FAQ Plastic!

[wfopete]

84 KDX200; my DG front fender broke off right at the base of the 3X clamps. Happened during a h/s race at the Mid-Ohio AMA VMDs event. I think UFO plastic would be better; Yes?

I'd would like to go with a narrower front fender and a MX style rear fender. Is this a big hassle or a relatively EZ mod?

Yes I did a search but after scrolling though numerous pages I gave up!

Bonus question! This bike has little low end or mid range power/torque but the top end power is crazy fast. It's like riding a 125 MX bike. The carb and intact has not been touched so I think the porting is stock. It does have a DG pipe/silencer but I can't believe that would cause this engine to run like this. I'm running out of reasons for this; right now I'm thinking the timing may have been advanced causing this condition.

Thoughts?

[Chuck78]

They're certainly was a sea of KDX is everywhere this year at AMA Vintage Motorcycle Days Festival! I probably saw yours but so many to keep track of!
I raced my '97 in Revolution 1. There were 160 riders for my race, WOW... The lineup was massive just getting into staging, and there were 5 KDX's within talking distance of me in the double file line!

Your DG pipe probably contributes a lot to having no bottom end, as well as being a pre-86 model. In 1986 the KDX got power valves to boost the bottom end.
You could have some porting done to increase the bottom end power. Eric Gorr still does this but is semi-retiring January 1st. Jeff Fredette / FRP Off Road will also do porting, as well as Tom Morgan Racing. All are Kawasaki gurus.

The OEM plastics are the strongest, but after 30+ years not as much, and usually not available new. UFO, DC Vintage Plastics, Maier, etc... All fairly similar but some may be stronger than others.

[Chuck78]

I don't have an exact answer for you, but I'd almost bet that an 82 or 83 KX rear fender may possibly swap onto yours, that's generally the way the KDX models go - it's based on the KX model of a year or so prior, or the prior generation of KX.
Compare them visually & judge for yourself if no one else has an exact answer.

[Chuck78]

@wfopete where ya from? Ohio area? Do you ride Wayne National Forest, Pike State Forest, or Perry State Forest?

[wfopete]

The volume of riders was bad enough but jeez that XC course is beat. I rode it a few years ago on my YZ465 and the course didn't seem that bad. For this VMD XC race I put in some heavier Race Tech fork springs in the KDX200 and was surprised at the amount of pre-load those OEM forks came with. I RT recommends no more than 5mm (.19"). I didn't have time to cut the spacers so in short; I got a pounding in a few spots. Need to find me a nice injected molded fender too. I'll check into the 82/83 MX models.

[wfopete]

@wfopete where ya from? Ohio area? Do you ride Wayne National Forest, Pike State Forest, or Perry State Forest?

Nope. Arkansas. Moved from Michigan in 1990 and never looked back. I have relatives in Michigan and Ohio

[Chuck78]

I noticed the course was pretty darn rough - shortly after we entered the woods singletrack as it rode along parallel to the back of the camping field after that low speed ditch, & leading up to where it turned left. Whooped out roots exposed, deep holes...
Then again towards the middle/ back section of the woods a few minutes later where you go through a small grassy clearing, when we turned left down a moderately steep hill it was REALLY ROUGH, then a hard right and then a left into the creek, that first downhill, WOW, it was BEAT!!!

Those two sections were the worst, and the only ones that I thought were really REALLY rough. They made me realize the shortcomings of an open chamber cartridge fork valved for woods, the cavitation became pretty significant in my fork oil running those at race pace with 160 riders on the 3.8 mile loop, all classes including a lot of pro level riders... Made me really REALLY scoot! Especially with a 1999 plus 2-stroke modern bike exhibition class riders, hot shots on my tail!!!

The high speeds on the rough tight "low speed sections" and those two really rough sections also made me glad I picked up a couple sets of '98 RM125 Showa Twin Chamber forks for KDX swaps! Those things will really really improve my KDX's in terms of fast aggressive riding when pushing it to the limits, and especially in racing.

Other than that, and the dusty conditions out in the starting fields, I thought the course was absolutely AWESOME
They actually re-routed several areas for 2023, to let the old well trodden and heavily rutted out areas heal.

[wfopete]

Other than Mid-Ohio I generally only race AHRMA X/C events so UDS is not allowed. I forgot to check my air pressures before the race and on the second lap I pulled off to check it (right next to the camping before the first downhill). The front tire was way too hard and I let quite a bit of air out before I could compress it with my hand. That seemed to help take some of the nervousness out of the handling. When I got back home I went out to check my tire pressure. It showed 18psi! And that was after I let probably let 5+ psi out at the track. Jeez. Here in Arkansas I'm used to the kind of terrain that Mid-Ohio had but between the tire pressure and hard forks I stayed fairly cautious in those woods. The steep uphill coming out of one of the creeks with the flat spot half way up was fun. After the race I thought that I should have got a better run at it and maybe I could have jumped past that flat area that slowed riders down. I also remember another downhill that went into a creek with a giant rock laying right in front. I just seemed to rag doll my way through that section every lap. You are right, there were sections that were good single track but they went by too quickly. This was my first race on the KDX in two years. If my 65 yo body let's me, I plan to hit four more this year. Next up is Diamond Don's X/C in Texas, then the ADR X/C race in Arkansas, follow by the Hayes Farm X/C in Ill. and finally Henrietta, Oklahoma. Trampas Parker puts on a great event there with X/C and MX events all weekend.

[Chuck78]

Other than Mid-Ohio I generally only race AHRMA X/C events so UDS is not allowed.

UDS???
Upside-Down Suspension?
If so, '96-'98 Suzuki RM forks aka "the best woods forks of all time" are right side up 49mm Showa Twin Chamber conventional forks. Earlier versions of the most modern technology in forks aside from TAC etc air forks or SFF single function forks (spring on one side, damping on the other), that is. They are basically just as relevant as anything else out there a new bikes, and they are not inverted.
Each year is quite unique as far as parts interchange, I made a nice breakdown of it in the fork swaps section here. They all basically function the same though, but 98 has the quick change compression base valve that threads out of the top just like all the modern Showa inverted closed chamber / twin chamber forks.
96-97 Bushings are no longer available OEM, but aftermarket bushings are available on ebay. 98 shares the same bushings as some DRZ400 models, I believe the supermoto & early S models.
The DRZ400E & all but the first 3-ish years of DRZ400S forks look identical to these, but are open chamber cartridge internals. Easier to set up plush for woods but will also be subject to cavitation under extreme racing use like the rough spots at Mid-Ohio Sports Car Course woods trails. Awesome forks though and they made them 1999 or 2000 through present. Much easier to come by and the other best right side up forks you can find for woods riding. 1997-1998-ish Marzocchi right side up forks on KTM EXC models were also amazing, and honestly better than almost all WP forks that followed them on KTM brand bikes...

I forgot to check my air pressures before the race and on the second lap I pulled off to check it (right next to the camping before the first downhill). The front tire was way too hard and I let quite a bit of air out before I could compress it with my hand. That seemed to help take some of the nervousness out of the handling. When I got back home I went out to check my tire pressure. It showed 18psi! And that was after I let probably let 5+ psi out at the track. Jeez.

Wow! 20psi is a scary amount of pressure for woods trails, 18psi isn't much better... I can barely stand anything much over 11 PSI and prefer 5.5 to 9.5 PSI depending on tire and terrain. I run Tubliss or Ultra Heavy Duty inner tubes. IRC or Bridgestone only.

[wfopete]

Actually it was likely more than 20psi. I was lucky I didn't slide right through the first turn on the start. I generally race at 12 psi front and rear unless unusual circumstances dictate otherwise. Around here 12psi is a good compromise between traction and flat prevention. If I'm just trail riding with nothing on the line I often drop to 8-10 psi (with UHD tubes) range. Yeah Bridgestone is my "go to" UDH tube also.

I should have said "Period Correct" but we all know most tech inspections don't look real close (most of the time) and it usually comes down to a protest from the competition. Most vintage MX and X/C courses are not too technically demanding for suspension but the technical aspect goes up in relation to speed so yes better suspension is always a good thing.