Riding into the Redline... By 150hornet (Read 970 times)

[150hornet]

I know that redline riding is said to cause damage to the engine. I'd like to know, more specifically, how a redline is established, and what's the point of a redline if you shouldn't ride into that zone in the first place? My redline starts at about 50 mph, which on this Chinese bike is in reality 40 mph. You're always looking for that extra push and the redline zone becomes enticing. What type of damage am I causing when riding into the red zone?

[roketamc70]

I'm not 100% sure but I believe that is how I destroyed my engine. Check out my string

scooterdoc.proboards.com/index.cgi?board=150cc&action=display&thread=6523

[sprocket]

Yeah these engine aren't designed to run WOT very long...most manufactures have different redlines but generally they are between 7600 and 8200 RPM

You want to keep them about 7500rpm at the most...but the tachs are as unreliable as the speedos...so it is guesswork ;D

You can do a bit with changing you top speed and keep your RPMs in a comfort zone by messing with the rollers and rear gear ratios...

Trial and error mostly and ever brand is different...

[Alleyoop]

Thats how my Trike 157QMJ used to be when I first bought it, would hit 50mph at around 8200 rpms, it came with 10Gram weights.
Put in a Prodigy Racing Variator and 12 gram weights and running around 7200-7300 rpms at over 50+mph.
Alleyoop

[rob63]

The redline is basically the maximum amount of rpm that the motor can achieve without significant damage taking place. It is determined by the manufacturer, and is worked out by taking into consideration the build quality and the balancing of the components as a whole. On a four stroke engine the first thing which becomes apparent if you go too far through the redline is that the valves will start bouncing. This is when the valve springs start rebounding against themselves, sometimes causing the valves to hit the top of the piston.
On a 2 stroke the problem is more likely to be the balance of the crankshaft/conrod assembly, where exceeding the maximum amount of rpm too often, has a tendency to bend or snap it.

[Bashan]

I use a Tiny tach and I'm assuming it's pretty accurate. I used to wind my Bashan 150 out to 8,500 pretty regularly and it survived. However, it was sounding pretty shrill at that RPM and I think that was about it's limit. We have had people on the forum say they took their GY6 up to 10K+ but who knows, that could have been BS. Rich

[sprocket]

Ya.. these are interference engines like the old VWs...the top of the piston and the valves share the same space...if they don't play nicely with each other ..hole in piston...or bent valve

[larrball]

When i first got my current scooter i had it up to 10k..once and only for 1-2 seconds.
Never, ever will do that again.
Still to this day i have no clue why it didn't just up and grenade given the sound of it... and me saying "Oh crap, shes going to blow"

So rich, it's not all BS, but i'd be willing to place a bet that if someone did it a 2ed or 3ed time more then likely there is some form of engine damage, and most certainly going to have them valve springs float.

[150hornet]

Thanks guys, i quickly learned after riding for only a few weeks that these little Chinese engines can only be pushed so far before you start to feel the consequences. And it didn't take me long to want something more...so soon I will be selling my Motobravo in favor of something...Japanese : )