looking for porting/tuning help

Discussion in '2 smokers' started by Touring XR, Jul 31, 2013.

  1. Touring XR

    Touring XR Adventurer

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    I've got a 2001 TM300E. Love everything about it except the MX like powerband. This thing has a huge hit and no flywheel. Being old and lazy, I'd like something more 2-stroke tractor like.

    No, I don't want to sell it and buy a 300 EXC.

    Who is still out there tuning that would radically retune my TM?


    Geoff
    #1
  2. joexr

    joexr Banned

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    Check around to see if anyone makes a weighted flywheel. Maybe an exhaust restricter , but then you'll get into jetting too. Otherwise you can't deport/detune a 2-stroke.
    #2
  3. stainlesscycle

    stainlesscycle Long timer

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    some very simple options would be to add a base gasket to increase squish... or increase flywheel weight... depending on how it's jetted now, you could jet a bit rich on the main and maybe fix the hit - sometimes hit is from jetting transition..but usually it's just port design/timing.. you could also gear it a bit different and maybe lessen the hit, but that would most likely lose the bottom end you want... a smaller carb could increase low end, but you'll lose that screaming top end - as would different pipe design, a longer intake tract could help too...(not really an option..) unless there's a carb spacer available - backing up the carb even 10mm makes a difference... adjust the power valve - haven't looked at that motor to see the power valve design... you could play with timing to lessen hit too.... either way you're gonna give up top end overrev if you want to mover the power around a bit...
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  4. joexr

    joexr Banned

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    Wouln't another base gasket make it peakier by raising the exhaust port?
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  5. stainlesscycle

    stainlesscycle Long timer

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    yes. i meant thicker head gasket. typing without thinking. don't know if that has o-rings on head, or copper head gasket. cometic probably makes a thicker head gasket (if it takes them...).... you can go thinner base gasket, thicker head gasket to keep compression the same, and move port timing around. i'm gonna bet the squish is pretty darn tight on that motor to begin with.... either way, the best way would probably be smaller carb probably the most effective way to get rid of hit.. you could get a different throttle too... since it's italian i'm betting it has a tomaselli/domino throttle - there are 2 different throttle tubes - the black one (from memory) is quicker, and the white one is slower...i'm gonna guess our favorite dumbass will chime in when his nursemaid wakes him up...
    #5
  6. slideways

    slideways permanent ex-pat

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  7. Kamala

    Kamala Long timer

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  8. Twin-shocker

    Twin-shocker Long timer

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    Firstly you are never going to make it run like a trials bike, but can certainly make it much more tractable and easier to ride relatively easily. The changes I am going to suggest are all small, and in themselves wont make much difference, but together should help with what you are looking for.

    Firstly get 2mm machined from the cylinder base, dry build the motor and machine cylinder head to get 1.5mm squish clearance. You will then need to accurately measure the combustion chamber volume, and get the chamber itself machined to reduce compression by 1 (if its 6:1 get it reduced to 5:1).

    Have a careful look at the flywheel, and see if it would be possible with the aid of a spacer behind the cover, to fit a specially machined brass weight to the flywheel, ideally this would need to be at least 500g.

    Next look very carefully at the pipe, and see if it would be possible to lengthen the front part where it exits the cylinder, possibly using parts from a used pipe from another bike.

    Finally test the modified bike, and make adjustments to the ignition timing which may be required to help the modifications work most efficiently.

    Those alterations will change the bike quite a bit, but are relatively involved, and will cost a fair amount of money, if you are paying someone to do the machining. All in all it might be better to look at getting a bike more suited to what you are looking for in stock form?
    #8
  9. anotherguy

    anotherguy unsympathetic

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    Never mind. I gotta stop that shit.
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  10. joexr

    joexr Banned

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    :rofl:rofl:rofl
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  11. sieg

    sieg Wearing out tires......2 at a time, day after day.

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    All good ideas here, except, the you can't detune a 2 stroke.

    Eric Gorr yes, when he got done with my wife's YZ 125 it pulled better off the bottom than my KDX. It had no hit but smooth power all through.
    #11
  12. Twin-shocker

    Twin-shocker Long timer

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    If you cant detune a 2T, then why dont all trials bikes run like MX or road race bikes?

    Those who profess to be 2T "tuners" on here, dont seem to have much grasp of very basic stuff though, and I would guess would only be able to suggest fitting extra head gaskets..................:rofl

    The things outlined in my earlier post, should go some way to helping achieve what the OP is looking for, but in terms of cost probably going to be more than changing the bike for something more suitable.
    #12
  13. slideways

    slideways permanent ex-pat

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    I would not not call what Eric Gore detuning.

    When I had him do my 01 CR 250 I was amazed and a bit skeptical when I got my cylinder back to see that he had epoxied in the intake tract and transfer ports and totally reshaped them. He explained to me that he increased the volumetric efficiently at low RPMs to give the motor more bottom end and a better spread of power across the rpm range.
    #13
  14. Flood

    Flood F5lood.

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    :eyes
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  15. B_C_Ries

    B_C_Ries Long timer

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    That is amazing, I never thought that there would be an epoxy that could survive in an exhaust port, must be incredible stuff..


    Eeer, never mind just re-read the post and saw that it wasn't the exhaust that was epoxied, I got a bit excited when I thought there was some epoxy with supernatural powers.
    #15
  16. PSchrauber

    PSchrauber Been here awhile

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    May be old fashioned, but this are some of the tweaks KTM made to tweak their MX models to Enduro bikes in the end of the eighties:

    - they restricted the air flow through the airbox, A
    - a thicker head gasket, B
    - a heavier flywheel, C
    - a more restricted rear silencer, D
    - a smaller carb, to add something else, ( will increase low and mid throttle and decrease high end power output ).

    A and C are certainly too done to get the moise output down.
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  17. Sp4rks

    Sp4rks Been here awhile

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    Maybe a pipe and expansion chamber that favors the low end? Provided you could find someone who makes one for that model.
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  18. anotherguy

    anotherguy unsympathetic

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    You can strangle output with pipe/carb/timing but it's the port timing that sets the stage for RPM efficiency range. Cutting the cylinder base .030"/.75MM and adjusting squish to suit will be the most efficient way to tame output. Some tuning from there will adjust to suit preferences. It will still be a compromise with the pipe/carb.

    Me? I'd give Scott Clough a call.
    #18
  19. Shocktower

    Shocktower Long timer

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    Also RB designs in Portland can/may help you too, nice guy and some what local to you :evil
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  20. Foot dragger

    Foot dragger singletracker

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    The CDI box makes a huge difference in how the thing runs,the box off the enduro model might make a huge difference.

    But any modern 2 stroke should have decent low end already rt out of the box,its the old clunkers that are peaky screamers.

    Make sure the top end is fresh and see what sort of flywheel can be fit.
    Also check that the power valve isnt stuck.

    Or buy a bone stock KTM 300 most any year,they run great!:lol3
    #20