Honda CX500D rebuild.


Strip Down


In Progress


After the bike turned up in the garage in various boxes and crates, I swung into action and re-assembled it into a bike of sorts. Then I ignored it for three years, shuffling it around the garage and the drive whenever it got on the way. However, its day finally came and up it went onto the bike lift.



If you excuse the sidecar chassis poking into the picture, here is the CX now minus the petrol tank and side panels, giving a clear picture of the bike. In principle it looks fine, requiring just refinishing. The frame is very low at the seat area, although the thickly padded seat brings it nearer to normal height.



Here's a close up of the engine showing the famously twisted cylinders. The idea is to prevent a carburettor/knee clash, but in order to achieve this, there is a camshaft driven by a timing chain which then operates the valves via pushrods. The timing chain tensioner is the main problem area and Honda did bring out various improved designs in an attempt to reduce warranty costs and, presumably, customer dissatisfaction. Fortunately they had the good sense to ensure that later designs could be retro-fitted so I can confidently fit a properly working system.

I'm looking forward to stripping this engine because of its wonderful unconventionality. Clutch at the front of the engine indeed. What were they thinking?



This shield thing sits under the tank, between the cylinders. The rubber on it is torn, so a replacement part will be needed.



Removing the water pipes to the cylinder heads revealed this crystallised goo. Still, at least it shows that someone has been using anti freeze, which is necessary in an alloy engine such as this even if it is only used in summer, due to the anti-corrossion properties.



The carbs just pulled backward because the air box to carb rubbers are missing and the throttle cables aren't connected. The carb to cylinder head rubbers shown here are rock hard and will also need replacing. I usually find eBay a good source for such things.



The coolant reservoir is bolted to the frame behind the engine and will not come free until the engine is removed. Which means that it needs to be fitted to the frame before the engine goes in when the rebuild happens.



In preparation for getting the shaft drive removed, first of all the rear mudguard comes off to give room for rear wheel removal. The tool box sits under the rear tail piece when it is all together. Removing the two bolts on the cross piece now releases the rear mudguard front part (don't forget to disconnect the electrical block connectors). The lever thing (it has a twin on the other side) is for seat removal.



With the spindle removed the rear wheel will slide off the drive gear.



The suspension unit can now be released and the three nuts securing the bevel gear to the driveshaft can be undone.



And here is the bevel drive gear in all its glory. It can be put to one side for now until it is time to take a closer look. Incidentally, the grease nipple indicates that it is a 500cc part, not a 650cc part.



The driveshaft runs through the centre of the swing arm tube.



The front end of the drive shaft meets the engine output shaft behind this gaiter.



Pull the gaiter back and remove the locating bolt. It may be worth checking the orientation of the bolt before removing the rear wheel, so it can be put into a more favourable position. With locating bolt removed, the driveshaft can be pushed backwards off the output shaft. The locating bolt is of a special type, hence refit it into the driveshaft so as not to lose it.



Because the shaft drive prevents the use of a "normal" swing arm pivot pin, Honda have adopted a slightly different strategy. The pin here only extends to where the larger diameter tube stops. At the other end, there is a roller bearing fitted into the frame lug and a pin on the swing arm. Hence, once the left side pin is removed, the swing arm can be removed.



I hope this picture makes better sense than my descriptions. Note the special locating bolt I mentioned and also the pin on the swing arm to allow it to pivot in the frame mounted bearing. The swing arm incidentally is not the original one from the bike. At some point in the past, the swing arm and frame were to be shot blasted and powder coated, but the corrosion on the swing arm was too severe, so this replacement was sourced. I now need to degrease it for powder coating. In case you are wondering, the frame did get powder coated but now looks awful, due to poor preparation. It will be done again, but properly.



When removing the shock absorbers, I noticed this. This is not as serious as if the bike were a high performance sports bike, but all the same is not a good idea. The shock absorbers are aftermarket anyway and will likely be replaced with other, more cosmetically pleasing, aftermarket ones, probably Hagons.



Before we leave the back end, this is the rear indicator. Notice anything odd? Three wires perhaps? This shows the US (or Canadian) roots of this bike as there is some sort of bizarre requirement to have the indicators light up whenever full beam is on or something. Whatever, it is achieved by the use of double filament bulbs (like a stop and tail light bulb) and hence the extra wire. Although it has been removed from the system here by the novel method of snipping the wire and taping it up badly, I'm wondering whether to put this back into working order. I see quite a few US market cars around with this and with stupid flashing brake lights instead of indicators, so I don't see why we wouldn't be allowed it. Actually, I can. We'll see.



Now, let's move to the front end.



I never bothered fitting all the headlamp when I assembled the bike because it was untidy rubbish. I reckon that it would be better to tidy the entire thing up and part of this will be to lose the ugly horn/horn bracket.



The bike still has ball bearings in the steering head. These will likely be changed for taper roller ones. The upper race is cracked anyway, so when these are removed so that the frame can be powder coated they will go straight in the bin. Well, they'll go in the box first in case I need them for reference.



And we're almost there. The bike is off the centre stand and dropped onto my handy-dandy engine plinth (which prevents things like sump plugs getting damaged).



And, once the A frame is removed, the frame can be lifted off the engine. The engine will be rebuilt because it hasn't run for years and I want to make sure that all is okay inside and the frame will be prepared for coating. I'll also go back through the boxes because I'll also want to have various other things coated.



I did, however, go back to the A frame issue.



One problem from the dry build was the A frame, which does not align and also has the captive nuts not missing - well, not missing exactly, as they are rattling around within the pressed steel structure. The best solution was to source another A frame from eBay and, once I'd established that alignement was nothing more than tolerance issue and the order in which I fitted the mounting bolts, this went into the powder coating box.



Before the frame gets powder coated I wanted to check all the threads. The suspension upper and lower mounts turend out to be M10 fine threads, meaning I had to order a tap and die to allow me to clean up the threads after coating.



The steering head bearing tracks also needed to be removed.



This is the swing arm bearing on the shaft side. Plan here would be to replace the bearing and seal and zinc plate the cap.





And that's it all apart. Next step is to refurbish all the parts and put it back together again - what could be simpler? I sorted out all the parts which need to go for powder coating, not just the frame and swing arm, but engine brackets and fan shroud and things. I want to include the brake caliper in this, but need to get the brake piston out and attempts with compressed air have proved unsuccessful. Otherwise, the parts need to be degreased before I hand them over to Triple S of Bingley.



With the parts returned, I concentrated on the engine. This would eventually need to be sent away for refinishing and I used this as an opportunity to also look through the boxes of parts to see what else needs to be done.



The rear brake stood out as something which needed thinking about. I studied literally hundreds of pictures of CX500s on the web before I finally decided that both the rear brake plate and the rear bevel drive housing would also be black. Using either stainless steel or zinc plated fasteners and things like re-chroming the brake lever arm should add a level of detailing.




The switches were silver as standard, and will remain that way. I stripped all the insides out so they could be powder coated. The throttle clamp, used as a cruise control, is made from plastic and hence will not stand the painting oven, so I will need to seek an alternative finishing method..



Parts for the chroming box here. I'm not sure how to deal with the speedo and instrument cluster, I've heard that black boot polish may bring back the former lustre but there are also cockpit cleaner products on the market which may also work.



The base of the master cylinder sepearates from the plastic fluid reservoir, so this can go in the powder coating box. Once I've removed the brake switch and the brake piston, both of which have resisted all attempts so far.





Strip down


Engine page one


Engine page two


Greasy Old Motorbikes