Thu Nov 28 18:26:54 1996
- Message No. 218
From: Sonic
Subject: front fork : oil, air or springs.
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This E-mail came from :
Raymond Fels
Geert Grootestraat 49 - 7009 MH - Doetinchem
The Netherlands
Sonic@gww.nl
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Hello everybody,
Martin wrote:
> There is a T-Tupe available at Hein Gericke, which does the same.
> "you should not add air in the front fork, it will damage the fork. (too much extenting)".
.......
> A better Idea is to replace the original fork oil with a harder grade (mixing some grades).
Micha wrote:
> I can confirm that. Two diferent mechanics told me that, too. And both of them seemed to
be qualified.
Pierre wrote:
> Correct. Honda manual states that fork oil must be changed at 12000 km with
SAE 25. I did it. Very positive impact on the bike behaviour. Note: put
exactly the qty stated in the manual.
> Raymond: I can also run over "speed-breakers" (*) at 100 km/h ... without adding
air in the fork.
I do NOT agree with the above statements.
If the front suspension is to slack, there are two things you can do:
1 Replace the orriginal spring with one with more force.
2 Put some additional air in the fork. ( talking about tenths of Atm.)
1:
If you wan to know if the orriginal spring is worn out, put the bike on
a vertical lift-bridge.
Remove the screw-caps on top of the forks.
The spring should come out of the fork.
The distance between the top of the spring and the top of the fork,
should be about 22 mm.
If the spring comes out for only 10mm, you should make a cylinder with a
height of 12 mm.
You should place this cylinder on top of the spring and mount the
screw-caps again.
If you want a harder suspension, make the cylinder higher.
2:
You can also put some additional pressure in the fork.
This has a little disadvantage, because with the change of temperature,
the pressure also
changes.
You also have to check now and then for the correct pressure.
The advantage of air pressure against the cylinder on top of the srping
is following:
You can play around easier. (put more or less pressure in the fork.)
If additional air in the front fork is bad, why did Honda put these
valves in the fork ??
They could save the money by leaving them out.
The risk of blowing out the seals, is verry low.
I put 0.9 Atm in the front fork.
My dealer thinks that when you put 5 Atm in the fork, the seals still
will resist it.
This only reflects the toughnes of the seals, it's not a thing to do in
practise.....
What about the oil in the fork ??
(The oil in the fork can not keep the XRV 'higher on his feet'.)
If you put other oil in the fork as recommended, you take risks !!!
There are some Teflon 'bearings' and they need special (good) oil.
If you don't refesh the oil at the requested times, the oil becomes
filthy.
There will come aluminium particles in the oil.
When they come between the bearings, the bearings wear out faster.
Honda recommends special oil called ATF oil.
Its comparable with a SAE 10 oil.
If you put thicker oil in the fork, the fork becomes stiffer. It feels
as if the spring in the fork is
stronger.
BUT....
The dampening of the fork is the only thing that changes. And this is
even dangerous !!
The front wheel has to come back on the road as fast as possible after a
knob in the road.
If the dampening is to high, the contact with the road is worse.
Think about you driving in a corner and the front wheel looses contact
with the road longer
than nessesary.........
SAE 25 oil is to thick for a normal fork. If the fork is old, you can
use it to help reducing the
play between the bearings.
If you drive through a long corner, and you feel the fork move in and
out, you need to change
the dampening.
This can be done by adding additional oil so the dampening will increase
a little at the end of
the ingoing movement of the fork.
You could also put other oil in the fork but there is a world of
difference betweeen a SAE 10
and a SAE 25 oil.
At last a question to Pierre:
What speed do you reach with about 200 Kg load on a Twin. (over a
speedbump I mean).
...........................................................................
Greetings from The Netherlands,
Raymond Fels.
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