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Discussion Starter · #1 ·
Hiya Guys



My first posting. I have an 81 Custom, American import to UK, which is pretty rare as are the customs over here. It has 35mm forks with leading axle and air pre-load and I haven't been able to find specific information for these. I have ordered the correct seals and dust covers and want to strip the forks down and put them back together with new oil. At the moment, the forks don't hold air pressure, seem a bit "soft" and I don't know how much oil is in them. They don,t appear to be leaking at the seals, but there appears to be a fine coating of oil above the seals. The bike is used daily and I have done 8000 miles in the last year



Can anyone advise or point me to a posting showing how to work on these forks and how much oil they require. I also understand that thickening up the oil is usually suggested, how would this affect the ride, bearing in mind UK roads are very rough and potholed, plus very bendy.



Cheers



Ross
 

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Type and sot of info, that just leave you worth the choice either 10W, 15W or 20w in thickness - depends on your weight and driving style.



Use with new request and the reset the flag
 

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Hi Ross, that's good advice to use standard oil types & see which suits you best. Thicker gives better damping, often at the expense of comfort! As a bonus, it doesn't leak so much either.

You ask about the air system. Like a lot of features on these bikes, the air forks may have been a good idea when new but that was some time ago. The system, when it works, does give a slightly smoother ride.

You may realise that the type of seal used on forks is really designed for rotary use, not sliding. Adding air forces the lips hard against the fork leg & leads to rapid wear if the components are less than perfect. As you found out, they often can't even hold limited air pressure.

IMO the seals that David Silver sell (Nikko?) are the best, being supple & of double-lip design. Avoid NOS as they will be harder.

Your fork bushes will be worn, allowing a certain amount of 'play' between sliders & legs, this is probably how most of the air escapes. You might say 'fine, I'll fit new bushes to cure the problem'. OK but it is not the whole answer as your sliders will be worn in the lower part of the bores too. And you probably have some pitting of the legs.

If you get my drift, I am saying air forks often don't work!



You are right about UK roads being increasingly poor. That's when you really notice the mass of the rear wheel & shaft assy! Bendy is good though.I like it a lot.
 

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Discussion Starter · #5 ·
Thanks for the input guys. CXer, I have ordered seals from David Silver, he does seem to get a fair bit of my cash. Shall schedule forks in after the oil leak from front crankcase seal which developed this morning and speedo failure which occured this afternoon.



Ross
 

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Use,"Bandit's" trick when doing the fork seals.Lay the old one on top of the new one and then use a piece of flat wood to press the new one home lightly tapping with a rubber mallet but never fast and keep the seal flat going in.Coat the sides of the new seal with some fork oil to help it slide.The spring side goes towards the oil.



After fitting the locking clip smear grease around the top of the seal.This serves to stop the clip ring corroding and the top skirt of the seal from drying out.You may have to wipe the fork legs a couple of rides until the grease ring stops appearing on them.



PS

David Slivers are superb service as are Wemoto who I have used for my fork seals as well,



http://www.wemoto.com/bikes/Honda/CX_500_A/79-80/







HTH
 

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Discussion Starter · #7 ·
Wemoto have also had a good few quid off me. I did a bit of digging for these as I am pretty sure the air assist forks are a different size to all the other forks (35mm against 33mm), so double checked the honda numbers. General seals etc for CXs in the UK wouldn't be right for these. I've also ordered all the other gubbins, circlips etc, as a quick look under the dust covers revealed corrosion.



Amongst other jobs I've also swapped the US carbs with, accelerator pumps, for UK spec ones, due to high consumption and rich running. which has added 20+ mpg, if reducing acceleration.



However I am thinking of buying a new bike so that I can ride at weekends instead of the joys of tearing her down and putting her back together again. It might be interesting seeing what something without half a ton of back wheel and transmission feels like across the pot holes.
 

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Hi Ross, sounds like all your troubles are coming at once.

Has your speedo packed in or is it the cable?

I'm not familiar with your model but if it uses the separate, round instruments I have a couple of them.Where you?

I see you mention corrosion in the tops of the fork legs. As you can imagine, this makes circlip removal really interesting!

The job is bad enough when all is clean & shiny due to lack of room to work in.

If you can't get the exact size of new circlip from a bike dealer, try a bearing supplier.

If you get the strong bearing type, weaken them by grinding a half-moon in two or three places or you will never be able to compress them to fit.

A Dremel tool or electric drill & small stone does a good job. No need to overdo it. Copy the original if you can get a large enough piece out.



You mention having US spec carbs. I have made a single carb manifold which improves economy & engine smoothness (and tractability) a lot.

Having increased the jets two sizes, I find the mixture is OK, possibly a tad lean but that's good.

Now grabbing a handful of throttle shows the lack of accelerator pumps. From what you say, the economy would take a nosedive again if I used them.

As I did the conversion mainly to reduce the engine's awful thirst, I don't much mind the lack of acceleration. I have some pics if you are interested.

I am slightly surprised that the US carbs are so poor, I recall they were set somewhat leaner than UK types for California emmissions rules.

It was the fact they ran so lean that forced the fitting of the pumps.



As for tearing down, one day you will get it just as you want. Then what will you do?



If you get another bike, with old-fashioned chain drive, you will definitely notice the difference over the potholes.



Thaks to Shep for the fitting tip. Not sure how you get the second seal out again afterward though. Fortunately for us, there is a size of UK plastic plumbing pipe that very nearly fits. Just cut n shut the end till it fits snugly. Make sure it is long enough to go over the top of the leg so you can whack it. The snug fit ensures the seal goes in true.



CXer
 

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Discussion Starter · #9 ·
Hi Ross, sounds like all your troubles are coming at once.

Has your speedo packed in or is it the cable?



CXer


This is the third time it's happened. The first time it was the drive dog in the front wheel (a washer with lugs) which distorted. When I took it apart last time the dog looked okay but it worked for a week after reassembly. The cable is a new honda replacement, which I got due to the wheel end drive breaking one pin off. I have a feeling this may not be engaging into the drive housing properly, the cable doesn't clip fully home into the drive and has a fair bit of slack. I fiddled with it last night and it's working again.



The speedo seems okay, but the screws holding the face on rattled off about a month ago and I had to split it to screw it back in (having lost one screw on the M40), it has also developed a crack across the face. A replacement might be nice, I am in Petersfild, Hampshire.



I'm not sure why the Accelerator pump carbs were so thirsty, might just have been age and crud, or because there are too few roads around here to cruise on, changing speed a lot just means we are pumping loads of petrol through rather than leaving a constant throttle setting. I gave them as thorough a cleaning as I could but wasn't able to ultrasonically clean them. I've now got three sets in various states of repair and could cobble together an improvement, but having to work in the road does damp my enthusiasm somewhat. At the moment, if I open the throttle abrubtly from lower revs it just splutters, smooth throttle works better and it does work very well from 7500-9500 revs.



It would be good to see pics of your set-up, it may give me ideas if I get a carb-excitement weekend.



Ross
 

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Hi Ross, I have tried to add the pics but don't see how to do it ! Old age perhaps.

My email is [email protected]

If you or anyone else who knows how can tell me how to add images, I'll do so & put them in the right thread too.

Otherwise just email me & I'll send the pics as attachments.
 

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Hi Ross, I have tried to add the pics but don't see how to do it ! Old age perhaps.

My email is [email protected]

If you or anyone else who knows how can tell me how to add images, I'll do so & put them in the right thread too.

Otherwise just email me & I'll send the pics as attachments.
send your photos to me,ill post them for you
 
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