Author Topic: RT-1 Transmission  (Read 1622 times)

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Offline Tahitian_Red

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RT-1 Transmission
« on: June 03, 2012, 05:34:04 AM »
With the broad power of the RT-1 motor, could you get away with racing MX with the wide ratio trans or should you switch to the RT-1MX trans?
The "Factory Novice"
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'74 Suzuki TM100, '75 Bultaco 250 Pursang, '77 Honda XR75, '77 Suzuki RM125B, '77 Yamaha YZ400D, '79 Honda CR250RZ Moto-X Fox Replica, '83 Honda ME480RD Mugen

Offline Iain Cameron

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Re: RT-1 Transmission
« Reply #1 on: June 03, 2012, 11:06:06 AM »
Ive never had a problem Red , but saying that Im not at the pointy end of the field . Iain
Yamaha tragic ; dt1, rt1, dt2, rt2, dt2mx , rt2mx , mx250, mx360,sc500, 74dt125, yzx125, yzc250, yzc400, yzd250, yzd400, yzh250, yzh80 , dt100 , xr75 ko xr80 03 , it175 82 . Not a member of any club

Offline vandy010

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Re: RT-1 Transmission
« Reply #2 on: June 03, 2012, 11:45:15 AM »
just off the top of my head,
i think 4th gears the same anyway.
so that leaves 2nd, 3rd and 5th to play with as 1st only gets used in the pits, so why even bother with it.
my RT1 has MX 2nd & 3rd yet retains the std higher ratio top gear.
i deliberately did that so i could trail ride it as well as MX it and the higher ratio top means i don't really need to change the gearing.
i did ride it for a while in MX with the std ratio's.
not neccesary but yes, it's an improvement for sure.
« Last Edit: June 03, 2012, 12:04:12 PM by vandy010 »
"flat bickie"

Offline firko

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Re: RT-1 Transmission
« Reply #3 on: June 03, 2012, 12:16:50 PM »
The trans in my piston port RT1 is now standard enduro after swapping motors and my new Hindall motor has a close ratio due to it being an RT2MX ::). I've also kept the stock ratios in my Hindall RT1 flat tracker mainly because that's all I had but I don't think it matters so much on dirt track. I've got the DT2MX ratio'd original piston port engine from the Cheney waiting in the wings for a new rod kit so it may go back once the crank's rebuilt and balanced. I've got a YZ250 A trans in the methanol DT1 engine from the DT1 from Hell which worked a treat with the peaky ported motor. I may swap it over into the Cheneys 360 if the stock ratios don't cut it.
In an earlier thread the DT2MX,YZ A/B and stock ratios were discussed and I recall it being explained that there were some ratio glitches with the DT2MX trans but can't recall the points that were made. My guessing is that the RT1 would be torquey enough to handle the stock ratios but the closer ratios would be a touch better.

I would have found out what worked next weekend at the Nats but unfortunately I've had to pull the entries for health reasons. I'm just not up for the journey at the moment so I'll have to wait until CD9 to properly sort the bikes.
'68 Yamaha DT1 enduro, '69 Yamaha 'DT1 from Hell' '69 DT1'Dunger from Hell, '69 Cheney Yamaha 360, 70 Maico 350 (2 off), '68 Hindall Ducati 250, Hindall RT2MX, Hindall YZ250a , Cycle Factory RT2MX flat tracker, Yamaha 1T250J, Maico 250 trials, '71, Boyd and Stellings TM400, Shell OW72,750 Yamaha

Offline crossedup2

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Re: RT-1 Transmission
« Reply #4 on: June 03, 2012, 01:32:46 PM »
I have always wandered if any of the MX360 gears fit. I picked up a complete gear set recently and wanted to compare. Like Vandy I'd be looking at a couple of gears only if the whole set does not fit (and work).

I scored a Nathan S project RT1 bike is a swap a couple of years ago and would really like to have it going for the CRC in July. I guess we'll see in the next few weeks if the gears swap over (and I have the time).

Regards

Peter B
Anything Yamaha. AT1, CT1 (X3), RT1, DT3 (x3), YZ125X,  YZ250E, YZ400D, IT175E, IT250H, XR500RC . Always looking for Pre 78 Yamaha stuff....

SPANISH ARMADA

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Re: RT-1 Transmission
« Reply #5 on: June 03, 2012, 06:34:40 PM »
leave all your trans ratios stock they all work fine try 14/49 it get things going get rid of that stock 46 rear cheers

Offline Freakshow

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Re: RT-1 Transmission
« Reply #6 on: June 03, 2012, 07:13:22 PM »
i reckon im on 15 /52,  ride around in 2 3 4th.  probally could be better but im bnever in a position to worry about it .
74 Yamaha YZ's - 75 Yamaha YZ's
74 Yamaha  flattracker's
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For sale -  PRE 75 Yamaha MX stuff, frame, motors and parts also some YAM DT1,2,A and Suzi TS bikes and stuff