Cylinderhead and cam questions
Konversation med Dave Dodge om kammar och toppar.
At 06:41 PM 1/22/2000 +0100, you wrote:
>I came just back from my garage where I opened the headcovers. There is some
pitting on some loobs, but it's on the >backside where the pressure drops
off. I don't know how serious it is but they haven't run down and the pitting is
only >partly on the loobs.
Very minor pitting can be controlled by adding an oil mod, but cams should be
replaced in the future for best performance and reliability.
>First of all some information so you know what I'm talking about and what I
have done with the bike so far.
>It’s a V65 Sabre '85 and I have about 53K miles on it so far. I bought it
brand new, so I know all its history and I'm doing all >the maintenance by my
self. All I've done to the motor so far except normal maintenance is
installation of a Dynojet kit, a pair >of Yoshimura slip-on's with
competition baffles, a more open airfilter and opened crankcasewent (I removed
the whole >breatherbox and pulled a 19mm hose strait out and connected a
small K&N crankcasewent filter at the rear end of it). By the >way, I've
always used non-resistor plugs DP 8 EA-9 instead of the DPR 8 EA-9, but can that
do anything for the power? I >guess maybe only a little better spark.
The dyno graph looks good to start. I have noticed no difference between the
resister and non-resister plugs, except for frequency noise. The best way to
improve spark is to add higher voltage coils.
>I had the bike on a dyno for a couple of years ago and it showed 105 RWHP
with a nice even graph and that was before I >replaced the airfilter. (I'm
including the graph in this mail if you what to take a look) I think that's
quite good for an almost >stock V65 bike.
It would also be interesting to see what the bike dynos with the airbox mods.
>I have a couple of questions before I start to make molecules of the motor
>I have been thinking of cams and headporting. Which kit of Stage I or Stage
II do you recommend and what kind of costs >are we talking about? I don't
want to loose any low- and midrange power, gain as much power as possible and if
possible >lower my very high fuel consumption.
You would want Stage 1 or 2 porting, and use my Stage 2 cams. There would be a
slight decrease in torque, but the midrange and top-end power would be improved
by about 10% with the proper jetting. When you add the cams you will actually
need to lean the mixture a little so gas mileage remains about the same.
>I ones read that your Stage II cams need to be degreed in with adjustable
cam sprockets. How is that done since the only >markings are on the
camsprockets and there are no on the cams them selfs except the in, out, front
and rear markings? And >you won’t be able to use those >markings with
adjustable sprockets. Can the Stage II be used without timing or will the >valves
collide with the pistons? Or is there any other reason that you have to time
To degree the cams we slot the cam sprocket mounting holes to allow the cam to
be advanced or retarded with the sprockets installed on the factory marks. You
would need some tools to position the cams, and the cams come with complete
installation instructions. For best performance and clearance the cams must be
>Do you use new cams and rockers or do you weld and hardface the stock ones?
(This is >maybe a dumb question) Do you >mill the heads at the time when
you are porting them? And in that case will the upper motor fittings still be in
line for the >treads?
I use new Honda rocker arms, but the cams are hardwelded and reground to my
specs. The cams also go through a hardening process that makes them stronger
than stock cams. When I do the porting and valve job I mill .005" off both
heads. This will not effect the engine mounting.
>I saw that you are recommending a cylinder hone in your full motor kit. I'm
a little sceptical to that since a hone increases the >piston play, not by
much but it gets you closer to a cylinderdrill. Isn't a hone is just for new
piston rings to get braked in? I >think I wait until it's time for a cylinder
drill, and then I thought of getting a balancing, blue print and gearbox fix at
the same >time when the crankcase anyway is open. So far I have good
compression and a fully normal oil consumption about ½ litre at >3000 miles.
Typically, the engine cylinder bores remain tight and the clearance is sometimes
under .001". When I blueprint a motor I set the piston clearance at
.0015" which allows me straighten an irregular shaped bore and provide a
good surface for new rings. If the bore does not straighten with the hone, you
would need to bore it out anyway. While apart, it is the best time to undercut
the transmission and fix it for good.
>I've heard a lot about gearbox undercutting both from you as well as from
others. Is there no disadvantage with that? Or why >are the factory not doing
it from start?
The factories produce engines in the most effective and less costly methods
possible. If the bike is ridden hard, speed-shifted or if the power is increased,
the trans becomes weak. This occurs on all bikes ever made including today's Kaw
and Suz sport bikes. The factory does not do to because it requires precision
machined surfaces, and the stock gear dogs are not machined which is less costly.
>Do you have a torque sequence schedule for the order in which the
cylinderhead bolts are to be loosen and tighten that you >could mail or fax
me? Since the Honda shop manual only >says that the bolts should be tightened
in a criss-cross pattern.
The head gaskets can probably still be okay, but you will need to do these steps
to ensure a good seal.
1) Make sure all coolant is drained from the cylinders by removing the two front
cylinder drain bolts. Removing these drains will empty both front and rear
cylinder coolant cavities.
2) Loosen ALL of the head bolts including the exposed outside ones. If the
outside bolts remain at full torque while the inside bolts are loose, it will
cause the heads to bow up in the middle allowing the coolant to get inside the
engine and threaded holes.
3) Remove each one of the head bolts (one at a time) and blow out the threaded
holes with compressed air. Then spray WD-40 in the holes and blow out again. The
reason the bolts were not staying at full torque is because they were full of
coolant, hydraulic'ed, and gave you a false torque reading.
4) With all of the head bolts loose, evenly torque them down in three steps from
the inside out in a criss-cross pattern.
a) First step is to torque ALL bolts large and small to 10 ft.lbs.
b) Second step is to torque only the 12mm and 14mm head bolts to 18 ft.lbs.
c) Last step is to torque only the 14mm head bolts to the final torque of 38
Remember that all torqueing must be done in a criss-cross pattern from the
inside bolts to the outside bolts to squarely seat the heads.
Now the last important thing to do which lets the head gasket adhesive re-seal.
Before adding coolant, start the engine and let it run until the heads start to
get warm. Shut off the engine, let it cool, then add your coolant like normal.
I hope all this info helps.
Dave Dodge – DRP