Chain keeps coming loose (with in 5min of ride)

Hi
As you guess'd I'm a newbie, & I'm a truck mechanic & can't ride (don't hold that against me) I fix em' when you's drop em'!

You've already answer'd one of my questions in your forum,(spirting Cooling system's)
So I'm on to the next one:-

It,s a 94 VFR 750 U series-Aust.edition-I know this cause I had to find the correct wiring diagrams- the American aftermarket manual is wrong for Aussie VFR's (claymore,clay-something?)

Q-
The chain will become extremely loose after an extremely short period of time, We have adjusted the wheel Numerous times (according to the Manual) We didn't torque the lock nut as hand tightening would exceed the measurement anyway with Breaker bar, just to stop it from moving.
With in 5-10mins of riding it becomes almost life threating...

Is there parts to replace in this mechanism or a possible cause on why it will always loosens off & can anyone give me info on how to rectify the problem.

I've read SCRAIG's post on adjustment & I'll do some measurements but it seems to be something else not quite happy! It's almost like when under torque load it will pull the wheel "in" towards the engine causing the slack???? to be honest I don't know (thats why I'm here) or could the swing arm be bent just enough to affect the settings? (it comes up within tolerance but is effectively wrong?)It has been to get wheel alighned (front & back ) after smash! the rider reckons it tracks well & does what its told.....??????

Any help in the matter will help save the bike cause I'm not really worried about the rider as he is already broken (broken back 4 times so far -he's still upright

INFO:-Bike & Rider

The rider :- to put it bluntly , knows how to land & is very good at fibre glassing now! & has speed sign dislexia

The bike:-30,000km's, doesn't resemble a viffer" any more we call it the MAD MAX conversion-we dropped 15-20kg's--after side slap'n in to a cliff face(no fairing, actually there was no front)
Chopped 14 metres of wiring out (fit after market gauges ,indicators,Head lights pretty much everything)
In Spray can Matt & gloss black - the matt finish hides the massive dents on the tank as the sun doesn't shine on it so it doesn't stand so much & its Cheap & easy to do.
It's been washed once & has 3 Spray can paint jobs since we got it go'n late last year & cost 1/10th the price of mucking around with fairings, Actually we couldn't get parts in Queensland AUS anyway in the time frame we had to get her go'n in.

I build Computers as well for a living to pay for my hobbies (928 Porsche,350 Pontiac Big block) & I've been to some very F#*K'D up forums in my time concerning PC's,
But I would like to commend the VFR community of VFR world on an informative & educational site http://vfrworld.com/forums/images/smilies/biggrin.gif
:biggrin:
Thanx
Painkiller

 

the eccentric chain adjustment MUST (??) be slipping.
make a paint or punch mark on adjuster ring and a reference point on swingarm and check for unusual movement.......

 

I'll check that .... Thanx
Do I have to replace the whole assembly (eccentric,bearings etc.) if it shows any funny movement?(out of tolerance)
Cause parts supply in AUSTRALIA for the old VFR's is getting very hard, we waited 5 weeks to rh foot peg from Japan !!!!!UNREAL (we are next door for "F" sake!)
at the moment all my parts for the 928 come from california (yes it's not a bike) so I know the issues in finding NEW PARTS!
The manual that I couldn't remember the name of is "CLYMER" 90-onwards IS USA ONLY!!!! not CLAYMORE!

 

The ONLY cause (unless someone corrects me) is a loose clamp bolt, which may be under-tightened or previously cross-threaded.......

 

The Clamp bolt may have suffer'd after the accident ,but this (you would expect) be found by the Mechanic doing the last Wheel alignment???
it's not Cross threaded but could be bent???
Anyway
I'll check that also
any info is greatly apprieciated

 

Wheel alignment????

A word of caution for a truck mechanic: do not over-tighten nuts and bolts!!!

 

My Slack adjective for the alignment!
i'm not aware of the clinical name of the bike alignment process,

the front tree's were out & Adjusted, the rear checked & adjusted when NEW tyres were fitted allround (FRONT/REAR)
(Straightened up)
I've changed enough studs & dug out ends of bolts when I was an apprentice so I HAVE learnt the hard way
But now I work on Porsches & build Drag motors I'm aware of what torque does
eg: the 928 has Aluminium Wheel nuts! (STANDARD IN 1982) yeah I'm aware thanx for the "Heads UP"

I don't bring the TRUCK gear to service the Bike thats for sure....
All by the Book!

 

You could also replace the clamp bolt, as it might have streched over time, thus causing the frequent loosening of the chain. If the bolt has streched, it will be to long to apply the correct clamping torque. It should be a fairly inexpensive part to replace, and yoyu might even be able to find a suitable replacement in a hardware store.

 

G'day Doug
Thanx -----
I need An exploded view of the arse end! (hub ,bearings,the lot)
with genuine part numbers so I can order the bit I need to get the Vehicle back on the road!
Downtime IS critical (Truck training)
It's a "get to work " machine

A Original "spare parts manual"
1:- I need parts :-we deal direct to Japan & have NO choise...
2:- Correct measurement on Tensile strength (Wrong WILL kill & Elongation
Tolerances. ("X"mm= new/ "Y"mm= old) like A.R.P.bolts & Fasteners
(7000 psi bolts? yep I use em")not for bike though----there is "DRAG GRADE" bolts out there but F&*@$K you have to KNOW what your DO'n>>>>

It maimed the Right hand side (crankcase & all) the rear wheel assembly (inc. Swing Arm) did not recieve full impact!

Please FAX Or Email to this address
if YA got ONE or Anyone else for that matter!!!!

to Painkiller
gma02285@bigpond,net.au

Fax: 07 5498 2196
(I don't know how to get out of your Country by PABX-- )
I'm in Australia
Queensland.

 

Also make sure that the eccentric is below the centerline. If it is above the centerline, the chain MAY be pulling the eccentric forward, if it is below the chain cannot do this.

 

Try this...

http://fiche.ronayers.com/Index.cfm...2/Model/VFR750F/GroupID/144492/Group/SWINGARM

Also sent to e-mail address listed in the post above

 

Thanx Everyonr for your help
I'm working on this weekend & I let all of ya's know how I when

thanx again

 

IMO, the bolt could NOT have stretched since it threads into alloy!!!!!!! However the threads in swingarm could be ruined, reducing tightening force.......

 

I'm wondering if the bushings for the swingarm are bad. That might allow the swinger to cock to the chain side when power is applied. My other thought is the chain itself; is it new, or are some links sticking? When a sticky link loosens up, the chain will go slack.


Lane

 

Good point, however it's easier to replace the bolt, although a heli-coil could also be installed in the swingarm as well. I should have thought of the Steel VS Aluminum thing, oh well, perhaps next time...