Fly wheel keys

[jeffrey]

Deleted.

[Thumper]

I was thinking the same thing. Head porting, opening up the exhaust, and a 2 degree key.

I have a cylinder/piton kit on the way. All together, I think it will add 4-5 horsepower on my 5-speed ZS172FMM-3A (19hp> 24hp or so).

I think a 4 degree key is extreme, and that it will cause overheating in hot weather, and the engine may behave poorly at low rpms. this may not be true, but overheating is a real danger. The head porting and exhaust work are supposed to be the most significant changes.

[JerryHawk250]

4° key is the way to go. No problem with overheating. I was running 11:1 piston and ported head. I have a couple laying around.

[Bill Hilly]

Originally Posted by JerryHawk250

4° key is the way to go. No problem with overheating. I was running 11:1 piston and ported head. I have a couple laying around.

Would you like to sell a key? I would buy one.

[Thumper]

Advance keys are available in small increments from 1 degree up. 4 degrees is not a magic number, and it is not optimal for every engine:
https://speedwerx.com/snow-performan...ming-keys.html

These are sold because they a different advance is ideal depending on other things including exhaust, head work, intake/carb.

And yes, advancing the timing CAN cause overheating. This is a WELL ESTABLISHED fact known for decades relating to multicylinder engines, but also applies to single cylinder dirt bikes. And these bikes are just AIR COOLED. Depending on other factors, maybe 1.5 degrees will provide substantial increase in power WITHOUT causing kickback or overheating. It is foolish to assume that one setting is perfect or ideal for every situation. It is also well known that advancing the timing is harder on the rod and piston.

https://www.visordown.com/features/w...and-resolution

https://www.thirdgen.org/forums/tech...g-advance.html

I will use ignition advance, but no reason to jump all the way to 4 degrees. Especially if I haven't done the most useful power enhancing mods (head porting, exhaust work, matching a larger carburetor to these mods). At that point a 2 degree advance might be all that is needed.

[JerryHawk250]

Originally Posted by Bill Hilly

Would you like to sell a key? I would buy one.

Sure. Send me a PM.

[Bill Hilly]

Originally Posted by JerryHawk250

Sure. Send me a PM.

PM sent. Thanks

[JerryHawk250]

Thumper, with the mods you are planning you will be safe with the 4° timing key. You will need to run premium fuel though. If you capabilities to add timing through tuning then that would be a better option.

[Megadan]

The timing on the CG clones is so pulled back that I have been running a 4 degree key with an adjustable aftermarket CDI that also advances the timing. I have run both with a cam and over 10:1 compression.

Never overheated. Never had a kickback. I still don't have any issues with cold starts.

[Bill Hilly]

Originally Posted by Megadan

The timing on the CG clones is so pulled back that I have been running a 4 degree key with an adjustable aftermarket CDI that also advances the timing. I have run both with a cam and over 10:1 compression.

Never overheated. Never had a kickback. I still don't have any issues with cold starts.

Are you talking about them aftermarket market CDI boxes that they sell on Amazon ?, Or something else that has an adjustment for timing? I just made a deal with Jerry on a 4° key, and I order stuff to self port my head. Should I also get a new CDI, and a coil ??

[Thumper]

Originally Posted by Megadan

The timing on the CG clones is so pulled back that I have been running a 4 degree key with an adjustable aftermarket CDI that also advances the timing. I have run both with a cam and over 10:1 compression.

Never overheated. Never had a kickback. I still don't have any issues with cold starts.

This is probably why these engines are so reliable. Starting with a reliable model, detuning timing drops power output. At the same time, it reduces stress on the engine. It's a good strategy to sell clones all over the world, and gain a reputation for durability.

We do see much higher horsepower output from same displacement engines from Husqvarna, KTM, Kawasaki, and even Honda (notorious for detuning in favor of reliability).

So the question just how reliably can we apply these performance upgrades with Chinese clones? You (MegaDan) have applied 4 degree advance and others posting here have as well, with good results and no significant issues... We hope that engine build quality is consistent enough to withstand the timing adjustment and maintain durability.

The stock CDI units are presumably retarded compared to otherwise much more aggressive CDI units in the KTM and Husqvarna bikes. So the bottom line is that you advance your clone at your own risk.

I can buy a replacement engine for about $500, and less drastic rebuilds involving rod, piston, can be done as well for less money, so the risk isn't too bad

[Megadan]

Originally Posted by Bill Hilly

Are you talking about them aftermarket market CDI boxes that they sell on Amazon ?, Or something else that has an adjustment for timing? I just made a deal with Jerry on a 4° key, and I order stuff to self port my head. Should I also get a new CDI, and a coil ??

Not sure what the current equivalent is but yes it is a CDI off of amazon with a potentiometer to adjust the advance curve to different points in the RPM range. It actually does work too because you can actually feel and hear the advance point change as you adjust it. Unlike the cheap units that just advance the entire curve this one allows you to kind of tune it in to a specific range. I have it dialed in where I really feel the power come on in the mid range from about 2500-3000rpm and then it tapers back off to almost stock levels at the top end.

Other than that unit the only other CDI that I have found to offer the best overall performance from the Hawk ironically has been the original Hawk unit.

As far as the coil. In my opinion there is nothing wrong with the stock coils in terms of power other than being cheap and eventually they get weak. I replaced mine after a while with a Nibbi unit and I could tell the difference at high RPM. We aren't talking some big boost of power but a smoother stronger pull from a more stable spark.

I would suggest to do the key and head porting first and run that for a while and determine if you need anything more.

[Megadan]

Originally Posted by Thumper

This is probably why these engines are so reliable. Starting with a reliable model, detuning timing drops power output. At the same time, it reduces stress on the engine. It's a good strategy to sell clones all over the world, and gain a reputation for durability.

We do see much higher horsepower output from same displacement engines from Husqvarna, KTM, Kawasaki, and even Honda (notorious for detuning in favor of reliability).

So the question just how reliably can we apply these performance upgrades with Chinese clones? You (MegaDan) have applied 4 degree advance and others posting here have as well, with good results and no significant issues... We hope that engine build quality is consistent enough to withstand the timing adjustment and maintain durability.

The stock CDI units are presumably retarded compared to otherwise much more aggressive CDI units in the KTM and Husqvarna bikes. So the bottom line is that you advance your clone at your own risk.

I can buy a replacement engine for about $500, and less drastic rebuilds involving rod, piston, can be done as well for less money, so the risk isn't too bad

That is exactly why they are so reliable. Like a big block engine from the 70's in the big family sedans they had mild cams with small ports and very very conservative timing with super low compression. They didn't make huge power numbers but ran forever and would run on the lowest octane fuel you could find.

I also agree that there is the potential to reduce overall reliability. I don't think a 4 degree key on its own will harm anything. Once you start bumping the compression up and advancing the timing is where you start getting into very high cylinder pressures.

I offset this a little with the larger duration cam which lowers the dynamic compression ratio a bit with the increased overlap. Before the cam my bike was pretty damn hard to kick over and my starter struggled against the compression a bit lol. After it came back down to a reasonable level.

Jerry and I have both been running our Hawks for some time now with all of this work and neither of us have had an issue in regards to reliability. We also both run large oil cooler setups to help regulate the engine temps, and I know that in my case it has likely contributed to the long term reliability of my bike. I push my bike hard on the highway at high RPM for decently long periods of time pushing a large man through the air. That cooler is earning it's pay so to speak.