looking foward to my motor arriving!!

crazyhorse · #1 11-10-2008, 01:26 AM

hi to everyone....
I have a "big mo" chopper style bike and found a motor supplier here in new zealand so have ordered a motrax two stroke kit for it. The motor looks very similar to the common ones that i have been seeing here referred to as a ?china girl? but with the importers sticker on the side.

I have been spending allot of time reading posts here to try and get a bit familiarized with motorizing a bicycle and have found this site to be a wealth of info. A big thanks to all the contributors.

I was wondering if anyone could tell me what sort of rpm range these engines peek out at normally. I have seen peek power quoted at 6000rpm but what sort of rpm do they tend to get to before flying apart?

Bicycle Motor Forum - Motorized Bicycle Engine Kits, Manuals, And Help)

Andyinchville1 · #2 11-10-2008, 01:48 AM

HI,

My owners manual for the Power King engine rates the engine at 5000 RPM and lists peak power at the same 6000 RPM you found.

I have had my Dax 70 up to 6400 RPM (shown on Sen Dec Fas Tach) BUT something (not sure what and didn't hold it that high to find out!) sounded "rattly".

Hope this helps.

Andrew

**Dave31** · #3 11-10-2008, 11:58 AM

Welcome to the forum

crazyhorse · #4 11-11-2008, 05:14 PM

thanks for that info.
I have been doing alot of reading here so much good info.

I havent felt like such a kid for a long time.... whens my engine going to get here!!!

Probably a good thing its takeing so long as it is giving me a good chance to look at what others are doing out there.

does anyone have any suggestions where to look for some discussion on running in. I have been doing some looking and am struggling to find anything major on it except fuel oil mix and keeping the top speed down for the first 500.?
I am trying to remember stuff about it that i learned 15 years ago when i got a new two stroke ringless model airplane engine...
keep fuel to air ratio rich?
extra oil
but i cant remember about throttle whether its best to run at different levels of throttle? whether its ok to use full throttle ocasionally at moderate to low rpm during run in etc.

any advice appreciated

Saddletramp1200 · #5 11-11-2008, 06:22 PM

Anything over 6400 rpm I suggest Kelvar undies. NEVER ride full out down hill, Never!

Saddletramp1200 · #6 11-11-2008, 06:49 PM

I use the ten minute idea. First ten, ride gently, then stop for ten. Don't bog the motor.
Vary the rpms. Let it cool off. Second ten, 15 mph and after 10 minutes stop and cool. Check for loose bolts! Motor mount bolts! Check your bike! After about a tank you can burst the gas a little. Don't do it long. After 3-4 tanks you will know what you can do, and what you can't. This is how I do it. But thats just me. I use Dax motors for my two wheelers. Honda for the trikes.

**Bikeguy Joe** · #7 11-11-2008, 07:02 PM

Quote:

Originally Posted by crazyhorse

thanks for that info.
I have been doing alot of reading here so much good info.

I havent felt like such a kid for a long time.... whens my engine going to get here!!!

Probably a good thing its takeing so long as it is giving me a good chance to look at what others are doing out there.

does anyone have any suggestions where to look for some discussion on running in. I have been doing some looking and am struggling to find anything major on it except fuel oil mix and keeping the top speed down for the first 500.?
I am trying to remember stuff about it that i learned 15 years ago when i got a new two stroke ringless model airplane engine...
keep fuel to air ratio rich?
extra oil
but i cant remember about throttle whether its best to run at different levels of throttle? whether its ok to use full throttle ocasionally at moderate to low rpm during run in etc. YES, but at moderate to high rpm. Don't give full throttle @ very low rpm.

any advice appreciated

Start with the needle clip @ the second from the top for most applications, even for break-in. 24:1 Oil mix, and vary the engine speed and rpm. Where some folks differ (that's me) is that I run up the rpm to 75-90% after the engine has had time to warm up, say 5 minutes. Always with a light load, and always de-cellerate slowly too. That will get the rings seated right away. After the first 15 minutes, then let it cool and ride it varying the throttle and rpm for a tank of fuel. After that, just ride it!
Important points- Always let the engine warm up with a light load and moderate rpm. Avoid prolonged down hill runs with the throttle closed- best to pull and lock the clutch. Check your plug periodicly for a "read" of how the engine is running.

..............................

crazyhorse · #8 11-12-2008, 03:44 AM

Its finally arrived. yahoo!!!!

thanks for the run in advice that gives me a clearer idea of how to do it.

Have decided not to go for mounting it in the chopper just yet and have got it mounted in my mountain bike instead.

should have everything mounted by bed tonight and ready for testing tommorow.

i am going to have make up a different tensioner as the one supplied does not even have a bearing in it.

I am really glad i have been reading so much here as i was expecting to be able to use the engine for braking down a few long steep descents i do regularly but now understand that this aint a very good idea due to closed throttle therefore lack of lubricant and i suppose cold running the engine. Shame but at least i found out the easy and cheap way not the hard and expensive way.

I now have a bit of a delema because those long descents i use to tackle by just using my "air brakes" by going 60-70kph (38-44mph) but i am worried that if i do that with the clutch in i will be asking for trouble as if the clutch for some reason accidentally engaged my engine would be toast and me probably to.
I am a big boy ~300 pounds and chew through the brakes if i try to use them on long descents.

oh well i better get back to it
photos tommorow i hope
thanks again for all the advice

**Bikeguy Joe** · #9 11-12-2008, 06:58 AM

How about a 6' parachute like they use in sports training?

jasonh · #10 11-12-2008, 03:59 PM

On the long downhills just hold in the clutch (don't lock it, just hold) and you should be fine. It would be a very rare freak accident if it magically engaged....either the lever or cable would need to break for that to happen most likely.

As for the brakes...I know what you mean (260 here). I think it's just one of those things you gotta deal with.