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View Full Version : Peak RPM or preferred powerband?


NickMcDonald
15th July 2012, 13:25
Hey all. After having a piss round with my vernier callipers, Ive managed to come up with some figures to punch into that 'pipe calculator' on the bucket racing website. One of the required fields is Engine RPM. Now is this the peak revs the engine will do? Or am I supposed to input where I want my engine to make peak power? Cheers.
Drew
15th July 2012, 14:08
Max RPM. 10 characters
NickMcDonald
15th July 2012, 14:53
Ah nice one! Cheers.
koba
15th July 2012, 22:14
Hey all. After having a piss round with my vernier callipers, Ive managed to come up with some figures to punch into that 'pipe calculator' on the bucket racing website. One of the required fields is Engine RPM. Now is this the peak revs the engine will do? Or am I supposed to input where I want my engine to make peak power? Cheers.

Get the book.

Even that is dated, there is plenty more info available about the place.
That calculator is a great way to punch through Bell's formulae quickly but there is more to it than that, if you read that book you will get a much better result.

Engine RPM is where you want the power in that case, which also happens to be at or a bit before where you think the engines safe max revs are.

EDIT: Ahh, you have the EN? That calculator is for 2 strokes so it's no use to you.

Start by just using a different muffler, just don't make it too loud.
The exhaust isn't as critical for your bike as it is for a performance two-stroke.
A carb upgrade will help too, dirtbikes or cheap OKO brand ones are a good place to start looking.
F5 Dave
15th July 2012, 22:26
But if you put a 2 stroke pipe on a 4 stroke, can you make it sound nice - instead of the dreadful farty noise they usually make?
gav
21st July 2012, 18:54
I thought he was modifying a GT125 twin?
F5 Dave
22nd July 2012, 21:44
It was just a question:rolleyes:
NickMcDonald
3rd August 2012, 16:47
Yeah I am having a go at a gt125! Cheers guys for the feedback. Got myself some nifty little steel sheet rollers to start knocking out some cone diffusers etc.
Drew
3rd August 2012, 17:03
Yeah I am having a go at a gt125! Cheers guys for the feedback. Got myself some nifty little steel sheet rollers to start knocking out some cone diffusers etc.How much for you to make a couple extras?
NickMcDonald
4th August 2012, 11:38
Aww man, Id have to see how mine turn out first before I start making others! If my attempt turns out to be passable, Id be more then happy to make some others. Ill keep you guys posted on how Im doing.