General Discussion Forum for TRX Enthusiasts...
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Rod.s
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by Rod.s » Wed Mar 26, 2014 11:48 pm
NWS870R wrote:Rod.s wrote:NWS870R wrote:As Phuk pointed out there is so little in it i can't see it's worthwhile, the Kent YAM9 re-profile is so mild that it certainly wouldn't warrant slotting the cam sprockets IMO. Had my head skimmed/flowed some 15 years ago & all is good without altering cam timing/slotting?
You might not see the worth, but I am sure EVERY quality engine builder in the world can

It's not only the gain in torque/HP but the engines total balance and a reduction is vibration that is gained. Sonic vibration has been known to atomise fuel in carburettors, starving an engine within a small RPM range.
Horses for courses, if you an't got the right horse you gonna lose, then all you are is a horseless looser

Loser? Was there any need for that Rod? Personally i don't give a toss what you fellas do with your engines TBH. I was just saying that unlike yourself i have met SDN & know what he uses the bike for & it will not require slotting of the sprockets.
Some people shouldn't be allowed near the internet

Wow, someone needs their sense of humour adjusted. The horse comment was a follow-on comment from dandywarhol's and relates to doing thing correctly otherwise you may end up with a blown engine and lose the race, hence a looser, that is why it was said in a separate paragraph.
Engine modifications should alway be based on engineering science, pure and simple

If it's not made in China, it's a fake!
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dandywarhol
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by dandywarhol » Thu Mar 27, 2014 12:26 am
I wasn't implying you had NWS - I was just appealing for a bit of calm

1996 TRX 850, blue, Ohlins 46HRCLS, Race Tech Gold Valves, 0.90 springs, Venom pipes, R6 brakes............
1974 Yamaha RD250A, Candy Blue
1998 Yamaha SZR660, blue of course
1967 Yamaha TD1C 250, Blue and white
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NWS870R
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by NWS870R » Thu Mar 27, 2014 12:45 am
I'm perfectly calm

Life is not about finding yourself, it's about creating yourself.
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QuickDraw
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by QuickDraw » Thu Mar 27, 2014 1:41 am
Rod.s wrote:QuickDraw wrote: I'm talking of skimming a head 0.25/0.40 mm to raise the compression - then you need to slot the sprockets
I hadn't thought of this ...good to know! Head-shave is coming up on my list in the next few weeks. How many cam degrees thereabouts would we be looking at?
Are you looking at skimming the head for the added compression or to true/repair the head?
Added compression is what I'm going for. I was going to check for related posts before starting another string, but since you're asking...
Cams are mild Tighe units. Intake has an extra 6 degrees ABDC so I figure I'd be slightly down on standard compression in the low-mid velocity range. So the questions I'm looking to answer are;
• What's a good ratio to aim for? I'll be using 98 octane like I always have. And no Cobba', I won't have programmable ignition to start with
• I'm guessing I'll need to have the engine assembled to turn over and measure valve-piston clearances with plasticine to determine what's reasonable to achieve.
I'm keen for any advice / experiences.
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SDN
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by SDN » Sun Mar 30, 2014 8:47 am
Cheers for the replies guys - as Chris said I am not a racer! The bike is used on roads only and I just want a bit of a seat in the pants increase in usable shove. TBH was quite happy with what I had, but was ripping the motor apart to deal with the ridiculous oil consumption and it was a case of I have a chunk of money - why woiuldn't I?
Hopefully the investment will deliver and will not spoil the power delivery - fingers crossed
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dandywarhol
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by dandywarhol » Sun Mar 30, 2014 11:24 am
My TDM900 had Yam9 cams fitted and porting by TTS before I bought it.
Coupled to Akra cans and a Power Commander it made it a responsive, torquey motor - not a huge power increase at 88 at the wheel but great mid range, just where you want it.
1996 TRX 850, blue, Ohlins 46HRCLS, Race Tech Gold Valves, 0.90 springs, Venom pipes, R6 brakes............
1974 Yamaha RD250A, Candy Blue
1998 Yamaha SZR660, blue of course
1967 Yamaha TD1C 250, Blue and white
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SDN
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by SDN » Tue Apr 01, 2014 7:18 pm
Good answer, if I wanted massive power I would just sell the TRX and buy an old R1 probably be cheaper as well! ( heresy I hear you cry, burn him at the stake). As we all know you can have lots of fun without scaring yourself silly with bhp
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SDN
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by SDN » Fri Apr 04, 2014 8:53 pm
Well cams are here, but TTS busy and head won,t be done till next week. BTW to glaze bust bores what grade of wet n dry is best?