~ K D X R I D E R . N E T ~

General Q&A :: RE: Replacement parts for rebuild. OEM, reuse or aftermarket?

Author: OLHILLBILLY
Posted: 11:05 am Feb 04 2012 (GMT -6)
Topic Replies: 4

Quote:

Hmmmm.

How do you define a "worn piston"?

If a piston is out of specs, diameter, ring lands, etc. by all means replace it. But a piston is considered a "non wear" item. It will, of course wear out, but unless something is wrong, not in 200 or even 500 hours.

Piston manufactures for years have extolled the virtues of replacing pistons at every rebuild. Wanna guess why?????

The only pistons I have replaced at every rebuild was on a top fuel motor I was on a crew for once. But I'm assuming you're not running 98% nitro under 60lbs of boost (on a wore out blower....).

Again replace the piston if you like, they are cheap, but don't expect any more reliability or longevity out of it. There just isn't a magic pill for that.

BTW, 'busa huh? Cool. I have an 06 -14 that I absolutely love.... I'll admit I have mostly chicken strips on the tires right now, but I do have scrape on my left front plastic that I didn't get from dropping it ....lol

Pete

200 hours on a 2 stroke dirt bike motor is a lot of time in anybodies book. 100 2 hour harescrambles, or a whole season of riding for even a lucky to have a lot of time to ride person. Unless you just putt around, seldom ever getting on the pipe, that piston IS going to be out of spec by 200 hours. As I said, cylinder replating is a $200+ job anywhere, why try to save $85 and risk having to spend $200 along with the $85? Not to mention risking a complete piston failure from pushing it too far.
Maybe just me, but I always go with the "spend a little now and save a lot later" theory.

And yeah, the Busa is a good time. I've done a few track days on it even. I bought it new in '07, and it's been a pretty much do everything bike. Always fun to give the youngsters on their 600s and liters fits on the Saturday morning twisties rides. What do you think of the new 14R?
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2004 KDX 200.. Coupla mods
2007 Hayabusa

General Q&A :: RE: Can't get bike to shift into first..?

Author: heckler
Posted: 10:29 am Feb 04 2012 (GMT -6)
Topic Replies: 6

"hit the case"
"hit the skidplate"

yup, bent lever. been there, done that

General Q&A :: RE: 1986-7 KDX200?

Author: dfeckel
Posted: 10:27 am Feb 04 2012 (GMT -6)
Topic Replies: 6

I picked up an '87 several months ago and have been cleaning it up and learning as much about it as possible.

I'm pretty sure that the pick of the litter is the '88 because it is the only year with a PWK Kehin carburetor. All others have a Mikuni round slide.

The forks and front brake and wheel are the same as the early E-series bikes ('89-92), but the triples are different. The front brake is a single pistion affair, which is better than a drum, but certainly not as good as a more modern brake. The rear brake is a drum, but I haven't actually ridden the bike more than around my yard, so I can't testify as to how it performs on the trail, particularly in wet conditions.

The rear suspension is an early Uni Trak design that uses a push rod from the swing arm to a rocker arm under the seat which actuates the shock. The rocker arm uses pretty generic needle bearings, which are probably easy to replace through a bearing house, but the push rod has heim joint/spherical bearings that you just can't find from All Balls. There are no linkage bearing replacement kits available from any vendor, so you'll have to forage to find what you need. I managed to get an OEM spherical bearing from Babbitt's, but it cost $76, and the bolt it rides on and the special seal is unavailable. It probably wouldn't have been too tough to fab up a correct bolt, but the seals area a different matter, so I wound up buying a good condition one from someone parting an '86. But the great thing about this archaic set up is that each pivot, including the main swing arm pivot, has a grease fitting, so you might potentially keep the bearings in good shape longer with minimal work.

The '86-'88 bikes have a trick electronic trip meter and clock that is resettable up and down by hundredths, which is exactly what you need for old-school time keeping enduros. They seem to be much more reliable than the mechanical odometers that the E and H bikes came with, but replacing the electronic pickup at the hub or, heaven forbid the whole unit, is pretty expensive.

They have a 6 volt electrical system, so don't expect to find replacement light bulbs at Auto Zone.

Regarding the motor, it shares a lot of bottom end parts with the E and H motors, but the shift shaft isn't one of those parts. Mine was stripped and badly welded, and I had to find a good used one on eBay. The top end has a plated cylinder with an early version of KIPS using two small rotary sub valves but no main valve. They seem to be more robust than the problematic E sub valves, or at least that's my impression because the KIPS in my '87 were perfect and they looked original. The sub valves in both my used E-series motors were trashed when I bought them. The stator and flywheel are not the same as E and H bikes, but I believe Jeff Fredette has a method of either repairing the stock stators or retrofitting them to work with newer stators. Pistons, small end bearings, main bearings, tranny bearings, gaskets and seals are all easy to find on eBay.

Ergos are typical old-school--big cushy seat, narrow bars that feel low and close, skinny foot pegs, pretty low seat height. The bike feels very thin despite the large tank because of no radiators and a pipe that tucks in neatly. It also feels quite light wheeling it around the garage, but I haven't weighed it yet to see if that's just an illusion. It has a great hand hold under the rear fender that is reinforced by the subframe, which makes it easy to lift onto a stand or out of ruts.

It has a weird air filter. I had some trouble getting it from No Toil (one of their premium reusable filters), but I eventually got the right one. The airbox is very waterproof, with an intake just at the lower margin of the seat.

I haven't put any real miles on mine yet, but from what I can tell around the yard is that it has very nice low-end power and will lift the front end easily in the lower gears. Once I get a few shake down trail rides on it, I very well may take it to a hare scramble or enduro this year just for fun. I don't think I'll be dicing it up with usual competitors, but it should be a fun, comfortable bike to cruise on.

Thumbnail, click to enlarge.

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David Eckel

General Q&A :: RE: Replacement parts for rebuild. OEM, reuse or aftermarket?

Author: Rjcapt
Posted: 10:20 am Feb 04 2012 (GMT -6)
Topic Replies: 4

OLHILLBILLY wrote:

With a useable compression range of 95-151psi, 110-120psi isn't really bad, but it isn't really good either. If you have over 200 hours on the motor, personally, I'd spend a few extra $$ and put a new piston in it. You can ring it and get it to last a little while if your on a really tight budget, but a worn piston is going to speed the wear process on your cylinder plating considerably. Replates are $200+. Pro-X pistons are less than $100, and are the same as OEM, do yourself a favor, spend a little more now and save a lot latter.
My .02

General Q&A :: RE: loud rattl???

Author: Rjcapt
Posted: 10:04 am Feb 04 2012 (GMT -6)
Topic Replies: 4

While kdxs DO ratttle. Not EVERY rattle is supposed to be there. Just ignoring an engine noise and assuming its by design is, well, not smart...

You have been given excellent pointers so far:

Is it new? The rattle, not the bike
Is there any time (rpm wise) when it's most evident
Is your pipe secure?
Any aftermarket pieces (skidplate etc)? Are they loose?
Does it go away when you pull in the clutch?

I found the rattling on my bike when I first got it to be, disconcerting to say the least. But, they are noisy motors. Now I find the rattle reassuring. If that doesn't work I ride my xr400 with a big noisy obnoxious 4 stroke.....

Good luck

General Q&A :: RE: loud rattl???

Author: Mr. Wibbens
Posted: 09:36 am Feb 04 2012 (GMT -6)
Topic Replies: 4

kdx's rattle

if it irritates you maybe you'd be better off on a loud obnoxious 4 stroke
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General Q&A :: RE: Replacement parts for rebuild. OEM, reuse or aftermarket?

Author: OLHILLBILLY
Posted: 08:43 am Feb 04 2012 (GMT -6)
Topic Replies: 4

With a useable compression range of 95-151psi, 110-120psi isn't really bad, but it isn't really good either. If you have over 200 hours on the motor, personally, I'd spend a few extra $$ and put a new piston in it. You can ring it and get it to last a little while if your on a really tight budget, but a worn piston is going to speed the wear process on your cylinder plating considerably. Replates are $200+. Pro-X pistons are less than $100, and are the same as OEM, do yourself a favor, spend a little more now and save a lot latter.
My .02
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2004 KDX 200.. Coupla mods
2007 Hayabusa

General Q&A :: RE: loud rattl???

Author: OLHILLBILLY
Posted: 08:35 am Feb 04 2012 (GMT -6)
Topic Replies: 4

Do you hear it mostly at idle? If so, it's the KIPS.
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2004 KDX 200.. Coupla mods
2007 Hayabusa

General Q&A :: RE: loud rattl???

Author: rbates9
Posted: 07:07 am Feb 04 2012 (GMT -6)
Topic Replies: 4

Could be the kips. Or a skid plate or other guard. When do you hear the noise?

General Q&A :: RE: 1986-7 KDX200?

Author: blanc
Posted: 03:42 am Feb 04 2012 (GMT -6)
Topic Replies: 6

Great idea....do you guys race old kdxs?

General Q&A :: loud rattl???

Author: Bruce
Subject: loud rattl???
Posted: 02:36 am Feb 04 2012 (GMT -6)
Topic Replies: 4

hi, i have a kdx200 and it has an irritaing rattle like a marble in a bean can. its not bottom end as i have recently replaced the main bearings and the big end bearing checked out ok. i replaced the little end bearing and the piston was fairly new.could it be the kips rattling?

General Q&A :: RE: 1986-7 KDX200?

Author: skythrasher
Posted: 11:50 pm Feb 03 2012 (GMT -6)
Topic Replies: 6

rbates9 wrote:

It seems there is a growing interest in pre E bikes lately. Might be time to add a section for them like the E's and H's have. It would help keep info a little easier to find.

+1
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2001 KDX200
1987 KDX200
2002 CR250R
1999 Gas Gas TxT270

General Q&A :: RE: 1986-7 KDX200?

Author: rbates9
Posted: 09:57 pm Feb 03 2012 (GMT -6)
Topic Replies: 6

It seems there is a growing interest in pre E bikes lately. Might be time to add a section for them like the E's and H's have. It would help keep info a little easier to find.

General Q&A :: RE: 1986-7 KDX200?

Author: fuzzy
Posted: 08:33 pm Feb 03 2012 (GMT -6)
Topic Replies: 6

Either year is first gen KIPS powervalve, plated cylinder, and front disc...being most desirable of the air cooled's.
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'95 KDX 200
'94 WR 250

General Q&A :: RE: 1986-7 KDX200?

Author: gsa102
Posted: 08:24 pm Feb 03 2012 (GMT -6)
Topic Replies: 6

I think it should handle pretty well with the right springs. Newer bikes have improved components, but chassis geometery has been refined over the years, not reinvented. KDXs have a reputation for being very reliable, but it is not a motocross machine. I expect most non-wear parts to only be available on ebay.

Read the posts for the early bikes and you will find out what goes wrong and how to fix it.
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"Common Sense is hardly common"

96 KDX 200, 07 WR450F