Magna V45 jumping out of 2nd Gear

JD...@psuvm.psu.edu

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Jun 14, 1993, 7:39:09 PM6/14/93

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I just bought an '83 V45 Magna that jumps into neutral (the
neutral light illuminates) when the throttle is opened in
second gear. It shifts OK and all the other gears are fine.
The previous owner thought it started happening soon after the
clutch was changed, but wasn't positive and didn't know much
about mechanical things. Does anyone have any thoughts on
on what is wrong and whether it is related to an improper clutch
replacemet? Also, is the transmission a SNAFU mess
on this bike and better be left to the dealer, or is it reasonably
accessable? (my previous bike was a Yamaha so I had plenty of
repair experience).

Also, is this the same engine which is currently in
production, or have they changed it? Anybody know the approximate Hp?
The engine put a smile on my face and I couldn't resist the price.
Thanks in advance for any advice/insight.
John jd...@psuvm.psu.edu
82 Yamaha Vision
(soon to be replaced)

Craig Powderkeg DeForest

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Jun 14, 1993, 6:35:29 PM6/14/93

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In article <93165.19...@psuvm.psu.edu> <JD...@psuvm.psu.edu> writes:
[2nd gear woes on '83 V45 Honda magna]

2nd gear troubles are chronic on older, powerful bikes. The V45 Magna
was about the fastest thing in its size class for a while, and a lot
of them got pretty abused. The problem is that 2nd gear is the one
that typically has the highest RPM difference between engine and
transmission, so the dogs and yokes take the most abuse.

Fortunately, my '82 is still serviceable -- but racing shifts are
right out. If you don't baby that gear (pretty much matching engine
and wheel speed), it doesn't go in -- just buzzes angrily.

I talked to a couple of places about fixing it. The cost of having a
shop rebuild the transmission (starting with engine in bike) is
>$1500. In short, they advised me to throw it away and get a new
bike.

On the other hand, if you're willing to do the work yourself, it
doesn't seem all that hard. As you probably know, it's a fuckin'
bitch to tune -- valves aren't real accessible; you need seven sizes
of wrench and have to pull the radiator and the ignition system to get
to the valve covers. The top branch of the V has the valve cover
split because there's not enough clearance between the engine and
frame to remove it in one piece. (At least the valves are
screw-adjusted, though -- none of those evil shims.)

But most of the problems have to do with the fact that there's a 750cc
45 degree V-4 engine more or less crammed into a frame that was
probably designed for a 500cc 15 degree V-2 engine [early Shadows]. Once you
get the engine out, a lot of the procedures look much easier. (tho' I
haven't pulled mine yet.)

Also, is this the same engine which is currently in
production, or have they changed it? Anybody know the approximate
Hp?

I've heard people say anything from 90 to 110 HP at the crank. I
haven't stuck mine on a dyno; I just like the feeling in my butt when
I go from 0 to 60 in first gear. Gotta love that 11,500 RPM redline.
Anyone know for real? (yeah, right -- this is USENET.)
--
DON'T DRINK SOAP! DILUTE DILUTE! OK!

Godfrey DiGiorgi

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Jun 15, 1993, 1:14:32 PM6/15/93

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> Also, is this the same engine which is currently in
> production, or have they changed it? Anybody know the approximate
> Hp?

The '83 V45 Magna used a motor similar to the '83 V45 Sabre and
Interceptor models, roughly, with tuning differences. The Interceptor
had the cylinders rotated back a few degrees to bring the crank
further forward.

While the overall design is similar in concept to the current Honda
V-Fours, there are many many detail differences from cylinder head to
crankshaft. Valve actuation and drive mechanisms, port sizes and shapes,
cams, combustion chamber shapes, gear ratios, crankshaft... the list
goes on and on.

The current series VFR750 is rated just over 100hp, the '87 VFR700FII
is rated at 87hp. The Interceptor motors are in a somewhat higher
state of tune than the Magna motors, which were worked for bottom end
and midrange punch instead. I would say that they probably have
70-80hp as delivered from the factory. Doesn't really make much difference;
it's a great motor with plenty of punch nearly everywhere.

Slipping out of 2nd gear says you have wear on the engagement dogs, the
shift forks or both. It's an inspect and replace task. You have to
dissassemble the engine's bottom end to get to the transmission.

Fixing the transmission is a complex but doable task. It's a lot of
work, that's all. Dissassemble bike and remove engine, dissassemble
engine, examine transmission for damage, replace worn or broken bits,
reassemble, reinstall, tune up. Buy a workshop manual and be prepared
to setup for a major bike overhaul in your garage. Probably cost you
$200-400 in parts and three weeks time if you're a decent mechanic
working in your garage, including 5 days or so for parts delivery.

Read the shop manual carefully and evaluate whether you feel competent
to do the work. It's the first, best investment.
------------------------------------------------------------------
Godfrey DiGiorgi - rama...@apple.com | DoD #0493 AMA#489408
Rule #1: Never sell a Ducati. | "The street finds its own
Rule #2: Always obey Rule #1. | uses for things." -WG
--- Ducati Morini Cinelli Toyota Krups Nikon Sony Apple Telebit --

Dave Tharp CDS

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Jun 15, 1993, 3:10:10 PM6/15/93

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In article <ramarren-1...@kops.apple.com> rama...@apple.com (Godfrey DiGiorgi) writes:
>
>The '83 V45 Magna used a motor similar to the '83 V45 Sabre and
>Interceptor models, roughly, with tuning differences. The Interceptor
>had the cylinders rotated back a few degrees to bring the crank
>further forward.
>

On shaft-drive Honda V-fours (Magna) the engine rotates in the
opposite direction from chain-drive V-fours (Interceptor). Very few
parts are interchangeable.