Huasheng Horror! Valves & Cams

[ccrydr]

Does anyone know where I can get cam gears that are made of metal? I've gone through two cam gears. The first was completely disintegrated into many pieces. The second has a hole wearing through on the cam lobe. I don't know what is causing the problem. Also I have been having problems with exhaust valves dropping. The first valve dropped on the first 142F engine with no damage to the cam gear. Both the damaged cam gears came from the second 142F engine which also dropped an exhaust valve.
I did what was instructed fom Bicycle-Engines.com with the second engine, using low grade fuel and a colder spark plug. But it still dropped the valve and I don't know why. Also would full synthetic oil have anything to do with the deterioration of the plastic cam gear?

 

[Tony01]

Dunno about the cam gears but for flat tappets you do need to use a zinc additive to your oil. I put 20oz oil and 1.5oz additive in my engines (150cc, 212cc)

 

[racie35]

When you say valve dropping...do you mean it floated and was bent by the piston? They normally don't just drop. If so, you may be spinning it go hard and might wanna either look at stronger valve springs or higher gearing on your bike.
If it does contact the piston,the cam gear could easily be damaged. I doubt your oil choice is the problem.

 

[ccrydr]

The valve stem snaps just above the seat and drops into the cylinder causing damage to the piston, spark plugs and valve seats. If or when I have anymore trouble with these engines, I'm going to boycott China and just buy a DAX!

 

[racie35]

That's china too

 

[ccrydr]

Dax Titans aren't built by the Grady bunch in CO? I know he doesn't have any metal cam gears. They are plastic too. He said he has never had these problems with his engines even back when he use to sell HS.

 

[scotto-]

It sounds to me that you are over revving the little engines and the oils used may have some factor to their destruction.

I have had the plastic cams start to fail, but they seem to be of bad injection molding with bubbles in them.

I have over revved my HS49cc engines in the past just too see what they can handle. They are pretty tough little powerplants that I've revved over 9,000rpm and have racked up thousands of miles on a couple of them with no failure. I maintain them well and change the oil much more frequently than recommended.

I run fully synthetic oils after I break the engines in....just the way I do it.