Cylinder bad?

[Mnolan660r]

Hey folks,

So the other day I was out doing the “monthly start and yard putt” on a 1997 kdx200, and I noticed a few things: it was hard to start. (New issue) and it wouldn’t idle real well. It was also making a new intermittent loud “knock”. So one thing lead to another, and I completely tore it down to just the frame. My question is this: the picture of the cylinder looks like it is pitted. I can’t feel anything w/ my finger, all feels smooth.
Looking for opinions from those w/ more experience, for a direction to go w/ this.

Thanks!

[Kawibunga]

From the pics, that looks like it sure could use replating......... just my two cents. But that's definitely not a nice new shiny cross hatch for sure!

[Mnolan660r]

Yeah, that’s the conclusion that I came up with also. I had one company look at it, and the guy told me that he thought the “spots” were from detonation. I measured the bore w/ a bore gauge, in multiple spots, and it seems like the bore is round and not tapered, so I’m just going to send it in for a re-plate and fit a new piston.

[Mnolan660r]

So an update-

Went down the rabbit hole on this one. I pulled the motor completely apart, new bearings and seals everywhere. I ended up buying a new factory cylinder, the old one was cracked in 2 spots around the intake port!! Sent the old one out to be repaired and plated. New Weisco piston, rings etc.
I went through the frame and found 2 cracks where the sub- frame connects to the main frame @ the rear master cylinder. Got the frame TIG’d up, and Re-painted the frame with some factory PJ-1 green, replaced evert bearing for the chassis and suspension.
I had a set of 92’ kdx250 forks and triples sitting around, so I sent those over to Jason @ MXTrend in Puyallup. He was able to get me the correct spring rate springs from race tech, and install gold valves, and all seals and bushings.

New factory brake lines, front caliper and a new 2015 KXF front master cylinder. I did a rebuild kit on the rear master and caliper. Just need to get the front bled out, and a new chain and sprockets on there, should be GTG for a while!!

I’ll post more pics when I have a chance!

[Chuck78]

Nice work! & quick, too!
Sometimes, when people go down the rabbit hole in this direction and strip the whole bike down after just one problem, they often end up taking a year or three to do a complete rebuild!

I'm hoping that once I start my original 220's rebuild, that I'm able to focus pretty intensely on it and get it done so that I can tear down my other 220 and do some minor work like water pump, and suspension upgrades, both bikes will get in 125 forks and 01-04 RM 125 shocks with KLX suspension links (7/8" lowering links when used on a KDX) and a 10mm lowering spacer in the shock (around 7/8" at the rear wheel as well) to level out the ride height.

It'll be nice to have a good backup bike and a loaner bike. On top of that I have another complete engine and an extra cylinder on top of that plus an extra couple of 220 heads!
I'll have to do a good build thread once I actually start wrenching on the 99. Actually I think I'll put the $1,000 worth of titanium hardware on the 97 after I do the suspension and engine on the 99...

[Kawibunga]

Beauty! And nice touch on the John Deere sticker on the silencer. And as Chuck said, quick turnaround. Impressive for sure.......

[Mnolan660r]

Thanks!

I have a 98’ 220 for a second bike, I guess that’s getting the same treatment, sans the chassis and suspension rebuild, that’s already been done.

Biggest time consumption was getting all the “specialty”tools again. Plus I wanted my “limited space” garage back, so didn’t bottle too much.

If anyone is looking for 96-2006 kdx parts, LMK, I have LOTS of spares, almost enough to build a complete 3rd (or 4th) bike!

[Chuck78]

If anyone is looking for 96-2006 KDX parts, lmk, I have LOTS of spares, almost enough to build a complete 3rd (or 4th) bike!

My spare engine I received mostly in pieces, crankcase halves are still together but everything in the clutch case area was all given to me in a box unfortunately.

I'm likely missing a few parts to things and may find some worn out parts as well, I found after realizing that my shift selector shaft was terribly bent, and finding a second one in the parts that was also bent enough to not want to use...

That just inspired me to learn how to use a 98-02 KX125 shift selector shaft modified to fit the KDX so that I can use the larger 1994 and up KX and KXF shifters, the splines are the full diameter of the shaft on those whereas the KDX splines are cut down to a smaller diameter for some strange reason, same with 93 and older KX if you wanted to tip on an aluminum shifter to replace your heavy steel shifter with, 93 KX125 250 and 500 fit, as does a KX100 of more recent years although those may be slightly shorter length and not conducive to large boot sizes.


I may need some miscellaneous engine parts here at some point, I'll post in this forum, and look you up!

[KDXGarage]

Looks great! Congratulations on the rebuild. Sometimes it takes complete disassembly to find all the issues.

[billie_morini]

Looks Super and story is, too!