Wayne Kennedy was having some clutch slip problems on his staggered crank XS650 and this is what he did to cure it:- I put new genuine clutch plates in the 650 but when I was doing so I measured some other steel plates I had and was surprised that there was two different thicknesses between them. One set was about 1.35mm and the other 1.6mm. (no they weren't worn) The early 6 plate had thicker steels, as I had put in a later 7 plate to try and stop slipping with the torque. I put the thicker steels in which saved me shimming up the springs, and also left out the rubber rings between the plates. Low and behold, no clutch slip and it is easier to get neutral when the motor is hot. A quick solution to anyone that has a hotter motor and having clutch slip.
Dave Bath also suggests it's a good idea to bevel the edges of the clutch friction plate fingers with a file (just enough to take the sharp edge off ) to reduce to possibility of these catching on irregularities in the slots of the clutch basket which is one of the causes of clutch drag. I've just done it to my new clutch and it seems to work. (Terry Gliddon)
Tony Warner also informs me that the XS650 has two different length clutch actuating arms situated inside the left engine cover, where the clutch cable attaches, so if you have a heavy clutch you may benefit from using the longer arm from an XS1 if you can find one.
While you are in there it is advisable to check the back of the clutch basket to see if you have any broken springs.
Mikuni VM36 Jetting
I am in the process of adding a few
extra ponies to my XS 650C, kit, carbs,
head, cam and pipe. Getting info
on "correct" VM36 jetting for
a kitted engine took a little
time....but here is what I managed to
get from Halco (UK) and the States (Bob
Bertaut). It might limit the
amount of trial and error....though some
members may well have all this baseline
info at their fingertips. The HALCO
pre-jetting is on the richer side and
the Bertaut is leaner. Both
specifications fitted with free-flowing
filters (K&N or Unifilters).
I'll will keep you posted on the
final jetting for my bike.
Methanol in Four-Strokes
things first, methanol is extremely
poisonous and can cause blindness and
insanity. It is absorbed through the
skin or its
inhaled, and once it is in your body, it
methanol will have an 8% to 17% power
increase over petrol.
burns slower than petrol so ignition can
be advanced 6-15 degrees to allow for
running temperature is much cooler than
petrol. This means that the air inducted
for combustion is cooler and so it is
denser and so supplies more oxygen.
Because of the greater oxygen, the jet
size is 2.2 times larger than those used
for petrol. The slides are cut away to
allow greater air intake.
needs less oxygen to burn
is anhydrous in that it absorbs water
from the atmosphere. If fuel is left in
the system, the water it absorbs will
corrode up the works.
ratios can be ran at 14:1 as detonation
is virtually non-existent with methanol.
doesn’t mix too easily with petrol
because of its tendency to absorb water,
but 3-4% acetone can be used to help it
mix of 60% methanol, 20% benzole, 20%
avgas, is a good substitute to 100%
methanol as it uses less fuel and so
requires a jet size midway between
petrol and alcohol. It still retains the
anti-detonation and cooling properties
is a danger of a washing effect of the
bore wall with a rich methanol mix. The
addition of caster based oil will
alleviate this problem. Valve guide oil
seals can be removed on the exhaust
valves to also help with this problem.
you are looking at a pure methanol fuel,
try 97.5% methanol, 2% acetone, .5% Castrol “R”.
fuel is expensive and is not as easy as
petrol to obtain, but, if you choose
this path, it would appear that you gain
extra horsepower and the motor becomes
more forgiving with regard to detonation
and overheating. I expect that this
could be a fair trade off for the risks
involved in running an
high compression ratio.
recommend EBC pads and a 13mm master
cylinder for the early 2 piston calipers.
The late ones benefit from Ferodo
Platinum and a 11mm master. Ferodo
replacement shoes( FSB 735) are a good
upgrade for rear shoes. Check the disc
brake tips at my website.
34mm Round slide Mikuni Jetting.
Some of the members have asked recently where to start with Mikuni jetting and I contacted the vertical twin discussion group for some input on this subject. Here are some of the responses:-
Alternative location for Vacuum Barbs For Tuning
I have attached some pictures of how I installed the Vacuum Barbs for the Balancing of the VM Mikunis when there is no vacuum barbs on the Manifolds.
Instead of drilling the Carburettors, I drilled holes in the flat area on the Cylinder Head that was used for the Balance Tube on the early models and threaded with M6 (The last portion of the hole is only drilled with a 3.0 mm drill).
During Carburettor Tuning, I install M6 Vacuum Barbs from 650 Central.
When not used, they are plugged with M6 Cap Screws and Copper Washers.
I think this would be possible to do with the Cylinder Head installed by using a small Right Angle Drill Machine.
You are welcome to use the pictures for the website or newsletter but only if you write the text as my English is not good enough.
told you that Göran, I
couldn't have written it any
Sunday, 20 August 2017