300cc big power(30HP) 4valve low price engine

[Tonywang]

You can just find this big power engine in CHONGQINGDONGBEN INDUSTRY CO.,LTD OF CHINA. Any questions pls let me know,I will answer

Pls contact me,

Tony
CHONGQING DONGBEN INDUSTRY CO.,LTD
Tel: 0086 23 62453892
Fax:0086 23 62483776
Mobile:0086 13667619232

E-mail ：wang72274@hotmail.com
http://www.alibaba.com/product-gs/386281035/ENGINE.html

[Tonywang]

300cc 4valve big power
max power:22kw/8500
max torque:25N.M/8000

Mail Structure
DOHC:auto engine tech
4-valve:more airintake,higher fuel burning efficiency
No Rocker Arm:fewer noise,less valve adjusting
Racing Power: Higher power and Higher torque
Balance Shaft:low vibration
Water-cooled:professional design,no overheat
Leading design Piston and Piston Ring:super resistance

E-mail ：wang72274@hotmail.com

[Weldangrind]

I'd be curious to see that engine with the valve cover removed. I have a four valve OHC XR250R, and it has rockers. I struggle to understand how the cam acts upon the valves without rockers.

[FastDoc]

The cam rides right over the valves, separated by shims placed in shallow buckets. This usually requires dual camshafts.

[FastDoc]

Here you go!

http://img.photobucket.com/albums/v25/maule/DOHC-Zylinderkopf-Schnitt.jpg

[Weldangrind]

Thanks for the explanation. I've worked on OHC cars before as well, but I've never had experience with that style of setup.

[FastDoc]

You can see why this arrangement is necessaraly a bigger PIA to adjust.... In some cases you need to remove the cams to adjust the valves, which is done by replacing the shim. This is the case on my Gold WIng. That's a project I don't plan to do myself. That bike has a lot of valves.

[Weldangrind]

That pic makes it even more clear. The shallow bucket that you described looks just like a shortened version of a pushrod lifter.

[ejcycles]

Hi FastDoc

Honda is using the same concept {Shim & Bucket} with a single camshaft in the CRF 150 & up model racers now.

[FastDoc]

I wonder how they make that work. It seems to me the valves would have to be parallel which would not make for a very efficent combustion chamber shape....

[Reveeen]

You can thank Kawasaki for this idea. There is a special hook shaped tool you can sneak between the cam and bucket that allows shim replacement without pulling the cam(s). At high RPM sometimes the shims can get spat out causing all manner of catastrophe..... there is a "shim under" conversion that does require cam removal to adjust. Nothing like a tool box full of $5 shims at tune up time!

[FastDoc]

My GS750 is shim on top of buckets, and I have the tool. It's a PIA but at least do-able.

My Gold Wing is shim under buckets, and I'm not even going there.

Now that I think about it they are due for their first check, I have over 25,000 miles on it....

I like screw type adjusters, and I really appreciated my Harley's hydraulic lifters.

[recracer]

this engine can not be brought into the usa at this time