yz426f only wants to start a little after top end rebuild


24 replies to this topic
  • shibby-rider

Posted December 11, 2010 - 06:47 PM

#1

Hey guys, I am stumped! I just rebuilt the top end in my bike stock everything piston/rings and I had the 00 valves put in my bike its a 01. Everything went back together smooth; but now when I go to kick her over she only wants to kinda start so i pull my hotstart and it starts for about 2 secs and shuts off. I figured it was jetting so, I went from a 45 pilot to a 40 and it kinda helped now I can get a blurp out of it with the choke on, where as I couldnt before. I am at 4500ft alt in arizona, if that helps any. Only things i have on it that are after market is a powerbomb header and a sparkarrestor end cap. I got it back together last weekend and have been trying to get her started for almost a week :thumbsup:. Any help would be awesome, Thank you in advance!
Oh ya the carb settings i ran before i did the top end was a 165 main 45 pilot and my stock needle is on the 4th clip, I am 2 turns out on my fuel screw.

  • gscx

Posted December 11, 2010 - 06:50 PM

#2

It sounds like your cam timing is off

  • shibby-rider

Posted December 11, 2010 - 06:52 PM

#3

bleh, any advice on how to check that? That was in the back of my head but I didnt think it would start at all if that was the case

  • gscx

Posted December 11, 2010 - 07:09 PM

#4

Did you rebuild the bike yourself? And it will start but be like what you are describing. How did you do the top end yourself but not know how to do the cam timing?

  • shibby-rider

Posted December 11, 2010 - 07:16 PM

#5

I set the timing and when i put the valve cover back on my lobes where facing out e and i on the cam sprockets where in the correct place and the bottom mark |-| was set in the middle

  • shibby-rider

Posted December 11, 2010 - 07:17 PM

#6

yes i put the piston in and stuff, had the head work and valves done by AS racing

  • gscx

Posted December 11, 2010 - 07:29 PM

#7

On the cam sprockets there are three dots. The middle one is supposed to be on top and the other two are supposed to be even with the wall on the head. You will see what i am taking about. And you are not supposed to use the H, you need to use the I on the flywheel. You need a manual

  • shibby-rider

Posted December 11, 2010 - 07:59 PM

#8

well i moved it to the H mark darn it I knew it, I have a manual its for a 00 though so i thought it was different. So to reset it I'll move my flywheel to the I mark reset the cams like you said and try her again. Why would my hotstart have an effect on it starting different if it was timing though, thank you for ur help btw.

  • gscx

Posted December 11, 2010 - 08:03 PM

#9

The bikes are almost identical besides the valves. Im not sure about the hot start though. You didnt mess with the carb any did you? Like take it apart or anything?

  • shibby-rider

Posted December 11, 2010 - 08:23 PM

#10

no sir just changed the pilot jet, and cleaned the main ones. I just noticed why kicking it just now im able to kick sometimes all the way threw without the compression lever i think my timings off......

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  • shibby-rider

Posted December 12, 2010 - 02:06 PM

#11

well i reset the timing and it still only wants to kinda start with the hot start out, almost certain its a fuel problem now. I did notice when i had the carb off, when i would turn the throttle it wasnt spraying the fuel threw the slide, like it was when i did the bk mod, would this effect the starting, if that was clogged?

  • shibby-rider

Posted December 12, 2010 - 03:10 PM

#12

any suggestions?

  • shibby-rider

Posted December 12, 2010 - 05:20 PM

#13

Got her guys I think i had something clogged in my carb, I bump started her and cleaned it out, Now I've got a hanging idle, which i can fix. Had a question though, my valves are ticking is that cause they havent seated yet, or maybe cause there stainless steel now? Thanks

  • grayracer513

Posted December 12, 2010 - 05:51 PM

#14

Put the 45 pilot back in and the hanging idle will go away. 40 is too small.

  • shibby-rider

Posted December 13, 2010 - 01:40 PM

#15

Ok. Will do. My valves are clicking is that because they havent been broken in yet? I adjusted them to spec.

  • shimla4

Posted December 14, 2010 - 09:34 AM

#16

Did you shim your valves to the 2001 or 2000 spec's there is a diff between them?

  • slodog

Posted December 14, 2010 - 09:45 AM

#17

Ok. Will do. My valves are clicking is that because they havent been broken in yet? I adjusted them to spec.


I've noticed valve train louder if shimmed on the wider end of the spec. If I shim them tightest, the noise decreases dramatically.:thumbsup:

  • shibby-rider

Posted December 14, 2010 - 03:14 PM

#18

I shimmed it to the 00 specs cause i had them put the 00 valves I wanted the SS ones, its an 01 head though. I tried to aim for about the middle on the adjusting as i wanted some room for when they seat. intake is like a 13 exhaust is like a 22 or 21. Manual said intake 10-15 and exhaust 20-25.

  • slodog

Posted December 14, 2010 - 05:12 PM

#19

YZF's usually widen. Honda's tighten.

  • slodog

Posted December 14, 2010 - 05:13 PM

#20

YZF's usually widen. Honda's tighten.


Actually, YZF's hardly move. Seating after break-in, they usually widen.





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