2017 250 EXC-F -- any opinions yet?

Discussion in 'Thumpers' started by KnowFear, Feb 12, 2017.

  1. Mikemm

    Mikemm Long timer

    Joined:
    Feb 15, 2011
    Oddometer:
    3,024
    Location:
    SE Florida
    im at 70 hours. Typically do oil changes at 15 hr intervals, although the last trip to Colorado I did a 20 hr interval and I haven't yet seen that much metal on my drain plug.
  2. bkoz

    bkoz test

    Joined:
    Dec 6, 2008
    Oddometer:
    1,437
    Location:
    Kamloops, BC
    In my experience once oil starts to break down the viscosity will drop out rapidly. It is very possible that Retumbo7 is getting to that point.

    I also run conventional Rotella in the white bottle with 7hr oil change intervals. If I let get over that point I get sludge build up on the plug and my shifting becomes very notchy. But I ride/race in the mountains with tons of hill climbs and slow speed single track. Heat is hard on viscosity.
  3. bkoz

    bkoz test

    Joined:
    Dec 6, 2008
    Oddometer:
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    Time to catch up on the rebuild pics.

    Don't forget to never seize these little buggers!

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    Who needs Slaven's $40 mud flap doo hickey when you have sheet metal and epoxy. I had originally epoxied a flat washer on and it lasted a surprisingly long time.

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    The kickstand will need to be replaced soon. I actually lube this pivot about every second oil change. I have seen too many broken ones.

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    I also replaced my custom foot pegs with some used OEM's. This is the 3rd sett IIRC.

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  4. bkoz

    bkoz test

    Joined:
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    Oddometer:
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    Lets finish the engine.

    The cam bearings and finger followers look great! The valves have not moved since the initial break in and had almost no build up on the stems/heads. I didn't bother to remove them.

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    Look at that casting flash on the finger follower, ugly.

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    The cams also look excellent

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    Just the slightest bit of pitting on this intake lobe. I will monitor it.

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  5. bkoz

    bkoz test

    Joined:
    Dec 6, 2008
    Oddometer:
    1,437
    Location:
    Kamloops, BC
    Head on with a new cam chain and the lower gears timed. Because I was waiting on parts I put the cam chain in AFTER the head was installed. It is doable but a PITA.

    PXL_20210115_142200443.jpg

    After timing the cams ALWAYS carefully bar the crank over 720 degrees to ensure everything lines back up. I was a tooth out and had to reset things.

    PXL_20210115_144115675.jpg
    I was getting lots of timing chain rattle after I dropped the bike and restarted. I decided to invest in a Dirt Tricks tensioner. Dirt Tricks recommends installing the tensioner after a 20hr break in period of a new engine. Because I had a new cam chain I was worried things would be a little tight with the Dirt Trick tensioner. I took a bunch of measurements and concluded I should be fine installing the Dirt Tricks tensioner. Fingers crossed.

    PXL_20210115_143422743.jpg

    Getting close now

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    The clutch intermediate cover went on next. Be aware the stupid little 2 piece water pump impeller can be reassembled out of order if you are not paying attention.

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    It's all in one piece now!

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  6. bkoz

    bkoz test

    Joined:
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    Oddometer:
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    A little more on the clutch cover. I would have to check my notes but I there is probably about a 100hrs on my JB weld repair.

    PXL_20210115_152639496.jpg

    From my research this clutch cover was only used on the 2017 and up 250 EXCF's and 2020 and up 350EXCF's. It looks like the odd spring washer/rubber gasket assembly on the inside was strictly used for noise dampening.

    PXL_20210115_152643968.jpg
    Of course this makes it significantly more expensive than a standard clutch cover. I ended up ordering and installing a regular 250SXF clutch cover.

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    The depth is different. Hopefully my oil window shows the correct level now.

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    I had some help buttoning things up

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    I threw the engine on the bathroom scale

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  7. bkoz

    bkoz test

    Joined:
    Dec 6, 2008
    Oddometer:
    1,437
    Location:
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    Engine in and subframe on. Damn I hate the new KTM subframe/airbox and wiring.

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    Time for some rad re-tweaking

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    Like new

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  8. bkoz

    bkoz test

    Joined:
    Dec 6, 2008
    Oddometer:
    1,437
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    The shock is next. About 60hrs on this oil. It was a little over due.

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    I am just getting some shock body wear. Premature wear of the shock body seems pretty common on these new Xplor shocks. Don't skip out on shock rebuilds!

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    The white washer is my lowering spacer. I installed this right after buying the bike to level out the chassis.

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    I will need a new piston band next time. I am running an after market MX Tech piston

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    The high speed compression adjuster. I can't remember why I took a pic of this, lol.

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    I had a locally suspension builder vacuum bleed my shock. Getting my vacuum bleeder up and running is on the to do list.

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    Home! Just need to reset the sag

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    My header has seen better days.

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    I tried the water an freezer trick. I have never had luck with this. I was thinking of blowing out the dents with air and torch like I do on my 2 stroke chambers but was worried about creating a good spot for cracks to form. The header is back on the bike as is.

    PXL_20210124_164405810.jpg
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  9. bkoz

    bkoz test

    Joined:
    Dec 6, 2008
    Oddometer:
    1,437
    Location:
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    With the back end back together it was time for the front end. The fork seals were just replaced so all that was really needed was to re grease the head set.

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    I noticed some play on the arm of my steering damper

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    Dammit! I broke the shear pin.

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    I also lubed and retorqued the spokes on my wheels. The front wheel needed a few new nipples. I was able to adjust the wobble out but the dent is going to stay. At least it is not cracked.

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    My brake pedal bearings were also seizing. Don't do what I did and order the bearings from the dealer. Way to expensive. They are simple 6000-2RS bearings. A propane torch, a vise and few sockets make the job easy. Sorry no pics.

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  10. bkoz

    bkoz test

    Joined:
    Dec 6, 2008
    Oddometer:
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    As the bike sits today. The grey fork guards were an accident but I like how it looks actually. I am still waiting on an airbox cover and new swing arm guards. I just have to swap on the front Trellie tire and plan to test ride/break in the bike tomorrow. It is supposed to be 12C out. I am pretty proficient at changing tires but that rear Trellie is a bitch. The 19" ones are even worse.

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    I threw my dongle on the bike and fired it up. The bike fired up and settled into a smooth idle quickly with no codes. The idle was a little low but I will not play with that until it is broken in.

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  11. bkoz

    bkoz test

    Joined:
    Dec 6, 2008
    Oddometer:
    1,437
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    One last post for today. A little electrical info. I am confident that wiring on the 350/450 and 500 will be very similar but I have not confirmed it. I also believe the 2020 and up bikes will also be very similar but I have not confirmed it.

    Engine LHS 1.jpg

    LHS Engine 2.jpg

    Fuse Block 1.jpg
    Fuses 2.jpg


    Under Battery.jpg
    Relays.jpg
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  12. bkoz

    bkoz test

    Joined:
    Dec 6, 2008
    Oddometer:
    1,437
    Location:
    Kamloops, BC
    Continued

    Under seat.jpg
    Starter Relay.jpg
    RHS Airbox.jpg
    TB 1.jpg
    TB 2.jpg
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  13. scotts630

    scotts630 n00b

    Joined:
    Feb 22, 2020
    Oddometer:
    8
    Location:
    Arizona
    Thanks for taking the time to write and post this type of info.

    Scott
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  14. N8

    N8 Masked pumpkin rider Supporter

    Joined:
    Dec 27, 2012
    Oddometer:
    9,298
    Location:
    Lancaster, PA
    Indeed. I don't even own the bike anymore and I feel your posts are gold @bkoz . Nice work!
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  15. bkoz

    bkoz test

    Joined:
    Dec 6, 2008
    Oddometer:
    1,437
    Location:
    Kamloops, BC
    I got the bike out for a test run today. We didn't quite get the promised +12c but it still ended up being a great ride.

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    The bike started right up and ran well. No leaks so far.

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    I can definitely feel the added torque of the high compression piston. It pulls harder right off idle and has more bark in the midrange. I pop stalled it a few times but that is probably more related to being on my YZ250 for the last 2 months.

    PXL_20210221_204948309.jpg
    I ended up having two of the biggest get offs of the snow season but walked a away unscathed. The bike ended up with a tweaked hand guard.

    A couple thoughts:

    The high comp piston was a great upgrade.
    My suspension is officially too soft.
    I really miss my steering damper. I will have to rob the YZ's until I can get parts.
  16. Retumbo7

    Retumbo7 Engineer

    Joined:
    Mar 12, 2017
    Oddometer:
    421
    Location:
    Reno
    As a follow-up, oil filter and screens were clean so at least it's only the magnetic slivers to worry about. Thinking about this more, the bike runs perfectly and I've had these at every oil change so I think it's unlikely to be anything besides little pieces of transmission gears or I likely would have experienced a catastrophic failure by now. I have to admit I don't use the clutch as much as I should when I'm bombing uphill at 9000ft while fully loaded with 50lbs of gear trying to keep up with friends on 500s...

    For the record, oil has been either Belray or Motorex (JASO MA2) since new, am going to go every 10h from now on as I don't like the sludginess of it at 15h from the clutch material

    Here are a few pics from the 60H service:

    [​IMG]
    Note how my new Oil pump gear has 4 stakes (It looks like Bkoz's had 1, so I wonder if they re-updated?). One of the teeth on the old gear was half missing, so probably a good thing I did this.

    [​IMG]

    Did a complete inspection of everything I could see on the clutch side (as well as the alternator side), and nothing seemed out of the ordinary.

    [​IMG]
    Plug at 60h. I'm not much of a guru at this stuff, so hopefully someone can chime in on what it means. Replaced with a new one because why not.

    [​IMG]
    Cam lobes look decent with a very light specking of wear (imperceptible to fingernail). Valves were all within tolerances.


    [​IMG]

    Was also having some issues with the rear fender collapsing/rubbing which may have been related to riding 2-up (bought some ebay passenger pegs [you can see lower left] and GF is surprisingly OK with being back there). Spent WAYYYYYYY too many hours trying to figure out how to make the Husky carbon subframe work for my kind of riding. I tried just about everything in the book (custom aluminum subframe, bent steel tube exoskeleton, epoxy coated metal anchors, etc etc). End result was this which sandwiches the carbon subframe and works despite looking a bit ghetto.

    [​IMG]

    Test run to make sure all was well. Pic is of my friend right before he ate shit on my old 520, but followed him down and all checked out!

    Also shout out to @bkoz for his amazing teardown/build photos. Also wanted to know if you figured out a way to do a leakdown with the engine in the bike, as there is no way in hell my air line is going to fit in the 2" clearance between the head and the frame.
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  17. bkoz

    bkoz test

    Joined:
    Dec 6, 2008
    Oddometer:
    1,437
    Location:
    Kamloops, BC
    You plug looks fine. Makes sense to change it when doing a valve set. You are in there anyways.

    I have a couple different leak down testers. My Motion Pro gauge works fine with the engine in the frame. I did a leak down test previously at around 100hrs.
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  18. Guoseph

    Guoseph Been here awhile

    Joined:
    Sep 8, 2011
    Oddometer:
    684
    Location:
    Alameda, California
    Hey guys,

    My bike dies when warmed up. Like it's not getting any more fuel, or maybe spark. I found a cracked spark plug boot and replaced it with new but problem persists. Doesn't get hot enough for fan to come on before bike doesn't want to run anymore. Any suggestions?

    Thanks,

    Alex
  19. Retumbo7

    Retumbo7 Engineer

    Joined:
    Mar 12, 2017
    Oddometer:
    421
    Location:
    Reno
    I remember you having an issue last summer... How old's the gas?
  20. Guoseph

    Guoseph Been here awhile

    Joined:
    Sep 8, 2011
    Oddometer:
    684
    Location:
    Alameda, California
    Hah, yeah thought I found the issue but didn't solve the problem and then work got in the way. Fresh gas now and new fuel filter.