Hot Start increases RPM...


9 replies to this topic
  • b2yz

Posted March 25, 2008 - 05:55 PM

#1

'02 YZ450F I just bought used in great shape. But it seems rather gutless (comparted to my YZ250) and seems to run rich. Have checked and cleaned carb - all stock jetting and fuel screw at 1 1/2

When I pull in the Hot start, it increases RPM - even at idle. What's up with that.

Where's all the fuel coming from.

Thx,
B2

  • grayracer513

Posted March 25, 2008 - 06:15 PM

#2

To some extent, that's what a hot start does.

But, did you check the float level?

Does the choke close?

What does the air filter look like?

Why do you say it runs rich?

  • rmzRacer293

Posted March 25, 2008 - 07:09 PM

#3

not sure on all the technical stuff but my 06' does that at idle too. dont worry about, its no big deal all thumpers do it.

  • Wiz636

Posted March 25, 2008 - 08:38 PM

#4

'02 450? :prof:

  • harwood39

Posted March 25, 2008 - 08:50 PM

#5

hmmm, didnt know they made a 450 in 02 unless its a honda.... 426 maybe??

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  • grayracer513

Posted March 25, 2008 - 09:18 PM

#6

Didn't catch that earlier. It's either an '02 426, or it's not an '02.

  • b2yz

Posted March 26, 2008 - 01:14 PM

#7

To some extent, that's what a hot start does.

But, did you check the float level?

Does the choke close?

What does the air filter look like?

Why do you say it runs rich?

Sorry - '03 450 (my YZ250 is an '02)

Float level is correct and no leaking, choke is closed and it looks clean on inspection. Filter looks so, so, but just got a new one anyway.

After riding pretty hard, pipe is still way sooty - which is why I figure rich - and it breaks up over 6 grand. Maybe it's actually a lean problem, so.....

QUESTION: It's 40 degrees here (CT). Is stock jetting just too lean for this temp

Thx,
B2

  • biznet1

Posted March 26, 2008 - 04:54 PM

#8

Is stock jetting just too lean for this temp

Thx,
B2


Most likely with the fuel screw at 1 1/2.

  • Thumpy79

Posted March 27, 2008 - 10:44 AM

#9

I believe that the hot start allows more air in to lean the fuel mixture out so it will fire easier.

  • thumpyz

Posted March 27, 2008 - 04:16 PM

#10

Put 3mm of slack in your hot start cable if you dont have any free paly. It might be getting actuated when you turn your bars just enough to lean things out, and if the cable is not in good shape, it might be hanging open a little bit. hope this helps.:prof:





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