Changing the timing chain
of a big Guzzi engine
This will be an instruction, how to change
the timing chain of a big Guzzi engine. Considering the engine
still in the frame it is usually only necessary to remove
the long front engine bolt. On flat floor it is even not
necessary to remove the oil out of the engine, because the oil
pan is deep enough. So take the speedo cable off and get ready,
hopefully with a soft cushion under your ass.
If you change the timing chain, I recommend a better than the
original tensioner, which is not really a tensioner but more a
placeholder for one. There is a really good tensioner available
with a spring preloaded plastic guide, which gives your engine
accurate ignition timing and stabile idle. In Germany it is called
Stucci tensioner. Besides this you need as spare parts:
- 27mm nut for the camshaft
- special nut for the crankshaft gear
with security washer
- new timing chain
- new gasket for the front cover
You will need these tools:
- 3mm Allan head (for Saprisa
alternator)
- 5mm Allan head
- 6mm Allan head
- 8mm hex nut
- 13mm hex nut
- 27mm deep socket nut
- special tool for the crankshaft nut
- a 55mm long 6mm thick pin and a 30mm
long M8 bolt
- a chisel and a hammer
The last preparation should be to turn the engine in left TDC
position. Take your time and follow the instructions:
- take off the alternator cover
- pull off the cables and remember the
positions
- take off the stator after taking out
the three bolts holding it
- turn out the bolt, which holds the
alternator on the crankshaft
- take the 6mm pin, put it in the hole
and screw the bolt into the alternator as long as the
alternator falls off
- take out all bolts of the front cover
(12)
- take the front cover carefully off,
don't destroy the gasket surface, there are two guide pins, so
don't hammer too hard
- check if the marks on the crankshaft
and camshaft gear are in line
- use a power wrench or a chisel to
loose the 27mm nut of the camshaft (top)
- use the special tool to loose the
special nut on the crankshaft (middle)
- loose the 13mm nut on the oil pump
- are the marks on the gears still in
line?
- take off all three bolts and pull the
whole assembly of three gears and the timing chain out
- be careful, on the shaft of the
crankshaft and the oil pump there are little metal guides,
don't loose them
- take out the old tensioner, as long as
the bolts doesn't hold the bearing, you can leave them out
If you now want to continue to take out the camshaft, you have
first to take off both cylinders.
Then you would be able to check the camshaft surface. If you
only want to change the chain and the tensioner, you can do as
follows:
- take the new tensioner, take off the
little 8mm nut and pull the tensioner a little bit from the
shaft, so that the spring stays just on the shaft
- now bolt it into the housing in the
appropriate holes
- take the whole package of three gears
with the chain and push it onto the shafts, make sure that the
two metal guides are still in place, the pin on the camshaft
wheel is also in the gear?
- Secure them all with the different
nuts, don't forget the security washers on all three
- Push the tensioner in the gap between
the chain and the housing, tight the 8mm nut of the tensioner
- Tight all three nuts on the shafts,
bend the security washer on the crankshaft so, that it locks
the nut
- If you want to change the sealing of
the crankshaft, now it's the right time to do so (grease the
inside a little bit after mounting
- Clean the surface of the housing from
the old gasket and the oil
- Put on the new gasket and push the
cover into place
- Tight the bolt all around
- Clean the conus on the crankshaft and
the alternator and put one on each other
- Put the long bolt of the alternator
through and tight it
- Mound the stator and put the three
bolts in
- Close the alternator cover, put the
speedo cable in place and that's it
DONE
Eric Koch, 1999