Breaking in a new motor- how do you keep the speed low?

B.K. Hosken

Local time
8:00 PM
Jun 4, 2008
I have only had my Dax 70cc for a week, but as instructed, I have kept the speed mostly under 2/3 throttle or so. My question is, how do you DO that!? I find my hand twisting the throttle more and more....I NEED to go faster...18-20mph at 2/3 throttle is KILLING me!! How do you others handle this?! I've only gone about 15 miles, and I really don't see how I can stand another 100 miles of this without freaking out.

Also, this little engine seems to be underpowered. Does it get more power as you break it in? I don't think this thing will go more than 24-26mph and it's mounted on a skinny-tire 27" bike. I weigh 220, is that what's limiting my speed?
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hi bk; you are doing right. go all out every so often. it will get faster. check all fateners and chain. just do that 15mi. run six more times.
As stude says - to run in a motor properly you need to run it in by varying the speeds slowly running up the time you use the engine at high or full power.

The trick is to run in the motor at all speeds since they move differently at all speeds and the wear is therefore different at different speeds.

You will get more speed as it runs in - its also possible to get different sprokets for better speed - however - more speed equals less torque so you really need to know what sort of roads and routes you'll be using and fit the according sprocket..

good luck with the bike

Jemma xx
Well, I would be happy with 3-4K miles. If I have to replace it I will buy a Robin-Subaru or Honda in a higher quality kit. I just wanted to try one, and see if I use it enough to justify having it.
There is more than one school of thought for ICE break-in.

Babied too much at constant speed and you glaze the cylinders....and the risk at full throttle is? Hanging on ports? Seizure world?

The reason for the heavier oil in the fuel at first is to deal with the asperites (basically high spots) on the metal wear surfaces. Anything too nasty from the factory machining will either get welded (seized) right away or get worn down rapidly. With the 16:1-25:1 ratios for break-in, after the first tank, excursions to full throttle for short bursts will no absolutely no harm.

I have been reading these sites for a year+ now (yeah young timer) and I don't remember too many earlier seizures. I'm sure **** happens, but I wouldn't sweat it.

Now get out there and ride the thing! Hard - like you stole it. :cool:
It's hard - but - try your best at holding back a little. Kind of wondering about your top speed - sounds like it is going to be low for a 70cc - but - I don't know much about your engine. I have a Subaru - quality engine - but - it doesn't sound like you would be happy with my top speed of 22.5 mph with a 1" friction drive. For now - Ride That Thing - Mountainman
Hey look at it this way without the motor you'd have to get a very expensive and light road bike and pedal your buns off to keep around 18-20mph. So enjoy the speed and power right now and take the opportunity to enjoy the bike and scenery. Generally as far as federal regs go anyways anything that is motored is not supposed to exceed 20mph without being a motor vehicle and subject to a whole list of legalities. Just remember that once your engine is broken in and you can top out around 30.
The more times I ride my bike to work, the more I realize that if my bike were only able to do 20 mph it wouldn't really be feasible to take it 20 miles each way. I'm averaging about 28 mph on my commute (when I'm moving) and the entire trip takes me between 45 and 50 minutes. Totally feasible for a commute. If it started taking over and hour (and especially if it took me an hour and a half), I probably wouldn't do it anymore. I'm cruising between 32-35 mph on my ride in. 20 just wouldn't cut it.

Well, it must be breaking in, because now that I have 25miles on it, it's got more power, running smoother, and top end is 30mph, (may be a little higher, but I'm limiting anything over 20mph to 30 seconds or less). I think this little engine will be GREAT fun, and I may actually use it practically. I really need to get a beach cruiser or something like that, and put a rack or a basket on it. Not cool, but if it can't carry at least a bag of groceries, it's a toy. Right now it's on a skinny tire ten speed (only thing I had). The advantage is the gears are on the headset/gooseneck so I didn't have to remove or modify them, but I don't use them anyway so a beach cruiser is on my list. More comfortable upright riding position.