Ok, my friend is looking for a high compression piston, and was all ready to install it, when they told him that it is only good for 10 to 15 hours of use. His DS is using oil and is 3 years old now. We suspect the stock rings are shot. The high compression piston is cheaper than a stock piston, hence we going for that. We are not really after more power, just a new piston and rings.

He got a Ron Wood stage 1 piston. Is it true it is only good for 10 to 15 hours. He races the bike for fun, but also do trail riding. If the piston is only good for 10 to 15 hours, then it is not worth it. Opening the motor once a month for the riding and racing he does is just not an option.

If he uses a JE or other make piston, will they last longer, or have he been given the wrong info about the RW stage 1 piston?

 

this info he was given is rediculous.
I ran an 11.5:1 JE for 4 years and over 500 hours, and when I removed it it was still perfectly fine and the rings were also still fine with no oil consumption at all.
I now run a RW CP14:1 and have over 10 hours on it, and expect to get several hundred as well.
RW pistons are made by CP, every bit the quality of JE, and some will argue more.

just deglaze and spiral hone a new crosshatch on the cylinder wall for proper ring break-in, make sure the rings are gapped right before install, and run the correct octane fuel. oh, and don't take fuel octane advice from the same guy giving you life advice!

btw I ran pump 92 with my 11.5:1 for all that time mentioned above.

 

Hightower,

Why did you replace JE if it was doing good and no oil burning?
And then why did you move to CP from a successful JE experience?



Thanks Greatly!

 

Thanks Hightower.

I thought as much. These things are not junk, so I could not imagine that they make a forged piston, and it only last 10 hour when a stock one can go for years.

 

I changed to new piston because a small e-clip came off my carburetor and sucked into the motor and scrored the side of the piston and also the cylinder wall. also I wanted to go to higher compression for added power. after doing so, with nothing being changed but my piston to the 14:1, the power increase is very dramatic on seat of the pants. have not been to dyno with this new setup yet, others that have claim a 5hp increase going from 11 to 14:1, and based on how dramatic what I feel is I believe it.

I went to CP for several reasons - the JE I had was a great durable piston, and CP's trackrecord is every bit as good. CP makes them for RWR and I have RWR cams. I was guaranteed of no piston/valve clearance issues with the CP 14:1 because it was made specifically to work with my cams being from the same vendor. While the JE would probably be just fine too, I was not guaranteed that.
I also wanted a gapless ring package that has been tested and proven in the field over time, and the CP's from RWR have this. I now have extremely low leakdown, no more blowby, and absolutely no oil loss from the crankcase vent tube - I mean not even a single drop after a full days ride.
Also, RWR charges same price for all pistons - $260 no matter what ratio. Others charge an extra $140 for JE 14:1 from what I've seen.

 

Hightower,

You had crank case vent tube oil blow by from new JE rings and prepared cylinder walls?
I heard you want oil usage on these engines, but didn't think it was meant to be vent tube blow by.
That don't sound good at all.

Those must be the Axtell cams. I read about him.
Sounds like a full race bike now.
If you ever get a dyno posted, that would be interesting.



Thanks!

 

it is very common to get oil out of crankcase vent on DS's in stock setup as well as aftermarket situations - the hose barb on the stator cover is mounted so low that in certain situations on inclines and hills of certain angle gravity places oil right in front of the breather outlet and even any small amount of piston ring blowby pushes small amounts of oil out. of course the reciprocation of the piston is always pulling air in and pushing it back out per every rpm, hence the need for a breather regardless of blowby, but piston ring blowby makes for more air being pushed out than brought in. the stock placement of the breather tube by Bomb has the breather tube routed into the intake, and this arrangement under these certain circumstances makes a mess in the airbox at times. it has always been a battle for many ds owners to keep his breather clean and tidy.

I have not personally compaired leakdown measurements of gapless vs. traditional, but it is said and written that conventional builds yield around 10-20% leakdown where gapless packages from Total Seal Technologies yield around 2%.

yes I have Axtell cams. I have a dyno from my previous build somewhere, if I can find it I will post it along with a new dyno of the new build which is all the same except piston. not sure when i will get to the dyno, may be a few months...but I will eventually. and it will be the same dyno, and wearing the same tires, for a fairly accurate representation of differences, except for different times and perhaps updated calibration of dyno unit, so will still be questionable...