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Discussion Starter · #1 ·
The Waco dealer is "personalizing" a 2001 Bonneville for me, adding the BC air box removal kit and Predator exhausts. The bike had the air injection removed when new 12,000 miles ago. This is a very experienced shop and I'm sure the bike will be jetted correctly and nicely tweaked.

My question is --- If the stock bike was advertised to have made 61 hp (I've heard 55 or so at the rear wheel) and 44 ft/lbs of torque (41 or so at the rear wheel) what will she make with the mods?
 

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The Waco dealer is "personalizing" a 2001 Bonneville for me, adding the BC air box removal kit and Predator exhausts. The bike had the air injection removed when new 12,000 miles ago. This is a very experienced shop and I'm sure the bike will be jetted correctly and nicely tweaked.

My question is --- If the stock bike was advertised to have made 61 hp (I've heard 55 or so at the rear wheel) and 44 ft/lbs of torque (41 or so at the rear wheel) what will she make with the mods?
Probably not much more, but it will SOUND like it's make a lot more!:D
 

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Discussion Starter · #4 ·
Dyno

I looked at the dyno thread, but the bikes there were either newer (EFI) or heavily modified (port/polish, etc.),
 

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Cant agree there guys!

If your tuner is as good as Pieman then this is what he can achieve.............



Im sure he wont mind my posting his dyno chart, but thats for his 790 Bonnie with stock internals.

A lot more than "not much" there!! :D



V.
 

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Discussion Starter · #6 ·
Great Info

Ventura, Thanks for the info. This bike was "baffle removed" -- does that equate to an airboxectomy?

Looks like 70 hp and 50 ft/lbs are attainable if you know what you're doing. Early articles that dynoed a 2001 Bonne showed 55 hp and 41 ft/lbs at the rear wheel, so the mods are good for a 27% increase in HP and a 22% increase in torque. Not bad . . .

It's all about the stock internals for me. The Triumph guys supposedly engineered reliability and longevity into the engine, and internal modifications can get very expensive. Also, how far can you push the top end without also doing the bottom end and you wind up with parts that only the specialty shop can support.

Are these bikes **** hot or what! I can't wait! Should pick up the bike in three weeks.
 

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Ventura, Thanks for the info. This bike was "baffle removed" -- does that equate to an airboxectomy?
The top two figures are those that you'll equate to, where the airbox has been removed and pods fitted.
The ones below that are progressive stages of airbox mods and jetting, but yours will be gone!

(NB... The "baffle" refers to what is sometimes called the internal "restrictor plate")

Enjoy your transformed bike when you get it back!
(But why three weeks??)


V.
 

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Discussion Starter · #8 ·
Three Weeks

It's a three week wait because the headers are off being ceramic coted and the pipes are en route. I'm travelling till then anyway.

Dropped by the shop in Waco today to look a progress so far and the bike looks great, even without headers or exhaust pipes. Their local paint guru did a great job with the Thruxston bodywork. They were about to close so I didn't wheel it out into the sun for photos, but I took a few on the showroom.

Still to come (I'll install these): D9 bracket, oil pressure gauge, ignition relocation. Should be a sweet ride.
 

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It says something about these bikes that it makes sense to do all this to a 10 year old bike.

Who says they won't be classics ;-)
 

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I have pipes and filters and my bike made 69rwbhp. I then smoothed the inlet manifolds and then had 70.8 rwbhp. I now have fitted billet inlets and it goes even better. Dyno to follow. Its a massive difference but if you want more go 904 Big Bore.:cool:

Chris.
 

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Discussion Starter · #12 ·
STW - "It says something about these bikes that it makes sense to do all this to a 10 year old bike."

Glad you think it makes sense! Putting $1500 into a $4500 bike makes sense only to gearheads. I'm an old fart an this will be my last bike, so I'm planning on keeping it forever. I could have spent $10K on a new basic Bonnie, but I think this ride will be way cooler.

The color is Porsche carmon red metallic. I post pics once I get it on the road.
 

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STW - "It says something about these bikes that it makes sense to do all this to a 10 year old bike."

Glad you think it makes sense! Putting $1500 into a $4500 bike makes sense only to gearheads. I'm an old fart an this will be my last bike, so I'm planning on keeping it forever. I could have spent $10K on a new basic Bonnie, but I think this ride will be way cooler.

The color is Porsche carmon red metallic. I post pics once I get it on the road.
A tastefully modified bike is always way cooler than a store bought model.
 

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STW - "It says something about these bikes that it makes sense to do all this to a 10 year old bike."

Glad you think it makes sense! Putting $1500 into a $4500 bike makes sense only to gearheads. I'm an old fart an this will be my last bike, so I'm planning on keeping it forever. I could have spent $10K on a new basic Bonnie, but I think this ride will be way cooler.

The color is Porsche carmon red metallic. I post pics once I get it on the road.
Did you ever acquire some updated pics/dyno run?
 

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STW - "It says something about these bikes that it makes sense to do all this to a 10 year old bike."

Glad you think it makes sense! Putting $1500 into a $4500 bike makes sense only to gearheads. I'm an old fart an this will be my last bike, so I'm planning on keeping it forever. I could have spent $10K on a new basic Bonnie, but I think this ride will be way cooler.

The color is Porsche carmon red metallic. I post pics once I get it on the road.
Too me it says a lot that you Bonnie is made for the most part in England where all modern Retro Classic's should be made. What if Harleys were made in Thailand?
I do not have a problem with any Triumph model being made in Thailans except the modern Classic models.IMHO.
I have a 04. with 904 BB kit. 82 h.p.
 

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Reality check

I'm not trying to rain on anybody's parade here but, a 25% increase in peak torque (40 lb-ft to 50 lb-ft) would require an equivalent increase in F/A charge in the cylinder. Getting that kind of increase from only external modifications and mixture adjustments would be close to miraculous. Some horsepower increase can be gained from raising the RPM limiter (i.e. spinning faster), but not the 32% shown. Unless either or both the intake and exhaust were severely restricted and very poorly matched to the engine, only a few horsepower could be expected at best.

Few manufacturer's claims for exhaust performance increases can be duplicated on multiple dynos run by objective operators, but such tests are seldom made. As an example, magazine exhaust comparison tests seldom come close to the gains manufacturer's publish. Real world dyno tuning seldom raises peak power much on a decently running bike, but can fill in dips in the torque curve resulting in more useable power.

There are some exceptional engines that have the ability to flow much better than average just as they come from the factory. Those engines may experience substantial gains from bolt-ons and tuning; but they are the exception rather than the rule. For example, it would be possible to fit a ported head to an othewise stock engine and have it produce near stock power with OEM intake, exhaust, and tune. That same engine would likely show substantial gains when fitted with a low-restriction intake and exhaust. However, that gain would be realized because the changes allowed the inherent flow capacity of the head to be exploited. There are certainly variances in flow capacity between heads that are produced on the same assembly line. However, those variances are unlikely to to be in the 20% range.
 

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I'm not trying to rain on anybody's parade here but, a 25% increase in peak torque (40 lb-ft to 50 lb-ft) would require an equivalent increase in F/A charge in the cylinder.

It's been done on these particular bikes many times Coroja. I guess the engine is simply capable of more stock than the inlet system will provide it with. Remember that the twins series was not designed to be a "performance" machine out of the box. Might be why tuning them is so much fun - you can get a pretty big increase right off the bat without much expense - just airbox removal and pipes and rejet. After that it takes quite a few more dollars, as you have to get into bigger carburettors, and then you start looking at cams and headwork, and cylinder bore. Gets pricey then, but still fun.
 

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carb bikes can and do pick up alot of power with the right pipes and getting rid of the air box.On these motors the stock head way out flows stock pipes ,air box or carbs.There is about 2or3 hp to be gained on 790 motors with more timing and higher rev limit.10 to 14hp gains are not uncomon with bolt on mods on a 790.On early 01 790 even more can be gained do to even better cams.
 
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