YZ450FX - 2017/2018 or 2019 for Snowbike Build
- Thread starter lanark_lad
- Start date
Interesting. I don't know much about gearing but could the same thing be done in reverse (ie: change an F 5th to an FX 5th gear). I'm leaning towards the FX but there are more F's around to choose from
I’m not sure about the 18 and newer models. Mine is a 16, so any 14 through 17 years will work. Probably though
M5, you previously asked me about my vertex single ring high compression piston kit. I have almost 150 hours on it now. I know, I know. I am on borrowed time. This season has been so good though that I haven’t wanted to take the time to rebuild as my engine builder requires a couple weeks. Plus, I’m still searching eBay for the right deal on gears. So I guess that the piston holds up pretty good in my experience. I will let you know more when it is torn apart this summer.
I did my 90 hour stock piston YZ and it was just wearing into the cylinder enough that a light hone cured it, no re-plate. The lighter high comp piston might actually be a better option for the FX. I've seen three stock FX,s crack pistons all between 105 and 115 hours. They all cracked in a line with the pin. Haven't seen a crack in a stock F, yet.
It doesn't get much talk around here but the FX flywheel weight also contributes to the differences in the revving of the two motors, slower to rev up and slower to slow down. With the extra flywheel weight and revving the pi$$ out of the bike in 2nd (wide ratio) then sudden decel is where we think the cracks are coming from. The flywheel wants to coast as in enduro riding. Bottom line is it varies from rider to rider depending on your style of riding and terrain.
I was going to tear down my engine again this summer and add the OD 5th but I didn't get enough hours on it to make it worth while for another rebuild. 1-4 F gearing with the OD 5th is where I want to be.
M5
It doesn't get much talk around here but the FX flywheel weight also contributes to the differences in the revving of the two motors, slower to rev up and slower to slow down. With the extra flywheel weight and revving the pi$$ out of the bike in 2nd (wide ratio) then sudden decel is where we think the cracks are coming from. The flywheel wants to coast as in enduro riding. Bottom line is it varies from rider to rider depending on your style of riding and terrain.
I was going to tear down my engine again this summer and add the OD 5th but I didn't get enough hours on it to make it worth while for another rebuild. 1-4 F gearing with the OD 5th is where I want to be.
M5
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Regarding the gas tanks, the 2019 fx is interchangeable with the 18 and 19 f. So the 2.2 gallon fx is a no-mod replacement for the 1.6 gallon on the f. If that isn't big enough, the guys at IMS said they are nearly complete with the 2.6 gallon, which will drop right into both.
One grenaded 2 didn't, usually they just lose compression and start running really bad so its obvious that something is wrong if you are on the ball about how your bike is running. The centers crack first right in a line with the wrist pin but the outer edges of the piston where its thick typically stay intact. The one that was bad a piece came out of the center which we all know that never ends well.
Another failure I've seen two of now in the FX is the countershaft bearing starts making metal and fails, happens around 150 hrs. One of them was a big bore, which I don't do anymore. I've decided its cheaper to do a top end around 80 hours then a complete rebuild after 150 including a new crank, valve job, bearings, cylinder replate yada yada than to repair a grenaded motor.
M5
Another failure I've seen two of now in the FX is the countershaft bearing starts making metal and fails, happens around 150 hrs. One of them was a big bore, which I don't do anymore. I've decided its cheaper to do a top end around 80 hours then a complete rebuild after 150 including a new crank, valve job, bearings, cylinder replate yada yada than to repair a grenaded motor.
M5
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P
portgrinder
Well-known member
I find parts are always cheaper to change in one piece.
That no kick and LI battery is a debacle if its cold at all. Add a recluse and now you can’t pull start it either. That would be top of my list to sort out.
That no kick and LI battery is a debacle if its cold at all. Add a recluse and now you can’t pull start it either. That would be top of my list to sort out.
FWIW...
The 16-18 WR450 uses the same engine as the FX, but in stock form it is detuned a bunch. The competition ECU, along with free flowing muffler and air box mod along with the power tuner completely changes the bike. I built a 17 WR450 on a snowbike platform, and I would do it again for the radiator fan, lights, and the ability for the stator to run heated grips. All (YZ, YZ FX, and WR) need suspension work for snowbike application.
The 16-18 WR450 uses the same engine as the FX, but in stock form it is detuned a bunch. The competition ECU, along with free flowing muffler and air box mod along with the power tuner completely changes the bike. I built a 17 WR450 on a snowbike platform, and I would do it again for the radiator fan, lights, and the ability for the stator to run heated grips. All (YZ, YZ FX, and WR) need suspension work for snowbike application.
Lead acid battery. Problem solved.
Kick start on a YZF
I have looked and cant seem to find anything online but does anyone know if you can swap the case cover off a 2019 FX and put it on an F? and then install the kickstarter? the case cover and the kick start kit are only $400-500? That would get me to buy an F over an FX and then rebuilding a new motor.
I have looked and cant seem to find anything online but does anyone know if you can swap the case cover off a 2019 FX and put it on an F? and then install the kickstarter? the case cover and the kick start kit are only $400-500? That would get me to buy an F over an FX and then rebuilding a new motor.
19 450 FX doesn't allow for a kickstarter
17-18 FX does, but I doubt the cases are the same as the 18+ YZ/19+FX
17-18 FX does, but I doubt the cases are the same as the 18+ YZ/19+FX
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