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Chain and sprockets change on a Honda CB 750

Chain and sprockets change

Changing the sprockets and chain on the CB750 Nighthawk is not a child play. You need force, you need some skills with the tools. But sometimes a man has to do what a man has to do and do his own maintenance on the bike to be a real “biker”.

Chain and sprockets for the Honda CB750 Nighthawk

After looking at the Tsubaki site I went (and that was a mistake) for the Tsubaki Chain kit HO-128,  a 525 chain with 112 links and JT Sprockets, JTF1332.15 (15 teeth) front and JTR1332.40 (40 teeth) rear (these sizes are clearly indicated here). After installing the chain and sprockets I found out that I should take on link out from the chain (now it’s a little bit too long). If you look at the JTSprockets site, here you will see the recommended chain and sprockets would be:

  • chain 525 with 110 links
  • front sprocket: 15 teeth
  • rear sprocket: 38 teeth

Once again, the recommended DID chain is: DID 525 V9/110 links, and the RK chain is RK 525 SM0Z5/110 both with 15/38 sprockets. In Europe, Regina recommends the same, which means the Tsubaki chain was simply too long.

Changing the chain and sprockets on the Honda CB750 Nighthawk

Before starting, you should know that if you are not using an endless chain, you will need a “press chain tool” which is used to fix the master link. Other than that, just regular tools and one extra pair of hands (to help from time to time) are needed.

Note: I’m only discussing non-endless chain change here. If you want to install an endless chain, you need to remove the swing arm.

Let’s go step by step:

  • place some newspapers under the bike (you don’t want to get dirt on your new chain when installing)
  • with the bike on the central stand, remove the bolts from the drive sprocket cover. You will probably not be able to remove the cover directly; if so, remove the “do not open” plastic bolt – don’t worry, if the bike is on the central stand, it shouldn’t spill any oil. With the “do not open” bolt out, is easier to remove the cover (just be careful, you don’t want any mud in your oil). After taking the cover off, put the do not open bolt back.
  • Put the bike on the side stand, shift into 5th gear and ask someone (the extra pair of hands are needed) to apply the rear brake.
  • Remove the drive sprocket (you will need to use plain force). Because  I was short of tools,  I used the wheel tool from my car and make it longer with an old handlebar.
  • Cut the old chain (at this moment you need to be sure you are able to put everything back together) and remove the chain
  • Remove the drive sprocket
  • Clean the sprocket area (usually there is a lot of mud+chain oil)
  • Install the new sprocket with the numbers facing out. Tighten the bolt (but not too much yet)
  • Now, getting to the rear sprocket. Remove the rear wheel, and leaving the driven flange installed, step on the tire and ask someone (the second pair of hands) to remove the bolts (probably once again using the handlebar as a way to apply more force)
  • Install the new sprocket, put the bolts back and tighten them well
  • Put the rear wheel back, and adjust the distance as close as possible to the front wheel for the moment.
  • Put the new chain on the drive sprocket, then over the driven sprocket in a way that both ends are re-united just in front the rear wheel
  • Using your riveting or press tool, install the master link
  • Adjust the chain slack as usual
  • Tighten the front sprocket!
  • Put the drive sprocket cover back (you might need to remove the “do not open” bolt – remember the bike should be put on the central stand first)

 


Exhausts for the Honda CB 750

For Europe, I found the following providers:

  • IXIL SILENCERS – part no H1918 RIGHT & H1919 LEFT, only the end canisters, chromed steel – looking very close to the originals.
    Address:
    IXIL SILENCERS
    Talleres Vic, S.A.
    C/ Arquitectura, 2 P.I. CAN CUIÀS
    08110 Montcada i Reixach, BCN, SPAIN
    Ph. + 34 93 565 06 60
    Fx.  + 34 93 565 06 61
  • BSM Exhaustspart no 1027, its a 4-2-1 exhaust in chrome. Also available on carbon and some more advanced stuff.
    Address:
    BSM Exhausts BV
    To Mr. W.A.W. Bull
    Burg. Langmanweg 4
    7021 BK Zelhem
    The Netherlands
  • Barracuda Exhaustspart no 1017 – 4 into 1, looking a little strange to me, but if you don’t need the original look, it might work. Here is the buy link.
    Address:
    Wom Online Store GmbH
    Hanns-Rottweg 68
    D-48165 Münster
  • Motad 4-1 replacement system – part no M75H .Downpipes and silencer manufactured from mild steel,(Stainless steel where specified) finished in a bright chrome finish.
    Address:
    Motad Limited
    Unit 1,Unity Buildings, Robottom Close, Leamore Lane, Walsall, WS2 7EB
  • Speed Products, 4 into 1, part no 170-1017-048
    Address:
    Speed Products GmbH + Co KG
    Zum Kaiserbusch 20
    48165 Münster
    Telefon: 0251-962540
    Telefax: 0251-96254-44
  • Laser exhausts, the Jama Original series, looking good, but they never reply their emails so it’s impossible to buy. (If they will ever read this, I would like to let you know that you lost a sale)
    Address:
    JAMA Engineering BV.
    Boonsweg 85
    3274 LH Heinenoord
    The Netherlands

There are a few more suppliers in US and Canada, so if you would like to have something added here, let me know.


Changing the spark plugs on the Honda CB 750

Changing the spark plugs

Changing the spark plugs  is an medium difficulty operation and also, you don’t need to change them very often – it’s a real permissive engine. The best way to do the change is with the tank near empty (tank has to be removed) and with a cold engine.

Getting access to the spark plugs

Put the bike on the central stand (optional). Start by removing the seat and the small side-panels. Remove the fuel tank mounting bolt – don’t worry the tank won’t fall.

Switch the fuel to off and take the hoses out – fuel hose and vacuum hose (left side, just below the tank). Prepare a surface to place the tank once is removed – some fuel might leak (usually a few drops). Remove the tank slowly by lifting and dragging towards the end of the bike.

Spark plug removal

Once you have the tank out, take a piece of paper and pencil and draw the position of the spark plug caps (the cylinders are numbered 1, 2, 3, 4 starting from the left side, but that won’t help much if it’s an older bike and the numbers are not visible on the wires, unless you make a draw). Remove the caps& wires and look at the spark plugs from above – you will notice a lot of debris around them – you don’t want any debris in your engine. You can remove the debris with compressed air – if you don’t have, just use a small hose and blow air around the spark plugs until the debris is gone (use protective glass to protect your eyes). You can as well use a small paintbrush, or a vacuum-cleaner.

Spark plugs debris
 Honda CB 750 spark plugs
 Click to see the larger image

Using the socket, loosen and remove the spark plugs. After removing each one, it would be a good idea to inspect them.

Inspecting the spark plugs

Spark plugs can indicate any problems with the engine.

  • light gray colored, normal gap – good engine
  • damp oil film – most likely worn piston rings
  • carbon deposits – fuel mixture too rich, clogged air filter

Installing new spark plugs

I’m using NGK DPR8EA-9 – the standard heat range spark plugs (work well, unless is really cold), or you could use Denso Hot U Resistor Plugs X24EPR-U9 . To install the new ones, screw them by hand to make sure they are not cross threaded. Once the gasket touches, tighten a little bit with the wrench. Put the caps back using the paper drawing, the fuel tank hoses, bolt, side panels and seat.