The weak Honda CRF 250 L Clutch , Final solution

schrauberklaus

Senior Member
Joined
Oct 15, 2014
Location
Phuket
Bikes
XR600,XR400,XR280,XR250,CRF250L
As many CRF250 L Riders know , the bike is a buget build and the Clutch weak .
And like me many looking for a solution to this Problem .

There are options on the Market
Like the Takegawa Slipper clutch kit that promise improvement. Useless , that thing goes after one week in my waste of money parts box .
EBC Clutch Kit , O.K. new , but the Friction discs last in my CRF only 2000 km then it was steel on steel .
Barnett harder Clutch Springs , work to a certain point but makes it hard to pull the lever , not everyones taste .
and so on.

Basicly there are 3 ways to improve the Clutch .
better , grippier Friction Discs what comes in case of my EBC Kit (imported for a lot of money from Germany) with a short live .
Harder Springs to Compress the Clutch better to give better grip , with the disadvantage of the harder lever action .

Or my final Solution
Increase the Friction surface of the Clutch .

Honda sell the CRF with 4 and a 1/2 Friction disks .
Change the half disk with a full disk is a small but noticeable improuvment .
So , why not add another Friction and Steel Plate to add more Surface for the Clutch to grip on ?

The Idea spinns around my head already for years and is not new , done on Race and Turbo Bikes for years but i was not able to find a Workshop well enough equiped with the machines to do the necessary Modifications on the Stock Clutch Parts, not to mention the lack of Machine operators that understand my ideas.
Depend just add a Steel and a friction disc is not possible , Honda left no room for that kind of improuvment .

But , as we say in Germany , Room is in the smallest House , you just need to find it .
And i did .
But depend of the lack of Machine shops and equipment i had to build first a small special Lathe/Grinder and some Adapters to hold all the Clutch Parts in Place befor i could start digging step by step for more Room .

The Clutch Basket , The inner and outer Pressure Plate and the then 5 Steel plates need to be modified.

And precisely or the Clutch will not work and that , on my selfmade Hack , measure everything twice with digital Calipers and Gauges was not easy .
0.05 mm can in some places already out of tolerance . Some Parts need to be Blueprinted to .

But i got it finally .
So here is the first 6 Friction Discs CRF250 L Clutch
78736


On the Outside , same dimensions as the Original CRF Clutch , build from stock Parts with 6 Stock CRF Friction and 5 Steel Disks .
78737


and CBR 300 Clutch Springs.
78738


A lot of manual work with small diamant file and sandpaper add time to the process . alone deburring all the sharp edges from the grinding correctly took one day .

I am fully aware that this mod weakens the Clutch Parts , but , the Clutch work so far now for one week flawless .
Easy 2 Finger Lever pull , perfect engagement and i try now for one week to get it to slip .
So far without sucsess.
And my 350 cc Engine really has the Power to stress the Clutch.
I have one of the steepest Roads i ever seen just around the corner (Clever Thais put a sign up " OLD CARS OR INEXPERIEND DRIVERS PLEASE USE ANOTHER ROAD"
with very grippy Road Surface . I wear my Tire of during the week , manage the Chain to jump over the sprockets but no Clutch Slip , nothing broken.
So the modified Parts seams to be still strong enough .


But until a Clutch Parts Manufacturer jump on this Idea and produce Billet replacement Parts it will be a one of a kind .

Klaus
 
Good info Klaus, I've been running with CBR 300 springs for a while but my 286 doesn't put as much stress on the plates as yours.
 
Klaus,

Nice mod.

How is it holding up?

Can you share more details to your mod? Perhaps with pictures of the clutch basket before and after mods?

Thanks
 
could send you pics , but do you think you can see the difference of 0,2 mm in a picture .
To see and understand what i have done i need to explain every detail with messurements and Pics and that would be then Close to CAD Drawings .
I put 6 month work in that clutch .
Sorry but i do not work for free for anyone that can pick up that Drawings to copy and sell then the final product .

The Clutch still work perfect , never a Problem .
Feel free to try to copy it , but for now the detailed mods stay under my copyrights .
 
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