A peek inside my '05 DE250

[2 strokes 4 life]

Wait CR250 pistons will fit in the Gasgas EC/DE250?

[AZRickD]

MonkeybuttParts is only a few miles from my house.

As for CR vs EC, the only cross reference I saw was with the TM250.

[Nick]

Any parts unlimited dealer can get you the Vertex

[widebear]

Originally Posted by AZRickD

MonkeybuttParts is only a few miles from my house.

As for CR vs EC, the only cross reference I saw was with the TM250.

I can assure you they work, two of my bikes are running them @ $113 each yet! Same goes for the rod kit.

[2 strokes 4 life]

Widebear thats amazing. Now I know what I am going to run next. THANKS!!!

[AZRickD]

CJ Chrome and Cycle said their supplier no longer carries this piston.

I called MonkeyButt and he was unable to locate the proper piston (he found some Size (B) pistons). I called Tom at GasGasSouthwest and he got 'er done.

[AZRickD]

The work begins tonite.

Any advice on measuring squish (I'm going to use squishy-core solder and then see what modeling clay will do as well)?

Any primo deck height I should attempt to achieve with my vast supply (not) of gaskets? I'd like to try just one gasket if I can get away with it.

Rick

[cvl05]

Rick, just make sure you get the solder across the middle of piston all the way to the cyl wall with no gap. Also loop in the middle out around spark plug hole, there is a detailed pic at rbdesigns web site. Very easy. Make several impressions, 3 would be enough. Then send your head off to RB. Doos not matter id orings are in place or not for this measure.

[AZRickD]

I took a look at the innards tonite. Everything looks normal. The BDC piston is almost but not quite flush with the bottom of the port. The power valve is really sloppy. I hear that's normal for Gassers.

Let's see if I can get some 2 megapixal cell phone pics to show...

If not, click on the link.

Bore:



Head:

[AZRickD]

The new Vertex piston and rings are now in the bore. The old piston (looks like a forged Wiseco) had at least one of the rings locked up, both out of spec. PV is now nicely cleaned up. We used one .5mm base gasket if only because that was the sole base gasket in the kit, which also didn't include that little water inlet gasket on top of the head next to the sparky plug hole.

My mechanic-buddy measured the piston at 66.25 mm which, according to this table, http://www.oemcycle.com/Item/product/1268 is a couple tenths of a mm below spec.

We did the squish band measurement. It's averaging around 1.93mm which is at least a one mm above spec IIRC. I look forward toward a new experience in throttle response when I get the head back from the machine shop to cut out the slop. Also, I tried using modeling clay to measure the squish and got a reading of 2.25mm.

On a very related note, yesterday I got a PM from our own "whodat." Unbeknownst to me, his office is just a few miles from my house and he regularly does silly hike-a-bike rides with some of my club members (he used to be a member as well way back when).

He said that when he got his squish mod done, he bought an extra head (from a part-out) so he wouldn't miss a weekend of riding. And he's loaned it to me (and gave me some .125-inch acid-core solder as well).

Yes, I won't miss a weekend of riding, but the other thing I'll be able to do is a seat-of-the-pants A/B comparison between my bike's performance pre and post top end, and then again pre and post squish mod. Coolness.