Finished! KDX-215

[beefking]

Well as some of you may remember a few months back, I had to split the cases on the trusty 89 KDX200 because the piston (stock!) shattered. I've had that part done for at least a month now, just had to save up some extra dough for the boring and replating.

I just finished putting the steed back together today with the Wiseco +2mm piston kit, and boy does the cylinder look good! Langcourt (http://www.langcourt.com) did an awesome job cleaning the cylinder, boring, and replating the cylinder. It really is spotless! Total cost was $235, with boring/honing/replating, shipping, wristpin bearing, and complete Cometic topend gasket set.

Back before the piston shattered, the exhaust valve teeth were completely gone and it was pretty dirty in there. After replacing the powervalves and "freshining" up the top end, boy does the bike run good!

The power is really great! Torque like a fourstroke (just about), and it seems like it will pull good on top as well. Still breaking it in, so I haven't been able to give it a good ride as of yet. I can easily do 3rd gear wheelies now w/out the clutch, 13/48 gearing. I think once it's completely broken in I should be able to do 4th gear wheelies no problem.

I had some concerns before with the clearance of the middle exhaust valve due to boring, but it clears with flying colors thank god. Also I was concerned that I may need to increase the head volume, but so far it isn't pre-detonating. I also advanced the timing just a tiny bit to prevent that. FYI, I'm running 94 octane with lead substitute, and Spectro SX 2smoke oil. Very clean burning at 32:1, not a spit of oil or smoke out the pipe! That is with 158mj, 48 pj, stock needle at 3rd clip. It already has PC Pipe, all smashed up though. I'm sending it out tommorrow to Pacific Crest pipe repair (piperepair.com) and then a Rad Valve I think is next.

I'm uploading pics right now, for those who would like to see what it looks like.
~Matt (one very satisfied KDX owner) :) :)

PS Sorry for rambling on, I'm just so excited that I finally got this pig running!!! ;)

 

[fatty_k]

Just to add to the comment you made about clean cylinder after replating. I got my Gas Gas cylinder replated and was really happy at how clean they got it. I was told by the guys at my local shop that they bead blast it. The cylinder looks entierly brand new. Brand new outside, brand new inside!

 

[canyncarvr]

re: I also advanced the timing just a tiny bit to prevent that (detonation I presume).

How does that work?

Perchance, do you mean retard?

 

[cweingartz]

Why may I ask are you running lead substitute? Does this offer some advantage over not using it?

 

[beefking]

Eehhh...now your making me think canyn! I turned the plate a hair in the direction the arrow points to on the magneto...so ya, I guess i did retard it. oops! Well it runs good anyhow. Maybe I'll try setting it back to stock, for kicks. :)

And about the lead substitute...the lead-type "substance" (its not actual lead in this formula) acts as a cusion on all the...eh, parts. Works wonders on preventing valve seat wear on thumpers, so maybe it will slow down wear on the rod bearings/piston rings. Makes the exhaust smell a little sweet too, always a plus when you have to ride behind the thing. ;)

Although I do have one question/concern...Yesterday, it burned VERY clean, not a single sight of smoke from the exhaust. Today, I made some more premix, same exact ratio/gas type as yesterday etc., but it smoked a little bit. Enough to fill the garage up with smoke (yes I had the doors open). It was about 20 degrees warmer yesterday, could that have anything to do with it? Or maybe all the oil settled to the bottom of the carb and got sucked up??? I dunno. Today the plug had a very small wet spot on the rim of the threads, but the electrode was a light gray (see pictures). Of course this is all at 0-1/2 throttle too.

Here are some pics of the project:
http://groups.msn.com/KDXRidersCommunity/zaiuspics.msnw

 

[canyncarvr]

Assuming the arrow you refer to points in the direction of rotation, moving the stator that way would retard the spark.

EG has noted that while a lot of bikes may well benefit from spark retard, very few benefit from spark advance. Indeed, advance is usually detrimental.

Retarding the timing will put a lot of heat in the pipe vs: the engine, will increase the 'hit' of any powerband effect and increase the so-called 'over-rev'. Bottom end pull takes a hit. I retard timing about .030" (on the stator) when I'm off to the coast or riding in more open areas that aren't going to involve much if any technical stuff. Makes the bike a bit harder to hang on to! ..and more fun!

Wouldn't worry much about smoke. Break it in, do some plug checks.

Watch for detonation! As you mention, head 'relief' is usually part'n-parcel of an overbore. I haven't figured the math in your case, but your static compression ratio certainly went up.

Thanks for the input on langcourt. I'm thinking of using their services next time I do a top-end. I have a bit of plating peel that needs to be addressed (thank you belray!). Probably have mr. gorr 'fix it' first. Don't think I want to sacrifice the range that would come from the 225 kit. I'll stick with a pro-x 'B', probably.

BTW..light grey isn't usually a good thing (additives notwithstanding). That's the color of vaporized aluminum. Unlikely what's happening in your case I'd suppose.

re: '..now you're making me think..'

oops. That sort of thing usually causes me some pain! ;)