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About drewnabobber

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    TT Bronze Member

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  • Location
    British Columbia
  • Interests
    Bikes and riding bikes.

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  1. drewnabobber

    2019 Beta Suspension options

    GNCC the terrain is easier to ride, doesn't mean it's easier to ride fast. One thing that thumpertalk has taught me is that one person's woods riding is another person's hard enduro and another person's GNCC. Same thing with 'singletrack', vastly different meanings depending on who and where you are talking about. So really it is kind of meaningless, but in very general terms a GNCC setup is stiffer than recreational 'woods' riding as its designed to handle jumps and g-outs short of racing motocross.
  2. drewnabobber


    I have no idea about street riding, but I did build a 250FX sumo race bike a couple of years ago, on a budget. For wheels, you can get what you need from Warp9, they are good quality and value. Definitely get the 16.5 front, you can't get the very newest tires in 17 size anymore, and in Europe Michelin is actually moving to a 16 inch rim. It is really tight to get the 5 inch wide rear on the 250, but you can make it work by carefully offsetting rim by slacking and tightening the spokes. Honestly I would rather run a 4.5 rim as the fat tire isn't needed by a 250, the 4.25 rim from warp9 is just too small IMO and messes up the tire profile; all race tires are a 160 rear. You can spend a lot on brakes, but the best value is the caliper and master from an Aprilia SXV. You can get an adapter from Purte1 to mount the caliper, but be careful that everything lines up, on mine I needed to get an additional 3mm removed from the mounting face, likely you can find a different caliper that will just bolt up. Other than that, you will want axle and handlebar sliders, plus a chain block to keep the chain away from the tire. Get what you need from toxic moto racing. If racing you will need a catch can for the radiator. I just use a "go kart catch can" from ebay. FX recirculates the crankcase breather to the airbox and back, so no need for an oil catch can, and FI means no carb overflow to worry about. Suspension I just run stock because I switch the bike between trail riding and sumo, and you probably can't find two more different sets of requirements for suspension. I turn the clickers in at the kart track and turn them out on the trail. It does amaze me just how well the FX copes with such different setups, it's definitely the most versatile bike I've ever had. A good thread from a friend of mine on his WR250F build, which is pretty much the same bike and I just copied him: https://www.supermotojunkie.com/showthread.php?169178-2015-WR250F-Build
  3. drewnabobber

    Beta EFI Two Stroke Patent

    I'm not sure the point of linking the 1300cc boat engine. It is difficult to fit the high pressure pump and associated hardware into a small-bore 200 lb motorcycle; KTM spent years trying and gave up. It is much easier to fit things into a 600 lb jetski.
  4. drewnabobber

    Beta EFI Two Stroke Patent

    It helps emissions by reducing the amount of oil that the engine is burning. Petrol is a really good solvent, so having gas go through your crankcase does a good job cleaning oil from your bearings and piston, so a greater oil:fuel ratio is needed with premix (or even just intake oil injection). By injecting fuel in the transfer port they can use much smaller amounts of oil (100:1 or less) at the intake since the film is much more persistent. Also, just generally better control of the fuel mixture will lower emissions as well. Still not as clean as 4T since, as you note, there is still unburnt fuel going out the exhaust port.
  5. drewnabobber

    Beta EFI Two Stroke Patent

    15 HP e-tec motor is 578cc. Very different power to weight ratio from a 250 or 125cc dirt bike.
  6. drewnabobber

    Supermoto front brake 2019 YZ450FX

    Caliper adapter matched to a KTM/Aprilia FTE or Brembo caliper is most cost effective. Aprilia SXV master cylinder is also good. Motomaster brake calipers and masters work well also. http://www.purte1.com/index.php/en/store/product/view/931/414
  7. drewnabobber

    Top end rebuild

    Now is probably a good time to check the valves... If it were my bike (woods riding) I'd have changed the piston and timing chain at 100 hours. Depends how you ride. Lots of people push it longer, some shorter. On my RMZ (racing) I change the piston at 12 hours. It's fine to ignore maintenance right up until it isn't. At a minimum, you really need to stay on top of the valve checks so that you can keep track of any wear.
  8. drewnabobber

    Thinking of adding a wr250f or yz250fx to the stable

    FX works better in open terrain than a 300 IMO, a lot more planted and the suspension likes a bit of speed and momentum. Works fine in knarly stuff too. But at no point is a 250f ever going to feel more 'grunty' than a 300 2t. It needs revs and decent clutch work to be smooth, main advantage over a 2t is just that it will rev forever. Probably you should be looking at a 450FX if you want more grunt. At that point I'm not sure what it'd be doing that your 500exc isn't doing for you now.
  9. drewnabobber

    YZ exhaust on a WR

    Short answer is no.
  10. drewnabobber

    Valve clearance and hard starting.

    Likely is your problem. Is this your first valve check? The wear is totally normal but it can happen a lot faster than 72 hours. Set everything to the middle of spec. Once you have the cams out you might as well. Valves definitely can both loosen and tighten. You need to check the valves more frequently, once they go out of spec things can go wrong really fast and it can happen before the bike is noticeably hard to start.
  11. drewnabobber

    Top End Rebuild Piston Size?

    You need to measure the bore, then check the manual for the clearance spec. Then you know what size you need. Anything else is playing the lottery. Alternative is to get a piston and then send it along with your cylinder to get re-plated to the correct clearance.
  12. FMF Q4 is louder than stock WRF and quieter than YZFX or YZF pipe. Db is a relative measurement and lots of factors affect the number. Honestly just stick with the stock WRF pipe (take out the smallest baffle) as it has a spark-arrestor and is nice and quiet; aftermarket is just extra noise for woods riding and pisses everyone off. If your bike is Canadian I don't think you need the kit ECU in order to use the tuner so double check on that. With the tuner you can make the power however you want it.
  13. drewnabobber

    Any 2018 125 RR owners out there?

    Is the 125 frame actually any smaller than the 250/300? All geometry numbers look the same across the range, does it lose any weight or bulk anywhere?
  14. drewnabobber

    FMF Q4 question YZ250FX

    My bike is a 2015. According to the parts fiche 2015-2017 is the same muffler on the WR250F, so any of those should bolt right up to your bike. 2018 should be the same as well if somehow you find one. Older than 2015 won't fit.
  15. drewnabobber

    FMF Q4 question YZ250FX

    Q4 is much quieter than stock FX. That said, you can put a WR250F silencer on your bike and that will be the quietest by far. I run one on mine at the local kart track where there is an 82 dB sound limit.