Yamaha XT250 Thread - All things related to the XT from riding to modifications.

Discussion in 'Thumpers' started by RL Lemke, Sep 23, 2018.

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  1. ESNystrom

    ESNystrom Adventurer

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    Thank you very much for the detailed response. These are 2 upgrades that are on my radar for the future.
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  2. NicKel78

    NicKel78 Been here awhile

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    Got the Cogent in tonight. Here is a little info for anyone who hasn't but wants to do this.

    Screen Shot 2021-01-28 at 12.21.28 AM.png



    Start by removing the seat and side panels. Remove the battery then pull the starting relay out and move over to access the upper shock mount bolt on the right side. Left side is accessible. Also remove the rear mud guard directly in front of the shock.

    IMG_8758.jpg



    Loosen the front connecting arm bolt and the upper shock bolt with two 17mm sockets. The upper bolt from the factory was stupid f'ing tight and I needed a breaker bar. Next, lift the bike up so the rear tire just clears the ground. I simply left the kickstand down and used a floor jack on the right side under the footpeg mount. Now remove the connecting arm bolt, then loosen and remove the lower shock mount bolt with a 17mm and 14mm.



    Yamaha leaves a cut out in the plastic box that holds the relay, battery, etc. for the upper mounting bolt but they either missed the mark by a long shot or I have done f'ed up my bike and seriously bent something although I do not see anything bent or broken. This picture shows how far off the cutout is to the bolt head. I had to loosen the box and pry/flex it over for the bolt to come out. Once I got the head cleared of the box I used a nut driver handle from the left side to push the bolt out while letting the handle retain the shock in place. Now supporting the shock, remove the handle, lift up carefully on the swing arm and slide the shock unit out the bottom. Lots of room here with the swing arm lifted up.

    IMG_8756.jpg



    Here is the old vs. the new.

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    At this point, reverse the process. Also, time to clean and grease linkage parts during this process. At 3k miles since new in July, there was almost no grease to be found on anything.

    It is probably worth sliding bolts in, setting the seat on, stacking any luggage on and rough checking sag at this point before tightening anything or going any further. I made the ASSumption the preload was set fairly darn close and needless to say that bit me in the butt. Checking loose, you can at least easily remove and adjust to get much closer in the ballpark saving lots of adjustment time later. I put five full turns on after together because of my ASSumption and still need more. Once in place, those five turns took a lot of time. As a reference, those five turns only brought me up about 35mm on the sag. Will call Cogent in the morning and see what Rick or Todd have for sag recommendations. I usually go about 35%. On the XT, rear travel is 180mm and 35% would be 63mm rider sag. Cogent general specs say to not turn the preload more than 5 full turns from original setting and set sag about 1/3 of total. I am at just over five turns and roughly at 70mm sag or around 39%. Once I get their recommendations based on where I am at, I can set final sag with everything in place properly instead of mostly in place. As a side note, on a bone stock XT with no luggage and me at 175lbs, the rear sag is right at 35% which isn't as bad as one would guess.

    IMG_8759.jpg

    IMG_8760.jpg

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    Final notes for tonight on the suspension... Install is actually very easy. Biggest time suck was fighting the top bolt because of the mismatched cutout and adjusting the preload after everything was in. Everything else was very straight forward. I sat on both the gf's stock bike and mine after rough setting the sag. Bouncing up and down is a noticeable difference on a low frequency bounce. Trying to bounce at a high frequency is very noticeable. The movement and response rate of the Cogent is very quick by comparison. The stock just feels like it is lagging way behind and just doing it's own thing with no regards to what's actually happening around it. Kind of like the lolly gaggers in the grocery store aisle that won't get the f out of the way when you just want to get your items and jet. Bastards. Anyway, I am very hopeful about what I saw bouncing the suspension as the whole point for me was to increase the high frequency response. I want my tires to stay much more in contact with the earth when riding the washboard and rough roads at 50-60 mph. Currently I feel like my rear tire is only in contact with the ground on that stuff 50-60% of the time. It's so bad that at 3k miles, my rear tire is just about worn flat in the middle. Have some new Motoz Tractionator Enduro I/T to try out but didn't want to spoon them on only to sand them off in short order with the stock suspension.




    Also, I have been meaning to check/replace the air filter and with the seat was off I took the opportunity to do so. Per the service manual the first check is at 4k miles, I'm at 3k. The service manual is BS if you ride this thing like a Euro bike. Should have replaced mine many miles ago, probably at 1500 miles. It's gross and so is the airbox. Very carefully cleaned the track the air filter slides in and making sure the clean side of the air box was and stayed clean was another 20-25 minutes. Might try a vacuum with a smallish suction tube next time. Can't say I'm impressed with the way Yamaha set the air filter up. Should be a lot more simple but I'm sure some of the design had to do with the stupid air induction system for the retards at the EPA. Airlines can burn how many thousands of pounds of jet fuel per plane in a high level of the atmosphere and my little 58mpg (because I flog the ever living piss out of it) 250 has to have an air induction system? Huh?

    IMG_8766.jpg

    :hide

    IMG_8767.jpg
    NewEnglander, Hogges, Skooter and 5 others like this.
  3. Milano.B

    Milano.B Been here awhile

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    Congrats, it does look nice :thumb
    You are all prepped up for the Baja 1000 :clap

    On the air filter, if you smear a little grease on the frame/guide, this will catch dust trying to bypass the filter media.
    I use 'No Toil' rim grease as it plant base (biodegradable)
    ESNystrom and NicKel78 like this.
  4. NicKel78

    NicKel78 Been here awhile

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    Thanks @Milano.B . I'm ready for last place now! Or no place after I get further and further into this bike. I feel like I would be spending too much time working on electrical problems and trying to keep the air filter replaced in those types of conditions without reworking some things. Between things like the air induction system, the silly bullet connectors all over the place and just some of the other things, I don't get the feeling Yamaha placed as near much emphasis on off-road as they market. Part of the intrigue of the XT in the Baja is that it wasn't designed for those conditions but I think it could be pulled off. Wouldn't be easy but I think possible after gutting the air induction and reworking electrical. Still a solid little bike and actually very capable as is, for what it is, as we know.

    Great idea with the grease on the filter. Will definitely be doing that before final button up and the seat going back on.
  5. Beeners

    Beeners Adventurer

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    Thanks for the excellent writeup. I ordered my Cogent suspension a couple of days ago and your post will definitely save me time. Interesting that the shock from Cogent seems to be less stiff than the stock one. I'm going to be very careful setting my sag.
    NicKel78 likes this.
  6. CloudSplitter

    CloudSplitter Putterer

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    Beeners, that spring is definitely not less stiff than the OEM spring. Both are steel (same modulus of elasticity), and have essentially the same coil diameter, but the Cogent spring has larger diameter wire, and is shorter (see NicKel's picture), both making it stiffer. The sag is affected by spring stiffness, but adjusted by spring preload. NicKel just had to increase the preload to reduce sag, but it bothers me that it was so far off, as supplied.

    It also bothers me that the Cogent shock appears to have significantly less travel than the OEM spring (compare distance from the end of the shock to the rubber bumper, in the side-by-side picture.)
    randypower, NicKel78 and Beeners like this.
  7. NicKel78

    NicKel78 Been here awhile

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    My thoughts as well. I did expect the preload to be dang close and the spring is higher rate for sure so that threw me off. On the length, the first thing I noticed was that difference. They are suppose to have the same travel though. In the picture the body also starts higher as well as the bump stop being longer. The lower spring perch is somewhat dished out and the stock is flat but impossible to see at that angle. The bump stop is also more significant all the way around in size but the finger poke test felt like a lower durometer for better compliance as well as having the taper on the ends for a more progressive bump rather that the hard hit of the OEM.

    I plan on running the piss out of it this weekend so will hopefully have great things to report at the end of Sunday.
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  8. ESNystrom

    ESNystrom Adventurer

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    I observed the travel difference too. I used a set of calipers to compare the side by side photo. If you were to adjust for scale, with no other changes to geometry, the Cogent would have about 2" less travel. My only question would be if the stock shock can use all of it's available travel, or is it limited somehow? I wouldn't think so, why else would it have a bump stop? That's a lot of money to spend, and lose travel. I understand that the valving and spring rates should be better. But........?
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  9. NicKel78

    NicKel78 Been here awhile

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    I will be calling Cogent here shortly to ask about the preload and will asked about the travel as well. Stay tuned.
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  10. NicKel78

    NicKel78 Been here awhile

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    Left a voicemail with Cogent so waiting to discuss the preload with them but per the service manual the OEM shock has 68mm of travel and per Cogent’s listed specifications, theirs has 69mm.
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  11. CloudSplitter

    CloudSplitter Putterer

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    Hmm. Well maybe it's just the longer, softer, bump stop, which would be good, in my opinion,
  12. ESNystrom

    ESNystrom Adventurer

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    I would think that they know what they are doing, very reputable company. Probably an optical illusion, or maybe the compression of the bump stop. I do now notice the concave recess on the bottom of shock body, and corresponding bevel on the stop. keep us informed of the performance, that's what really matters.
  13. NicKel78

    NicKel78 Been here awhile

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    Well, I talked to Todd today and he gave me a list of things to do and data to collect. On his side he is going to have the numbers re-run for the spring. Preliminary it seems we are under sprung and after running through my list tonight I feel pretty confident that we are. Short story is I have added 12 full turns of preload which amounts to 18mm spring preload and my rider sag is still shy by about 10mm. This is with riding gear and the luggage allotted on the build. Good news, it is close enough Todd told me to ride all I want this weekend and we'll touch base early next week after they can look over the data I am about to email and recheck numbers. I have no doubt that even off a bit, the improvement over stock will be very noticeable. I also have no doubt we will get this dialed in very nicely. One thing about Cogent, while I have only talked to them four times now between the front and now the rear, they are always happy to talk, share lots of information and I have learned something every time. Absolutely a fantastic company to do business with.
  14. Beeners

    Beeners Adventurer

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    I agree wholeheartedly. You'll get you shock sorted.
  15. NicKel78

    NicKel78 Been here awhile

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  16. WettBanditt

    WettBanditt Adventurer

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    I haven't seen that year minus decals. Not too shabby. I still think the tan models require the decals removed to look the best.
  17. NicKel78

    NicKel78 Been here awhile

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    The color in the picture makes it look white but this is indeed a tan model and I very much agree about it looking far better without the decals.
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  18. ESNystrom

    ESNystrom Adventurer

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    Looking for an answer for something that I have wondered about for a little while, and can't find any info. On Yamaha's website, they say the rear shock has rebound adjustability. I have looked in the owners manual, factory service manual, and searched online, to no avail. Does anyone have a clue?

    Attached Files:

  19. CloudSplitter

    CloudSplitter Putterer

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    ES, I just searched the service manuals and owners manuals for all post-2000 XT250s and XT225s, and can't find such an adjustment. I think you'll have to read that note as, "adjustable preload, and it has rebound damping"

    Sorry
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  20. NicKel78

    NicKel78 Been here awhile

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    What @CloudSplitter said. It most definitely does not have rebound adjustment unless somehow they are counting the gas charge as an adjustment. There is a schrader type valve on it and that is it. But you have to have it out to access that and there is no where that Yamaha states anything about it, even as general service.