Yamaha TRX850 Enthusiasts Forum

Best laid plans an all...

I planned to do some more work on the TRX, but its currently tucked under a blanket in the garage untouched.

Sometimes life (or other motocycles) get in the way!

It only took one week off from work to gather energy to go to the garage and get something done. Bleh...

But I did manage a few small things between christmas and new year.

Gearing
A bigger and lighter Renthal 44 aluminium sprocket in the rear. According to Gearing Commander my wider and higher 180/60 rear wheel negates the larger-than-stock 41 rear sprocket, something I didn't reflect on until I couldn't get bike to redline in 5:th like before. Not even with TDMR's mounted. So, compensation calculated to a 44-cog. Will need to get a longer chain, but I did gain 500 grams in weight.



Rear light
A bit of massage, not really a modification but looks much better IMHO without tucking it in completely as is common. Cut out the rear of the undertray, chop off the end of the frame tubes and angle the end slightly. Saving the fittings at the very rear and using them for the new mount made from simple 1 mm sheet metal. Result is a light that sits 15-20 mm better. Measurements was a bit off, so height of the plate was ca 3 mm too much at lower bend. Some gentle persuasion cured that, but the drawing needs updating. Holes were spot on believe it or not!



You have your own bike to compare with, so no point in putting up a "before" pic.

but I did gain 500 grams in weight.

...and the extra weight added by the bigger tyre and longer chain is...

trixynut wrote:

but I did gain 500 grams in weight.

...and the extra weight added by the bigger tyre and longer chain is...

Naught. It's 900 grams lighter than stock... Oh, minus guesstimated 100 grams for the two new links in the chain.

Stock rear wheel with 160-tyre: 13,4 kilo
R6 rear wheel with 180-tyre: 12,5 kilo

Breather valve
This is not new, actually fitted it before last ride 2019 but only today got a filter in place. After reading a bit on crankcase ventilation and shifting pressures I installed a one way valve in the hose between valve cover and air box. The theory being this will let pressure out but not let the engine suck air back in somewhat eliminating foaming and overpressure. We'll see how that works out...

A brake servo inline valve from eBay and a K&N breather filter to end the hose now that the airbox is removed.

1 question..
Where is the “LIKE” button on the forum???? Mmmm
That’s right.. back to emicons

nice work. I think there might be something in that. I had a similar positive crankcase ventilation setup on my essentially stock 900 motor, and used to scream right round to the rev limiter

There will be no engine rebuild this year, although sorely needed bike will have to keep it together for another season of 5-8 track days. This is one way of trying to ease the existence for the engine so hopefully it'll help a tiny bit.

As for something else... something from the history of the bike. When people ask what exhaust I have on my TRX:



But that's not a TRX you say? True, but only difference is collector pipe and that is easily modified.

So why not take the tdm motor out and put it in your trx?
How often do you use 1st gear on the track anyhow.

cobbadiggabuddyblooo wrote:So why not take the tdm motor out and put it in your trx?
How often do you use 1st gear on the track anyhow.

Simply because I sold that TDM back in -06 when I first bought the TRX, but kept the exhaust.

The TDM I have left is an old 3VD with 180-crank and way more mileage...

Updated v96 firmware for the TCIP4. Build 200124 compared to the previous 1909**. No new functions what I can see, so not that important. But I can't help myself...

Rear shock
Not much of it. Sent it away to hopefully be re-shimmed and serviced (I thought the spring seemed somewhat adequate). Got it back today only serviced, "lighter oil change" they called it. Seems that's the end of that. At least an oil change after 15-plus years is not a bad thing. So unless a lottery win or something happens, I'll be easing a stock shock around the tracks another season. Fortunately the raised rear and changed geometry seems to make the job easier, I'm not undone but it's shortcomings just riding the pegs if full throttle turns get uneven...



Front end
So, seems like I committed to a paint scheme by dropping a splash of silver on the front fender. Now just need to match that with some wrapping on the fairing and maybe fuel tank. Watch this space for 2020 design...

Spark plugs
Not exactly much of a mod, but dropped a pair of NGK JR8C in today. Short start and bike sounds strong and smooth. Will do a warmup later when I have proper amount of coolant in it.

List of Ohlin's springs that fit the TRX rear shock...I'm running the 01099-31y/95

Huge update today!

Nah, not really. Replaced a few of the old and not-so-old-but-ugly cable ties today with happy ones in velcro! Very tidy and visual.