900cc high compression conversion

philk · Post by **philk** » Tue Jan 08, 2008 1:40 pm

OK I have just had a lengthy conversation about pistons with TTS and they would be willing to get a batch of 900cc high compression TDM900 pistons made up.
The idea being that I will order a new TDM900 barrel from Yamaha.
Advantages being I get the ceramic bore and high comp pistons and 900cc.

I will have to order four pistons as minimum order,this will cost aprox Ãƒâ€šÃ‚Â£500+vat.
so for a kit this will work out at Ãƒâ€šÃ‚Â£250+vat.
Plus barrel cost Ãƒâ€šÃ‚Â£291.86 inc

I also discussed a batch of carillo rods @ aprox Ãƒâ€šÃ‚Â£200 each.again a min order of 4.

So first question, does anyone have a TDM900 piston i can either buy very cheap or can borrow to get the oem spec from

2nd question Im guaging if any one is interested in buying the second set from me....or even a group buy let me know.
I am not looking to make any money out of this so the price will be what ever it costs me.ie cost price only.

Post by **phuk72** » Tue Jan 08, 2008 1:58 pm

I'd be very interested (had I not already got an 878 big bore). You get the benefits of 900cc, hi comp pistons and ceramic bore. Try on the Carpe site, I'm sure you'll have plenty of takers.

Any chance you can do a before an after dyno?

Surprised about the cost of the rods - seems very cheap to me.

Also, do the 900 barrells just drop straight on. IIRC teh rods need reaming to work on the 850 crank -* or will the Corillo rods sort this problem?

Keep me posted - and don't expect TTS to turn stuff round very quickly or to actually come in on price (was it Paul you spoke to?)

philk · Post by **philk** » Tue Jan 08, 2008 2:06 pm

I believe it was Paul i spoke to , although i have spoken to Richard as well.

The pistons will be TDM900 so yes the oem TRX rods will require reaming out. Im not trusting of Yamaha rods (owned a FZR600 mk2) so i want carillo rods and yes this will sort out the problem.

my understanding from this site is that the TDM 900 barrells drop straight on, and they only require skimming to raise the compression, which will be sorted by the high comp pistons im having made up.

barnarda · Post by **barnarda** » Tue Jan 08, 2008 3:47 pm

Hi i'd be very interested to. i am planning on an engine job soon. i had thought about the big bore.
let me Know what work is needed and the tolerances for the machining. how much is Yamaha asking for the 900 barrels
anyway keep me posted. andy

wicky · Post by **wicky** » Tue Jan 08, 2008 3:52 pm

ya the barrells will need quite a bit of skimming work to achieve a reasonable compression ratio. I too would NOT go down the route of having the little ends of the stock rods reamed out as i asked a bike enjun builder about this and he advised against it and suggested custom carillo rods or stock TDM 900 rods (which do fit the TRX crank and are about 11%-15% lighter than the stock 850 rods.) Might be worth machining off the '897cm3' which is stamped onto the barrells and paint them silver or black depending on yer TRX's enjun colour if your not going to inform the insurance company !!

edit; might be worth 'joining' http://www.carpe-tdm.net as we get a further 5% off Yamaha parts from Damerells in Plymouth 01752201807, ask to speak to Jamie as he's feckin' on the ball and will mail em out to ya. Don't be afraid to haggle over the discount....

anudder edit! the stock TRX camchain tensioner will apparently NOT work with the TDM barrells so i would suggest you use the latest modified TDM 900 tensioner which is...... (WiCkY waddles off to Carpe to get the part number)

latest modified TDM 900 cam chain tensioner 5PS-12210-10, and the tensioner gasket 5JW-12213-00.

cheesie · Post by **cheesie** » Wed Jan 09, 2008 10:43 pm

this is interesting, thing is I have an ohlins shock stash, 3/4 of the way there the money has gatherd quicker than I thought

maybe start a new poll upgrade my shock or big bore.

Quan-Time · Post by **Quan-Time** » Thu Jan 10, 2008 2:02 am

after looking into this a fair while ago, i pushed the TRX sleeves out of the block, made new sleeves, bored the block out, pushed them in.

carillo custom rods, yammy TDM pistons. At a later date i will change over to JE more than likely.

Im not fussed about the ceramic bore. Yes its nice to say you have it, but its not "needed". The engine wont burn itself out within 1000km or anything.

Changing to a TDM block is no end of problems. It can be done tho.

I wasnt aware the TDM rods were lighter than TRX ones.. interesting.. altho 200 pounds for a carillo rod does seem surprisingly cheap. Mine cost me just over $500 each AUD, so go try that on http://www.xe.com and see what it converts to.

I have a clean TDM piston here i can measure up and send you info on if you wish.. Take pics, etc..

Post by **phuk72** » Thu Jan 10, 2008 9:20 am

cheesie wrote:this is interesting, thing is I have an ohlins shock stash, 3/4 of the way there the money has gatherd quicker than I thought maybe start a new poll upgrade my shock or big bore.

No brainer - decent supsnesion will make you way faster than an extra 10 bhp.

youngy · Post by **youngy** » Thu Jan 10, 2008 12:05 pm

Oh yeah. Decent shock.

Quan-Time · Post by **Quan-Time** » Thu Jan 10, 2008 1:55 pm

i have to agree with the shock thing also..

If you REALLY want some extra oomph.. thought of getting a dynojet kit for your carbies, nice air filter and a larger rear sprocket ?

Those things combined should come in at not very much at all compared to a fork respring / revalve, or even replacing the whole front with a USD unit of some sort..

cheesie · Post by **cheesie** » Thu Jan 10, 2008 8:45 pm

ohlins it is then, on my last bike it was the best pound for pound enhancement, but then it had realy poor suspension to start with

allan · Post by **allan** » Sun Jan 20, 2008 12:28 pm

I have done the 900 conversion using custom made flat top pistons and TDM barrel, I had to grind out front and rear of the crank case as the outside diameter of the barrel is a bit bigger than the TRX barrel, to get the piston to deck height at .015'' I had to machine .015'' of bottom of barrel, the head only had .001''machine of to clean it up, using TDM base gasket and TDM head gasket with a .040'' squish I end up with 11.2:1 compresion ratio, when I mesured the standerd TRX compression ratio it was 9.9:1 If you are getting pistons custom made you could have the gudgin pin made to 20mm and the height from gudgin pin to top of piston raised so then you do not have to machine of the bottom of the barrel, and have the piston made to the same weight as the TRX piston. I had the piston skirt coated and the top ceramic coated as well as the combustion chamber valves and exhaust port cermic coated, the inlet valves are 1mm larger SS, new valve springs with S01 coating all done through HPC coatings, ports have been cleand up, cams are a Waggott grind set up at 109 ex 105 in, 41 FCR carbs K&N pods custom made 2-1 exhaust, still fine tuning to be done but need to that on a dyno, happy with end result but it has been a costly exersice but then you cant put a cost on a obsesion.
If you want the best power gain for money spent go for FCR 41 carbs K&N pods and a good exhaust.
But I could not settle for just the carbs and exhaust I had to go all the way.
Allan

cheesie · Post by **cheesie** » Sun Jan 20, 2008 12:41 pm

what was the cost allan if you dont mind me asking, sounds like you did most of the work yourself, how does the bike ride around town small throttle openings with the work

kookimonsta · Post by **kookimonsta** » Tue Jan 29, 2008 11:26 pm

i could be interested in some carillo rods any ideas if it will just be one lot there getting in of if there readly avaliable?

Quan-Time · Post by **Quan-Time** » Wed Jan 30, 2008 9:59 am

carillo rods aint cheap, i got some.. took AGES to get em aswell.

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