Table of contents:
BEST Investment if you intend to own a CB750 SOHC is A SHOP MANUAL....|...
Best Investment if you intend to own a CB750 SOHC?...|...
does G.O.T.F. stand for?...|...
can I upload pics so I can share them with others?...|...
there any Chopperhedz in my area?...|...
year was my bike built?...|...
can I get my bike posted in the Gallery?...|...
(the forums) Questions...|...
Section: What type are my carbs?...|...
do I clean the carbs?...|...
can I get Carb Rebuild Kits?...|...
Pods and Drag Pipes where should I jet?...|...
Mill: Which oil line
is feed and which is return?...|...
Metal shaving in my oil pan, Should I be worried?...|...
Hell: How do I wire this Beotch?...|...
Words of Wisdom on Alternators and such:...|...
and such: What size Chain do I need?...|...
What frame do I have?...|...
and Such: Some asshole keeps winning all the cool chopper parts on ebay!...|...
to find parts?...|...
are the laws in my State for Motorcycles?...|...
The BEST Investment
if you intend to own a CB750 SOHC is A SHOP MANUAL.
rules but a manual NEEDS to be in your shop. Can either buy new or
used, Amazon.com or eBay
are both reliable sources for this purchase. Clymer and Haynes
both have a manual that is specific to these bikes. Chilton's has
a broader ranging manual available called "Chilton's motorcycle repair
manual". And of course there is the Honda factory shop manual.
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Second Best Investment
if you intend to own a CB750 SOHC?
Spend a good bit of time digging through the
pages of Hondachopper.com.There
is a ton of information already assembled there for the taking. Spend
an extra bit of time in the garage, links, and engine sections. Several
of the questions that come up over and over again have the answers already
contained in these pages.
What does G.O.T.F.
This is a perfect example of a question that
can be answered by reading through the Membership
page. (Gang Of The Four, by the way).
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Where can I upload
pics so I can share them with others?
There are a number of free hosting sites.
and Flickr are the three most
often used. When you create online albums be sure and make it available
for public viewing. YuKu also allows you to upload images in your profile
under "Image Management".
Are there any Chopperhedz
in my area?
See the "Be
Recognized" Thread in the community forums. If you want to
be added to the list, just add a reply using the same format as the other
names on the list. (BoardName, City, State)
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What year was my bike
Note: The frames and engines DO NOT have matching
serial numbers; make sure that you are looking in the correct column. Check
the chart HERE
to determine the year your frame and or engine were made..
How can I get my
bike posted in the Gallery?
Get some good pics of your bike in a decent
setting, type up some history and info along with specs on the bike, and
follow the instructions at the bottom of most of the pages in the Gallery
Currently our own Lowrider Tommy is the Gallery's editor in chief.
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YuKu (the forums) Questions
Yuku has a fairly extensive help system that
covers just about everything HERE,
and those things not covered can always be posted in the forums and someone
will chime in with suggestions or help.
Carbs Section: What
type are my carbs?
The casting marks are stamped on a flat spot
on the flange of the carb up by where it attaches to the rack on older
"round tops" and on the later "keyhole top" carbs it is on the right side
of the castings along the edge where the bowl fastens to them. Yes it is
very hard to see sometimes, but it is there. It will be something like
"7A", "657A", "086", or "42B". There is a table you can refer to HERE.
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How do I clean the
There are usually at least a couple of pages
up on the web that cover carb cleaning. At the time of this update there
is a walkthrough HERE
for the older round top carbs and a thread HERE
which covers the later keyhole top carbs..
Where can I get Carb
is probably the least expensive for the 77/78 acccelerator pump kit #20-9040,
but the caveat is you must spend at least $35. They are once again carrying
the rebuild kits for the 77/78, and 71-76K but these kits do not have the
needle jet nozzles so yours must be in good shape to use these kits.
(olypen.com/retro/) carries several kits for both early and later
style carbs, and the ones they do carry come with the needle jet nozzles
at last check. Click on "Carburetors/kits & Components" in the menu
to the left.
CB750 (www.vintagecb750.com/products/6/fuel-system) carries several
kits, but the ones they do carry do not come with the needle jet nozzles
at last check, however, they do carry the repacking kits for the 77/78
carries several kits, and it shows they do carry the kits that containg
the needle jet nozzle.
Consilidated (www.siriusconinc.com), although usually VERY pricey,
is sometimes the only source. The other two sources above are your best
bet so try them first. There are also several dealers on eBay that regularly
make kits and other carb components available. At the time of this FAQ
update Sportingforless is one.
Running Pods and Drag
Pipes where should I jet?
125 jets on the mains is a good starting point.
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The Mill: Which
oil line is feed and which is return?
On the motor, the rear is the feed and the
front is the return. With regard to the oil tank, if you are
not sure which is the feed then pour mineral spirits in the tank, the hole
it runs out of is the feed (supply), the other is the return. The
vent should be obvious.
Found Metal shaving
in my oil pan, Should I be worried?
Been said that if you can't read a part number
on any of the shavings then don't sweat it!! Seriously, these
motors are around 30 years old got to expect some wear. Clean the
screen on the oil pump and remove the shavings from the pan and you should
be good to go, definitely want to keep the oil flowing.
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Big Bore Kits...
The Wiseco kits not only increase the size
but the compression is bumped to 10.25 as well. I must preface this post
with the fact that I am not a mechanic.. but I have experienced a variety
of mods to 750 motors. Just setting up the 836 kit will give you a noticeable
improvement in performance, but if you have the heads ported and flowed,
add a cam, some bigger carbs, and so on, and so on..... you will experience
Although the 836 is a good starting point,
bigger is not always better. You need to address the other components and
coordinate your changes if you do more than one. For example.... you could
probably have a standard bore 750 with modified head that will bump the
compression as well as breath better, bigger carbs, and cam, and probably
be able to stomp the guy that only installed a 900 or 1000 big bore kit.
Doing your research and matching the proper components is vital to get
the max horsepower.
Brothers like Motortard and Fastmax are
the guys that can give you a better outlook on what to do, rather than
myself, but I'm sure they will agree with this. Wiseco big bore kits come
with pistons, ring sets, piston pins, circlips, and a graphite head gasket
available through Lowrider Tommy HERE.
Electrical Hell: How
do I wire this Beotch?
Several wiring diagrams can be found in the
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Sawsall's Words of
Wisdom on Alternators and such:
There are 3 or 4 parts to the Stock CB 750
1. Stator Bolts to the inside the left
side engine cover.
2. Field Coil Also bolts to the inside
the cover (the smaller of the 2 pieces).
3. Rectifier Finned unit bolts under the
4. Regulator also bolts under the seat/side
when the key switch is turned to on; battery
power is fed to the regulator. The regulator controls how much voltage
gets fed to the field coil. The field coil is basically an electro magnet.
The magnetic field created by the field coil is transferred to the stator.
The serrated metal rotor that bolts to the crankshaft rotates between the
field coil and stator. As the rotor spins, the serrated portion causes
the magnetic field to pulsate. This pulsating magnetic field is picked
up by the stator and sends pulses of AC voltage to the rectifier. There
are 3 separate windings in the Stator, (the 3 yellow wires coming out of
The rectifier changes the voltage to DC
and sends the current thru the regulator to the battery. Depending on the
state of charge in the battery and the draw of current required by devices
using the power (lights, coils etc.) the regulator figures out how much
voltage gets sent to the field coils. The more power required, the more
to the field coil, the more power at the field coil, the stronger the magnetic
field, the stronger the magnetic field, the more voltage made by the stator.
With the ignition switch off you should
have 12-13 volts at the battery. Start the bike up and rev to 2000-3000
RPM, you should have 13.5-14.5 volts at the battery with the voltage increasing
To test the field coils and Stator, disconnect
the wire plugs that go into the left side engine cover (The stator &
field coil wires. They should be 3 yellow wires, white wire and a green
wire). The green wire is the ground for the field coil, run a jumper to
a ground or to the negative terminal of the battery (-). The white wire
is the power wire to the field coil. Hook a jumper to it and long enough
to go to the positive terminal of the battery but do not hook it up yet.
Hook the positive lead of a multi meter up to one of the yellow wires with
the meter set on AC voltage and the negative lead of the meter to a ground.
Start the bike up and hold at approx 3000
RPM. Hook the jumper wire for the white wire to the positive side of the
battery. Read the voltage output on each yellow wire. It should be 40-50
volts AC on each wire... If so, no sense in pulling the left engine cover
off. OH, YES, IT SHOULD HAVE OIL IN THE LEFT COVER.
So if the stator/rotor test was good,
the problem is the regulator or rectifier. Note: Someone may have upgraded
the system and removed the separate regulator and rectifier and replaced
them with a combination electronic reg/rec unit in which case the entire
unit will need to be replaced.
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Different systems interact in a smooth running
engine and cannot be considered apart. A tune-up should always be performed
in the following order:
A. Compression test
B. Tighten cylinder head bolts (see Chapter
C. Cam chain adjustment
D. Valve clearance adjustment
E. Spark Plugs
F. Condenser (capacitor)
G. Breaker points
H. Ignition timing
I. Air cleaner
J. Carburetion (if needed)"
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Instructions and tune-up procedure provided
Tune up Procedure
1. Remove the 10mm nut and hexagonal washer
assembly. (end of advancer)
2. Disconnect yellow and blue wires from old
3. Loosen and remove plate mounting screws.
Remove ignition plate.
4. Rub chalk into timing marks and smear grease
around points cam.
5. Gently install new plate with the word
Honda on the bottom and timing sight hole at the top.
6. Plate is mounted full CCW for 750K's. Plate
is mounted with screws in center of slots for 750SS.
7. Connect blue wire to 1-4 points (rear set)
and yellow wire to 2-3 points (front set)
Cam Chain Adjustment...
1. Set idle to 2500 rpm
2. Switch up for 1-4 timing mark
3. with wrench adjust points till timing marks
4. flip switch down and repeat 2. & 3.
on the 2-3 points and timing mark.
5. compare timing marks by flipping switch
up and down. both marks should be in the same relative location.
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1. Remove the valve adjuster caps from No.
1 (left outside) cylinder, and all four spark plugs.
2. Turn the crankshaft in the normal direction
(clockwise) until the "T" mark for the 1-4 cylinders align with the timing
3. Check that there is clearance at both valves
for the #1 cylinder. If not rotate the crankshaft another complete
turn (360 degrees) and check again. To be effective the adjustment
must be performed when #1 cylinder is on the compression stroke.
4. When both valves are free, continue turning
the crankshaft clockwise until the spring peg on the spark advancer is
to the right of a line drawn from the index. At this position the
#1 and #4 cylinders will be at 15 degrees ATDC, and the adjustment can
be performed. Caution: Do not rotate the crankshaft counterclockwise (opposite
direction of normal rotation) if you have turned it too far and gone past
the timing mark. Instead, rotate it clockwise through two complete
turns so that #1 piston will again be on the compression stroke and you
can position the spring peg just to the right of the timing mark without
having to turn the crankshaft back. Otherwise, the chain slack will
not be positioned properly and the tensioner may not be able to take up
the full amount of slack.
5. Loosen the locknut and back out the
adjuster bolt until you can turn it with your fingers. At this point,
the adjuster bolt has released pressure on the tensioner rod, which has
automatically moved in to take up the slack. Tighten the adjuster
bolt to 5.9-7.2 ft lbs, then lock it in position with the locknut.
The valves must be adjusted when the engine
is cold! In the following procedure, the cylinders are numbered 1 to
4, going from left to right from the point of view of a rider sitting on
the machine. The firing order is 1-2-4-3.
1. Remove the fuel tank.
2. Unscrew the eight adjuster access
3. Remove the ignition points cover.
4. Remove the spark plugs.
5. Turn the crankshaft in its normal
direction of rotation and observe the No.1 cylinder (far left) intake and
exhaust valves. When both valves are fully closed (clearance at both
rocker arms), the piston is close to Top Dead Center of its compression
stroke. Next, align the timing index mark and the "T" (1.4) mark
on the ignition advance rotor. Thsi should put the cam and crank in the
correct position to adjust the "A"
valves (see chart below). Looking down on the engine
from the rider's position the cylinders are numbered left to right #1,
#2, #3, and #4.
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6. Measure the clearance between the
adjusting screw and the valve stem of the "A"
valves described in the chart above using a feeler gauge.
7. If the feeler gauge of the proper
clearance thickness will not fit between the adjuster screw and valve stem,
or if it slides through with little or no resistance, the clearance should
be adjusted. To obtain the proper clearance, loosen the adjuster
screw locknut and turn the screw until the feeler gauge just fits, and
slides with some resistance. Tighten the locknut firmly (but do not
overtighten) while holding the screw to keep it from turning. Recheck
clearance in case it changed as the locknut was tightened.
8. After all four "A" valves have been
checked and adjusted, rotate the crankshaft one turn (360 degrees) in its
normal direction of rotation and align the timing index mark and
"T" mark exactly as before. This will position the No. 4 cylinder
on its compression stroke, and the "B"
valves in the chart can be checked and adjusted in the same manner as the
Chains and such: What
size Chain do I need?
69-76 K series 530 chain, 75-78 F and 77-78
K series 630 chain Still not sure what size chain you have? Look
on the side of the link; it should be stamped there. And last but
not least, if all else fails measure, 530 chains 5/8" spacing, 630 chains
3/4" spacing. 530 chains are cheaper and easier to find and custom sprockets
are easier to find for them.
site has a complete table showing the ratios for different sprocket
combinations. A quick and dirty but effective method is to divide the number
of rear sprocket teeth by the number of front sprocket teeth. E.G. an 18/48
530 stock ratio would be 2.66:1.
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Frames: What frame
do I have?
There's a nice collection of vintage frame
to help ID your frame, and also more HERE.
Rake and Trail?
There are a number of sites on the web that
explain rake and trail Here are just a few:
Springer Front End - Explanation of terminology and illustration.
- Both and explanation as well as a calculator
Steel - Although it is meant to illustrate the appearance of different
handle bars, has a simulator that allows you to visualize what modifications
to forward/up stretch and rake will look like.
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Two items a Chopperhead needs in his shop:
First is an Impact Driver-the kind that you hit with a hammer-next to the
manual purchase this will be the best $10-20 purchase that you will make.
Second is PB Blaster, Liquid Wrench, WD-40, or other rust penetrant.
Ebay and Such:
Some asshole keeps winning all the cool chopper parts on ebay!
Do what they do. Snipe the auction! It's simple.
Don't place any bids until the last ten seconds of the auction. You can
also do this unattended by utilizing free services such as Esnipe,
make sure that you put the maximum amount that you are willing to go and
check regularly to see if you need to up it if the bidding reaches your
maximum. Remember, in the end the only bid that counts is the one that
goes higher than all the rest.
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Where to find
One, Forking by Frank,
by Summers, PartsNMore,
Class Choppers, and check the Hondachopper.com
Links Page. Also check the forums
as members are always finding new sources for parts.
Approximate weight 225 pounds and approximate
What are the laws
in my State for Motorcycles?
The American Motorcycle Association keeps
a fairly accurate and recent list of state regulations and requirements
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