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About 2grimjim

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    If it rolls, floats, flies, or makes loud noises, I probably like it.

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  1. Absolutely not true.... When Susuki first came out with the RMZ 450, they made the mistake of using a manual adjuster from the factory and they required frequent adjustment. I constantly had customers bring those early RMZ's to my shop thinking the top end was bad when all they needed was the cam chain adjusted. They needed adjusting about every 10 hours. Long before the top end ever needed serviced.
  2. If the OEM design has a history of reliability, leave it alone. If the is a specific machine that had a history of failures, but the manufacturer made an update (DRZ400), then switch to the improved OEM design. The only reason you should ditch a perfectly functioning stock chain tensioner is if you are running a non-stock valvetrain (stiff springs, big valves, aggressive cams) and competing in some type of racing where engine rpm changes are violent, like drag racing, flat track, etc. These are situations where there are loads on the cam chain that are well outside what the factory ever intended the stock chain tensioner to handle.
  3. You are going to need at least 100 watts of electrical power to get anywhere close to what you need to power an EFI system. That's going to require a flywheel/rotor considerably larger than whats on your YZ250. There's just not going to be enough magnetic field strength, or room for stater coils. Injector sizing is going to be based on fuel mass flow. Injectors are usually rated in how many pounds or kilograms of fuel they will pass per hour at a specific pressure rating. The fuel flow rate for the injector is based on the maximum hp of the engine. Another consideration is the injector 'slope'. This how linear the flow rate is when the injector is opened for a very short period to open 100% of the time. If the fuel delivery at idle requires a very short opening time, the injector will 'peg out' before full horesepower/rpm can be reached. This is why some fuel injection applications use dual injectors. for each cylinder (Ducati's come to mind).
  4. 2grimjim

    Fork/Axle Lug Repair

    Find a competent welder and have him/her weld it. Take a small grinder or Dremmel tool and reshape, re-drill, and thread. You can probably have this welded for $20 or less. I've done this repair several times on different bikes.
  5. 2grimjim

    Top End/Bottom End Fitment

    Almost everything on a YZ/WR250F engine will interchange from 2001 to 2013. But there are certain combinations of parts you will need to make things work. All heads, cylinders, cases, transmissions, clutches, cams, and side covers will swap.... BUT you can't do some things like put a '03+ WR crank in ANY YZ cases. Or put a YZ crank in a '03+ WR. The three biggest distinctions to make are: is it an electric start bike?; is it from a steel frame or an aluminum frame bike?; is it from a 2010-2013 YZ? The '03-'13 WR cases are electric start and use a different crank, stator, and flywheel. The cases were changed slightly on all WR/YZ in 2007 by adding a sight glass for the oil and making the sump deeper. The cases for steel frame bikes will fit in aluminum frames, but the cases for the aluminum frame bikes may have some clearance issues in the steel frame. And you may have issues with oil lines. All heads will interchange from '01 to '09. The two differences are in '07 the combustion chamber was redesigned, and the intake manifold bolts to the head. The '10-'13 heads will fit earlier bikes but the head stay is in a different location. In 2003, the crankshaft taper was changed on the YZ's. An '03+ crank will work in a '01-'02 if you use the '03+ flywheel. All transmission parts, clutch, cams, pistons, rods, oil pumps, clutch covers, and water pumps swap from 2001-2013.
  6. 2grimjim

    yz250f 2016 hot cam stage 2 ?

    Where do you want more power? Low RPM? Mid RPM? High RPM? Making cam swaps is going to add power in a specific RPM range. The Hotcams 4272-2IN intake cam should be used with the 4273-2E exhaust cam. The intake has a lobe center of 111 degrees. This is going to move the torque up in the RPM range, but sacrifice some low end torque. If you are looking for an across the entire RPM range increase, try going with a big bore kit.
  7. 2grimjim

    2016 YZ250F Ecu maps

    Tuning on the new FI bikes can be really subjective. Just start playing with the timing settings to see what effect it has on how the bike runs. The Yamaha tuner won't let you change things enough to get you in real trouble with reliability. Adding timing will increase torque and throttle response. Removing timing will soften power and make the engine more docile. Making changes to the fuel setting are not as dramatic but can be necessary if you do things like change the exhaust or cams, or decide to use race gas.
  8. 2grimjim

    Advice on WR250F PLEASE!

    This is why I don't use KBB and neither do any car dealerships in the country. An asking price has no relation to whatsoever to what it actually sells for.
  9. 2grimjim

    YZ250FX running hot?

    Overheating? Start with the simple stuff first! Are the radiator fins packed full of dried mud? Did you try shining a flashlight through the radiators to see if they are clean? You have no idea how many ATV's, dirt bikes, and UTV's I've had to work on where the customer complained of overheating and they had dirty radiators.
  10. 2grimjim

    2007 Yamaha WR250

    If you buy it, replace the manifold between the carb and head. These things split like clockwork after about 5 years.
  11. 2grimjim

    Bob's 2002 YZ250F build

    Look into picking up a newer front end (forks / triple clamps) on eBay. In 2004, Yamaha went to 48mm fork tubes, but these were still the still the old style open chamber forks. Stay away from the 2005 YZ forks. They are the first version of the dual chamber forks and they have issues. The best forks are 2006 and newer. Triple clamps vary slightly between YZ and WR, and there are two different length steering stems. The 125 and 250F's used a stem that's 10mm shorter than the 250 2T and 450F's.
  12. 2grimjim

    Bob's 2002 YZ250F build

    Yamaha changed the came chain tensioner in 2003. The Yamaha part # for the 2003+ tensioner is 5TA-12210-10-00. It's $60 on RMATV.
  13. 2grimjim

    2007+ rear fender on 2002 WR250F

    No. These are different fenders.
  14. 2grimjim

    Frame Swap?

    Is this a 2 stroke or 4 stroke? A 2002 250 4 stroke will fit a YZ250F (4 stroke) from 2001 to 2005, or a WR250F (4 stroke) from2001 to 2006. A 2002 250 2 stroke will fit a YZ250 from 1999 to 2019.
  15. 2grimjim

    Advice on WR250F PLEASE!

    Go to NADA website and look up the value on the bike. KBB stinks (there data is unreliable). It's still a 13 year old bike, regardless of condition. Take what you find on NADA and some copies of ads from Craigslist, eBay, etc. and show the seller if you try to negotiate a deal.