 165 is) also check your plug gap it should be .039-.043

I’m going by the Rocky Mountain ATV. Stock sizing and also the 175 jet removed. #45 pilot and went with stock spark plug but haven’t checked gap. Is there any other spark plug heat ranges and how they effect the performance. Any info? I’m installing a #48 pilot to help on the lean.

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2 minutes ago, GD10 said:


I’m going by the Rocky Mountain ATV. Stock sizing and also the 175 jet removed. #45 pilot and went with stock spark plug but haven’t checked gap. Is there any other spark plug heat ranges and how they effect the performance. Any info? I’m installing a #48 pilot to help on the lean.

i run an irridium plug theyre slightly pricey i dont remeber the part number but i run a heat code 8 the heatcode will be the number in the part number like for instance ngk br8es (just a random part number not what you should use) actually i think thats what i run in my kx250 thats why it came right to mind lol

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i run an irridium plug theyre slightly pricey i dont remeber the part number but i run a heat code 8 the heatcode will be the number in the part number like for instance ngk br8es (just a random part number not what you should use) actually i think thats what i run in my kx250 thats why it came right to mind lol

Ya I’m running NGK Laser Iridium IFR8H11

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6 minutes ago, GD10 said:


Ya I’m running NGK Laser Iridium IFR8H11

when you nail the throttle does it hesitate? or does it just have no power? (while ridding)

Edited by Adin 244

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On 2/11/2019 at 8:05 AM, GD10 said:


The stock jets are installed cause I did rebuild the carb with kit. Looked up jet sizes #175 main and #45 pilot and that’s what’s in the carb. In repair manual it says if you have a hesitation in acceleration it might be cause of lean conditions. It does feel like it’s a lack of enough fuel on accel. I will look at what clip position it’s in as I just put it in the same position as it was in the old needle. I bought the bike without running and rebuilt carb/adjusted valves/ and now starts and runs but when test drove it accells but feels like it cuts out and then picks up quickly and repeats the faster you go.

did you put an upgraded needle in or a stock replacement??

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when you nail the throttle does it hesitate? or does it just have no power? (while ridding)
[/
Its hesitating on throttle. Pulled plug and slightly on whiteish side. What are you turning you air/mix screw at?

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2 minutes ago, GD10 said:
15 minutes ago, Adin 244 said:
when you nail the throttle does it hesitate? or does it just have no power? (while ridding)
[/
Its hesitating on throttle. Pulled plug and slightly on whiteish side. What are you turning you air/mix screw at?

 right now mine is maxed out at 2.5 turns but that doesnt matter my motor is built not to mention im still in the tuning phase

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did you put an upgraded needle in or a stock replacement??

Stock replacement.

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Stock replacement.

I do have to play with tune since it’s a new bike to me. Im going to look at her more tomorrow and see if I can run through some diagnostic.

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2 minutes ago, GD10 said:


I do have to play with tune since it’s a new bike to me. Im going to look at her more tomorrow and see if I can run through some diagnostic.

true im waiting for jets in the mail to tune mine. but yeah im not 100% sure but i feel like you should try a 170 main also keep in mind the clip positioning on your needle might have been wrong when you bought it so if you just put it how it was then that could also be your problem. if you move it down 1 notch it might help that will let more fuel in

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