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why is my bike so hard to start when cold?

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every since i did the headwork/cam/hi-comp piston the bike takes many many kicks to start it when it is cold. and it wont start with the choke on! have to give it at least 4 blips and several hard kicks and when it does start i have to hold the throttle open or reach down and pull the choke. jetting feels fine but may not be perfect! thanks.

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OK that's weird! I was going to post the very same thing. I have an YZF 470 and have head work also, but this past weekend I installed Hot Cams. I'm also running the Edelbrock carb. Before the Hot Cams it started on the first or second kick, hot or cold. Now only when it's cold it a real bear to start. It seems it likes little twist on the throttle to start, after messing with the fuel screw I got it to start a little better when cold but one click leaner or richer and it doesn’t want to idle, very finicky.

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Hey Brucas and Chazlom,

What fuel are you running. If you are running higher compression you will need to run a higher octane 'race' fuel.

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I'm not sure I have this right but I am fairly certain, if it is hard to start cold it is rich, hard to start hot it is lean. Or is it the othere way around? :cry:

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I wonder if the cam profile makes it that way being that it is more agressive. Actually all the mods together probably make it that way. It seems to me that an 50 would start easier than a 450 anyday because of its low compression and smaller piston :cry:

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the race bikes that i have been building here in michigan start the first kick .dave if your enrichener is not working it means to much air is getting by the slide also since you blip the throtle and are manualy feeding it fuel from the pump that indicates the same thing .check and make sure your sealing plate is instaled corectly on the slide also chech to make shure the Quad seal is good when toching the plate through the bore there should be some flex or bounce in the sealing plate if not the seal may be folded up behind it .were using stock needles and pilot jets and use MR9 fuel MXR01 nutec s5 and we also have used premium no lead and they all start fine.i also have heard of this problem with the hot cam and wonder if it has somthing to do with wher the decompresor is located you might try altering the adjustment on your decompresor to see if it makes a difference.Ron

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Thanks Ron,

I'll take a look at it, I didn't pay that much attention to the decomp. while installation, I just remember that it looked similar to OEM.

I triple checked my valve lash and they are spot on, I think it's strange that on the intake side HC prefers the lash on the loose side of manufacture specs, but on the exhaust side they are on the extreme tight side. Either way they are set to HC specs. Plus I only have a "break-in" ride on the cams, maybe they need a little more running time. :cry:

Plus i'm going to recheck the carb settings.

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