Frame, Body, Chrome, Etc.
- Tool Kit
- Tire Pumps
- Colours and Tank
- Horn
- Shocks
- Fuel Cock
- Seat
- Pipes
- Airbox
- Swing, Grips, Etc.Airbox
- Cobra Project Menu
Tool Kit
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Tire Pumps
With Contributions by Eric in North Virginia, USA
There were at least two styles of tire pump fitted to the early T500's - the one at the top of the photo on the left has 'Made in Japan' printed length ways on the pump handle and came from a first year T500, and the one in the lower part of the photo has 'Made in Japan' printed on the end of the handle , wrapped around where the nozzle is stored. Both pumps are the same length of 20 cm, uncompressed with the nozzle protruding another 1 cm. The pump casings were made of aluminium.
The pumps were both about 45 cm when fully extended. Below in the centre photo are close-ups of the printing on the handles of the two types - left is early, right is later. A photo on the second from the right shows the nozzle removed from the pump end - relative to a bicycle tire pump, the nozzle is quite long. And finally, on the right is what I have decided to go with for the present at least. These pumps go for silly money when they do come available, so I'm using one that cost $0.99 at a garage sale and have cut it down to fit. From a couple of metres away, it looks the part ! Just click on any photo for the larger version.
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Colours and Tank
A close look at the tank had shown that it had been filled with body filler, and my hope was that underneath all of that the tank would be in good enough condition to use - it was a bit of a gamble, but after several hours and the removal of just over 2 kilos (4 1/2 pounds) of filler I was pleased to see that it actually looked quite good, and the threads for mounting the side panels are intact ! In the middle photo below you can see the original chrome side panel mounted back on the tank for the first time in many years, together with some of the filler I removed.
I was also able to clear away a large enough section of the blue paint from the oil tank that the fellow doing my paint will be able to get a good match. Just click on the photos for a larger version
And here is the tank after being painted.
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Horn
The Suzuki MK I T500 Cobra had a horn that was mounted on a post that passed through a rubber bush on the frame just under the right front side of the fuel tank. This was changed with the MK II model to be a bracket mounted version. In photos I've seen two styles of horn for the MK I which were similar - what I had available to me was a (somewhat) working horn suitable for a 1972 model GT750 which appeared to have the same chrome face, but which mounted with a bracket. So I modified it !
The horns are held together with aluminium rivets - on the back of the horn are actually two adjustment points. The large anvil in the centre of the horn body which also serves as the attachment point for the bracket when moved in or out slightly alters the pitch of the horn, and to the side is a small Phillips headed screw which adjusts the contact gap on the electro-solenoid that does the vibrating and creates the sound. There is a service bulletin on servicing horns (see General Bulletin #8 at this link), but the anvil in the centre I suspect was not meant to be played with.
In the photo to the left below, you can see the MK I style of horn from a period advertising photo. Next to is is the disassembled horn I've modified - item #1 ,marks the moving part of the solenoid and item #2 is the moveable anvil it vibrates against. I drilled out the anvil and tapped it with a 10x1.25mm thread and made a stud of the right length for the bush in the frame. The centre and right photos show the stud and the horn once fixed in place. I have the horn face out to be re-chromed and will also paint the rest of the housing and then use either new aluminium rivets or possibly small stainless steel bolts to reassemble it.
Update: after doing all that work, I stumbled across the correct horn and snagged it for what I considered to be a reasonable cost. Murphy's Law never fails eh ?
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Shocks
The Suzuki MK I T500 Cobra was the only model in the T500 line that had a fully enclosed rear shock/damper with a painted upper shroud and a chromed lower shroud enclosing the spring. This causes two problems - suitable after market copies are not easy to find (actually I haven't found any), and as a minimum they need to be disassembled for painting. There is a trick to taking them apart that is quite useful to know !
Jim on the Sundial board was kind enough to post some 'how to' information on these specific shocks/dampers. Most of the Showa shocks used by Suzuki require you to depress the spring enough to be able to access a nut on the damper rod. Loosen that off and the upper eye-bolt fitting comes off and you then (very carefully) uncompress the spring and away you go. The MK I differs in that the painted shroud is threaded - if you try to compress it in a jig as you would for the later dampers, you will ruin the upper painted shroud. I was surprised at how easy they were to take apart - no doubt that will not be the case on reassembly !
In the photo to the left below, you can see the MK I style of rear shock/damper fully disassembled. Next to it is a close-up of the upper shroud and the threaded fitting. Second from the right is a shot of the crimped shock body end cap on each damper - if I want to have these re-chromed then these will need to be opened up and replaced with a threaded end cap and seal carrier making them rebuildable. To the right are the shock upper and lower bushes which are worn and also needed to be replaced.
Of course, the damper bodies were never intended to be taken apart, or repaired. At this point I'm not 100% sure it can be done, however these shocks are very similar to others used on Honda's and a very talented fellow by the name of Graham Curtis has shared his experiments on shock rebuilding over on the Honda 305 board at this link. I've corresponded with him and plan to at least try it as they do need to be re-chromed. One issue is that there is very little clearance between the spring ID and the OD of the shock body. As well the wall thickness of the shock body isn't - thick that is ! I have discussed this with Joe at RPM south of here as he has the equipment required to do this sort of job and we will see what happens. The rubber bushes are available from a company in the UK.
Update: After reassembling the shocks with the painted upper shrouds and re-chromed lower sleeves I took the bike for a ride, and while they are not 'great' they actually aren't too bad either. As a result, I'm delaying having them fully rebuilt till such time as it is really needed.
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Fuel Cock
Like most of the Suzuki fuel cocks, the Mk1 T500 is vacuum operated, and this one had been butchered at some point in its life. Suzuki doesn’t sell most of the consumable parts you need to repair them. In the photo below, the face seal item 1 is not available, but as Mikuni supplied other brands, I was able to use a Yamaha part (137-24523-00), and also could have used a Honda part (16955-268-020) as they appear to be interchangeable. items 2 and 3 are still available from Suzuki, the screen item 4 is not, neither are the filters (5). The small atmospheric vent gasket (item 6) was not listed by Suzuki but is the same as the Kawasaki part 92065-052 which is also not available, but which you sometimes see on eBay. The diaphragm item 7 can be re-manufactured by an outfit in Germany at this link - more on that in a minute. The o-ring on the pintle itself, item 8, I replace with a viton o-ring of the same size (and I use a method suggested by a friend of mine – Rick – of using a bamboo chopstick to polish the seat that the o-ring seals to). The spring – item 9 is shorter than the ones used on the triples (to match the shorter pintle) and so are unique to the twins. Item 10 I’ll get to in a minute.
This fuel cock had been apart previously ( the screw heads were well rounded ) and someone had drilled out the check valve in the back plate. Till a year or so ago I hadn’t realised there was a valve in these. Allan, another friend of mine, mentioned it to me in passing as we were talking about methods to get these vacuum valves to seal properly. I’m pointing to the check valve in this photo.
Normally, if the check valve working, if you gently blow or suck on the vacuum line connection you can hear the valve click, plus when blowing it should shut and not allow you to easily blow through the valve. On bikes that have been sitting for years, these check valves set up (corrosion and in one case of mine a spider nest) and they get stuck. If you have one handy, look at the hole I’m pointing at in the photo and you should see that there is a small – less than 0.5mm – restriction hole visible. On this fuel cock, the check valve had actually been drilled out completely with roughly a 1/8 drill. I suspect the effect this would have is that the fuel cock would be slamming open and closed as there is a lot of pulsation at the carburettor inlets on 2 strokes, which in turn would have affected fuel delivery. As this valve was messed up anyway I took it apart to see what the internals looked like.
In the photo to the right, the cavity the arrow is pointing to holds the valve. You first have item 3 which is a small rubber gasket, then item 2 which is a small brass plug which normally would have a restriction orifice of about 0.5mm in it. This plug slides into the brass housing item 1, the head of which is what you can normally see when you look at the inside of the back plate. I have a box full of J/K fuel cocks for GT750′s – some are working correctly and others are seized up – on this one for the T500, item 2 was actually seized in the barrel (item 1) whether from having been mutilated or corrosion is difficult to say. If the valve is seized the fuel cock should still work – although probably would be slow to open and so restrict fuel flow initially. And if the orifice is plugged with spider web or something else, it won’t readily open at all and so starve the engine of fuel.
I released the brass barrel that holds the valve plug by using a Dremel to relieve the punch marks holding it so I suspect that it may be possible to actually repair these in those cases where you want to maintain the originality.
As mentioned earlier the fuel cock on the T500 had been played with. Although I had got it to the point it worked well enough, I had noticed that the diaphragm was on its way out and actually leaking slightly as there was fuel seepage evident on the vacuum side of the rubber membrane. This was a problem as these haven’t been available from Suzuki since shortly before the stone age and despite checking with local gasket and materials supply places servicing the oil patch I had yet to locate something similar enough that I would be able to take a run at a repair.
And then I happened across a web site in Germany that seemed to have the solution to my (and many other’s) problems. A fellow by the name of Volker Schultz in Frankfurt, Germany is making replacement diaphragms and repair kits for a wide range of these older Suzuki fuel cocks – and they look really, really good !
In the photo to the left, the new diaphragm can be seen together with some of the parts included in one of Volker’s rebuild kits which you can order via his web site at this link: www.hard-to-find-parts.de . The site is in German, but most modern browsers will offer to translate the site into your preferred language, and do a passable enough job that you should have no problem figuring out what it is you are looking at. He also sells on the German eBay site – the prices are the same.
Diaphragms are sold on an exchange basis – while the membrane and pintle are new, the grey plastic separator that fits between the two membranes is recycled and so he needs these back. Before installing the new diaphragm it pays to first polish the seating area of the new o-ring a little bit as otherwise you may find that you do not get a perfect seal immediately, although any very small drips should seal up within a few miles of running.
The other thing to note is that the pintles are slightly different, one model or model year to the next. In the photo to the right, the 1968 MK1 version pintle is to the left and notice it has a shoulder that the MK2 does not have. The valve casting also appears to be a slightly different shape and so the new style MK2 pintle will not seat properly on the older MK1 style valve casting. Just another thing to check and be aware of.
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Seat
My seat pan was rotted out around the perimeter and while it was repairable I also was interested in seeing whether there were other options available. Later seat pans are a different shape and profile – the one used on the Cobra was another ‘one year only’ item so using a later pan was not a perfect option. Repairing what I had was doable – but to get it done well (ie: by someone other than myself) was going to cost a few beer tokens. So it came down to, which option was the most cost effective – repair or replace.
There were some discussions with other owners around the globe about getting Cobra seats reproduced, but after well over a year I got tired of waiting and so I contacted a place in Vietnam that was selling rough and ready pans and covered café racer seats just to see if they were even interested in doing a low volume pan for me. After a few backs and forths via email and a phone call, I sent my old pan to them and then somewhat nervously sat back to see what would happen. If it all went into the ditch, then not only would I not have a new pan, but I wouldn’t have the old one either and so be completely scuppered as these things are as rare as hen’s teeth.
After even more emails, the pans finally arrived back here in Calgary, and I admit that I was pleasantly surprised ! The new one is a pretty faithful copy of the old one and fits not too badly at all. In the photo at the top, the old original is in the upper half and the reproduction pan is below it. As you can see the new pan has been hand formed – basically a sheet of thin gauge steel has been pounded into the right shape using a hammer and dolly. As a result, it is not a 100% faithful copy – the edges of the pattern are not crisp for example – but it is a good likeness. The second photo to the upper right shows the two pans – original on top, new one below it – and as can be seen, the profile is very close to being the same. The one thing I’d ask for next time is for a stiffener to be spot welded around the inside edge as I’m not as svelte as I used to be, and I think some added rigidity would be wise (note that the original one did have this) . Of course, when the pan is covered, and bolted to the frame (this model does not have a hinged seat) you can’t even see the underside of the pan once it is installed – certainly not the top either – so really, so long as the profile is good and the shape is correct then frankly I’m OK with it.
The original padding was not foam, but rather a sort of composite rubber that was deep in the centre of the pan area and then tapered out to the front and the back so as to look flat when covered. the third photo immediately above shows the original pan with the original rubber foam on it, and the last photo below shows the new pan with the original rubber foam.
I had the old rubber re-covered with a very thin layer of new high density seat foam material glued to the original, just to soften it a bit and restore some of its shape. The bike came with a replacement seat cover that closely resembles the original look – again, this was a one year only special suede look leatherette which is hard (read really expensive !) to find. The final result by Calgary Seat Covers turned out well and I'm pleased with it. Somewhere down the road, I may explore repairing the pan I have, but it isn't urgent.
If you need a 1968 Suzuki T500 Cobra seat pan for your own use, send Truong an email at texavina@gmail.com, and tell him you want the same as he supplied for me. He also has a web site at this link if you want to see what else he has to offer.
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Pipes
So the reproduction mufflers arrived from Marcel in NL - and my initial impression was that they were perfect.
Well - as it turns out I was wrong. My wife tells me that often, so perhaps sometimes its even true ! :? The shape is correct, the 'dimples' are in all the right places and the diameters are correct, but there are actually two issues that caused me a lot of faffing about to sort:
- The flanges/seams on the welds are far too wide
- The hanger mount on the muffler is off by about 4 or 5 mm (the old ones are about 33 mm off the centre line, and the new ones about 28 or 29 mm)
This meant that when mounted on the bike, the mufflers I received (I have no way to know if this is true for all the ones Marcel sells) were tight to the lower frame rail, and the lower weld flange was in the way of the side stand so it could not be mounted. In the photo below, the arrow points to an original muffler on the top and the lower weld flange/seam - you can see its almost non-existent. On the reproduction muffler below it you can see that the flange is quite wide and extends about 8 mm further than the one above.
To fix this, I shimmed out the muffler at the hanger using some stainless washers so that when bolted up it would just clear the lower frame rail, and I used a block of 9 mm stainless plate to shim the side stand so that the side stand pivot bolt can clear the under side edge of the muffler. That actually has a positive effect as it means the bike stands a bit more upright on the side stand now, so it isn't all a bad news story. And note that were I to do it all over again, I'd still buy from Marcel - they do look and sound fantastic and are a quality product, its just that 'some fitting is required'. 8)
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Air Box
The intake airbox on my bike had been modified by drilling a load of holes in it, which I welded up and used a bit of JB Weld to smooth over any pin holes etc. (I'm not the world's best welder). I've been told that at one time, adding these holes was thought to help the engine breathe better, but I suspect in practice they just boosted the air intake howl so it sounded like you were going faster.
On the back of the airbox - right where it would get scraped by the battery mounting strap lug, is a foil Nippon Denso lable with the Suzuki part number which is 13700-15070. Reproduction Decals can supply a similar one - there appear to be perhaps three types. The one I have from them is a newer style but I've stuck it on - perhaps at some point I will have the original style recreated.
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Swing, Grips, Etc.
There are a lot of little 'one year only' things you start to notice as you work on this model. The swing arm for example doesn' have a grease nipple on it, niether does the clutch cover. The parts list shows one on the kick start lever boss, but it wasn't installed on this one. Likewise, the handle bars differ from the later ones in not having a cross brace, and as the wiring is run inside of the bar, there is a reinforcement 'tube' welded in the centre. This original style of bar hasn't been available since shortly after the bikes came onto the market so as the pullback and reach was about the same as for a later bar, I drilled the holes for the wiring and made a centre collar which I welded in place and then had the entire handle bar re-chromed.
The touring (puffy) grips used on these were Suzuki part numbers 57111-15010 (throttle) and 57211-15010 and are interesting as they are a built up unit per the photo below. These changed over to 'thin' grips which were part number 57110-15110 (throttle) and 57211-15110 sometime during the MK2 series production.
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