Tarwetijgers Winter Works

[Tarwetijger]

I started today to take the TRX apart. In order to get the bigger sanddune51 valves in, but also to reduce oil consumption while I am at it.
With the cams out, it showed there is actually some damage done to the journals I bet the cams were tightened too tight. Also the inlet cam turned quite heavily. It is not beyond repair, but the buckets can not get out now.


The valves itself don't look bad, I have seen worse. This engine has done between 25 en 30 thousand km.


The pistons look odd! There is some soot that is getting loose for some reason. It gets off very easily so no prob here I suppose.


Another funny thing: the longest bolt trough the oil reservoir was loose. It appeared to be broken. I had exactly the same thing with another TRX engine. Is this a typical flaw?


Well that's what I did today, I will post an update every now and then.

[sanddune51]

If there is a little wear that prevents removal of the cam follower, it is not too difficult to scrape a 0.3-0.5mm x 45degree bevel around the top of the cam follower bore.

I use an engineers "half round" or "triangular" bearing scraper to lightly remove the overhanging aluminium that is preventing the follower from being removed from it's bore. Scrapings can be washed away when head is fully dismantled.

Good luck with the overhaul and big valve job


Mark.

[Tarwetijger]

I don't have a bearing scraper but it is already done. With a sparkplug socket with a small piece of sanding paper around it.
The valves are out. I will buy some storage boxes because this is not going to end well.


As a japanese model the engine is black. But it looks like the inlet, inside the engine, also have been painted. The paint resolved and disappeared for the greater part.


These are the ones that will get in. Meanwhile they are sorted to outlet and inlet. There are two different lengths for the inlet.
Still a lot of valves for 'only' a twin cilinder.
http://imageshack.us/a/img34/8376/umpz.JPG

[sanddune51]

http://imageshack.us/a/img34/8376/umpz.JPG

I recognise those little beauties


Mark.

[Mincehead]

She`s been burning some oil Tarwetijger, that`s what`s been creating the deposits.

[Tarwetijger]

She`s been burning some oil Tarwetijger, that`s what`s been creating the deposits.

I knew that but why is it getting loose? I've never seen it like that before. Loads of soot, yes, especially on the valves, but solid as a rock!

Well as for oil consumption I need to get the cilinders and pistons off too and get them measured.
Back to garage again.

[Mincehead]

It`s soft because very likely the last time the bike was run it wasn`t run hard n hot for long, the residual hydrocarbons and fuel additives have softened the soots.

[Tarwetijger]

Last week I brought the cil.head to the lad that is going to do the porting/flowing.
He has quite some experience with this and built his own flow-measuring-equipment!
Although I didn't see it, I guess it is something like Quan-time wrote about on this forum before.
He will measure the orginal head, with the bigger valves and subsequently after flowing.
It will take some time but it will be very interesting stuff!

Today I got the cilinders and pistons off. The piston rings are beyond "service limit" for sure; almost 1 mm.


The cilinders itself look good. They are so smooth it is almost shiny. Too smooth??


The pistons don't look too bad either, I've seen worse. It looks like only on the side of the piston, some oil passed the piston rings.


One more test: Put the pistons, without piston rings, in the cilinders. They just dropped down without any resistance. I could even make them rattle a little.


I'm bringing the cilinders and pistons to a bikeshop, for measuring them. I wouldn't mind to fit oversize pistons, but lets see how it goes.

[cobbadiggabuddyblooo]

Yamaha no longer have any stock left and no longer available of oversize pistons .5 & 1mm but they do have the oversize rings to suit so it shall have to be an aftermarket set. A real art flowing and tuning heads. The old fella doing mine has had it for 3mths fitting the larger valves and tuning the head to suit the Kent cams , valves and Akrapovic system.. Remember tho if you go with JE pistons they are heavier so once I get get head and specs on where its tuned for optimum power, its off to have the pistons and crank balance to suit the tuning for that midrange punch out of the corners taking meat of the pins and lightening the pistons..

[Tarwetijger]

So no longer available eh? Hmm. Well, while I am at it, I might as well put some decent pistons in.
But balancing the crank, oomph, that sounds like a lot of extra work. Since the cil.head and pistons can be done with the engine in the frame.

[sanddune51]

That's strange, I had no problem at all obtaining +1mm Trx pistons from Damerells in Cornwall, U.K. just 5 months ago.

Is this an issue that may only affect Australia


Mark.

[Tarwetijger]

That's strange, I had no problem at all obtaining +1mm Trx pistons from Damerells in Cornwall, U.K. just 5 months ago.

Is this an issue that may only affect Australia

Maybe, I will find out.

Isn't it strange that aftermarket pistons have to come from the US? I know JE and Arias are the brands for pistons, if you want something for the TRX.

[cobbadiggabuddyblooo]

I know the oversize where available about 12mths ago but Yamaha told me they had no more 1mm oversize.. only the rings about 2mths ago.Just checked again my appologies, they still have .5mm oversize pistons... Maybe you have a little stock stash over your way of 1mm oversize...
It's costing $200 to balance the crank,pistons,pins,rods.. He will just spin the crank to the RPM's where things are flowed to work.
I know I needed new rods...
TRX rods are pretty solid but the only downfall is they don't like being overrevved as they stretch the bottom cap and your bearings start to wear.
Maybe thats why your cam followers where worn from lack of oil pressure at low revs, due to wear on the bottom shells and loosing pressure there... Food for thought...

[Tarwetijger]

Food for thought? That is just scary sh*t you telling me Cobba, please stop it!

[misterdimwiddy]

To give you some hope, my crank went this year and the LH big end and all mains were shot with BIIIIG clearances and yet my cam bearings were not in bad shape (some light uniform wear but had not picked up/scored at all). I do however think that the motor had low oil pressure (blinking oil light that stayed on below 2k rpm when hot!). Should have seen that as a sign of things to come but did not believe the switching pressure was right.

My advice would be to strip and check the bottom end condition esp if you are going for big bore high comp pistons and head work. Can you feel vertical play in either rod or when swinging on the generator rotor? My mains knocked very clearly when doing this by hand.

My tired motor did not last long once it had to deal with 878 and FCR's.

Now the pain is behind me and I am going for cams and a skim to give 12.0:1.

Good luck and hope you just need new shells (or nothing more than some gaskets and seals).