T500 sort of cafe, sort of not, mix and match build

Retro, Wild, Cafe, etc. The stuff only your imagination can come up with.

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Goldnrust
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T500 sort of cafe, sort of not, mix and match build

Post by Goldnrust »

Hi guys. I've been lurking here for a while, have been meaning to get round to posting about my t500 build for a while. A dull wet afternoon in November seems like the right time to sit down and type it all out. :)

First off, I’m Steve, I live just south of Birmingham, England. I’ve been riding bikes for about 10 years, since my late teens, and have most had small capacity sports bikes and a couple of supermotos. Along side this I’ve had a number of classic cars, but with life moving forwards, new responsibilities and reasons to turn up on time for work, I decided to buy a more modern car and dip my toe into the world of classic bikes.

Straight away I knew I wanted a 2 stroke, I had an RGV250k a few years back and it was brilliant. With this in mind, my search started by looking for a gt250, but the more I read around the more I was tempted by the T500, as a large capacity 2 stroke would be a different riding experience to anything else I’ve ever tried.

Late January this year, I took the plunge and purchased this fairly rough 1972 T500J.

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It’s an American import, still needs to be UK registered, but I have the NOVA and the US title, so hopefully when the time comes that won’t be too bad. Engine turned over with some sense of compression, there’s a few bits missing but nothing vital and the wheels look to be in reasonable condition. It seemed as good a starting point as anything else.

The plan is to build a bike that will look cool, sounds cool and be suitable for me and my wife to go for rides on sunny Sunday afternoons. I quite like the look of the minimal stripped down look of some of the modern cafe racer inspired builds, so I will be taking some influences from that. Equally I need the bike to be fairly comfy (as a contrast to having my knees folded into my chest and head down on my CBR400RR) and it needs to work for 2 of us, so some influences from the brat / flat tracker scene may come in here with the handle bars and seat design. I have no aspirations to fit into a particular scene, so ultimately I just want to build something that looks how I want it to look.

Anyway, bringing my self back to earth with a bump, it was time to strip down my new purchase and see what I’d bought. It doesn’t take long to strip a bike down, so by the end of the first day I’d got a few boxes full of parts

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And a rolling chassis with an engine sat next to it.

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So far no great surprises. :) And unlike this stage when dealing with classic cars, I’m not just looking at a pile of rust that used to be a car!

So lets pop the heads off the engine and see how thats looking…

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Thats not a good start. One of those head bolts, is not like the others!

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Oooh yes, and a nice home made 3mm thick cork head gasket, with plenty of silicone sealant in there too, I’m sure that would have run nicely!

Having seen signs of such good workmanship, I knew any hope of just checking the engine over and popping it back in had gone. The only option now was to properly strip the engine down and make sure it was right.
Goldnrust
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Suzuki 2-Strokes: T500 RGV250

Re: T500 sort of cafe, sort of not, mix and match build

Post by Goldnrust »

So having ready found a couple of hidden horrors in the engine, there was nothing for it but to dig deeper and see what else showed up. Starting with the top end...

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Thats a nice gouge in the side of that piston. And a nice set of chewed up marks in the bore also. Wonderful.

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The gearbox oil was 1 part oil, 1 part water and 1 part mud, which again was lovely.

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The first bit of good news was that when I split the cases, despite it being an early bike with the 1200cc gearbox oil, all 5 gears looked in good condition, with no obvious signs of wear or damage.

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The final bit of bad news was that some of the location pins for the bearings look chewed, possible at some stage someone has tried to reassemble the case halves without properly locating the bearings. :roll:

Knowing that it could be a long time till I would be working on the engine again, I did my best to be organised and bagged up and labelled all the engine bits before taking them away out of sight and out of mind!

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So now I know what I'm dealing with. The frame and running gear seems in reasonable condition really, and the engine is at least complete but its in poor shape and will need a complete rebuild. Knowing how much work there will be in the engine, I decided that the best course of action would be to build the rest of the bike, then do the engine almost as a separate project afterwards.

This meant there was nothing for it, but to get on with the dirty job of cleaning 40+ years of American dirt and oil off the frame.

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Then I could strip it and the swing arm back to bare metal, another dirty job, but one that was quite satisfying.

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Having experienced plenty of restorations where at this stage I have a pile of rust o the floor where I should have had the cars floors/wheel arches, and also having been recently forced to condemn my Gas Gas endure bike due to rust, I was pleasantly surprised to find just how solid and rust free this frame was.
rngdng
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Re: T500 sort of cafe, sort of not, mix and match build

Post by rngdng »

Well, you certainly got the frame clean! Welcome to the board, and keep us posted. I can't believe somebody tried to use cork as a head gasket. :shock: :shock: :shock:


Lane
If you stroke it more than twice; you're playing with it.

Too many bikes, too much time, ENOUGH SPACE, FINALLY! Never enough money.........
Zunspec4
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Re: T500 sort of cafe, sort of not, mix and match build

Post by Zunspec4 »

rngdng wrote:Well, you certainly got the frame clean! Welcome to the board, and keep us posted. I can't believe somebody tried to use cork as a head gasket. :shock: :shock: :shock:

Lane
And the tapped hole + bolt in the piston is an interesting way to increase the C/R :lol:

On a positive note, if you are faced with a full engine re-build at least you know it will be done properly.

Cheers Geoff
Goldnrust
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Re: T500 sort of cafe, sort of not, mix and match build

Post by Goldnrust »

haha, yeah you do have to wonder about people sometimes...

Cheers for the welcome :)

Back tracking slightly (now I've found some more pictures), before I started the cleaning and painting process of the frame, I'd done some rough mocking up of the parts to get a feel for how the bike might turn out. I looked at a couple of different bar options, before deciding on using the pair of mid rise Renthals that I had lying about from my old Gas Gas. I also decided that I'd like to ditch the rev counter and idiot lights and just have a single centrally mounted speedo, so I knocked up a quick bracket for that. I also had a think about exhaust routing. Part of the plan for this project was always to have a go at building my own expansion chambers, so I trialled a couple of card mock up exhaust routings.

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Ultimately, as I have decided that I don't really want to make any mods to the frame that stop me putting it back to standard, the best routing would turn out to be the stock location, albeit with more of a kick up at the end of the baffle cone and stinger just because I like how it looks. Running the pipes under the bike didn't work, the bracket for the centre stand just got in the way too much.

I also decided at this stage, looking at the rusty mess that was the original seat, that I would be building my own seat from scratch. After some cardboard mock-ups, I made a start on this simple seat base, again using the stock mounting points, but hugging the lines of the frame closer than the standard seat. You can also see I've cut down the stock rear mudguard.

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The final bit of mock up work I did, was to consider the oil tank. The oil tank that came with the bike was pretty battered, and I decided I wanted to have a tank that sat inside the frame, tucked up out of the way to accentuate that stripped down look of some of the cafe racers. So I cut the filler and tap from the original oil tank and used them to help me knock up a new tank. The shape was inspired by the bits of cut off mudguard.

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It tucks up here under the seat.

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Onwards with the build. We've made it to about mid April now. Having spent many hours carefully removing the old black paint, I decided to paint the frame black... :lol: It was also time to put my wallet to good use and start buying parts. First up, some new swing arm bushings, as the right hand side original was badly corroded and scored, and a replacement swing arm pivot bolt the my original was a little bent.

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Before I popped the rear shocks back on, I gave them a once over with some metal polish and they at least look half respectable. From what I've felt so far they feel pretty damn agricultural though... I'm not sure if they will make it to the road or will be replaced by something more advanced. I'm normally a 'big picture' kinda person, and often overlook the details but I'm making a concerted effort with this build to not do so. So starting as I mean to go on, when fitting the shocks I used all new washers and polished the original acorn nuts. Whether I'll keep this up, or get bored of it, only time will tell!

Across the summer I methodically worked my through the repetitive process of cleaning, painting and reassembling various parts of the bike.

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The forks were rebuilt with fresh seals, and filled with 30wt oil, which from what I've read on here should give them some form of damping! I even polished the springs. No prizes for guessing which fork leg I've done here and which I haven't....

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I had a nasty shock when it came to the front wheel.

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I discovered a number of ugly looking cracks in the hub, again something I was wise to thanks to reading about it online. Whether or not it could be repaired, it made me feel pretty uneasy. After looking around for an alternative front wheel option, I settled on a Honda CB77 wheel, it also has an 8" twin leading shoe drum, admittedly with marginally narrower shoes, has the same axel diameter and also came with an 18" rim, which appealed to me. What I wasn't considering was that the 18" rim was only 1.65" wide. So in the end I rebuilt the hub onto a new 18 x 1.85" rim. I painted the wheels, stripped the brake mechanisms, fitted new shoes and polished the back plates.

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Now we're starting to get somewhere. :) Starting to put the pieces of the puzzle together, I was pleased with how it was coming along.

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I also picked up some relatively discrete indicators, and a generic front headlamp. Both lighting elements in the original sealed beam headlamp were broken, and it would have been set-up for riding on the right, so easier just to get a modern lamp thats for UK roads with a replaceable bulb. I drilled the headlamp ears, just for the looks, and like most of the bike they got painted satin black. The handle bars also went black.

One thing I wasn't sure what to do about was the fuel tank paint. When I bought the bike it was sporting a decidedly DIY paint job on the tank, that was pretty weathered. I thought about lots of different tank colours I could go for, but none of them quite felt right. For now I decided that this weathered old paint job was part of the bikes history, part of it's story to tell, so I have simply clear coated over the current paint so once polished it will shine a bit more.

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As you can see from the picture, I was also making steady progress with the seat. Having experimented with various combinations of foam, I'd found something I was happy with. I was making my lift difficult as I was attempting to find a balance between the low profile, slim seat that I liked the look of, and the deeper, wider, more comfortable seat that I knew I'd appreciate after an hour in the saddle.

Once I'd got a shape I was happy with I spent a few nights, with the help of my wife, making up a cover for it. For my first attempt at this sort of thing I was very pleased, but I also know what I'd do different next time!

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That brings us nearly up to date. I'll grab some fresh pictures tomorrow of how the bike currently stands. :)
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Re: T500 sort of cafe, sort of not, mix and match build

Post by dgoodsy »

I like the work done on this bike, and really liking the DIY seat, looks great! If you don't mind would you share what type of foam you used and where you got it, and also what you would do different next time?
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johnu
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Re: T500 sort of cafe, sort of not, mix and match build

Post by johnu »

You are moving right along! I like what you are doing and that you aren't getting too upset that you have uncovered a can of worms inside the engine. I'll be following along.
I ran my pipes under the frame as you can see in the pic but I don't have a center stand. I think if I was running the pipes in standard position I would go with a set from Dave Swarbrick, they come as a kit so you can orient them however you want.
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titan performance
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Re: T500 sort of cafe, sort of not, mix and match build

Post by titan performance »

I'm enjoying this project......always good to see how other folk go about it. Some good work here, being done by a guy with obvious experience.
Keeping old 2 strokes alive !
Goldnrust
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Suzuki 2-Strokes: T500 RGV250

Re: T500 sort of cafe, sort of not, mix and match build

Post by Goldnrust »

Thanks dgoodsy :). It was a bit of a trial and error process to find the right foam. I ended up buying a number of different types to find the right combination. Most of the guides I read suggested using firmer foam at the bottom of the seat and softer foam on top.

On top of the metal seat pan I put 1/2" of closed cell foam, similar to that described as 'race seat foam' for track day bikes and alike, which is very firm. Followed by 1 1/2" of reconstituted foam, sometimes called chip foam. This was the kinda breakthrough in finding a mid firmness foam, apparently its often used in gym mats and alike. It comes in different weights/firmness, I went for 6lb, but would probably go for a firmer 8lb foam next time. I used contact adhesive to hold the layers together, then when it was dry shaped the seat with a sanding disk on an angle grinder. Finally I topped the seat with a 1/2" of the upholstery foam.

I got all 3 foams from eBay. The upholstery foam is easy to find, and the close cell foam also but the reconstituted stuff is a little more elusive, so here's a link.

http://www.ebay.co.uk/itm/RECONSTITUTED ... 2809adb53f" onclick="window.open(this.href);return false;

The other thing I'd do differently is to assemble the seat cover in a different order. I made the top of the seat by gluing some foam to the back of a piece of vinyl, and a piece of cotton to the other side, then sewing across it, to create the ribbed pattern. This made the vinyl bunch up a bit, when I sewed the sides of the seat to the top, the vinyl then stretched out back to nearly it's original length. I had no taken this into account with my templates, so had to do a little on the fly adjustment to get the back of the seat to line up, and the end result is that the rear two seams are not as neat or even as the front two.

Don't worry Johnu, I was plenty grumpy when I found the engine problems, many rude words were said! hahaha But that was the best part of a year ago, so water under the bridge. It's also fair to say that when I bought an unregistered import, I pretty much expected to find problems like this. You're bike look great! Yes I would very much have liked to have run my pipes the same as yours, that exactly the sort of look for the pipes I like. But without removing the centre stand bracket it's just not practical, which is a shame.

Cheers Titan :)
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Re: T500 sort of cafe, sort of not, mix and match build

Post by dgoodsy »

Thanks Goldnrust, I appreciate it. I contemplate DIYing seats on my bikes so I look for input where I can, this sort of advice goes a long way.

I look forward to more progress on this bike!
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Goldnrust
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Re: T500 sort of cafe, sort of not, mix and match build

Post by Goldnrust »

No worries :) I'd not be able to even begin to attempt this kinda stuff without internet forums and youtube guides, so only fair to share what I can.

This is the last of my past progress reports, that brings the project fully up to date. One of the missing parts when I bought the bike was the front mudguard. As I'm now using the Honda front wheel, I would need to sort a torque arm for the brake. So I decided to try and integrate this with a fork brace and mount a mudguard to this. The finished brace is more function over form than I had intended, but at least it's nice and stiff!

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The mudguard I've temporarily mounted to it was one I bought before I knew I was going to be using an 18" front wheel. I tried to reshape it a little, but failed, so that will be going in the bin and I will buy an 18" mudguard.

With that done, there was only really one thing left before it's engine time, and that's the exhausts! I've read a couple of book about two stroke tuning, including Bell's one and have based my exhaust dimensions most on that.

Now, I've never ridden a T500, but I've read that the standard power curve is quite flat, with good low end power and you don't need to ring it's neck to make progress. I'm quite used to riding small capacity bikes which I have to work to get the best from, so for that reason I plan to do a little porting and build my exhaust with the knowledge that I will loose some low end power, but gain some at the top end and hopefully end up with a slightly more 'scary' two stroke, which feels a bit more wild as it comes on the pipe.

Going by what I've read, it seems the exhaust port timing on the t500 is extremely conservative. According to the calculations in the books its timing of suited to a very low revving engine. The intake and transfer port timings, again only going by the books I've read, are about right for a engine looking to make max power at 6000 RPM, which seems sensible. Having read online about the modifications to build a TR500 spec engine, it also seems that some of the biggest porting changes are in the exhaust port. With that in mind I intent to lift the exhaust port a little, to bring it's timing up to suit an engine making max power around 6-7,000 RPM. I have then based my exhaust measurements from this. The intention is that the exhausts are tuned for maximum performance around 7-7,500RPM.

I've spent quite a few hours working out the calculations for my pipes and engine mods.

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I wanted to do things the hands on way, I spend enough time with computer at work, so I drew out my own cones, and worked out how I would section them. This did limit me to a pretty basic exhaust design, but I'm pleased to have worked it all out myself, rather than had some program do it for me. I then transferred the card templates to steel.

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With that there was nothing for it, but to try and roll them up and take them together. First, and easiest, section tacked on, and the first of my calculated sections lined up nicely.

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So I got my head down, and got the rest of the right side pipe tacked together.

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I'm really pleased with how it's come out, all the hard work carefully drawing and calculating curves was worth it when all the sections dropped together with little to no fettling. :)

And that is where I've got to today.

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Over the weekend I'm hoping to the left hand pipe put together, it should look rather similar to the right if all goes well. After then I need to sort some silencers, and then the project will probably slow down a little while I earn some money to pay for the engine parts! haha.
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Re: T500 sort of cafe, sort of not, mix and match build

Post by dgoodsy »

this is great, making my own exhaust is another thing I dream of doing. I look forward to hearing your impressions on their performance.
What steel type and thickness did you use and how did you roll it?
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johnu
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Re: T500 sort of cafe, sort of not, mix and match build

Post by johnu »

Exhaust looks great :clap: I'd be interested to find out what diameter the center section is on your pipe?
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Re: T500 sort of cafe, sort of not, mix and match build

Post by rngdng »

Most impressive. I do not have the welding skills to do my own pipes. I would love to learn.....maybe someday.



Lane
If you stroke it more than twice; you're playing with it.

Too many bikes, too much time, ENOUGH SPACE, FINALLY! Never enough money.........
Goldnrust
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Re: T500 sort of cafe, sort of not, mix and match build

Post by Goldnrust »

I'll do my best to give an impression of their performance, dgoodsy, but as I've no other t500 experience to compare it to, I might not be able to say much that's meaningful! The steel thickness was a bit of a gamble, finding good info about homemade pipes online is hard work, lots of people are pretty secretive about their designs. I went with 20 gauge in the end, so just under 1mm thick.

I rolled the pipes using a number of different improvised anvils, a soft faced hammer and some good old fashioned muscle (not that I've got much of that... :lol: ). So for example, with the diffuser cone I clamped an old fork stanchion firmly in the vice, then bit by bit I started to bend the steel shape round the metal bar, just by hand. I drew some radial lines on the flat steel that allowed me to make sure I was keeping the bends in the right plane. It was pretty time consuming trying to carefully bend it round without bending any one section too far and create a corner. On the edges of the pice I used the soft face hammer to tap the metal round where I couldn't grip it by hand. Once I got the two edges to meet, I tacked them in place. More carefully bending and tapping got the middle section of the seam lined up and tidy, so I could pop some more tacks on. After that I drew some concentric circles on a piece of card, and using a combination of hand bending and hammer taps, both against the work bench and over the fork stanchion, I rounded out the cones.

With the straight sections it was easier, I basically found something round of roughly the right diameter and then hand bent / hammered the flat steel round it, before doing the final rounding out by eye with the help of my circles on card again.

As if by magic, I was working on the basic rolling of the right hand pipe today. This is the baffle cone coming together, round a random piece of old aluminium tube I had lying about. It needs a bit more work to get the seam to line up neatly.

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I shaped the belly sections by bending them round this old paint spray gun can.

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Then carefully tweaked them round, using the circles to guide me, I'll let you decide which was the before and after!

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Johnu, the centre section is 105mm. The books I've read suggest you really want the belly to be approx 2.5x the diameter of the exhaust port. But they also acknowledge that most bikes cannot accommodated pipes much over 100mm diameter, and that if space is a problem than 2.2x the port diameter will be fine. I've got the t500 port/header size down at 46mm, so 105mm is a fraction under 2.3x the size.

Ultimately my pipes are just based upon reading of books, mostly Bell's book, and my own interpretation and guess work of the suggestions and calculations found therein, they aren't based on any real work knowledge or experience, so who knows how well it will work out! haha. With that in mind I've no problem saying this is my plan, based on a 3mm lift to the exhaust port:

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I may yet end up modifying the pipes, as they are currently the first thing that will ground out, though only a little before the stroke foot pegs. The question is whether I'll ever dare to ride this bike hard enough for it to be an issue.

Cheers Lane, who knows whether my welding skills will truly be up to the job! These will only be MIGed together, and the welded dressed afterwards.
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