TDMR40 upgrade

Please share your secrets! What mods have you made to your TRX?

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WoTi
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TDMR40 upgrade

Post by WoTi » Sat Jun 27, 2020 8:05 pm

I have had my TRX for over 15years, and finally after thinking for many and many years I finally decided to update to flatslides.
I bought the Mikuni TDMR kit made by Topham at Germany.
Currently the bike has full Akrapovic exhaust system, so wishing to have about 10hp more.
Bike is driven about 45k km.

today when I removed the old carburetors the intake looked like on the picture. Never before looked inside 4-stroke motorcycle head.
Is this looking like original TRX? The rubbers are about 36mm and the aluminium intake hole is few millimeters bigger measured with finger.
How much is the rubber limiting?

Image

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jpe70
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Re: TDMR40 upgrade

Post by jpe70 » Sat Jun 27, 2020 9:01 pm

That is stock.

Considering it's not a high performance bike at all that is nothing you'll notice without optimizing a bit more first. So for that to make a difference you need more mods, start by putting the bike on a dyno to get a correct jetting of the carbs. That is a bigger issue. :)

I have same setup as you with Akra 2-1 and TDMR.

WoTi
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Re: TDMR40 upgrade

Post by WoTi » Sat Jun 27, 2020 10:08 pm

Thanks,

I have a dyno near me. Have to get it running again first and test with assdyno.

At this stage I think no extra tuning for the engine will be done. I will use the std airbox with K&N inside.
Topham kit is jetted for that but there is always some misalignment due to exhaust system etc.

If significantly more power is needed maybe SV1000 or something else is more reasonable.

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jpe70
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Re: TDMR40 upgrade

Post by jpe70 » Sun Jun 28, 2020 8:10 pm

WoTi wrote:Thanks,

I have a dyno near me. Have to get it running again first and test with assdyno.

At this stage I think no extra tuning for the engine will be done. I will use the std airbox with K&N inside.
Topham kit is jetted for that but there is always some misalignment due to exhaust system etc.

If significantly more power is needed maybe SV1000 or something else is more reasonable.
Essentially you are correct. If you want 100+ figures another bike is only viable option. Way too much work and money involved getting the TRX over 90-ish figures just for sunday rides. SV1000 or even better an Aprilia RSV.

I'm using the TRX just because I can and it puts a higher demand on me as a rider, not because it's fastest. Seriously lacking in punch I'm way outmotored most of the time, but small enough track and around 100 hp is all that can be used and new 1000 can't go much faster than me. But it's a change from my Yamaha R1 endurance racer with 170+ hp on rear wheel.
Last edited by jpe70 on Mon Jun 29, 2020 2:26 am, edited 1 time in total.

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Tarwetijger
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Re: TDMR40 upgrade

Post by Tarwetijger » Sun Jun 28, 2020 8:56 pm

The rubber looks standard but your inlet ports doesn’t!

WoTi
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Re: TDMR40 upgrade

Post by WoTi » Sun Jun 28, 2020 9:12 pm

The inlet port was what i was interested of.
The surface anď the valve inlet edges looked a bit strange.
When I bought this it had micron cans, stock carbs
and some cheap pod filters..

You think someone has tried to improve the flow?

WoTi
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Re: TDMR40 upgrade

Post by WoTi » Sun Jun 28, 2020 9:27 pm

First impression from test leg was that the bike pulls quite well now. And runs otherwise nice, except when opening full throttle it does not pull just chokes, when turning the throttle back some amount it stars to pull again..

As said Carbs have the Topham setup for std airbox.

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Tarwetijger
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Re: TDMR40 upgrade

Post by Tarwetijger » Sun Jun 28, 2020 10:10 pm

It does look like the inlet has been reworked, yes.
WoTi wrote:First impression from test leg was that the bike pulls quite well now. And runs otherwise nice, except when opening full throttle it does not pull just chokes, when turning the throttle back some amount it stars to pull again..

As said Carbs have the Topham setup for std airbox.
Sorry to tell you but that's the whole point of flat slides. CV carbs do some smoothing for you with the butterfly (?) valves. With the flat slides you directly open the slides and then there is nothing left to obstruct the flow of air and fuel to your engine! So, smoothing the rough edges off, you have to do this on your own with your right wrist from now on!
Get rid of the airbox to open its full potential, especially since you have Akra headers and probably a tuned cilinder head.

WoTi
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Re: TDMR40 upgrade

Post by WoTi » Mon Jun 29, 2020 7:16 am

Thanks for clearing that. Always learning something new.

I think I will try to find the previous owner and ask if he remembers after about 20 years what has been done to this engine...

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