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sherco29

TL250 Honda rehab

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Right, today I put this cardboard template into production for my new TL250 seat.

All measurements in the photo are in mm. Cut from a single sheet of aluminum it should require either one or two simple folds per side. The first one to wrap it around the frame and a second fold might be needed to bend the lower panel inward once it's cleared the frame. It should end up the same width as the original at seat pad height, and about 40mm narrower than Honda's push-on panels at the base of the side panels point. Base material is 3mm thick. 2mm felt like it would bend too easily. Looking down vertically, an RS250 seat is 180mm to 200mm between the outside of the frame tubes at its widest point at the rear. The Old TL has wider hips by about 25mm at the same point but she is a good 40mm wider up at the seat and tank junction.

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I was planning to go with two side panels and weld these to the tank to create a single tanks eat unit a la TLR200. But it quickly fell into the too-hard basket as I can't weld myself and I kept seeing that I would have to cut and reshape the tank as well. Unlike the flat bottom tank on an RS250, the TL250 has a distinct down turn at the very end of its tank which complicates getting a single flowing line. Anyway, if I'm unhappy with the final look and feel of the aluminum seat, I can always use it as the mould for a fibregalss or cabon fibre seat base The process would be as simple as turning it upside down, cutting it down the middle and inserting a 6mm strip in the cut line to allow for 3mm thickness of fibreglass one each side. Then lay the fibre glass up inside the upturned base. I'll mount the seat only from the top and not through the original side panel mounts. There are two mudguard bracket mounts in the right place already and there's a cross bar (that the original seat tongue slotted under) about 75mm back from the base of the petrol tank that I can drill a hole in and add a third riv-nut. No welding required.

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And I've had an idea about the seat pad> Buy a surf board Tail Pad. These are roughly triangular, made of grippy foam and come with a quality waterproof 3M self adhesive backing. About US$40 on ebay. They come with one end of the pad raised for your heel (if you are a surfer) but if you turn it around to face the other way the raised lip could butt up nicely to the base of the TL tank. More pics in about a week when it all comes together.

Edited by Ross Brown

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I've broken my own rule and actually added weight to the TL; but only by a smidgen. I've splashed out on new adjustable-reach ASV levers with gorgeous alloy perches that have a forward bending motion to the levers protecting them from breakage. My first lever replacements were cheap black painted aluminum ones that not only looked just like the levers we used in the 1980s, they snapped just liked them too. The very first time the bars touched down from a fall off the stand onto the garage floor. You get what you pay for! All the ASV sellers on ebay claimed "universal clutch lever" with no brake lever assemblies for sale other than hydraulic ones. Well of course if you horizontally flip a clutch lever assembly - you get a cable operated front brake lever assembly. DirtBikeBitz UK sold me the ASV levers; and they had a free-international freight offer. A bargain in the long term!

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Just trying to balance on the bike in the garage - it is still a non-runner as the wiring from the stator needs replacing- you can feel the benefits of being able to move your body weight around more easily on new pegs that are twice the width of the ones that the bike was originally sold with. Are bicycles bikes ahead of us in this department? The sort of pedals that Danny MacAskill uses on his trials pushbike are CNC machined from quality grade aluminium, weigh less than 240g each and are closer to a square in layout than our foot pegs. There are mountain bike pegs out there that are 115mm long and the same wide. Compare this with some 'extra width' Raptors at 52mm and the stock TL pegs at about 35mm. Wider pegs, or pedals, offer a whole lot more surface area to 'push' weight through. I wonder if super-wide pegs would help us to bunny-hop as they would be easier to load/compress prior to unweighting?

Still waiting on the swingarm, seat and assorted brackets now in their second week at the powder coaters.

Edited by Ross Brown

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they snapped just liked them too. The very first time the bars touched down from a fall off the stand onto the garage floor. IMG_0580.jpg

Mick Andrew's video tip that I do remember is don't do the levers up too tight - just tight enough to stay and lose enough to move/slide when you drop it.... makes sense to me

:blush:

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The new seat base came back today.

And it came back from the powder coaters the wrong colour.

The young employee who spec'd the colour for painting no longer works there.

You knew it was never going to be an easy rehab project!

Here's the stick-on seat pad waiting for the sat base to return. Made by X-Trak in the U.S. - "The world's best grip for you board". Cost 29 Pound which is a helluva lot for a piece of foam. But it finishes the seat better than any DIY Blue Peter mash up I could make. Gorilla Grip is a similar brand and maker of stick on surf board Tail Pads. They had a red one, but it was of a 3-piece construction. This is a single piece which means that when I trim it - about 30mm needs to come off each side - it should have less risk of peeling off the seat base if it gets hooked by say a boot buckle.

I figure that if the 3M adhesive backing is waterproof and good enough for a surf board it should be good enough for an occasional soaking at a trial. You can see the white adhesive backing under the pad. Opposite end from the "X" is a kicked up lip (on the right in the photo below of the pad sitting on the car bonnet so you know what you are looking at) that will be the front of my seat and sit against the tank. On a surf board it is to the rear. It is for your heel to push off from when surfing. Whereas, for me it will provide separation between testicles and tank.

IMG_0703.jpg

Edited by Ross Brown

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Swingarm came back from the powder coaters today. Re-profiled lower shock mounting holes are now 35mm higher. The new shock mounting position brings two benefits: by raising the rear of the frame it steepens the steering head angle, and it increases the ground clearance. Critically the extra clearance is at the rear of the bash plate just ahead of the wheel. Ground clearance is now 310mm (12.2 inches) ie. the same same as a Beta Evo 250 2T. Someday soon I am expecting to really need those extra millimeters of ground clearance to get the TL over a dead 20th Century log.

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The down side of having raised the shock mounts is that the bike now has a slightly higher CoG. Offsetting the Centre of Gravity shift from the shock mounts is the weight reduction and the improved control feel from wider pegs, fatter bars, and smoother levers. New chain guard is from Shedworks and half the price of what people are asking for the original plastic chain guard on ebay. Mudguard extension is a piece of white rubber strip as used by the food industry.

I remember that my first TL back in the '70s was also my first bike with the then-very-trick factory installed chain tensioner. This was a seriously good bragging point.

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Vertical supports have been welded onto the inside of the swingarm to stop twisting. But the LH one had to be ground down to half its thickness to allow clearance once the spaced-out sprocket was fitted. Sprocket bolts missed the swingarm reinforcement by about 2mm. It was just too tight to live with. Space is now about 5mm (You can see bracket standing proud of swingarm just to left of the sprocket bolt.

Speaking of cogs, with the smaller countershaft sprocket - down from 14 to 12 teeth - the chain now runs on the edge of being impossibly close to the top of the swingarm. In the top photo, the clearance between the moving chain and the upper surface of the arm is 10mm at rest. There could well be moments when a fast and lose chain wants to saw through the swingarm. I'm betting on 36 years of improvements in thermoplastic polymer production in the form of a new chain guide pad glued to the swingarm top to hold back this catastrophe-in-waiting.

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Talon sprocket with BJ Racing sprocket adapter uses bolts not studs to mount to hub.

Back to 2011. New Old Stock (NOS) plastic swingam bushes went in easily. Will upgrade to bronze from a CR125 of similar vintage next time around. They don't have to stand up to the same impact forces as a MXer, so there may be a few years of wear in the plastic bushes yet.

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The new seat base came back today. It is lower and lighter than the original.

Tank has yet to have dents taken out or be repainted. I wanted a neutral colour scheme and will eventually extend the same gun-metal grey to the tank. Two screws at the back of the seat fit the existing mudguard mounts and use 6mm rivnuts mounted under the frame cross member; previously there was just thread in the cross member which was fine for a mud guard mount but under strength to anchor a seat.

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Gone are the industrial weight steel mudguards, seat base, sprockets, steel bars and pegs. In come replacements in plastic or alloy. I should add at this point that any weight saving on the bike has been negated by 36 years of weight gain on the part of the rider. I'm almost 10Kg (wet weight) heavier than when I owned my first TL. If I start to feel weight (of the bike) is a problem, I can always lower the foot pegs mounts.

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I haven't decided yet on which shocks should replace the stock ones. Rockshocks look good, but the price to NZ is an issue. It's getting a bit hard to ask the Mother-in-Law to carry a pair of shocks on the plane journey out from Manchester as this Xmas she's already committed to bringing a spare right hand magnesium engine case in her luggage.

IMG_0734.jpg

Edited by Ross Brown

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TL still a non-runner. This is the left engine case looking from inside out. Oil positively flowed out of the clutch pushrod cavity. As fast as I poured oil in, it hit the garage floor. The clutch cavity is supposed to be totally dry. At first I thought the grommet may have shrunk - it happens - and this was where the oil was escaping from. Oil leak must have started some years back as the oil has worked its way into the electrical insulation making it rot. Wiring passes through grommets from stator to clutch pushrod cavity, then out and to a third grommet where it exits the cases.

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Once I had the left hand engine case off (had to grind 2mm of a washer on the lower frame mount to get the engine case pass the frame mount; strange this. I don't remember any such washer on my first TL) I could see lots of gasket gunk the previous owner had used to try and stem the oil flow and to stick back a part of the aluminum cases that had broken off just ahead of the sprocket. Complete gasket set arrived from Canada this week. Will have to order a complete oil seal kit next! Lots of fun.

Edited by Ross Brown

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Hmmm bummer! I had the exact opposite with my clutch arm. It was dry and rusty in the cavity, shaft had really bad pitting, pivot bearings totally siezed solid.

Was able to source a work-able bearing from mcmastercarr.com.

New used shaft in great shape from ebay.

Keep at it and keep us posted Im still watching! :thumbup:

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New Seat Attempt - Take II. The aluminium seat base was just too abrupt for my liking at the point of the seat and tank junction.

So this morning a lovely new shiny glassfibre seat arrived from Shedworks. Don't worry about the black look. Black was my colour of choice. I thought about white (late '70s HRC racing) or red ('80s RS and RTLs) but I'm going for a different look. The hardest bit was taking a hacksaw to cut it straight down the middle.

RS250-trails-seat.gif

RS250 seat overall length is good. but width is out as the TL has much wider hips than an RS. Don't have exact size yet of the new fibreglass 'plug' I have to make to insert between the two halves. It is going to be about 1cm at the front expanding to approx 3cm at the rear. I can't get the exact measurement because if you look closely there is a raised horizontal cross-strut back from the tank that needs to be cut off the frame before the seat base will sit flat. This strut is the original forward seat mount where the Honda seat tongue slips under it. I've got to cut this off as the RS seat sits flat on the frame rails. This will lower the seat height but will make for a less than smooth tank-to-seat junction (will deal with that when I get around to the tank cosmetics). Having the seat base sit flat on the frame rails will also constrict the airbox breathing, so I now need to rethink the airflow into the airbox. It could breath be straight up through the seat top as that works for 4RTs and 315Rs mudguards/seats. Or I could cut a hole into the top of the box and let it suck in air through the side. I'll post a pic when the new wide-seat is done.

Edited by ross brown

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Got a call yesterday to say that my newly widened seat base was ready to be picked up. The firm has been busy making carbon-fibre canoes /kayaks for Olympic rowers so a 36 year old trails bike seat is rather low on their priorities until today.

IMG_2363.jpg

And it works! You start by taking one shiny new RS250 seat base from Shedworks. Pick up a hacksaw, breath deeply and begin to cut lengthwise through your new seat base. Then insert a 25mm (1 inch) plug right down the middle. Constant width from head to tail. Good old Honda must have just wound out the jig in the factory by an inch when they came to building the TL.

The excellent news is that the seat is significantly narrower at the tank as the orginal side covers flared outward to cover the frame tubes and the airbox. Looks like the previous owner :moon:- the one who twisted the swingarm - must have 'dressed to the left' judging by the top of the tank.

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While the RS250 has the carb protruding on the right hand side of the bike, the TL250 has a very cube-like airbox sticking out on the left. So the flare in the new seat base is on the wrong side! I've had to trim some material away from the leading edge of the seat on the left hand side to clear the top of the airbox.

Next step, with the seat width and length just perfect I now have to consider what to do with the sides to finish off the bike cosmetically. I like the shallow sides of the RS seat compared to the deep original side covers. In the pic below you can see the three brackets and their holes where the original side covers push-fitted into rubber grommets (when you see that the third one is at the bottom of the airbox you realise just how far down the covers went). I think I will now try and build up the sides with fibreglass myself so that the seat butts up to the base of the tank to try and capture some of that '80s works look.

IMG_2372.jpg

Edited by ross brown

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How's the seat base progressing?

This thread needs photos. Alas, we're selling the house and the estate agents have said NO 1976 Honda trials projects should be on view! So the bike is off site for a couple of weeks. Anyway, thanks for asking - progress is good and I feel that adapting the RS seat is THE RIGHT approach.

1.

I wasn't sure about whether to mount the seat base absolutely flat and lying along the top of the frame tubes (seems logical) or angled more upward the closer it gets to the tank (surprising how many bikes have non-flat seats once you start looking. An '86 RTL 250, for instance, starts off at the rear sloping down, then turns and climbs upward towards the tank).

I've opted for the seat-lying-flat-on-the-frame RS250 look but this means that the seat base finishes about 1inch below where the TL did. (TL as it comes from the factory is flat from the rear for 70% of its length then turns its nose up).

2.

I've discovered that a seat-lying-flat-on-the-frame also seals the airbox so the engine can't breath! Ill take a grinder to the top of the airbox where there is a 'chimney' that sticks up about a quarter of an inch. If I make four cuts and just fold thre of the sides down (left, right and the rear) then there should be sufficent airflow into the box and the front side will provide a barrier to water splashes.

3.

I've taken a hack saw to the rear frame loop and have used the opp to drop the bike into a machine shop that can heat the tube ends that remain, squash them flat so they become new mudguard mounting points and weld themup along their edges to prevent water ingress. The new mounts will let me create a new loop on 25mm x3mm aluminum and push the height of the mudguard up almost 50mm. This makes the overall look more modern AND closes the 10mm gap that would otherwise exist between the top of the mudguard and the underside of the RS250 seat base. Killed two birds with this stone.

4.

Oh, and a new 280i Ossa black front mudguard has arrived. I've mated this to a 4RT mudguard brace and am now working on fabricating aluminum brackets to fit the brace to the TL fork legs. Rear mount for the front mudguard needs to be 90mm high and the front 100mm high. I found this out after buying a TL125 ammy Miller mount and shipping it aroundt he world only to find it needed a minor adjustment with a major hammer.

Photos in a week or so.

Cheers

Ross

Edited by ross brown

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Last weekend, at the 2-day Ihatove Trial (Nelson, New Zealand. See pic below) I was fortunate enough to be given the chance to grab a short ride on someone else's TL250; many thanks Wayne.

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Jumping straight from a 4RT to the TL, I then got to go back and ride 6 sections after the trial had finished. So how does 37 year old technology feel?

Engine off and just jumping on the pegs it feels surprisingly small. The top triple clamp is lower so standing on the pegs it feels as if you are standing over the TL rather than 'in' it as with the 4RT. The net effect is this makes the Tl feel shorter. Funnily enough the front end didn't feel heavy at all. The rear bake is tucked in nicely and while the bars are standard width, which is to say an inch wider each side than my 4Rt, all the controls felt normally weighted and fall nicely to hand. Feet were another matter. Period foot pegs are simply too narrow. First kick starting and again a surprisingly light force was required to move the kick starter through its arc and to the point where the engine caught and came to life.

Once under way all feeling of lightness disappears.

My 4Rt has a low geared 44 tooth rear sprocket on it so it felt like TL-1st was equivalent to 4RT-3rd. Which is too say a magic gear for hill climbs, but too highly geared. Section One had a steep down hill entry into a rocky a stream bed followed by a tight "S" once back up on the side of the stream bank.Let me try that stream section again. On second approach and now that the drum brakes are wet, I did not enter the stream in a more controlled manner. Instead, I came off the bank down into the stream with all the finesse of a rented Transit Van. No amount of squeezing the front brake lever back into the bars produced more stopping power. There was just none to give.

I could give up twin-shock riding for the brakes alone.

(My own TL has grooved EBC shoes so we shall see how they work in due course).

Open the throttle on a more flowing section with a long uphill and you feel as if the torque of the TL could shift Daylight saving back an hour! This is why there should be one in everybody's stable! Buying Old Tech was the right choice after all.

Let's try that downhill drop to the stream again. Revs drop way below idle and to half of what they are on a 4RT governed by the fuel-injection system mandated 1,800rpm idle. The clutch was lovely and I realised the bike does not want to stall when asked to grunt away from low revs. This is how I remember Thumpers to be. Knowing that the brakes are poor I adapt my riding style accordingly. And still I end up in the stream bed faster than I had planned and for an ungracious single dab. Balance? Well the weight is tiring. Narrower bars and wider pegs would help. Betor shocks worked well enough. No complaints there.

The weight is as appealing as a choosing to travel by RoadMaster Bus. However, the motor has the appeal of an '80s Muscle Car. It's more raw than I remember. I handed it back to its rightful owner and I now have a renewed respect for pre-65 and twin shock riders.

My TL is still in the metal workshop. The Rear frame tubes have been cut off and now need to be heated, crimped then welded closed to stop water ingestion. Then an Alu bracket made to support the mudguard. Here's the mudguard shown in the original position pre-cutting the tubes. You can see where the frame loop went over the top of thew guard. Note the 2cm, gap between the top of mudguard to underside of RS seat base.

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Below is the newly raised mudguard. Gap to the seat base has disappeared and mudguard has more of a 'modern' look to it.

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Ever wondered why TL250s feel heavy?

Look at the thickness of the steel walls of the frame loop. All this just to support the rear mudguard.

IMG_3614.jpg

Edited by ross brown

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