Off set key

Gonna be hard to check, there are no points to check it with. All you can do is run it and use a plug fired timing light. Most automotive lights won't work. I have a xenon spark fired light I save for these motors. Dim, but it works when nothing else will.

Steve
 
I have over 25K worth of tools not counting my machines like boring bar, valve machine, lath, Sunnen honing machine and more. I have worked on MANY CDI bikes. I all so have MANY degree wheels. Much off my living has been working on motorcycles. I think I will be able to figure it out.
One of my babies and my instruments. I have build many a crank as well. My bike will never be started till I check the true of the crank. I will all so be putting much better crank bearings in the case.
Thanks
Jeff
 

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*waits to see what becomes of this expertly hand crafted engine*

2rs or zz bearings?

what tolerance class? what abec ratings? p2, abec 9?

and what clearance designation? c1? cn? or maybe a c5?

not many people stock anything but CN...

maybe some 7XXX series would be more suitable? a, b, c, or a5?

not sure how one would keep the preload on them... :D

ahhhh, choices, choices, choices...

all them funny letters actually mean something? :eek:
 
My experience was that the stock motor/head was easily prone to detonation under heavy load (hillclimbing) even in Canadian winter temperatures. The last thing I'd want to do is advance the timing with this going on. I needed to solve the detonation. That is what my long-winded illustrated lecture above was all about. Now with chamber shape improved and no signs of detonation you'd think I might be tempted to increase advance?

Timing advance is worth playing with, but I know from other engine experience experience that improved squish reduces the need for advance.

Steve
 
Time will tell as I will try one to see. The key could be used to retard the timing as well. I will be trying many things. I am going see how the stock engine performs first. Before I ever start the stock motor I am going to check it out well including checking crankshaft true and cylinder bore.
Thanks
Jeff
 
None of you need to change the timing ... we are doing way over 70mph with e85 with this China motor ... 65+ on gas all day guys

Britt vanegas on fb
 

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None of you need to change the timing ... we are doing way over 70mph with e85 with this China motor ... 65+ on gas all day guys

Britt vanegas on fb

Would like to see a video of your bike being clocked running what you say until then that is all it is talk.
 
215 lbs of me is getting 60kph (37mph) on an almost stock Grubee Skyhawk on a heavy fat tired mountain bike. The only mods are what you cold do with sandpaper and a file.

A skinny rider on a sleek roadbike with a tall sprocket in a tuck would have no problem getting 10 kph faster with this motor. I have no problem believing Bufu racing#1's comments that 40mph is easy with a stockish motor and that much higher speeds are possible in purpose built bikes, especially if these bikes capitalize on speed over anything else. The earlier generation of Happy Time motors seem have been limited to about 6000rpm. This 2015 Grubee can rev to 8000 without problem, which seems to explain some of the differing views from older members.

The most important point to take is that huge timing changes have not been needed. An offset key is perhaps all you need to experiment to find out if this is true.

Steve
 
Off set key is a VERY SMALL change far from huge. This is by far not my first with timing changes just was wonder what others experience with these little motors are? 65MPH all day is totally ridicules with these little motors unless the displacement was increased a LOT and you have a 35 pound driver! I did notice he has gone from 70mph to 65mph.

I am not building a race motor but those that do it is not one thing you do to get more performance but a bunch of small things that added up.
 
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77.1 kmh I got I don't see it getting much better unless you want a piston in the face.
 
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