Yamaha TRX850 Enthusiasts Forum

What's better than a TRX?

Two TRX's!

I picked this one up today, the previous owner is Lars.





Is has a broken engine, but has some nice extras: bluespots with braided lines, Laser mufflers, WP front suspension and came with an extra fairing. One of the cams got stuck (don't know how to explain properly) and caused damage to the crank. I know someone who could fix that for me though and I have a spare cil.head. So, it's a projectbike!
I expect something like 666mph showed us before, but less dramatic.

Having two is just greedy! Good luck with the rebuild.

Tarwetijger wrote:What's better than a TRX?

Two TRX's!

I picked this one up today, the previous owner is Lars.

Absolutely. Well done mate, it's always nice to have a project.

Nice Tarwe

Trx for her (Mrs Tarwe)....

As I'm a couple of days off, I've started with the new project immediatly.

Temporary parking space.


A jammed cam caused the damage to the engine. The traces on the cam don't look too bad, but it turns heavily.


Damaged crank


Close-up


All exhaust valves are bent


And a cam chain with special features


Halving the engine


The crank is held into place with these weird bolts! The carton is a tip from the Haynes book, so I know which bolt goes where later on.


Loads of parts, don't know where to place them!


Found a lot of crap and sludge in the egnine.


Tomorrow I'll get the damaged crank and this one from a TDM (3VD) to a specialist, who can make one good crank from two broken ones.

Plenty to do, hope you got her at a bargain basement price?

We don't need words for this....

After this project you'll be a trx master

Mincehead wrote:Plenty to do, hope you got her at a bargain basement price?

The price was okay I guess. At least I knew the engine was damaged.
But I found the first disappointment already; the cilinders are oval.
I brought the crank(s) to the specialist today and he has cilinders for me, which are in good condition.
With new piston rings it should be alright. The only thing I have do is to order a new cam chain, then I'll be good to go.
Yes it all adds up to serious money, but in the end I'll have a healthy TRX for a very reasonable price.

The bores are oval!!!
That must have burnt oil like a mother humper. The cam chain was obviously worn beyond tensionable limits hence the jumping off the crank sprocket, all fun and games.At least you`ll be incredibly familier with the `workings` of the TRX motor by the time you`ve got her back together.

Hi Tarwe, You'll have to excuse my ignorance but I've a couple of questions: What model TDM is this crank out of - It appears to not be a 270 degree crank like the TRX one - will this crank work in a TRX motor & will you lose the feel & sound that the TRX has if using this style crank? Also, one of the TDM conrod journals appears to be damaged (the lower one in the picture) - can you get this repaired over there as Mr Yamaha probably doesn't make undersize bearings. (as with the TRX) But....looking at the colour of the two cranks, maybe the TDM crank isn't heat-treated like a TRX crank is - TDM crank may be grindable with undersize bearings available?

I think he`ll only be using the section with the camchain drive sprocket on it pbear62, therefore the `throw` of the crank is unimportant.

Mincehead wrote:I think he`ll only be using the section with the camchain drive sprocket on it pbear62, therefore the phasing of the crank is unimportant.

No probs Pbear62, it is exactly like mincehead says. Only the small sprocket will be used of the TDM (3VD) crank. It will be literally cut off and put on the original 270 deg. crank. Looking at the cranks it is hard to believe it is even possible to do this. But they assured me that did it like this before!
You're right that the conrod journal is damaged, it's the reason I could get the crank cheap. Although I don't need that part, that specialist I mentioned showed me a crank where such a journal was actually repaired, so they even can do that!

Yep,modern metal spraying and heat treating techniques mean that even badly damaged bearing faces/journals can be reground to stock dimensions and tolerances.
It`s just about the bucks really,if you can afford it, it can be reclaimed.

Time for an update. I got all the parts back, so it's now just a matter of getting it back together... which is easier said then done of course.
The crank is back in place. Quite a job to make the timing with the balancer shafts correctly, but I managed.


I had to buy an other set of cilinders, because the old ones were a little oval. The pistons were allright though.


I'll be using the original cylinder head. It appeared that the spare head I already had, was even worse.
The guys who fixed the crank also had a go on the cil.head, the cams move smoothly again.
Here's a funny shot of the exhaust valves, they were all bent.



One of the bolts of the oil reservoir was broken. A small piece of it was still remaning in the bolt hole. I got the engine to the local garage (where I always bring in my car), but they didn't want to help me. I borrowed a tool, for which I don't know the english name, but it worked!


I think that oil was closed in by the bolt when it was put on earlier on. Before my time anyway because the remains of the bolt just dropped out when I was working on the engine.