Damage reconstruction problem

[MagnaJeep]

Hi,

Being busy repairing the damage of my 620 Monster,
I've noticed this:

Bike is lifted in the air.
New fork legs have been slid through the lower yoke to the the approximate
fitting height. Placing the upper yoke over the stem I notice that the tubes are out of alignment, pointing a few (3-4) millimetres to the front (both) :worried:.

Does that mean that the lower yoke is bent or is it some kind of allowance due to the
fact that it doesn't stand on the ground?

I do have a second lower yoke, but before i start to replace maybe someone has got an idea?

The upper yoke has been split in half because of the crash, if that is any help.

[desmo]

has the front wheel has been hit in an accident?
It sounds like the frame could be slightly bent where it joins the headstock?

[Pedro]

Hi,

Being busy repairing the damage of my 620 Monster,
I've noticed this:

Bike is lifted in the air.
New fork legs have been slid through the lower yolk to the the approximate
fitting height. Placing the upper yolk over the stem I notice that the tubes are out of alignment, pointing a few (3-4) millimetres to the front (both) :worried:.

Does that mean that the lower yolk is bent or is it some kind of allowance due to the
fact that it doesn't stand on the ground?

I do have a second lower yolk, but before i start to replace maybe someone has got an idea?

The upper yolk has been split in half because of the crash, if that is any help.

Sounds like gravity just pulling them out of alignment when the bike is lifted - with no top yoke they will "flp" around a little, had the same when I swapped the legs on Jules bike. Best thing to do is fit the top yoke, pinch up the lower yoke bolts then bung the wheel back in and put the bike on the ground. Look down the tubes from above and you can align everything by eye properly then

[MagnaJeep]

Front wheel has been hit, but I gave it to service and there was no
damage whatsoever (bearings have been changed nevertheless) and I really hope that the frame isn't the weakest point.

As the quite heavy front wheel (i really am surprised :scratch:) is attached to the forks already, which isn't really necessary now, I would like to believe that gravity pulls the fork legs to the front.

I'll give your advice a go tomorrow, Pedro.

Thanks :thumbsup:

[Capo]

The fork tube should pass easily through both the bottom and top yoke, if the bottom yoke is tightened, this will eliminate the 'gravity' factor. If gravity is having and effect (I've never seen it) have you tried removing the weight?

I doubt the frame is bent more like the bottom yoke column.

[MagnaJeep]

I have checked the upper yoke with an undamaged lower yoke, not the one mounted on the frame, with two fork legs and they fit together quite well. :hissy:

Now there can be only two things wrong, the steering tube is bent or the spindle of the lower yoke.
How can i tell if the steering tube is bent?

[Trent]

Did you try doing the same test with the suspected bent lower clamp?

If the steering tube is still "round" where the bearings sit (ie it hasn't been turned into an "Ellipse" by the smack to the front) then I doubt that the steering tube is bent...

On that note... did you change the steering head bearings? Might be worth thinking about if it's taken a whack bad enough to break the top clamp...

If it's just the forks not lining up, then it's either the clamps are bent (they are the only things that hold the forks...) or Pedro's suggestion...

Since you have an undamaged lower clamp, why don't you fit it together with that clamp and see what happens...

[MagnaJeep]

No I haven't checked the damaged lower clamp, and haven't fitted the undamaged parts to the steering tube, so that's the plan for later when i'm home.

The steering tube looks almost perfectly round at the top and bottom, no paint chipped off and no visible deformation whatsoever.
The shim above the upper head bearing was deformed slightly towards the front.

Steering head bearings will be changed as it seems that they aren't rotating smoothly in their carriers.


Will report a soon as I know more.
Thanks :thumbsup:

[MagnaJeep]

Hey!
No more guessing, here are the results of todays investigation:

The lower yoke is bent forward a bit, after checking it like Trent suggested,
but more important than that, it's the lower bearing of the fork stem that
destroyed the carrier into a few pieces pushing it backwards and bent the steering tube into a barely noticeable oval shape.

To fix this issue I will have to reshape the tube and new taper roller bearings will replace
the quite fragile looking (and easy to bend) oem bearings both on top and bottom of the yoke stem.

Why does Duacti show the more solid taper roller bearings in the parts list instead
of the really mounted open ball bearings?

Funny fact is though, you can get both taper roller bearings very cheap from Fiat,
used in the large volume production Fiat 126 as rear wheel bearing.
Price about 10 pounds as you see:
http://allegro.pl/item631859307_fiat_126p_126_p_maluch_lozysko_kola_ tyl.html

I fear I can't finish the bike till summer. :banghead:

[desmo]

Hey!
bent the steering tube into a barely noticeable oval shape.

To fix this issue I will have to reshape the tube :

That will not be an easy diy fix.

[MagnaJeep]

It will not be me who will fix this, that really is beyond my capability,
a motorcycle mechanic will do this.

[MagnaJeep]

Update:
The Fiat 126p rear wheel bearing fits the 900ss and similiar models that have the
thinner yoke stem (26mm diameter).

The Monster 620ie and probably all later injected except the 900ie have a 35mm stem
and a toyo 32907 jr2 or jr3 fits just fine.

Some Kawasaki bikes have them fitted, for example a set I bought:
http://www.louis.de/_1019a018009722d10e33a24c9b150e25be/index.php?topic=search&searchterm=10051197&cmd.x=3&cmd.y=8

[gary tompkins]

I would personally replace a damaged lower yoke + stem with another that's 100% sound

Wouldn't be happy with a DIY fix to something as safety critical as fork yoke's, when they've obviously suffered a bad hit & crash damaged. The Alloy yoke could have been compromised by the impact, and that may lead to stress cracking and failure later on.

[MagnaJeep]

You are right, and every damaged part will be replaced with a new one.
The steering tube will be checked by a professional.

The taper roller bearings are just an upgrade, I don't like the oem ones.
I hope to have most parts assembled till the end of the week.

[Capo]

I had problems with the rubber on the seals contacting the taper bearing race and binding the rotation.

[MagnaJeep]

Well thanks for that!
I'll keep that in mind.

Any help is gratefully appreciated :)

[MagnaJeep]

Finally, the front end is fixed and assembled again:
The steering now feels extremely precise and stable.

This is how it looks like now:
http://up.picr.de/2351869.jpg

Fitting the lowered headlight bracket and clip-ons was time-killing,
but i do like the outcome.

Another question that bothers me now:
The side stand is too short, the angle of the bike leaning on it is scary,
are there any possibilities to resolve this problem?
SxR sidestand for example?

The bike hasn't been risen or changed in height as far as I know, but
the s2r 800 and it's aluminum sidestand are more trustworthy.

Thanks in advance :thumbsup:

[squiffything]

Of course the side stand was short I had little legs :D

It's starting to look good can't wait to see the transformation.

G

[MagnaJeep]

Has the seat height been changed too?
I can't tell a difference between those two:

http://up.picr.de/2353315.jpg

And what kind of map has been used on the Power Commander,
I don't know if it's still there after 6 months not being connected to a battery.