KDXRIDER.NET

Hi all,
I've been working on getting my 2001 KDX200 into shape and was hoping to get a bit of guidance. When cold, my bike takes at least 10 kicks to get going, but when it's hot usually starts on the first kick.
The bike has an FMF Gnarly pipe and Turbine Core 2 silencer, though I don't know which Gnarly pipe I have. Is there a way to check?
I have rebuilt the carb, including the jet block gasket. It is using factory jets and clip position. I live in Minnesota and elevations are about 1000-1500 feet.
The reed cage is stock and the reeds of are unknown age, though they looked to be even on visual inspection.
BR8ES Spark plug is relatively new and has not made a significant difference since replacement about 200 miles ago. The Plug has some carbon buildup and looked a little wet when I checked it this morning.
When I bought the bike, the igniter box was not secured and part of the wiring appeared to have been rubbing between the gas tank and frame rail, thought I don't think it has rubbed through the insulation.
The previous own said they had performed a top end rebuild with about 10 hours on the new piston when I bought it. I don't know how much they went through the KIPS if at all. The plug in front of the left side KIPS cover has seeped a bit, but is not leaking to a drip yet.
I have put 20-30 hours on the bike since buying it in 2019. Are there some specific items I should check first? I am new to diagnosing this sort of issue.

With regard to the FMF pipes, I had the same issue a while back. I was not sure which pipe was which.. There is a model number on the pipes that will tell which it is.. Here are pics of the two pipes on two bikes. The bike on the left has the woods pipe, its shape flattens out on the bottom. the bike on the right had the rev pipe on it. The pipe on the bottom of the tailgate is the woods. At least that is what I remember.. I run the woods on my 200 and probably should run the rev on the 220 but I am too lazy to change it out. Hope this helps.

Do you use the choke?

How wet is the plug?

How long since the carb work?

Do you leave ethanol gas in the float bowl and carb, and for how long?

How's that air filter looking?

Pipe is definitely the Woods pipe. Thank you Architect!

Cold start procedure is:
1. Turn on petcock
2. Lean the bike over till a little gas comes out of the cab
3. Turn on choke.
4. Kick till I get tired

When it's hot, the bike seems to start better when I crack the throttle a bit.

Carb work was performed just before taking the bike up North for a few days and getting in about 100 miles of fire road/trail riding. I have been lucky with getting ethanol free gas, though the first start up North was with gas about 1/2 of a tank that was getting on a year old. My mixture could also be part of the issue; I've been running Dominator Synthetic at around 44:1. I did not change spark plug after the carb work either. Air filter is lightly dirty, will get picks of it and the plug tomorrow.

Amsoil Dominator mixed at 44:1 should be fine. I mix it at 50:1

What is your compression like? My bike takes 6 or 7 kicks to get going if it has sat for a week or more, 1 kick always once warmed up. But my compression is starting to drop and I am needing to do a top end rebuild. Just because the PO said they did it doesn't mean they did it right, if at all.

Please drain the fuel and put in a fresh mixture.

I've got a compression test kit sitting in my Amazon cart, should I put together a leak down tester too?
On the topic of top end rebuilds; I watched a video from Rocky Mountain ATV/MC video on doing a top end on a KTM 300 that mentions checking the deck height during reassembly and using different gaskets to get the height right. Is this a KTM only thing? The PO specifically stated they did not remove the top of the cylinder head during the rebuild.
(Video link to around where they mention)


Old gas is totally gone now, new stuff is non-ethanol.

The deck height is from the crank centerline to the top of the cylinder. How do you measure that accurately with the head on? Maybe I get to learn something today.

I have always used factory gaskets, never had a problem. For a normal rebuild, I don't see the necessity to measure that dimension.

On the KDX you don't worry about it. As long as the piston doesn't clear the top of the cylinder with it torqued down you're good. A leak down tester is a great tool for gauging overall engine health (crank seals, etc), compression is good for top end stuff. If you plan on doing all your own wrenching having both in your toolbox is a good idea.

Changing base gasket thickness is something European bikes brands have done for years to change squish and port timing. It also helps that the Euro bike makers actually offer base gaskets in many different thicknesses to accomplish this. Japanese manufacturers do not encourage this and only offer one base gasket per model.

Not saying it can't be done, as I know it has, or that there could be be a benefit for some riders, but it's a little more involved on a Japanese bike as you'll be cutting your own base gaskets. You'll also need to understand how the base gasket affects port timing and how that affects power and how it's delivered.

Funny that this same thing popped up over on TT and now here. That's the most I've ever heard of Japanese bike owners talking about base gasket thickness in my life!

Results!

I did the compression test today; with a cold bike I got 175 PSI. According to my repair manual, the bike should be 90-150. Any guesses on what the high pressure reading could mean?

I think the spark plug is a bit past the time when I should have replaced it...

What is the goop on the electrodes?

looks like carbon build-up, I noticed on the last ride that there was more gunk coming out of the muffler. I think the bike might be too rich after the carb rebuild.

Make sure to set float height at 18mm and not the stock recommended 16mm. You didn't soak your carb or use brake parts cleaner did you?

I totally disassembled the carb, soaked it, rinsed it, then rebuilt the carb including the jet block gasket. That plug probably isn't a great indicator of health when it's the only one I've put in the bike since buying it.

Anyone have a guess on what would be causing the high pressure reading? Should I be concerned about the KIPS?

comradealexie wrote: ↑08:40 am Aug 01 2021 I totally disassembled the carb, soaked it, rinsed it, then rebuilt the carb including the jet block gasket. That plug probably isn't a great indicator of health when it's the only one I've put in the bike since buying it.

Anyone have a guess on what would be causing the high pressure reading? Should I be concerned about the KIPS?

Probably have a thick layer of carbon built up on the piston by the looks of it. It's bumped your compression up significantly.

Take the exhaust pipe off and look into the cylinder to see the top of the piston.

I hate to say it but my 220 had the same cold start issue you are describing. I tried everything I or anyone else could suggest to no avail. Finally switched to an RB carb and the problem went away. 2-4 kicks cold and almost always one kick afterwards. For kicks I installed my buddy’s carb off his 200 and it cranked right up too. Sometimes I just think these old carbs look ok but aren’t. Good luck!