Want To Turn TM 125 IN CR eater

[brent j]

To fit the YZ80 ignition I made a stepped plate to take up the difference in size between between the TM backing plate and the YZ one.
To fit the rotor, I set up the TM one in a lathe and set the compound slide to match the TM taper. I then bored the YZ rotor to match. There is enough meat to do this but not a lot to play with.
*I lapped the rotor to the crank, set the timing with a dial gauge and just bolted the rotor on. Don't bother with the keyway, it doesn't match up anyway.

*with thanks to Lozza

[brent j]

Here's my take on making a TM fast. Keep in mind that this is from a guy who ran nearly last in class at the Nats but I will plead bike problems which I have since sorted (I think!)

Don't go overboard with trying to get too much power out of the motor. They have fairly wide spaced gears and if you get them too peaky they won't carry the next gear. Try to just increase the standard power characteristics. They can get out of corners well with a wider spread of power.
Are you building this to race for your self? if you are going to get some 55kg kid to ride it then bomb it up to the max and let him try to kill it. If you're a bit like me, 80kg and a bit out of shape you don't want something that is going to wear you out and have you tap dancing on the gear lever all the time.

Sort the suspension!! These bikes are very stable and turn well. Good shocks set up for your weight, damping valves in the forks and heavier fork springs. At the Nats I found that while I was down on power I could take any line I wanted and know I was going to stay on and straight.

[Lozza]

Hey Loz, would a YZ ignition be good for an RM125B ?  All those early TM/RM ignitions look the same.  Has the YZ stuff got a more comprehensive advance curve?

I would have to see the RM curves to know for sure.

[suzuki447]

hi i,m doing up two tm125 at present .one has a gem reed valve block and bassani upipe.other will have bassani downpipe.question ,will the reeds make much diference.

[John Orchard]

I always wanted to put reeds into my TM125; is your reed block large enough?  I guess you'd have to trim a large cut-out from the intake side of the piston as on other reed valve engines (or you'd get less power lol).

I use to swap back & forwards with a Bassani down-pipe and a Terry Bryant shortened stocker with a straight-thru muffler, the shortened stocker gave heaps more power.  The Bassani was all low-down (as much low-down as a 125 two-stroke mxer makes lol).

[Doc]

The reed may have looked the goods but no real world difference build it stock, match the ports and gaskets, fit larger TM250 front forks/front brake, 3.50x18 rear tyre and ride it like you stole it. The TM125 has better low to midrange power and will stop and turn in a blink. Trying to match it with a CR in straight line HP will cost a kings ransom to even get a look in so 'in my opinion' look at the other options. Handling and brakes    

[Lozza]

Unless you put added ports in the reed will make little difference. Hey Doc you forgot to weld that kick starter on

[Doc]

  took some grinding to get the bastard off I can tellya Loz! I couldn't understand because after it was removed there was nothing wrong with either splines

I'd reckon with the reed at high rpm it could well hinder the flow. It was my way of thinking, the ports cut in the skirt at said high rpm wouldn't achieve much  and low end power wasn't the issue Although there was a 'little' more down low it wasn't noticeable unless puttering around. The carb was a 28mm and the jetting seemed pretty much in the ballpark so I removed the reed and left well and good enough alone        

[vmx42]

Big Bore!!! Nobody will ever guess, until you start winning... 

[Lozza]

.......... so 'in my opinion' look at the other options. Handling and brakes    

That's code for TS185 shocks 

[Doc]

TS185 shocks with Koni spring keepers Loz..amazing how much extra performance can be found in swapping just the keepers but shhhh..it's a secret  

[Lozza]

off to scour ebay.....................................................................

[Dono113]

That motor is way too pretty to race Doc

[Doc]

That motor is way too pretty to race Doc

Cheers Dono, while I may not race that's not to say it hasn't been used. Nothing is above being thrashed


CD7

[firko]

Hey Doc, I know it's a long way from sunny Bris Vegas but are you coming down for CD9? It'd be good to see you.