Saturday, 6 September 2014

History of a well loved XT600 - Gaz's ongoing project



Here's a load of info Gaz just wrote for me about his 1983 XT 600. It's a bit of a beauty which has just undergone a fair few changes to make it lighter, more nimble & to adjust the weight distribution a fair bit... plus to while away a few hours/days/weeks etc...



Hi Steve. Here's a load of guff regarding the XT. Use or abuse all or none at your will. I'll give you loads more stuff than you need but just for your own info/interest here's the lot.

First off, my bike started as a Yamaha XT600 z Tenere (34L) 1983, kick start only model. I bought the bike a couple of years ago as a back lane runabout. It was a bit tired and shabby but in working order and completely standard. The clock reads in Km so I assume it is an import model. I fell for its thumper charm and decided to give it a tidy up/restore things just to freshen things up.


I stripped the bike down and had the frame powder coated. Whilst the frame was away I stripped the engine as it had a persistent knock. The knock was down to a worn main bearing the replacement of which was beyond my skills, needing to be pressed on and balanced, so I handed the motor over to Dave at Sapphire Motorcycles in Kendal, Cumbria. Dave has a depth of knowledge/history with Yamaha singles and was a great resource. Dave replaced the main output shaft at the same time as this was showing signs of imminent demise (not uncommon on old thumpers). The bike went back together as standard with new piston rings, gaskets and small end bearings. The bore was in good order so I simply de-glazed the bore with a honing tool. Fluids, bushes, o rings,and bolts were refreshed along the way as needed.






The bike came back together in a couple of weeks of evenings in the shed and was back out on the back lanes in Cumbria. I was pretty happy with the results. A nice tidy, healthy example of this old 80's Yam single. I had never intended to use the bike off road but living in Cumbria it was only a matter of time before I ventured off road to see how things went. I have no Enduro or MotoX experience but grew up riding Trials down in the Midlands (Bultaco, Yamaha TY & many Gas Gas TXT's). I spent a few great days checking out the local green lanes and had a lot of fun. The bike performed pretty well but lets be honest it was a handful. I tried a few simple trials type sections and quickly decided that that was not a good move.

It was only when my buddy Steve returned from working in Antarctica with plans to do the TAT trail that we headed out onto the Cumbrian green lanes with a view to honing our skills that I started to get frustrated with the XT's off -road limitations. Simply fitting knobbly tires only gets you so far. Whilst most of the stuff we have been riding has been pretty easy going, the Cumbrian Fells can offer up some quite technical sections where the bedrock breaks through the trail surface. With a trials background that's the stuff I like. Whilst the XT600 is never going to be a trials bike I was sure I could shed lots of unwanted weight and vulnerable bike parts. The first thing to touch down in a spill is the huge 5 gallon tank (made of steel) and how often do you really need a three hundred mile + fuel load. It was pretty clear that that tank was not going to last long before it was beaten to pieces. The seat height was always an issue for me, even on the road. I'm kinda average height at 5'10" but always had to find a curb or something similar to boost my height in order to kick the beast over. You can imagine the fun that can ensue when you stall on an off camber trail section.

You know the first bit, too heavy, too big, too tall. I first got inspired after viewing HL500's on-line. These were based on XT500's, folks stuffed the thumper motor into Husky two stroke frames to try to keep the four stroke crosser alive against the new breed of two stroke racers. Yamaha took notice and made around four hundred factory jobs. Many enthusiasts made their own and some still do today. These bikes are things of beauty to my eye and there are some fabulous creations out there. Check out the Aberg replicas on the internet. Looking at these bikes suggested to me that an old school four stroke single might be hidden inside my XT.

My plan was to reduce the weight as much as possible, reduce the seat height and remain road legal.

Stuff I took off was the tank, the seat, the rear fender/light/numberplate etc, indicators, clocks, headlamp, chain guard, speedo cable, tacho cable, hand guards, mirror. stacks of metal brackets and bolts. There's a photo of all the stuff laid out on the lawn. Be interesting to weigh it eh.

Stuff that went on:
The replacement fuel tank is an aluminium job from a 1976 YZ 400 (I wanted a YZ125 as that's what they put on authentic HL500's, some used YZ175's). I would have fitted any of these but a YZ400 came up on ebay and has a bigger fuel load (2 gallon) so I was glad to grab it. Of course it didn't fit and the mounting method was different. I home fabricated some new brackets and modified the tunnel and rear bracket. It came with a nicely crafted aluminium fuel cap but no fuel tap. I tracked down a new fuel tap to fit which was sourced from Yuniparts in Derby. It's an unusual thread and you have to get the correct one.

The seat is a YZ125 seat cover over a modified/butchered YZ125 seat foam all fitted to a custom seat base I fabricated from fibreglass. I cut down the foam to fit the lines of my frame and lower the seat height. Cover was supplied by Moto Sport Services in St Helens. The Foam was supplied by J K Racing UK in Westcliff-on-Sea.

The rear fender is a UFO universal vintage MotoX item from M D Racing products in Somerset.

The headlight unit is a second hand item from a GasGas TXT pro trials bike thanks again to the wonders of ebay.

Tail light is an aftermarket jobby and of fairly poor quality but it does incorporate a clear lens for the number plate. I found plenty of cool well made 'tail-light-only' offerings but as I'm trying to stay MOT friendly I went for the cheap and cheerful one, It failed 10mins into the first ride. I've re-soldered the rubbish connections to get it working again but I suspect I'll most likely have to revisit it with more mods in the near future.

Mini indicators are of unknown manufacturer but are easily found on ebay. I did notice that different suppliers sell them with different bulb specifications so anyone buying them should take care to get the correct spec for their application.

The Dash/clocks were replaced with the very clever Trail Tech Vapor computer and Indicator dash. This little unit comes with sensors that collect data from all your essential components and is customisable for your needs. I purchased a universal model suitable for air cooled motors with 'right-way-up' forks. They come in bike specific kits all tailored to your bike and there is a large range, but not one for my old XT.



Speedo information comes from a fork mounted sensor which picks up a pulse from a magnet. The kit comes with a special (magnetic) bolt which replaces on of the disc mount bolts on the XT. This in turn means I loose the old gear driven speedo cable. The cam driven mechanical tacho cable is also replace by a wire which picks up data from the spark plug lead. There's air temp and engine temp data too. The unit also has a clock display. The little unit can off course process all this data to give you all sorts of info in your display. You can program a shift light indicator and a rev ceiling warning light. The displayed information is shown over three screens and the unit is backlit. I've had no battery drain issues as the unit will self cancel when no info is received from any of the sensors. Don't be put off by the reading/programming stuff it really is straight forward. I've used cycle computers that were far more complicated. I opted to also purchase the Indicator dash. This is simply a plastic surround that has four bulb holders in it. The dash is a bit pricey for what it is but comes with a nice set of little lenses with the usual dash board graphics printed on (high beam, indicators etc) which you customise to your own needs. I opted for the dash because the XT is pretty tricky to get into neutral when up to temperature on the trail, and a neutral light is essential. I also have a indicator light and a high beam light. The connectors and wiring is of good quality and the kit comes with both traditional bulbs and LED's (the LED's are brighter but are +/- specific, this simply means that the current has to run in the right direction for them to illuminate). The kit comes with a couple of mounting bracket options. There's an aluminium bracket and a plastic bar mount. I have fitted mine with the bar mount item but consider it to be a temporary measure. I'll fabricate something after the first shakedown rides.

The old exhaust can and link pipe were shot. I had welded them up so many times that there was little of the original left. So here was another chance to shed weight. I had on my shelf a DanMoto end can and link pipe from a CBR600 track bike project. The Can sat quite nicely on the bike but the link pipe was unsuitable. I could have butchered something together out of mild steel but decided to get a proper job done. I spoke to lots of specialists who could do the job but most seamed uninterested in my project and required transporting the bike and leaving it with them. All reasonable requests but hassle none the less. I'd heard of the skills of a local chap who has a workshop locally and a good reputation for 'one-off' and 'fabrication' with cars, although not a 'bike' guy he's clearly enthusiastic and loves what he does. So I handed the bike and exhaust parts to Jonathan of JDM Dyno in Kirkbride. He made a lovely job of the link pipe by re-fabricating and modding my existing link pipe & adding extra bends all in good quality stainless. It's worth visiting him just to see what he's working on. On the day he did my exhaust there was a mean looking El Camino, A Mk1 Escort (which I've seen on the drag strip) and a super clean Capri sat on the Dyno ready for mapping and a whole bunch of other cars/projects around. If your local he's definitely worth getting to know.
I'm in the process of fabricating a couple of side panels from fibreglass and a paint job is planned to bring it all together (although I'm getting to like the mishmash of different colours and parts). Paint won't make it faster or lighter will it?
The first ride out with Steve and my brother-in-law Roger was a hoot (140 miles mixed green-lane and road. Thanks for the day boys). The weight loss was considerable and enough to make the bike feel completely different. The weight loss means I can change direction easier and correct mistakes as I go. I can choose lines better and react when things go wrong. There are also unforeseen benefits, access to the motor is easier. I can change the spark plug without taking the tank off for instance (which in turn needed the removal of the seat). Moving forward on the bike on climbs is now possible whereas previously the tank width was in the way. Not everything has worked out though, the tail light is rubbish quality and failed straight out of the driveway (now fixed) and the exhaust is way too noisy (Jonathan is fabricating some internals for the can as we speak). I've been relegated to the back of the line for the time being 'cos no one wants to follow my noise (great from where I'm sitting though).
I had reservations about 're-engineering' the XT as now they are becoming a bit rare but now I'm here I'm glad I did. I'm now familiar, even intimate, with every nut bolt and washer of this bike, I know it's strengths and it's weaknesses and have thoroughly enjoyed the build (so far).

Gaz


So that's the lot from the horses mouth so to speak... hope you like it!!

Have fun all

19 June 2014 - A new paint job on the XT... she's looking good!!!