Jetting 2005 - Can we do this again?

Guys, I feel like i've done all the research a noob like me can do and I still have a lot of questions. I'm not technically retarded, but some of you might think so after we go through all of this.

 

I purchased a used 2005 CRF450R. This is my 2nd bike (first is/was a 97 CR250).

 

First, the good stuff:

The guy I bought it from had the suspension tuned, skid plate, bark busters, desert tank, exhaust, etc etc. His plan was to race the Baja 500, but he never did it, so the bike sat for several years. First thing I did was tear it down and check everything I could figure out how to check. Valves are in spec, everything else looks great. Cleaned the carb and it fires up nicely, runs well enough, and feels like it has a lot of power. But then again, I don't have another 450 to compare it to, so maybe it's running super weak - I couldn't tell you.

 

Now the Bad(?) stuff:

  • Stock jetting on the 450 is 165-Main 42-Pilot (as you all know) The jetting on my bike is 160-Main and 48-Pilot  (There's another jet in there that is labeled 72) I don't know what position the needle is in.
  •  
  • It was set up and ridden in California before I had it. I'm in Utah at 4500', temps vary a lot, but 50-80 F is probably average riding temps
  •  
  • This thing backfires like the 4th of July on deceleration.
  •  
  • The header heats up to glowing at night within 45 seconds of starting the bike.
  •  
  • The exhaust is aftermarket, and I don't know a thing about it.

All of this would lead me to believe that the bike is running super lean but I pulled the plug and it's black and sooty, not white at all.

 

Anyone want to pitch in and help me out with what is possibly wrong with this thing? Like I said, it feels like it has a lot of power, but I wouldn't really know any different.

 

Thanks in advance.

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1. remove the pilot, clear the passage above the pilot with fishing line and spray brake cleaner

    (inspect the carb for white or green corrosion, and replace any brass part that is black or green with corrosion) 

2. install BRAND NEW pilot (more on size later). 45 should be fine.

3. install new fuel screw oring ( your best option is a new R&D remote fuel screw)

4. install a new slide plate seal

5. set the fuel screw at one turn out.

6. get the bike running, warmed up (HOT radiators)

7. now set the idle very low, so it still runs.

8. now adjust your fuel screw for max idle

9. if you are under 1 turn out, you need a bigger pilot. Over 2, you need a smaller. That is the only way to determine pilot size correctly.

10. you might have to lower the idle again with the idle screw and start over, if the fuel screw adjustment makes the idle too high.

11. once you get the idle correct USING THE FUEL SCREW you should not touch the idle screw again, accept for cold starts, where a 1/2 turn in may assist in starting. You drop it back down after it's warmed up.

 

Now you should have a bike that runs well and idles.

 

If you still have lean (back fire, glowing header) issues, you need to visit the hot start system (cable, nut, plunger) for problems/leaks/dryness, as well as the header crush washer, junction, and carb boots, all for air leaks.

 

Once you get all you lean issues sorted out, you can re-visit the adjusting of the fuel screw, main jetting, needle, etc.

 

170

45

NCVS NEEDLE 3RD CLIP

NEW PLUG

STOCK POWER JET

STOCK AIR JET

STOCK NEEDLE JET

Edited by Krannie

Awesome description. I may have some questions as I do this.

 

3. -Fuel Screw = Pilot Screw?

 

3. -This the one you're referring to? http://www.rockymountainatvmc.com/p/43/53/213/1151/3604/-/184988/R-%2526-D-Racing-Flex-Jet-%2528Remote-Fuel-Screw%2529#!addToWishList

 

7./8. - So I adjust the idle down as low as it will go with the bike still running using the standard idle adjuster, then I use the fuel screw to turn the idle back up? What is "max idle"?

 

I've checked the carb boots for leaks (using starting fluid). I might need a new crush washer in the header. Any way to check that, or do you just install one every time the exhaust has been removed?

Awesome description. I may have some questions as I do this.

 

3. -Fuel Screw = Pilot Screw?  YES

 

3. -This the one you're referring to? http://www.rockymoun...#!addToWishList - YES

 

7./8. - So I adjust the idle down as low as it will go with the bike still running using the standard idle adjuster, then I use the fuel screw to turn the idle back up? What is "max idle"? RAISE THE IDLE AS HIGE AS IT WILL GO USING THE FUEL SCREW. IF IT GOES TO HIGH, DROP IT ALL THE WAY DOWN WITH THE IDLE SCREW AND REPEAT.

 

I've checked the carb boots for leaks (using starting fluid). I might need a new crush washer in the header. Any way to check that, or do you just install one every time the exhaust has been removed?

NO, JUST LOOK AT IT FOR 'NULL' SPOTS.

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