maximum RPM/speed



FurryOnTheInside

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Sep 23, 2013
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5500 RPM, huh? I'm using the stock CDI, but 5500 RPM means 53km/h for me, which is a cruising speed for me. My max. was 70km/h at 7500 RPM still with the stock CDI. So what are we talking about? Without any load it can rev up to 10 000 RPM.
We're talking about how to begin the process of tuning the engine not by leaping straight to the exhaust port and raising it. :)

There's good reason to begin with getting the most out of every stroke. Making good torque is essential for the bike to get the speed so you might actually get 1.5 times the RPM or whatever you dream of. There's enough torque to gain by tuning (such as retarding ignition at high RPM) that you could run a smaller rear sprocket and raise the top speed RPM too. :)

If you can do 43mph at only 7500 then you likely already don't have a stock 2014 engine. It clearly makes more torque than the stock 2014 engines that are commonly available in South America and the rest of the world, so tell us how your engine makes its torque! Is it a newer version? Grubee? Zeda? Did you tune it to make the best torque? What did you do? :)
 
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FurryOnTheInside

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Sep 23, 2013
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7.5mm carbide drill bit View attachment 80825
Very nice but you also have the drill press to put it in!

Is no one selling drilled out wrist pins? Would be a bit cheaper than a drill press lol.

Not to worry though, if anyone doesn't have the machine shop in their garage; It is possible, IME, to get the vibration so low it isn't a concern at all at any speed, and is totally comfortable at cruising speeds.

I retarded the timing (AT ALL RPM) by making an offset magnet key, and I drilled balance holes in the crank without removing it (and with a common cordless drill!), and I lightened the piston and upper part of the connecting rod, but I didn't have to drill out the wrist pin or split the case. So if you have limited space or resources you can still do enough to make a big difference, even without any seriously large, heavy or expensive tools.
Hopefully I can also have total comfort and better torque at high RPM with a better CDI. ;););)
 

FurryOnTheInside

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Would a lathe work? I have one of those kicking around.
I should think a lathe is preferable but there's only so many members have either so I'm just pointing out that the less well equipped members and lurkers can still get good results by doing all the other stuff I mentioned which doesn't require any larger tools. Although it would be better and easier to lighten the wrist pin, if you can. :)
 

Stoneman

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May 20, 2017
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I should think a lathe is preferable but there's only so many members have either so I'm just pointing out that the less well equipped members and lurkers can still get good results by doing all the other stuff I mentioned which doesn't require any larger tools. Although it would be better and easier to lighten the wrist pin, if you can. :)
Yes defiantly, I agree
They can be pricey so if you buy hoping just to use a hand drill I wouldn’t attempt it and may be an expensive lesson
Even a bench drill will be tricky without a good vise.
As Jag mentioned it’s probaly easier to go to a machine shop

I had the idea of drilling them out and selling them, see how it goes

I’ve been very lazy in doing it all though haha
 

FurryOnTheInside

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Sep 23, 2013
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Yes defiantly, I agree
They can be pricey so if you buy hoping just to use a hand drill I wouldn’t attempt it and may be an expensive lesson
Even a bench drill will be tricky without a good vise.
As Jag mentioned it’s probaly easier to go to a machine shop

I had the idea of drilling them out and selling them, see how it goes

I’ve been very lazy in doing it all though haha
I wouldn't attempt it with a hand drill either! There's absolutely no chance of getting the hole centred all the way through the pin, and it is a very hard steel which will need to be cooled and lubed with cutting fluid.

{{ Mainly aimed at future lurkers:
It's okay to use a hand drill and silicone lube aerosol spray to drill balance holes in the crank because they don't require such precision and I think it's just a mild steel.
Still, use a 3/16" carbide bit for the pilot holes before using the 3/8" carbide bit to finish the radially drilled balance holes (about 15mm deep seems to do it). }}

If you find it's economical to drill out individual pins to sell that would save a lot of work lightening the piston and rod so they should be popular (if people have sense). I just expect it to take too much time and carbide bits to be viable. If the pins were manufactured with thinner wall in the first place it might be a better way.
 
Joined
Jun 11, 2019
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5500 RPM, huh? I'm using the stock CDI, but 5500 RPM means 53km/h for me, which is a cruising speed for me. My max. was 70km/h at 7500 RPM still with the stock CDI. So what are we talking about? Without any load it can rev up to 10 000 RPM.
How please teach me I'm very very dumb to this because I'm new but I will remember if you make it easy for me tnks
 
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