Suzuki TU250 - anyone seen/ride one?

Discussion in 'Thumpers' started by anomad, Dec 10, 2008.

  1. NJ-Brett

    NJ-Brett Brett

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    You can likely reuse the O ring.
    I only replace them if they are old and hard.
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  2. LuciferMutt

    LuciferMutt Rides slow bike slow

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    Well, didn't get the service done over the weekend :bluduh

    Barely even got any riding in. Way too busy with life. Ugh.
  3. LuciferMutt

    LuciferMutt Rides slow bike slow

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    Got my 600 mile service finished over the last two days. Oil/filter change yesterday, and valves, other checks today.

    Amazingly, both valves were exactly in spec, right where I was planning to put them if they were not: Exhaust .004" and intake .002" -- right in the center of the tolerance for both. Still, I learned how to remove the tank, find compression TDC, all that jazz. Definitely the simplest bike I've worked on.

    I bumped the idle speed up a bit ( 1/2 turn CW on the brass screw was enough to hear it rise ) after having some problems with the bike stumbling off idle. Like when you go to rev throttle up, it coughs/bogs and doesn't respond before revving up. I actually stalled the bike leaving the gas station yesterday because of this. This is a fairly new problem that seemed to be getting worse. Increasing the idle helped a bit, but the stumble is not completely gone. I'm becoming quite annoyed with the fueling on this bike. The factory map is god awful. I'm looking hard at the power commander -- not for more power because that won't help, but just to make the bike run right. I don't need the 89MPG I've been getting -- I will settle for fewer MPG and an engine that runs smoothy and responsively.
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  4. MYUMPH

    MYUMPH 'Ol Timer Supporter

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    Have you ever heard of boosterplug.com? They supposedly make a plug and play fix for the TU throttle response. I never had too much of an issue with mine, but it was different than any other EFI bike I've ever owned. I found having zero play in the throttle cable helped, and you almost had to slowly give it throttle, as opposed to "blipping" it on any other bike. Mine was most noticeable coming in my long gravel driveway, it would just kinda spit and sputter at low rpm's.
  5. LuciferMutt

    LuciferMutt Rides slow bike slow

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    I did adjust the throttle freeplay to the spec in the manual.

    I have heard of booster plugs. The TU uses a (mostly) closed-loop fuel injection system that is monitoring the exhaust using the O2 sensor, and adjusting fueling on the fly. Thus the booster plug does very little to nothing to the fueling during most of the rev range, as its only input is to lie to the ECU and say the intake air is colder than it is. I suppose it might help an off-idle stumble since I think the ECU is not using the O2 sensor there. Kind of an expensive gamble, whereas a power commander is a sure-fire (and also expensive :lol3) way to adjust your fueling as desired.

    EDIT: Have done some more research and am a little more intrigued. The booster plug is definitely overridden by the O2 sensor while cruising and at higher RPM, but the O2 sensor is ignored by the ECU during "transitional" periods -- engine braking, off idle, low RPM crawling, low speed throttle on-off stuff -- right where the TU is most annoying and surgey. It is during these times the booster plug would seem to be helpful. It's less than half the price of a PCV so it might be worth a try. Lots of satisfied testimonials out there; more than a few are posted on ADVrider.

    My snake oil meter is still on the red zone though. Gotta do some more reading.
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  6. LuciferMutt

    LuciferMutt Rides slow bike slow

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    So I decided to say screw it and installed a Booster Plug on the TU today. I did a ton of reading about them, and nearly every person who said they were junk hadn't actually installed one, or were erroneously believing the product claims to increase horsepower (it does not ever make that claim -- it's all about improving throttle response). OTOH, of the people who actually did install one, very few said they didn't like it. There was a pretty large number of positive reviews from happy owners. Information on people who had specifically put one on a TU was fairly limited, other than those who put one in with the Brogue exhaust at the same time.

    Anyway, my symptoms were:
    1) awful off-idle response -- crack/rev the throttle and the engine would choke/hesitate before revving up and actually stalled on me a couple of times
    2) lean surge at low speeds between 20-40 MPH at partial throttle -- very annoying and hard to hold a speed. In fact, if you had the bike sitting still in neutral and try to smoothly rev the engine up and then maintain a specific RPM -- it was nearly impossible. The engine would rev up and down and generally be all over the place at a consistent throttle input. I have checked for vacuum leaks and there are none..
    3) Snatchy throttle at low speeds -- on/off throttle transition was very poor and jerky, then if you were trying to be smooth and roll into it slowly, you got more lean surging too.

    These symptoms are with a totally stock intake and exhaust, and so are the results below

    So did the Booster Plug do anything? After a 50 mile ride with it installed this morning, I think it has, but the difference is not the "night and day" that some people describe. Regarding the symptoms above in order:
    1) This is much better. I had no near-stall events today and the off-idle rev response is definitely improved. I did still have a slight hiccup once, but it was much less severe than before and only happened once. Idle is definitely smoother.
    2) This is also better, but not completely gone. I did immediately notice it was a lot less severe leaving my neighborhood -- it used to be worst when the engine wasn't warmed up yet.
    3) This honestly isn't much better. Maybe a tiny bit better, but I'm calling placebo on that until I ride it more. The damn cush drive has a whopping 1/4" play though (bike has 700 miles...wtf) so I need to shim it and re-evaluate, ,and I can't do that until I can modify my Trackside paddock stand to lift the TU properly. No cush drive should ever move that much. They should have zero detectable play - the rubber can still absorb the shock without a physical gap between it and the sprocket carrier. Excessive play leads to broken parts.

    Other changes? Butt dyno says there is a touch more low end and mid range torque available. I was able to hold speed against a specific hill without downshifting to 4th this morning, and I've never been able to do that. Immediate "response" after shifting gears seems "fatter." The bike seems a bit "fuller" overall, if that makes any sense, so I really think the mixture is in fact being richened up a bit here and there when the bike isn't running in closed-loop

    In all, I can't say I'm impressed or not yet. I need more seat time. There are subtle positive changes, but I may need to run with the plug installed for a while, then unplug it and go back to stock for a while to see if that change is noticeable.
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  7. MYUMPH

    MYUMPH 'Ol Timer Supporter

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    Can't remember if it was here or TU forum, but cush drive play seems to be the norm. Never really heard as to why, but I think they all have it. When I noticed it on mine, I thought O sh_t! But I went and looked at my son's and his was the same. Then after looking around is where I saw other TU owners saying the same thing. I've never had another bike have play in it like the TU did.
  8. NJ-Brett

    NJ-Brett Brett

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    Got my 2nd one yesterday:
    [​IMG]

    Put 150 miles on it already.
    Needed quite a bit of little things done/checked, but it was cheap as chips as some say...

    I don't notice much driveline slop, although I bet its there.
    Love this bike, its just silly fun.
  9. V0R2G0

    V0R2G0 Been here awhile

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    Congratulations Brett!!

    Now ride the wheels off:clap
  10. LuciferMutt

    LuciferMutt Rides slow bike slow

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    Nice! Did you trade or sell the SR400?
  11. NJ-Brett

    NJ-Brett Brett

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    Sold the SR400 for $2000.00.
    One of the best bikes I have ever owned, sad to see it go, but I have no room or time for four bikes.
    As good as it was (it looked great, sounded great, ran great, handled great and was totally trouble free), the TU is more fun.
    Care free hoolaganisem is how I would describe it, hard core road racing at lower mostly legal speeds....
    Stupid easy inexpensive fun.
    Once again, the lure of more power has been vanquished by the fun factor of the TU.
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  12. NJ-Brett

    NJ-Brett Brett

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    You might try plugging up the air injection and looking for exhaust leaks.
    Stock, the fueling is very good on my bikes.


  13. TheHeretic

    TheHeretic Been here awhile

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    I've also developed quite a fetish for small bores in my old age.... I've always liked the classic style of the TU Brett....congrats on your new ride!
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  14. NJ-Brett

    NJ-Brett Brett

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    I removed the secondary throttle plate last night, I do not feel much if any difference.
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  15. LuciferMutt

    LuciferMutt Rides slow bike slow

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    How many miles on the new ride?
  16. NJ-Brett

    NJ-Brett Brett

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    Came with about 4200, I have put on about 300 so far.


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  17. LuciferMutt

    LuciferMutt Rides slow bike slow

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    Took a very nice 60 mile ride today on the TU. It's running fantastic - best it has since I bought it. I think the Booster Plug is helping -- I had no fueling hiccups at all today. Fuel light came on at 192 miles on the trip odo and I gassed up at 203 and put in 2.4 gallons. Fuel economy is down about 5 mpg after installing the Plug. I can live with that.

    I also finally "modified" my trackside paddock stand to lift the TU and gave it a proper chain cleaning and lube. I ended up wrapping old inner tubes around the rubber lifting blocks and then wrapping gorilla tape over that -- it adds about 1/2-3/4" of height on the lifting blocks which is juuuuuuust enough to prevent the stand from hitting the exhaust when you try to lift the bike. I did make a drawing of a modified bracket for the stand a few weeks ago that will give me another inch of lift, but I have had zero time to make them.
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  18. NJ-Brett

    NJ-Brett Brett

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    I have been getting 60 to 80 miles a day on the TU, 400 miles so far in between working on it.
    What a fun bike.
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  19. LuciferMutt

    LuciferMutt Rides slow bike slow

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    My TU is rapidly becoming one of my favorite bikes I've ever owned. It doesn't matter that it's slow -- I really enjoy riding it. This bike has some kind of "it" factor I can't put my finger on, but it's just such a pleasant bike to ride and own.
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  20. IkeKant

    IkeKant Adventurer

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    I just installed a Boosterplug today. The bike has never been smoother and there is a bit more low and mid range torque. Definitely worth the $160.
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