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About TheSlicer

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  1. TheSlicer

    2002 YZ426 part throttle stumble

    Zip Ty did all the carb work on mine before I bought the bike. The AP squirter acts like a freakin' fire hose and shoots a stream of fuel half way across my shop when pulling up the slide to remove the needle. The little thing does well even against big bikes on straights!
  2. TheSlicer

    2002 YZ426 part throttle stumble

    Apparently these engines are made out of cheese and I didn't notice when building the engine. Well, that and I guess Yamaha didn't notice either and screwed up writing the service manual. 0.10mm clearance for intake valves does not seem to be a suggested minimum valve clearance at room temperature but instead the point where the valves hang open when it warms up. I tore the engine apart piece by piece measuring everything 10 times and finding nothing so I decided to see what the valve clearances were when the engine was still hot. I could not believe it. I could fit a 0.025mm feeler gauge on the right hand side valve and nothing on the other two meaning they were hanging open! They were all right around 0.08-0.11mm cold. I find it hard to believe everything expanded that much! What the heck is up with that? I set all the intake valves to 0.15-0.16, took it out for a spin and everything felt good but I did not trust it for trail rides. I put some motard wheels on it and took it to the track. Flawless. Started first kick hot or cold and I was quicker on the straights than any of the 450's out there (other than my Aprilia). The jetting was a bit off due to prior troubleshooting but the thing ran perfectly. All the rest of my bikes in my personal collection have intake tolerances in the range of 0.05-0.12mm. The Yamaha tightens that much just when it warms up?! I am starting to see why so many of these bikes have valve issues. Edit: On second thought, at least it looks awesome in motard trim sitting next to my Aprilia.
  3. TheSlicer

    Yamaha YZ125 (2005)


    Love it! Tons of power and feather light. I love throwing it around and doing wheelies everywhere. Suspension is a little rough and the front brake has no feel but I still love it!
  4. TheSlicer

    Yamaha YZ125 2005

    Love it! Tons of power and feather light. I love throwing it around and doing wheelies everywhere. Suspension is a little rough and the front brake has no feel but I still love it!
  5. TheSlicer

    Yamaha YZ426F (2002)


    It's fun when it wants to run. Starts first kick when cold and picks the front end up in every gear.
  6. TheSlicer

    Yamaha YZ426F 2002

    It's fun when it wants to run. Starts first kick when cold and picks the front end up in every gear.
  7. TheSlicer

    2002 YZ426 part throttle stumble

    The jetting was correct for the altitude. It had a 152 main, 42 pilot, 3rd from top needle position and the bike never gets ridden under 8,000ft. I ended up putting the needle all the way down (top clip position) and the bike cleared up a bit but still wasn't right. It does 5th gear power wheelies with the 42 pilot, second needle position, and a 140 main jet but it dies randomly and will not start after riding unless I let it cool down enough to stick my hand on the header without it burning me. I know it should be lean as hell with a 140 main and the needle as far down as it is however it will not run with the jetting that it SHOULD have at this elevation. When the guy behind me on a '03 450 is running a 158 main, 42 pilot, and 3rd clip position without any issues and mine won't even accelerate with that jetting tells me something is wrong. I've tried 3 different spark plugs as well. I rebuilt the engine after the last guy blew it up and it should have run fine. There is virtually NO leak down on this engine, valves and piston rings seal extremely well. Valves are adjusted, cam timing appears to be correct. Yamaha shows the timing mark on the flywheel as a big line but when I look at the flywheel there is no such mark so I had a bit of a laugh at that. I am running out of things to check. I pulled the top end apart again but I have not found anything wrong. Checked the coil and CDI, both fine. I'm going to keep digging through the bike until I find something out of place. It's rather annoying when it runs great but won't start if I shut it off or stall it. At least I still have other more reliable bikes to ride in the mean time.
  8. TheSlicer

    610 Piston Compatability question/ headache

    It is. Thick 3mm ring. I'll take it! I just want to get this thing back together.
  9. TheSlicer

    610 Piston Compatability question/ headache

    All the 610s from 1991-2005 and the 570 are 98.0 x 76.4mm and use the same wrist pin diameter so they would physically fit. I am not sure what the differences are, valve reliefs, dome height, wrist pin height that might cause valve/ head clearance issues. All I know is the part numbers changed between '98 and '99 and it's easier and cheaper to get the newer pistons. I know the later engines have a wider connecting rod, wider crank due to the rod, and different case casting. They look the same at first glance but aren't. I just don't have a piston from a newer (1999+) engine to compare.
  10. To start off with I feel like a total idiot at the moment. Today I broke my very first piston ring in the 16 years I have been building engines and it's one that is impossible to find! What I have is a 1995 WXC 610 and I really just need another set of rings but I cannot find any. Dealership said NO to having any before so I went searching for a piston and a few hours of research in and I have more questions and a bigger headache than when I started. There are 1991-1998 610 pistons, there are 1999-2005 610 pistons, and then there are the 2001-2002 TC and TE570 pistons. I cannot figure out if they are interchangeable or not. The only difference from what I can tell, the electric start models were lower compression? I am confused more than normal. Anyone have some insight on the topic for me? It seems like information for these bikes is a little hard to dig up and parts are even worse. I have already dumped quite a bit of money into this bike and I don't want to give up now that it's just an oil ring away from running again. Even if someone has even a used oil ring kicking around, I'll take it as long as it's not scratched, bent, or cracked. At least my compression ring is new. I'm getting desperate.
  11. TheSlicer

    best looking 426 anyone

    You want nice? I'll show you nice! (just ignore the header dent)
  12. TheSlicer

    Ressurection YZ426F

    The 426 CAN be a really nice bike if you throw enough money at it. I bought mine cheap with a blown engine and I'm still working bugs out of it but from what I can tell it has more than enough power. I want to see what it looks like after you are done!
  13. TheSlicer

    2000 sm610s No spark while cranking

    You're right. It did NOT run initially. The pick-up coil was replaced and wired in according to wire color. The pick-up coil wire colors were the cause of the issue, they were opposite of what they should have been and had no instructions. When common sense was used when installing it, it got wired backwards. It would spark at low rotating speeds at the wrong time with the pick-up coil wired in backwards. Kind of like when an old Yamaha CDI goes bad and blows a hole through your boot if you try to kick start it. Aftermarket parts are not always user friendly.
  14. TheSlicer

    2002 YZ426 part throttle stumble

    Dent is big but not big enough to be a problem. The bike has moments of clarity and will do power wheelies in 4 gears. I've still got a few things to try but it's driving me up a wall.
  15. I've done my research and I am usually REALLY good with diagnosing carb issues but this thing has me baffled. It sucked a valve and that's when I bought the bike and rebuilt it. The engine is fine, cam timing is spot on from what I can tell. The Yamaha manual shows the mark as a big line on the flywheel but apparently the '02 markings are different? The bike starts on the first kick one day and the next I have to push it down a hill to get it to fire off. It idles fine and runs fairly well wide open but anywhere between is horrible. My first guess was clogged jet/passage way but it still runs the same. Took the carb 100% apart, checked every single passage way and cleaned every single part, found nothing. The accelerator pump shoots a nice big stream, brand new NGK spark plug, I am lost. I know people have issues with off-idle bog when they snap the throttle, high RPM breaking up, etc. but I can't find anyone with my same issue. Here's a video of what it's doing. Here's a picture of the bike for those interested in seeing something awesome.