AS ANYONE PUT THERE BRIDGESTONE GTR350 ON A DYNO.

[reed]

AS ANYONE PUT THERE BRIDGESTONE GTR350 ON A DYNO.
Have you put a Bridgestone 350 GTR on the dynamometers.
I would like to know the true BHP on these remarkable engines.
Let me know .
Thanks.
Reed.
 

[Toystoretom]

Dyno time is expensive. I Dyno'd my Rocket III and it was a learning experience. First, you establish a baseline, and that right there cost from $50 to $100 ($50 if you are going to continue on and make adjustments or $100 if that is all you are going to do). The base line gives you a starting point and shows horsepower, torque, and mixture ratio across a RPM vs load scale. We used a Power Commander dyno at Olathe Suzuki. The Harley shops wouldn't let us in, same dyno, just staffed by pr*cks.

Which is kind of funny, because the guy before me had a Screaming Eagle Electraglide that had over $30,000 in it according to the owner. They messed with that thing for over an hour and just beat the holy living crap out of it and finally he was able to get just over 100 HP at the rear wheel. We rolled the Rocket up there and did 165 rwhp for the baseline and got it up to 175 in just a few minutes. I have Neville Lush mild cams, a Power Commander and predator exhaust on it. I may upgrade the cams and put some pistons in it, supposedly that nets you 220 rwhp with a little headwork. It is just scary strong right now, so I may leave it. The more HP you want the more it costs, exponentially. It makes more torque idling than most Harley's do at full throttle.

A GTR might pose some problems, because they way these dyno's work is that they put an exhaust probe in a muffler that monitors the air/fuel ratio. I'll bet the two stroke oil the bike burns would wreak havoc with that, and they might not be able to calibrate the dyno to get an accurate reading. They might have to start with some "canned" tune to get a baseline. I wouldn't be surprised if RWHP was around 28 or 30. The Power Commander dyno is computerized, of course, and makes adjustments by changing the settings on a bikes electronic fuel injection. That ain't gonna happen on a GTR, you will have to pull the bike off of the dyno and change timing and jets, and put it back up there to see if you did any good or hurt it. Dyno's are in high demand during the riding season and you would have to find a sympathetic dyno guy to mess around with something like this. Every time you put the bike up there they want to charge you, as well they should. It's an expensive piece of equipment and they have paying customers waiting to get up there.

I ended up paying $250 for essentially a quick, no hassle dyno run, you could rack up a lot more than that with a GTR.

[Toystoretom]

Just a little more insight, when they dyno a bike they really wind the thing up and put large loads on it. After they were done with the Harley it had developed a top end ticking noise, I think they may have overheated it. It was pushing the very edge of what that bike could do to get that 100 RWHP reading.

The Rocket is water cooled. It has radiator fans that kick on and the dyno has it's own cooling fans that we directed right at the radiator. It wasn't even breathing hard when we hit our numbers, and it basically is way under stressed most of the time. I think we crossed the 100 RWHP mark at about 3000 rpms.

A GTR might get hot being a two stroke. I'd probably put a little extra two stroke oil in the gas but from what I understand that right there changes your mixture ratio, so I don't know. I do know that I would have the dyno's fans hitting that engine perfectly and I would have them on high. I'd hate to lock up a GTR seeing that cylinders are kind of hard to find.

[Toystoretom]

I keep thinking of stuff...

The theory behind this is that your bike runs pretty efficiently around the 14.7 to 1 (I think thats the number) air fuel ratio. This is by weight, so you would want 14.7 grams of air to one gram of fuel, and this is for a 4 stroke motor. All the fuel is burned up  along with the available oxygen so it's going to make the most horsepower it can for that amount of fuel. In the real world, I think they actually go a little bit lean, i.e. there is more oxygen than needed so all available fuel gets burned up. This hurts the emissions however, but makes the most HP.

I have no idea what the target would be for a two stroke, and they burn dirty anyway, meaning there are a lot of unburned hydrocarbons going out the exhaust normally. If you lean it out it will over heat and lock up. I guess you would just have to ignore the A/F numbers and play with it until the HP numbers go up. It would be kind of fun to try. I'll bet somebody somewhere has some two stroke dyno experience and could fill us in on what to shoot for.

[reed]

On the dyno subject.
HP or torque on a dyno is calculated by taking a fixed weight of the dyno roller and it will measure how quickly you can
Accelerate while checking the RPM OF what the motor is doing.So say top gear at 7500 RPM 40 HP maybe at the rear
Wheel.Dyno jet measures Total gear ratio what gear you are in sprocket size and tire size etc.
All i would want is the HP at the rear wheel for now. So if i was going to put my Bridgestone 350 gtr on the dyno.
I would check the timing and plugs set -up the carbs do a plug chop and if i was happy with the way it runs.
Put on the dyno top gear hit 7500 RPM turn the motor off and maybe and just maybe 40HP at the rear wheel etc.
PS the dyno i used had fans on the motor and we could check how hot the engine would be running!
This is just for fun i would not be say using it for racing.   
Thanks.
Reed.

[Toystoretom]

I'd be shocked if someone were to get 40 HP at the rear wheel on a stock bike. I think most of those figures were taken at the crankshaft, the engine on a bench, and anything that robbed power was lost or disconnected (like the alternator guts or even the primary or the tranny) and I'll bet even then they kinda fudged it up a little.

I don't know if you guys remember when they rolled out the original Triumph Trident (along with it's BSA cousin, the Rocket III) and the first Honda 750 four. Triumph listed the HP at something like 67 but Honda said theirs put out 69. All the cycle mags tested them and found the Triumph actually made a little more than advertised but the Honda was actually down in the high 50's. Quarter mile times proved them right, and BSA won Daytona over Honda (Dick Mann may have had a little to do with that) all of which prompted cranky old Edward Turner to say of Honda "Lies, more lies, and Damn lies!" I think there was a lot of wishful thinking back then.

[reed]

Toystoretom
On Bridgestone they calculated there HP from the output shaft so it could as low as 35 HP if you do all the tuning mods they give
48 HP. (That's what Bridgestone said in the day)
Thanks.
Reed.