85&86 250R clutch mod

[don250R]

all i can say at this point is WOW!
i stumbled upon this mod at airfoolers.com
they were trying to figure out how to adapt this to the aircooled world
this mod can save your clutch fibers and your clutch basket too!
trying to get solid part numbers for a really great post
but here goes anyhow:

Ok, if you look at how the clutch works, think about this now, when you pull on the clutch lever the clutch arm moves on the engine & in turn pushes a rod up against the pressure plate. When the pressure plate is pushed, it relieves pressure from the springs that are pushing all the plates together breaking their bond.

When a clutch slips under torque from the engine it s because of one or several reason.
One being not enough pressure to bond the plates together tight. Some other reasons, sometimes to thick of an oil used in the trans & when the lever is released that thick oil has to be squished out of the way before the plates can bond.
Smoothed out metal plates, if they are not ruff surfaced then they cant bond as well to the fiber plates.
Sometimes using different brands of fiber plates, some are not as thick as others & some bonding pressure is lost.
Installing a new set of fiber plate dry & have not soaked them in oil at least a day or so makes a difference. An installed dry set of fiber plates in an oil bath transmission are on their way to destruction before you ever pull the clutch lever the first time.

You got to understand a spring, how it works.
When you compress a spring, more you compress it harder it is to compress any farther. All springs are not like this though, some compress to a point then they stay the same, no more greater force from the spring no matter how far you compress it.

Have I done any good so far.

Now to the fix,,,well I cant tell you that because you got to pay me first.

Just kidding:D
Its all about clearance, less clearance you have more bonding you will have.
Tighter you can compress the clutch spring, more pressure it will apply to the clutch pack when released.

Fix for 250R clutch,
Remove 1 of the 250R steel plates & replace it with one 400EX steel plate.
New set of SOAKED fiber plates, dont make any difference in brand, high priced or cheap as dirt no difference at all.
Set of CR 500 springs
The aluminum washers that go under the transmission drain bolt on a 250R engine, use one of those on each clutch spring bolt, under the bolt, NOT down in the pressure plate.
If the basket is grooved real bad, wouldnt hurt to file it some, get some of the cup shape out of the groove.
After you have done this mod & have the 89 clutch update, probably wouldnt hurt to get another bearing flat washer for the rod end at the pressure plate to take up some of the extra clearance there because there will be some & then an EASY pull clutch lever.
Easy pull lever, why, because after the mod & you ride like normal on an MX track coming out of a corner in the wrong gear & start to fan the clutch lever to make the engine pull, about a lap & those left hand fingers will be through, gone, give out.
When you do this mod, clutch plate slip & replacing fiber plates are over.
Been using this mod for years on a bunch of 250R engines & all report back with the same results.

[don250R]

this is a post from neil(aka C-Liegh Racing)

Hey,, check this out, what we ran on my daughters 250R back in 04.
I built this 330R engine just as a test bed to see how long it would run, well it ran until right at the end of the 07 season until when I found the piston was cracked & then at that time I replaced the piston along with installing one of the new Wiseco cranks.
It ran the rest of 07 season & then 4 races into the 08 season the tin started coming off the crank & ended up siezeing up the piston.
After that, I completely rebuilt it to run the rest of 08 & into the 09 season with custom TRX/CR250R combo crank, crank bearings & seals & an old used welded on patched up 350 Pro-x cylinder. We finished out the 08 & all of 09 with that build & only thing changed was spark plugs, jetting, & the carb pulled off one time, checked out & cleaned.

Guess what & this has been since 04, same Hinson clutch basket, inner stock basket, springs, aluminum washers, pressure plate, metal plates from 04 & since I got a big stack of fiber clutch plates about a foot high from various engine builds, at 08 when it was rebuilt, I just went through them & picked out the best looking ones measured the thickest with the less wear on the ears & thats what in it right now.
Those fiber plates lasted from 04 to about mid of 08 season & only reason changed out then was because the ears were worn quite a bit & even then I put used plates back in to replace those.

That engine has been a test bed, since day one of its build cylinder & clutch wise. One of these days I'll sit down & figure out the hours, amount of gas & oil & laps that engine has been through & ran.

And just think, that old welded on, patched up, 350 Pro-x cylinder, that one of my customers thrown in the trash can, went on to get repaired & got my daughter a Open B/C class championship last year, thats right you read it here, #1 Nationally in the B/C Open class with an old junk cylinder.
Maybe we should change from C-Leigh Racing to ol Poor Folk save a dollar Racing Team.

[don250R]

and this is part of a PM from Neil:

Been many years ago I got that clutch mod from somebody, but I got no clue who it could have been told me about it.
I dont guess it would be a problem, opening it up displaying it like that, just be sure to address that I got the idea from somebody else.

Far as the years for part numbers, I cant remember year models, but I have some of the springs & those aluminum washers in stock to get the part numbers from. No metal clutch plates though. Best I can remember, the 400EX metal plates are the same all year models.
If the 400EX metal plates are hard to find, taking two of the 250R metal plates & putting them together right in the middle of the clutch pack will work just as well( i personally dont agree with this).
Far as the fiber plates, it really makes no difference if it is the highest price or cheapest price set you can find, because any will work.
The whole idea behind this clutch mod, is to stop clutch slip & burning the fiber plates up.

The biggest reason you have burnt up clutch plates, is from riders going into & coming out of a corner in the wrong gear & then they got to fan the clutch lever to bump the rpms up on the engine to make it pull.
Well, once you stiffen up those springs, that bike will end up with one heck of a clutch lever tension & after about say a lap or two fanning that clutch lever, those left hand fingers are through & they'll be lucky if they can hold on to the handle bars.
More or less, it makes the rider learn a different riding style & shifting gears to maintain power instead of burning out clutch plates every race.

[don250R]

this is one mod i personally will try
look for more info on this one!:headbang:
Don

[NOS_350X]

I think your over thinking things a bit EH umm alot.

The fact is, if you have good fibers and take care of your oil you wont have problems. I use HD springs, and the pull is about half what my shee is. No fancy spacers, or plates needed. My R has the whole 89 clutch seup. My banshee ive been racing hard on for 4 years now. Its all about taking good care of your bike.

[MagicJames]

Can you still buy the 89 clutch update?

[don250R]

i bought mine 3-4 years ago from the Honda dealer.....

[fire1]

Can you still buy the 89 clutch update?

http://cgi.ebay.com/ebaymotors/TRX250R-ATC250R-TRX-ATC-250R-250-R-Clutch-Upgrade-Kit_W0QQcmdZViewItemQQhashZitem2c5180e79aQQitemZ190345963418QQptZMotorsQ5fATVQ5fPartsQ5fAccessories

[don250R]

Honda no longer makes it, so ebay is ur best bet

[don250R]

and dont knock this til u try it
im harder on the tranny than the clutch and i still have clutch problems
(oldschool no clutch shifter)
this is a cheap and easy mod for LONG fiber disc life
with CHEAP clutch kits
(did i mention cheap?)
no billet basket,
no high $ clutch kit,
and wear life TWICE normal....
need i say more?
race-proven!
oh one more time....
CHEAP!
Don

[BRIANS ATV]

I Order One Two Weeks Ago And Recieved It ,the 89 Update Kit If You Want I Can Try Again And Just Stock It If Your Not Interested In It, I Would Be Curious To Know Anyway........

[dansvan]

Several sources have said the CR500 springs are lighter duty than the 250r.

[jenndnn3]

I would like to know those sources..

Thank you

[NOS_350X]

I got an update from honda about 6 months ago, It was in the just under $100 range.

I have herd that the 500 springs are a lighter also.

SOO easy soulution, get HD springs. no question about that one.

[Mr. Richard]

Cr 500 Springs I Took Out Of Mine Are Lighter Than 250r Hd Springs :d

[don250R]

so you could basically do the same thing with 250r springs?
ive been looking at a set of barnett HD springs for around $17
like i said earlier, this is not my mod..........
but i definitely will try it

[don250R]

i asked neil about this and he said:

I've never tested any of those 500 springs & you could be right, but best I can remember they were just a bit longer than the TRX.
It was just an old school thing we all did, it worked & never thought much about it.
Just out of curiosity, I would try a set of stock springs & see if it was any difference.
I hear the Barnett springs are a bit stiffer than any of the others, but I dont know never tested any.

Would a valve spring tester, for car engines work the same on our clutch springs, ???.
Neil

which makes me wonder if we could use the rest of the mod(400explate,washers,etc.)
to stiffen up the clutch

[jenndnn3]

It would be nice Don to have some MM differences in the parts being discussed for swapping.. specifically the steel plates,,

My "issue" so far(being the key word here) was resolved in getting rid of aluminum and went to 500 HD springs, New clutch lever, everything else is still 85.

This is what I have heard the on the cr500 springs, that they are heavier duty, never discussed their weights. Recommended to me by a couple local shops. If I remember correctly I thought they were just barely slightly longer then 250 ones, but dont recall to well. Either way, I am still curious on the sources.


by the way good topic

[don250R]

thx jenn
and borrowing another idea from the 4wheeled world,
the cr500 bearings will fit in an ATC250r
the 500 bearings have 1 more ball than the 250r bearings
can you back this up MrKasey?
trying to get part #s as i type.......

[jenndnn3]

I believe not all 500 bearing hold that truth .. Certian yrs do. 200xbasket has some info on this as well.

But yes they have an extra ball..

For sharing ill give you something as well.. the 85 flywheel is lighter then the later yrs as well.. :kiss: not significant, but a nice trick..

yeah partfish used to yield part #'s easy,, now they all running some new program, kinda a bugger but oh well..

I think this will be my next major update for the site,, partfish with partnumbers.. the maybe expanded to replacement part numbers..

[ballz338]

this is what works for me:

factory honda fibers and metals
cr500 springs with 400ex washers
hinson inner and outer baskets
'89 update
rtc pro pull lever and perch


http://photos.imageevent.com/kevinstutzman/miscstuff/large/DSC00656.JPG

http://photos.imageevent.com/kevinstutzman/miscstuff/large/DSC00663.JPG

[don250R]

as promised part numbers:

400ex steel(all years the same) 22321-MV4-000
cr500r springs(85-89) 22401-KA5-740
aluminum drain washer 94109-12000

and on the main bearing issue

91008-KAE-731 fits 85-01 cr500r and 88-9 TRX250r
8 balls

[don250R]

as promised part numbers:

400ex steel(all years the same) 22321-MV4-000
cr500r springs(85-89) 22401-KA5-740
aluminum drain washer 94109-12000

and on the main bearing issue

91008-KAE-731 fits 85-01 cr500r and 88-9 TRX250r
8 balls

oopsy.....
the cr500 springs ARE light, the cr500 uses 6 springs, where the 250r uses 5
im gonna try the 400 plate and the washers with barnett HD springs
we'll see what happens

[pegleg]

great write up!

[cbx1170]

He's right! As an long time Jap wrench I have done many mods petty close to don250r. I have taken many worn discs and made clutchs that work and last a large percentage of times. Crispy disc is a done disc. It has to have some good material on it. Surface the metal discs and/or light bead blast it makes 'em mate to fibers fast. I used Yam shims from an old Yam service bulletin that lists nearly every Yam shim out there. Find a shim ID, OD, thickness, that compresses the stack enuff to keep the strongest tension on pack WITH enuff travel left for disengagement KEY KEY KEY. Not partially engaged or "dragging" or "sticky" with (longer) lever pull. Also the old take 1 extra spring and clamp in vise and hacksaw down lengthwise to give you 7-8 "rings" to use as shims works too. Install in bottom of clutch outer. Bend em flat, deburr and sand down thickness to desired. Not to sure of the aluminum washer thing tho.