A peek inside my '05 DE250

[AZRickD]

While it was up on the stand (tire changes) I decided to take off the pipe (to straighten it), and take some pics of the piston and stuff in preparation for my June-ish top-end inspection and R & R.

A series of photos starting with the exhaust area.

The photo's aren't showing so just click on the links...

Next is a pic of the side of the piston (no rings showing)...

Next is the top of the piston with a little ring action...

And finally a glance at the back of the cylinder wall. Notice the cross-hatching direct from the Spanish factory...

 

[Eric K]

It looks like you have a lot of carbon in there.

 

[GMP]

Thats due to come apart. What oil was run in that bike? Very dirty PV, my bikes PV parts and exhaust port have been little more than stained brown running Amsoil.

 

[AZRickD]

I run Maxima at 40 to 1.

Usually jetted just a little richer than optimum.

One thing to keep in mind is that digital flash photography (mine was in Macro mode), makes things look pretty nasty. It's like watching your local news on Hi-Def and discovering that your the hot news anchoress has an issue with wrinkles.

 

[AZRickD]

Let's revive this ol' thread

In two weeks I'm going to do my top end (with the help of a mucho-experienced buddy).

We'll do the squish band measurement for RB-Designs and then commence with the tear-down. We'll give everything a good cleaning and see if my deck height is where it should be.

I'd appreciate some advice on the best vendor and manufacturer for the gasket kit, piston and rings. I've used Wiseco before but I've always been concerned with the forged piston heat cycle thing. I'd be willing to consider others.

Thanks.

 

[Eric K]

The dimension to the top of the piston varies by manufacturer. The top of the replacement Vertex piston was 0.2 mm higher than the original piston as measured by squish. I would measure the squish after installing the new piston.

 

[AZRickD]

Okay. I'll do that.

Any advice on a source for piston/rings, gasket kit?

This is the link to the gofasters page http://www.gofasters.com/index.php?main_page=index&cPath=65_283_308&sort=20a&page=1

The piston is $200 to $300 !!

Going back in time... this from Glenn "GP" over at woodsracer.com from 2005:

GG OEM Wiseco pistons were expensive because GG specified A - D micro sizes like the Jap OEMs and Vertex. Standard Wisecos were just offered in two sizes. GG has since gone to Wossner for OEM. What sizes are the FBF piston available in?

This site has GG Vertex pistons ('02-06 models) for $111 (for all four sizes). Is that around the ball park?

This appears to be the price for the kit (including rings, circlips, etc).

http://motorhelmets.com/htm-engineparts/vertex/pr-engineparts-vertex-pistons-2-stroke-gas-gas.htm

While I'm at it, this site has some pics of a GG top-end teardown http://www.scottysdirtbikespares.com/gas-gas-set-up-tips/how-to-change-2stroke-base-ga.html
Thanks.

 

[GMP]

OEM is now Vertex. Last Vertex kit I bought in winter '07/'08 was around $130. I hope those prices are a mistake, $300 is just stupid expensive for a two stroke piston. The Vertex piston is and always has been the same for a TM250, and I beleive is listed as a standard Vertex part. Call around, there has to be a dealer with a 250 piston in stock for a reasonable price. Failing that, if that $300 is for real, try getting one direct through a Vertex distributor (Sudco I think).

 

[GMP]

This site has GG Vertex pistons ('02-06 models) for $111 (for all four sizes). Is that around the ball park?

Now were talkin'

The kit should include rings and pin, ring kit for re-ringing later if desired.

 

[AZRickD]

I just got an e-mail from Go-Fasters. That was the "a la carte'" price. The kit price is $182. Another $15 for the gasket kit. I'll ask him what type of piston it is.

Answer: Wiseco.

I think I'll give Vertex a try.

 

[blitz11]

Don't forget the piston pin needle bearing. It's a shame to do the top end and not replace that. Those tiny needles are taking the full brunt of each internal explosion. That same load is transferred to the big end, and look at the size of that bearing/those needles.

Don't cheap out here.

In the old days, we'd get a needle bearing with a piston kit. Not so anymore. Make sure you get the needle bearing.

blitz

 

[AZRickD]

Good thought. I'll look to see if motorhelmet or GoFasters has the needle bearing kit.

 

[AZRickD]

I ordered the piston kit through motorhelmet.com and the gaskets and wrist pin needle bearings through Gas Gas Southwest.

 

[widebear]

Just for reference. Here's a pic of what I believe to be, a piston from a properly jetted, my mc 250 engine. amsoil 100-1 @ about 100 hours running time. Notice the less than perfect transfer pattern.

 

[AZRickD]

What do you make of that transfer pattern? What's the fix?

Nice pic, btw.

 

[widebear]

You can see the clean spots on the piston where the cooler incoming charge enters the cylinder but one off the transfers seems a little out of balance with the rest, still not to bad though. Alot of attention to detail would help but bear in mind that this is just a snapshot so to speak of the internal goings on. I'll bet that after the most recent work Ive done on the engine the pattern will be more pronounced.

 

[AZRickD]

I ordered the piston kit through motorhelmet.com

Crud !!

I got an e-mail from motorhelmet.com that they were "out of or no longer carry the piston.

I went to OEMcycle.com from a member who said he got his Vertex piston kit there (numbered as a TM250) and all they list are kits for Suzuki, Kaw, and KTM.

Poopie.

Advice appreciated.

Edited to Add: Google is a wonderful thing. No matter how poorly a small business's web site is hyperlinked, Google can find it. http://www.oemcycle.com/Item/product/1268

ETA: Oh poo -- "Sorry, this item is not currently available"

ETA: CJ CHROME & CYCLE to the rescue. Southbend, Indiana $111

 

[widebear]

monkeybuttparts.com. Application 86 to 96 honda cr-250. they sell Wiseco and Athena in stnd and marginal oversizes.

 

[AZRickD]

I'm trying to find a vendor that sells wrist pin bearings.

Is this a standard bearing that will fit any piston make (Wiseco, Vertex, Pro-X...)?

What should I get for the my 250?

 

[widebear]

Well yeah, think about it, all those piston choices available all have to work with the factory con rod. So yes one bearing. Wiseco easy'st to get.Once again , monkeybuttparts.