Yamaha TDM Riders

Discussion in 'Land of the Rising Sun: ADV Bikes from Japan' started by BuellDualSport, Sep 28, 2005.

  1. Butters

    Butters Kwyjibo Supporter

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    On my bike, with a delkevic exhaust, I had to use bigger idle jets to get rid of the low throttle stumble. I know some others, at least with US models, had to go bigger on the idle jets. From memory, I want to say I went up two sizes from 37.5 to 42.5. I am pretty sure I posted in this thread somewhere. I think once you get past about three turns, you aren't doing much and need to jet up.

    I will say, once it was dialed in, it ran awesome.
  2. Foil

    Foil Adventurer

    Joined:
    Jul 24, 2019
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    11
    Location:
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    I'm leaning towards a combination of the jetting and the emulsion tubes.

    I caved in and bought a full kit with new jets and tubes (pretty expensive at 100€ for both carbs) and am now in the process of maybe acquiring a few pilots.

    Is there a specific way of getting mikuni part numbers?
  3. Harvey Krumpet

    Harvey Krumpet Long timer Supporter

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    Worn emulsion tubes is common, they wear oval. Will be replacing mine for the second time on my MKII. Indicators are a smell of petrol while riding, back firing and rough running at low revs.
    PaydayGabe likes this.
  4. Foil

    Foil Adventurer

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    Yeah, I do get some popping, especially when warming up.

    After it gets warmed up, then it starts cutting out at low throttle/low rpm's until I go past around 3000rpm.

    I'm getting the feeling that the PO tried backing the fuel screw at some point in order to mitigate the over fueling by under fueling the idle.
  5. Foil

    Foil Adventurer

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    Oh, another thing.

    Any tips on adjusting the float height? I've seen anywhere from 12mm to 14mm (actual float height, not measuring on the outside).
  6. Harvey Krumpet

    Harvey Krumpet Long timer Supporter

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  7. Foil

    Foil Adventurer

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    Jul 24, 2019
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    Found some advice from the ducatistas:

    http://www.ducatisuite.com/jetkit.html

    Looks like I set the float height using the one. By "diamond shape" they mean the pentagon, instead of the rhombus (which I would associate with a diamond shape)...eh.

    No wonder it's running like garbage right now.
  8. lithodave

    lithodave brachy850

    Joined:
    Jul 29, 2013
    Oddometer:
    42
    I had brittle and non-sealing airbox rubbers that I think contributed to stumbling engine characteristics.
  9. Harvey Krumpet

    Harvey Krumpet Long timer Supporter

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    Sack of hammers at low revs and very revvy top end?
  10. Foil

    Foil Adventurer

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    Just a small update after lots of fiddling around.

    Turns out that the 14mm float height will put the fuel height at 8mm, which is right in the middle of spec.

    The reason I was so adamant on checking the floats, instead of fuel, was opening another can of worms, which ended up rearing it's head. A hairline crack in the fuel drain casting. As soon as I loosened up the left one, I could tell it wasn't going to seal again.

    A bit of quicksteel to the rescue once again.

    Putting things to factory spec returned an absolute turd that could hardly pull away from a parking lot and used about 9l/100km. In order to get a functioning motorcycle until I get the full carb kit, I had to go against my gut, but treat the symptoms.


    Carb sync, with my highly scientific (but proven to work on my dual carb honda civic!) method of covering the carbs with one hand and figuring out how long it takes for the engine to stumble. Turns out that the right bank was pretty much useless at idle.

    A bit of noodling at it was idling much better, and felt much snappier.

    I leaned the needle one notch, then held the engine at around 2500rpm (the neighbors loved that, I could tell) to tune the fuel screws. I settled on two turns out. A bit lean, but no popping, so good enough.

    The test ride was so good that it ended up lasting around 160km in total.

    It still stumbles a little bit in top gear at 2500rpm under load, but overall, it's MUCH MUCH better. At least I can finally ride the damn thing.


    I'm starting to think that cleaning the carb was pretty much what killed it from the go. It was probably so gummed up that the ran fine (mostly, apart from the lean poping at round 1600rpm), until all the junk that was filling in the gaps was washed away.


    I won't be keeping it like this, but at least I've got something I can actually ride for now.
    Marto71, Butters and tuscan like this.
  11. lithodave

    lithodave brachy850

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    Jul 29, 2013
    Oddometer:
    42
    Aye. I rebuilt with MonkeyBoys recipe. Slick!
  12. Foil

    Foil Adventurer

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    Turns out that the full kit arrived a couple of days after all that noodling, but since the bike was running ok-ish, I left it until yesterday.

    I used this kit:

    https://www.ebay.com/itm/2x-MADE-IN...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

    Replaced all the o-rings (yet again), main jet, pilot, tubes, needles, etc. The only ones that I couldn't get out was the air jets (the ones in the carb throat). I mean, I tried, but since my flathead started bending, I left them alone.

    I also didn't split the carbs, to keep from opening up another possible can of worms.


    While inspecting everything, it looks like the edges on the diaphragms are getting hard and cracking. I replaced the worst one with a spare that I had around for my dr350 and repaired the other one with some superglue. Looks like I need to do some more shopping.


    The kit for the petcock also arrived. Replaced the o-rings and re-enforced the outlets with some epoxy (I've dealt with a couple that leaked around the press fits).

    I've also not had a choke since day 3-I think- the plastic thread snapped off. Since it's summer right now, I haven't cared enough to track down a replacement. A couple of pops while warming up, but nothing major.

    The bike runs extremely well after all that. No more stumbling, the engine pulls clean from ~1500rpm onward and it doesn't feel "blubbery" anymore.
    Harvey Krumpet likes this.
  13. broken_cynic

    broken_cynic perpetual n00b

    Joined:
    Apr 13, 2007
    Oddometer:
    16
    Location:
    Fredericktown, OH
    As of Saturday morning I'm not sure I had ever heard of the TDM. I've read enough of this forum that I probably have seen them mentioned, but they certainly weren't something I recognized. I saw an ad on Craigslist for a bike that looked like it would be my kind of ride, at what seemed to be a more than reasonable price. Initially I thought it might be a scam, which, as I read more and more of this thread over the course of the day without getting a response to my email, started to feel a little tragic.

    But it turns out they weren't answering promptly for the same reason they had to offer the bike at such a fair price, they were packing to move on short notice... and I was the beneficiary to the tune of a '92 TDM 850 with ~23k miles for $800USD.

    She sat for most of the past year and needs some carb work, but that is the only obvious, immediate, must-have. Going to get a professional opinion (hopefully this coming weekend) on what else she might need that is less obvious to me. Then go find some southern Ohio roads to ride. :)

    20190805_183546_compress12.jpg
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  14. SlipChip

    SlipChip Adventure Commuter

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    Great Deal! You're gonna have fun!
    broken_cynic likes this.
  15. SlipChip

    SlipChip Adventure Commuter

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  16. lithodave

    lithodave brachy850

    Joined:
    Jul 29, 2013
    Oddometer:
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    20190727_134559.jpg Nice bike! I paid much more for mine, with same mileage. I love it. Very reliable. I go camping a lot with mine.
  17. broken_cynic

    broken_cynic perpetual n00b

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    Apr 13, 2007
    Oddometer:
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    Location:
    Fredericktown, OH
    So, after learning over the weekend that TDMs exist, and buying one, today I learned a new thing:

    I learned that dealers (at least in this area) that sell new bikes do not service bikes more than 10 years old, and other shops generally won't do it outside of the slow winter months. My last bike was also pushing 20 years old, so apparently the couple of times I had it serviced must have been at the right time of year since I never ran into this.

    The dealer back home did at least give me a referral to a guy who runs a small shop as basically a retirement hobby, but it is two hours away (on the plus side, I'm pretty confident he will know what to do with a carb.)
  18. lithodave

    lithodave brachy850

    Joined:
    Jul 29, 2013
    Oddometer:
    42
    I experienced the same thing in my town regarding dealer shop: not interested in working on this old of a bike. But I found another shop with people who specialize and like working on these older ones. (Hello, Vicious Cycle in Portland Oregon!) But once I got the carbs sorted out, the bike has not needed much in 25k+ miles. Find any help you need on the carpe tdm forum.
    broken_cynic and Harvey Krumpet like this.
  19. Foil

    Foil Adventurer

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    Jul 24, 2019
    Oddometer:
    11
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    After the whole tuning ordeal, I've been having a lot of fun on mine.

    [​IMG]

    [​IMG]

    [​IMG]

    If I've learned anything in the short time of ownership is to not even think about it. Just get the carb kits and then start tinkering. That would've saved me tearing the thing down 5 or 6 times and a lot of frustration.

    Right now I'm looking at getting some braided brake lines. I mean, it brakes, but they feel pretty mushy, even after bleeding.

    Oh, and the seat is gets pretty uncomfortable for me within an hour or so. Testing a 30€ ikea sheepskin right now :D
    Steinbergs, Marto71 and SlipChip like this.
  20. GuyLR

    GuyLR Been here awhile

    Joined:
    May 12, 2015
    Oddometer:
    181
    Location:
    Atlanta, GA
    Congratulations and welcome to the TDM brotherhood.