Yamaha TRX850 Enthusiasts Forum

Hi All,
seeing as though in the main all the work is done on my TRX900, I have decided to progress my dad in laws TRX project for him. he is currently getting some house work done and his bike was being stored in my garage, so it would be rude not to really

so a bit history on it:
I found it on gumtree, through a link on here actually. I called the guy up, and the bike turns out to be a Bemsee thunderbikes championship winning bike, and comes with 878 big bore, kent cams, and 41mm FCRs, 2 into 1 'custom' exhaust system, and a shed load of spares including fairings, belly pan, wheels, and what looks like an entire spare engine in parts.

When I had a good look at it it turns out hes done a lot of work stripping of parts that are not necessary, including all none necessary wiring like indicators etc. I also noticed a lack of a rectifier, so I suspect it was running a total loss system. I am hoping he wasnt too thorough and pulled out the alternator from the engine. If thats the case then we have spares to go in



You will notice the crash bungs have been nicely 'shaped', and judging by the dents in the petrol tank its been down the road a bit!



I have fitted the complete uncut wiring look from my TRX, so that was that sorted, need to adapt the ignition barrell wiring from the R1 into the TRX loom.

Also I cant seem to find the 3 pin feed from the alternator, can someone take a photo and show me what it looks like? I have a 3 pin connector in the correct area, but its a completely different fitting. I have used the rectifier from my TRX so the connectors should match up. I have used the entire tdm900 wiring and components on my TRX so I have a lot of spares - handy.

So thats about it so far, one of the curious things on this bike is the guy has drilled the clutch cover and fitted 2 big pipes that come up to the front of the bike. I am thinking positive crankcase ventilation, but why two of them?









I will try and get some regular updates on this.

oh also, those of you that have FCRs, what have you done about the throttle cabling. we only have the R1 cables here and they are way too long.
do the stock trx cables work?

coxylaad wrote:oh also, those of you that have FCRs, what have you done about the throttle cabling. we only have the R1 cables here and they are way too long.
do the stock trx cables work?

I got two bicycle cables from halfords... Use the Trx cables housing, round cables ends in the throttle housing and on the carb side, some tension adjusters and screw on nipples to set the cable length. Cheap and cheerful, used for over two years & 10000mls without issues.

cheers drix sounds like a plan to me.

so all I need to progress now is a picture of the wiring from the engine alternator to the loom. I expected it to be 3 thick white wires, but I cant find anything apart from a different style thinner three prong connector with multicoloured thinner wires on it.

any ideas?

Wonder why he had the Ducati sticker on it?? In humour?

coxylaad wrote:oh also, those of you that have FCRs, what have you done about the throttle cabling. we only have the R1 cables here and they are way too long.
do the stock trx cables work?

You can get all the bits to make custom cables fron Venhils - quite cheaply

Trixed wrote:Wonder why he had the Ducati sticker on it?? In humour?

It has to be taken off.

Nice bike though! After some cleaning that is.

Can anyone tell me what the feed from the alternator on the engine looks like?

I am expect a three pin plug with white wires behind it, but I cant find anything. There is a 3 pin plug there but its got a few different ones and its the wrong shape to fit into the regulator.

a picture would paint a thousand words.

I am starting to this the guy who had this before has run it as a total loss system and maybe even removed the alternator altogether...that will be fun to reinstate.

well this has sat dormant for 3 years and now its changed hands from my father in law to my dad.

we will be getting in running shortly as a track only bike

He `may` have calculated how much air can be displaced from the crankcases and decided to install two breathers to carry the volume of air away. They run uphill to allow oil to run back obviously, most folk put extra breathers in the other side of the motor but hey it matters not where they are as long as they work.

I was thinking on this last night too Mince, I wonder it it also keeps the clutch a little cooler too breathing from the RHS clutch cover.

Big breathers are a sign of four stroke performance ignorance. The rest of the world found out a long time ago that big breathers cost horsepower. Where do you think the power comes from to pump that air in and out of the cases? From a performance viewpoint even a totally sealed crankcase is better. A superior setup is to have a fast acting one way valve in the breather line that will pull a vacuum in the crankcase. This has several benefits and crankcase vacuum is standard on high performance engines.

lenny wrote: A superior setup is to have a fast acting one way valve in the breather line that will pull a vacuum in the crankcase. This has several benefits and crankcase vacuum is standard on high performance engines.

A popular mod among the Brit twin frat is to use the reed-valve crankcase ventilator from the XS650. Readily available from MikesXS in the states. (Only issue being shipping is more expensive than the part price!) Dunno if anyone has ever adapted one to a TRX.

can you not use a valve from a brake servo on a car? they must be pretty fast acting

Get one free. Go to any wreckers, find a car with a brake booster on the firewall (most cars)... You will see a hose that runs from the booster to the inlet manifold. In that hose will be a high quality fast acting one way valve that is ideal. Incidently, the tdm has a reed valve setup in the head and valve cover that is easily replumbed to provide crankcase vacuum.
I think he was trying to impress numpties, big breather and fake braided hoses, what a laugh.