Hondachopper.com FAQ
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Table of contents:
...|...The BEST Investment if you intend to own a CB750 SOHC is A SHOP MANUAL....|...
...|...Second Best Investment if you intend to own a CB750 SOHC?...|...
...|...What does G.O.T.F. stand for?...|...
...|...Where can I upload pics so I can share them with others?...|...
...|...Are there any Chopperhedz in my area?...|...
...|...What year was my bike built?...|...
...|...How can I get my bike posted in the Gallery?...|...
...|...YuKu (the forums) Questions...|...
...|...Carbs Section: What type are my carbs?...|...
...|...How do I clean the carbs?...|...
...|...Where can I get Carb Rebuild Kits?...|...
...|...Running Pods and Drag Pipes where should I jet?...|...
...|...The Mill: Which oil line is feed and which is return?...|...
...|...Found Metal shaving in my oil pan, Should I be worried?...|...
...|...Big Bore Kits......|...
...|...Electrical Hell: How do I wire this Beotch?...|...
...|...Sawsall's Words of Wisdom on Alternators and such:...|...
...|...Tune-Up......|...
...|...Maxi-Dwell Instructions......|...
...|...Cam Chain Adjustment......|...
...|...Valve Adjustment......|...
...|...Chains and such: What size Chain do I need?...|...
...|...Sprocket Ratio Chart?...|...
...|...Frames: What frame do I have?...|...
...|...Rake and Trail?...|...
...|...Shop Essentials:...|...
...|...Ebay and Such: Some asshole keeps winning all the cool chopper parts on ebay!...|...
...|...Where to find parts?...|...
...|...Engine Shipping?...|...
...|...What are the laws in my State for Motorcycles?...|...

The BEST Investment if you intend to own a CB750 SOHC is A SHOP MANUAL.

Yes, Hondachopper.com 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.

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What does G.O.T.F. stand for?
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. Photobucket, Webshots, 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".
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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 built?
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..
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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 HERE. 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.
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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 carbs?
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..
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Where can I get Carb Rebuild Kits?
www.PartsNMore.com 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.
Retrobikes (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.
Vintage 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 keyhole carbs.
Rusty Riders (stores.rustyriders.net/-strse-364/Honda-CB750-Keyster-Carb/Detail.bok) carries several kits, and it shows they do carry the kits that containg the needle jet nozzle.
Sirius 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.
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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.
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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 more, obviously.
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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.
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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.
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Electrical Hell: How do I wire this Beotch?
Several wiring diagrams can be found in the Hondachopper.com Garage Section.
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Sawsall's Words of Wisdom on Alternators and such:
There are 3 or 4 parts to the Stock CB 750 charging system:
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 seat/side cover.
4. Regulator also bolts under the seat/side cover.
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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 it).
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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.
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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 with RPM.
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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.
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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.
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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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Tune-Up...
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 Four, Camshaft)
  • 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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Maxi-Dwell Instructions...

Instructions and tune-up procedure provided by RakeNtrail.
  • 1. Remove the 10mm nut and hexagonal washer assembly. (end of advancer)
  • 2. Disconnect yellow and blue wires from old points assembly.
  • 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)
Tune up Procedure
  • 1. Set idle to 2500 rpm
  • 2. Switch up for 1-4 timing mark
  • 3. with wrench adjust points till timing marks line up.
  • 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.
Cam Chain Adjustment...
  • 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 index mark.
  • 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.
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Valve Adjustment...
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 caps.
  • 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.
Cylinder
#1
#2
#3
#4
Clearance
Exhaust
A
A
B
B
 0.003"
(0.08mm)
Intake
A
B
A
B
 0.002"
(0.05mm)
  • 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 "A" valves.
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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.
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Sprocket Ratio Chart?
Dropbear's 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 ads HERE to help ID your frame, and also more HERE.
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Rake and Trail?
There are a number of sites on the web that explain rake and trail Here are just a few:
Jeri's Springer Front End - Explanation of terminology and illustration. 
RBRacing - Both and explanation as well as a calculator
Classic 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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Shop Essentials:
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.
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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, AuctionStealer, or AuctionSniper. Just 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 parts?
Cycle One, Forking by Frank, Lowriders by Summers, PartsNMore, Retrobikes, CycleReCycle2, Working Class Choppers, and check the Hondachopper.com Links Page. Also check the forums as members are always finding new sources for parts.
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Engine Shipping?
Approximate weight 225 pounds and approximate dimensions: 24"x24"x24".
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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 HERE.
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