Top speed

dirtymark

New Member
Aug 6, 2012
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I have know way to know how fast im going, so im wondering if you guys could give me an estimate on my top speed, my blaster is bored to a 240cc, hot rod crank, port/polished, wiseco pistons, vforce3 reeds, 35mm mikuni carb. thanks
 
havent touched the gearing. its all stock. im not too big on that so i couldnt tell you the exact ratios.
 
Gearing is NOT the only thing that determines your speed, 1996BlasterBoy.

If a 240 Blaster and a stock Blaster raced and had the same gear ratios, do you think they'd be going the same speed?
 
one has more torgue and would just get to that speed faster:)But with more torque you would regear it with a taller gear to gain more speed.
 
one has more torgue and would just get to that speed faster:)But with more torque you would regear it with a taller gear to gain more speed.

Well, that will work Rich, but it is not the whole story.
Power and rpm enter into it.
Put higher gearing on the stock motor and the top speed will drop.

The stock motor labours to hold 50mph. Increase the power and you get 55mph.
Even more power doesn't deliver much more speed, partially due to the exponentially greater needs of power for speed,
but also because you are approaching the power rpm peak. Any more revs and power drops over the peak curve.
Not enough power to make more speed. So, if you increase the rpm peak of the power curve, you would likely see more speed.
A shorter pipe or exhaust porting would likely raise the rpm peak and top speed.

OP, My guess is that you are doing no more than 60mph, but that is a wildly irresponsible guess.
Better for you to buy or borrow a GPS and do a test run with it.
They have a max speed option on all of them,maybe the phones do too, I don't know.
The Trail Tech speedometers have no calibration and can be fudged to read whatever you want. No help.

From my experience, any more than 60mph is putting you into the Death zone and taking from your felt power.
 
55mph down hill with a wind to your back ...if youre lucky.lol nah 55mph is about right.

Easiest way if you dont have a gps unit (WTF DONT HAVE ONE THESE DAYS) is to have your buddy in a vehicle ride along side of you on a back road.
 
Well, that will work Rich, but it is not the whole story.
Power and rpm enter into it.
Put higher gearing on the stock motor and the top speed will drop.

The stock motor labours to hold 50mph. Increase the power and you get 55mph.
Even more power doesn't deliver much more speed, partially due to the exponentially greater needs of power for speed,
but also because you are approaching the power rpm peak. Any more revs and power drops over the peak curve.
Not enough power to make more speed. So, if you increase the rpm peak of the power curve, you would likely see more speed.
A shorter pipe or exhaust porting would likely raise the rpm peak and top speed.

OP, My guess is that you are doing no more than 60mph, but that is a wildly irresponsible guess.
Better for you to buy or borrow a GPS and do a test run with it.
They have a max speed option on all of them,maybe the phones do too, I don't know.
The Trail Tech speedometers have no calibration and can be fudged to read whatever you want. No help.

From my experience, any more than 60mph is putting you into the Death zone and taking from your felt power.


if you have half a brain in your head and set up the trail tech its very accurate.Ive checked mine on the banshee with the gps and theyre a few mph's difference.I have the vapor.

If you feed it incorrect info yea it will be off.
 
dont forget that calculator does not account for resistance. 70mph on pavement wont be any where near 70mph in sand. not to mention wind.

and yeah the trailtechs are only as acurate as the fool that set it up.
 
With more torque you have the power to run a taller gear to gain more top end and still there is plenty of power threw out.If you improve the torque by installing a big bore it has nothing to do with raising the rpm so the final outcome is both will have the same top speed one just has the torque to get to it faster there for regearing is ideal when you have more power to use to make the best of it.But then when you start changing your power band curve to the top end and pipe intake ect.What ever you can do to get the fuel to flow threw it faster you are going to gain a higher rpm and gain a few mph out of the same gear ratio.Then when you get into port and pollish now your talking about race fuel.With my blaster set up for trail with 14/38 sprocket and 19 inch tire I can hold a constant safe speed of about 50 and not be in the back of the pack with all the 4 pokes but top speed is 60 plus ish.70 is pushing it this little motor wont last long at that speed.Thats beon redline and for people who drag and rebuild there motors ever other few races.In my opinion.