Honda CB500T hints & Tips

Valve Clearance Adjustment.

ACCORDING to the Haynes manual these are 0.001" for inlet and exhaust. Not only is this difficult to achieve in practise but also the potential source of expensive repairs.

Cam/cam follower wear can be a serious problem on these engines usually resulting in the cracking of the cam follower face. It would appear that this is due to one of, or a combination of the following: irregular oil changes, lack of oil! (don't laugh I came across one of these), zero valve clearance or way to much.

Back to the valve clearance. I have settled on a happy medium of 0.002"(0.05mm) as this ensures there is at least some clearance. Always turn the engine over a few times and check again afterwards.

The adjuster spindles must also be fitted with tiny mark in the correct orientation i.e. pointing away from the spark plug on both spindles.

Camchain.

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CHECK camchain tension regularly, excessive engine noise is usually down to a way too loose chain - unless it's of the more terminal type of rattling or knocking.
If the chain is allowed to run loose for any length of time it will first destroy the teeth of the numerous plastic rollers, the resulting swarf may then find its way onto the oil pump strainer as mentioned above. It's worth stripping the tensioner off the engine occasionally and making sure it operates smoothly, cleaning and greasing as necessary.

For those who may wish to delve a little deeper into their engine; when rejoining the camchain, do this at the rear of the head. Our trusty friend the Haynes manual emphasises the delicate nature of joining the chain, but doesn't tell you how!

Allow a good length of chain at the front when lowering the head into place and then have hours of endless fun threading the chain over the two cam sprockets. However before you do this, stuff some clean rag below the sprockets so that nothing can fall into the cavernous depths.

Align the almost invisible marks on the cams and bearing housings whilst the chain is pulled taught over the sprockets and then bring the rear section of chain up onto the inlet sprocket and slip the joining link through. Pop on the side plate and peen the ends of the pins over.

Camchain tension should be set regularly, I normally do ours every 3000 miles.

Oil Filters

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ENSURE that both oil filters are clean. This is particularly important if you buy a bike as they rarely seem to receive attention. At this point it is a very good idea to acquire the necessary 'O'rings and a clutch cover gasket.

Drain the oil and remove the clutch cover, now you will see the gauze strainer below the oil pump. Make sure this is clean as bits of chewed up camchain guide sprockets can cause a severe restriction.

Now move to the centrifugal filter on the end of the crank were you must first remove the retaining circlip.
If this is stuck, gently tap the inner part of the filter adjacent to the circlip with a suitable implement (not a screwdriver!). Once the circlip is removed use a long screw (6mm) as an extractor to remove the inner part of the filter, now you can get to work with a small screwdriver.
If the filter has never been cleaned there will probably be a rubbery layer several mm thick! Its difficult to clean the thing out completely but just make sure that nothing loose is left, otherwise it will end up somewhere unpleasant when the engine is started.
The inner section of the filter should slide back in easily, if not clean off any burrs.

WHILST you have the oil filter cover off have a look at the spring loaded relief valve and make sure it operates smoothly. It bears against a brass insert in the filter inner body, sometimes both parts can get in a bit of a mess if some twit has run the engine low on oil. As engine oil pressure relies on these two parts pressing together, its obviously important things are in good condition.

The 'O' ring shown in the diagram above is usually damaged or at least stretches when removed. Make sure you have a new one before pulling the filter apart.

Starter Clutch

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THIS is another weak spot. If you buy a bike or have never checked yours, put it on your list of things to do.
What usually happens, is that the 3 crosshead screws holding the clutch to the back of the alternator stator work loose. This spreads the alloy retaining tags (part of the stator-very expensive) which then allows more play to develop ruining lots of expensive bits! Honda were obviously aware of the problem as the 3 screws are staked and threadlocked, however the vibration gets to them eventually.

Obviously the alternator stator has to come of the end of the crank to attend to this little problem............DO NOT use a three legged puller to remove it as suggested in the Haynes manual.

From Raoul Punt in Australia we have a qoute from the factory manual regarding this troublesome component: "Clean the rollers with petrol and dry thoroughly before applying a light coating of silicone grease to entire surface of the rollers before assembly, using a fine hairbrush Character of the silicone grease: a) Little change quality from low temperature through high temperature: b) Temperature causes very little change to the friction coefficient (on coated metal surface).

AS previously stated the rear of the stator is aluminium and will almost certainly be distorted.
I've come across quite a few of these.

After the stator retaining bolt is removed you will see that the stator is threaded to take an extractor bolt (M16x1.5mm), so pop along to your friendly bolt dealer and buy one before starting this job. Just screw it in, give it a 1/4 turn to nip it up and then tap the end with a copper hammer.

Take care not to loose any bits of the starter clutch, though they should stick to the magnetic stator. If the 3 screws are loose, refit them with some retaining compound as opposed to threadlock.

Vibration

INEVITABLE with a parallel twin unless you are contemplating major crank surgery as suggested by Phil Vincent.

The 500T isn't too bad with it's 180º crank but it can be irritating at higher revs. Also the rumbling transmitted through the frame in the headstock area makes you wonder how long the engine will last.

Salvation is at hand; remove the head steady. This modification may not improve frame integrity, but then if you bought a 500T for its handling - test ride a modern bike as soon as possible.

JUNKING the head steady transforms the bike: it develops a mild shake at tickover and then smoothes out as the revs rise, better still it cuts mechanical noise.

Hard to believe but it does actually give the bike a vague hint of character, reduces weight, and you get to keep your fillings!

Ignition

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Timing
SETTING the ignition timing on these bikes is a real pain, principally as there is only one backplate. Because of this, the only way to set the timing of one cylinder relative to the other, is by adjusting the CB points gap.

This is not very satisfactory and only works if both sets of points are in good condition. I've considered producing a new set-up with dual backplates, but I'm sure aftermarket electronic ignition is the sensible answer.

I use a test lamp to check timing. Just make sure you set aside an hour!

First set both points gaps to 0.015" and then set the timing correct for the left cylinder (looking forwards). Now check the right cylinder, hopefully it won't be too far out. If it is, you need new sets of CB points. Otherwise move the backplate to get both cylinders roughly the same amount out, and then adjust the gaps to get both cylinders spot on. Remember that a larger points gap advances the ignition timing and vice versâ.

Both Team Fang and Raoul Punt from Australia have encountered the following problem: Missfire or not firing at all on one cylinder, removing the points cover cures this. If you have a mystery missfire check this first.

Coils
IF you suffer from poor starting, slow running and cutting out at tickover your coils are probably past there sell-by date. Lets face it they are more than likely 25 years old, and expecting them to produce a decent spark is asking a lot!

On 'The Fang' I fitted Dyna coils as used by most drag racers. I was assured by the vendor that 3 ohm was the correct rating, but when they arrived the instructions clearly state that 5 ohm coils should be used for CB points ignition. I had to fit a ballast resistor, so be warned.

It was worth fitting them though as we now have a nice fat spark and better performance.

I'll be fitting a set to the road bike when finances permit and will post details of any brackets required, as they wont fit the standard location.
Auto Advance
I've had one of these self distruct, and twice on our road bike the 'E' clips holding the bob weights in position have fallen off. Don't throw away your old sets of CB points as the 'E' clips from these can be used on the auto advance unit.

THE standard bike feels a bit 'busy' and it is well worth raising the final drive ratio. Easiest way to do this is to replace the 15 tooth gearbox sprocket with a 16 tooth Superdream item. These are usually available from accessory shops. It isn't really possible to do much at the rear as the standard 33 tooth sprocket brings the chain pretty close to the hub.

Standard final drive ratio is 2.2:1
A 16 tooth gearbox sprocket will give 2.063:1
Our road bike which is quite a bit lighter than standard and has a Kawasaki KLR650 rear wheel, runs a 17-35 setup giving 1.94:1. This gives a very relaxed feel in top gear and still adequate performance.

Gearbox

VERY occasionally 3rd gear has been known to fail on these engines, the dogs fall off! In road racers this can become something of a problem with higher power output. Obviously with a supercharger and methanol we are going to expose this weakness pretty soon!

More info when it happens.

A few owners have asked about cam followers and wear.

The first indication of bad wear, is if the valve clearance adjuster spindles will not take up the adjustment without moving out of the permissible range (see Valve Clearance Adjustment at the top of page). If the tiny marks on the spindles point towards the spark plug rather than away, this is a sure sign that the followers are probably in the 'Useless' range as shown at right.

A couple of owners have asked about the box spanner necessary to remove this nut buried deep within the oil filter housing. I made my own and you can too by downloading the drawing in pdf format.

Only one dimension is fairly important and if you can find a suitable piece of tube, it can be made in 15 minutes.

CB450 fan Raoul Punt in sunny Aus sent the following tip: The oil filter nut spanner can be quickly made out of a spark plug socket.

Click on the pdf logo to download the spanner drawing.