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Hi All,

thought you may be interested in the first dyno run for our new 904s Sports Big Bore Kit.

On this dyno there are three runs showing, EFI 865 OEM, EFI 865 with TTP Stage 2 Power Induction Kit and 904s with Stage 2 kit.



The bike was an 865 EFI Bonneville fitted with the TTP Stage 2 Power Induction Kit, Tune 12 & short free flowing silencers vs. the same bike with 904s Big Bore Kit installed with 904s Tune 12.

904s St2 vs. 865 St2 - Peak Power +12% (78.76 bhp), Peak Torque +18.1% (61.21 ftlb) & Max Torque Increase +20.5% @ 5,735 rpm.

904s St2 vs. 865 OEM - Peak Power +29.8%. Peak Torque +30.6% & Max Torque Increase 34.3% @ 4,173 rpm.


We're really pleased with the results, not bad for an OEM engine using the 865 cams and 904 big bore. The bike pulls really well through the rev range, which isn't surprising as it has more mid range torque than our carb 904 with Stage 2 kit, 790 cams and Keihin FCR39's carbs. The carb bike had 4bhp more at the top end due to 790 cams and FCR39's.

Next will be the same EFI configuration, but using the early 790 cams for more top end power........
 

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Nice result.

I seem to remember with the old triumphs that you could advance or retard the inlet cam 1 tooth and get a small power gain, does that still hold true with the newer versions?
 

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Pieman, just spotted this on your website. Bloody good effort for doing this. Makes such a big difference, doing a big bore the correct way, re-nicasil etc.

My question is do you have any plans on a 994cc??? I would be interested.

Chris.
 

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Hi Chris,

no plans for 994cc big bore or any other larger size, just the 904cc. Anything larger than 904 is quite specialist along with a complete engine strip down and very few owners want to go there.

The 904s is a bolt on upgrade which is relatively easy to install compared to anything larger. The power and torque results of the 904s installed on a "bog standard" EFI 865 engine are very good. We spent many hours on the dyno getting the ignition advance spot on for the 904s tight quench, 12:1 CR pistons, this helped tremendously with the figures obtained and ensures no pinging problems, even in mid summer temperatures.

We have the 904s tunes for ARC with pods and long/short free flow silencers complete, we are now working on the same but with 2-1 exhaust system. Then it will be tunes for the same, but with performance cams.
 

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Hi Mike, Love what you have done. I really need to pick your brain, I'm living down Plymouth now from Scotland. I changed from 2-1 to 2-2 exhaust aswell as the temperature rise and its rich everywhere. Had it on the dyno today and i have a flat spot from 4k-5.5k. Just too rich but still managed 82.9bhp. Would love to give you a bell mate see how things have been getting on and what you recommend settings wise. Will PM you.

Chris.
 

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excellent results Mike........with the 790 cams and head work, plus bigger TB's i reckon it would be about where mine is :grin2:


p.s.
i still haven't forgiven you for releasing this 904 kit 12 months after i spent a nasty amount of money on a TPUSA kit :wink2::laugh2::laugh2::laugh2:
 

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you pay your money and make your choice as they say Chris, but i feel that taking these twins beyond 904 with that comp gain is alot of work and trouble for marginal gains.

what i mean is the expense doesn't justify the gains in my book,
i feel that a good spec 904 is the sweet spot for these twins.
 

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Wish I could have packaged this with the ARK and Stage 2 kit a few months ago when purchased. I want to hear some reviews from owners on the forum but thinking I got to do this upfit this winter!


Sent from my iPhone using Tapatalk
 

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you pay your money and make your choice as they say Chris, but i feel that taking these twins beyond 904 with that comp gain is alot of work and trouble for marginal gains.

what i mean is the expense doesn't justify the gains in my book,
i feel that a good spec 904 is the sweet spot for these twins.
unless you get to ride a a good 994 or 1087 they make a 904 seam mild
 

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A few years ago I had South Bay Triumph put together their TPUSA 904 engine for my 2009 Thruxton. As I remember that included cams, bigger valves, clutch and sending the throttle body over to England. I already had different coils, D&D two into one exhaust, and air box delete. After I got it back we put a power commander 5 on it and took it to the dyno.

We were just at 85 HP and 59 ft lb of torque, so your horsepower readings are almost the same as mine with less work...congrats.

I have been running my bike for a few years now and about 5000 miles with no issues except when the engine kicked back and broke a boss on my engine case. This is known to happen occasionally to these bikes even when stock, Triumph replaced my cases with later models at cost.

My bike with a fairing and gearing changes ran 140 mph at the Bonneville Speed Trials in 2016. I have taken it to the drag strip and got 12.75 at 110 mph from it. So while it doesn't have 110 hp at rear wheel the real world performance is quite good.

I think your 904 kit is a great idea.
 

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unless you get to ride a a good 994 or 1087 they make a 904 seam mild
i think you mis-understood what point i was making Mike. i wasn't saying 994 or 1087 isn't a noticable improvement on power and torque over a 904.
what i was saying is, i don't feel paying about 4 times as much as i paid to do my 904 (not including the cost of the chassis improvements the extra power/torque would require) is justifiable for about 15hp and about 8ft/lb more than my bike.

i could buy a used ZX10r with all it's power and chassis advantages and still have some cash left-over for some track days with the amount of cash required to do a 1087 properly :wink2::grin2:
 

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Well thanks very much Mike !! LOL. There was I thinking it was time for a few more of your mods and you chuck this out there.
So my cheapish mods have now gone through the roof. Will probably need to do a bit at a time. Now where to start...…. Oh wife, can I...…. but...…..well Mike said...….
 

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Well thanks very much Mike !! LOL. There was I thinking it was time for a few more of your mods and you chuck this out there.
So my cheapish mods have now gone through the roof. Will probably need to do a bit at a time. Now where to start...…. Oh wife, can I...…. but...…..well Mike said...….
Guess you'll just have to join the club and start saving . How much money can I raise if I sell some of my toys .:|:|
 

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Guess you'll just have to join the club and start saving . How much money can I raise if I sell some of my toys .:|:|
Already started my friend. LOL :wink2:
 

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Glad to see someone putting together a nice 904 kit. I've got the TPUSA one with their cams and headwork, and your throttle bodies and tune.

96rwhp! Although that'll change with my swap to 2-1 exhaust.
 
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