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LG's 1985 Yamaha TT250 Thumper


Lord Gruntfuttock

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39 minutes ago, Lord Gruntfuttock said:

Yeah saw a youtube vid on that. Gentle pressure with a dry buffer on a drill, brings up like factory finish.
Will give it a crack...

i found a rope mop worked the best, soft one didn't do anything

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Sanded rear guard and looked at fixing cracks. Main one was about 5mm wide and would spring open if held closed...
Q8yTtMJ.jpg

So hit it with hot air gun and held it in position till it cooled...
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Then bodge-welded from the back with a soldering iron...
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And roughed up underside surface, degreased, applied fibre tape and 4:1 epoxy resin...
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Front guard had cracked mounting point...
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Did similar, held in position with some plastic 'welding', cut sticky fibre tape to shape and applied...
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Covered holes with duct tape and poured in some resin. 
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Will drill holes when set, hopefully the poxy sticks to the plastic? Did some QA50 guards yrs ago and they held up ok ...

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  • 3 months later...

Stumbled on this last night, great work these old 80,s trail bikes are fantastic. I am doing up a TT350 and the main part I want to replace is the swingarm as mine is worn away on the left from the side stand rubbing on it. Trying to find out if the 250 swing arm is the same as the 350. I can seem to find part numbers for both, any idea? 

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  • 2 months later...

Tidied the garage in the weekend and thought it'd be good to start putting this back together. The rear wheel looked ok, so I thought it'd be a simple cleanup and new tyre job, but oh no, nothing's simple. 
First mission was getting the ancient tyre off, was a real mission as was hard as fuck, so cut the sidewalls with a hook blade Stanley knife, removed the tread and tube, and levered off the remaining bands...
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And the obvious signs of corrosion worried me under what looked like orange insulation tape...
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And yep, disturbingly shitty... :(
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Wire brush on the drill appeared to clean it up ok, and at this stage was still hopeful it was recoverable...
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But serious cracks mean otherwise...
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So thought I'd just lace up a new rim, fairly standard size so should be no probs...
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Except it has some weird spokes that go right through the hub on one side. Never seen them before...
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Turns out they're Z-spokes, an innovation Yamaha brought out in '84...
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And discontinued cos they were a bit shit...
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So that's where I'm at. You can get new spokes, but they're stupidly expensive. Annoying as I thought this wheel was ok and just needed some paint.
So can either clean it up and use with cracks, or look at other wheels/hubs that'll work... Will see what looks similar/is available...

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Nothing to lose so had a crack at it, remembered to measure offset beforehand., just with a ruler from a flat surface..
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And a combination of heat, penetrant impact gun and force got them moving...
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Until I broke my favourite old spoke tool, was a bloody good one too... :(
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So out with the vice grips for the last few stuck nipples...
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And success. All spokes out without breakages. Should be able to clean them up and re-use with new nipples on a new 32 hole rim...
uqOEVVv.jpg

Pretty pleased with that as I've already bought bearings  etc for this hub... :thumbleft:

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  • 2 weeks later...

Since I had the wheel apart I thought I'd paint a bunch of stuff...
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Stripped old bits...
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And sprayed with Durepox primer, a mix of grey/black depending on the final colour, when they chip the undercoat of epoxy should be similar in colour...
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And just top coated with VHT wheel paint. Will be interested to see how this goes...
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Brake plate was quite pitted but seems sound, smoothed out quite well with few coats of primer and paint...
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And spokes look as good as possible I guess, seeing it's only silver paint...
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And lower triple clamp looks pretty sharp. Had some drips on this from spraying too heavy but wiped them smooth and the wheel paint seemed to recover itself...
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Sort of waiting on Ali new rear rim to arrive now to give me some enthusiasm to start rebuilding shit, paint will harden in the meantime... :)

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That 1984 YZ 250 I use to have had a rotten front rim, I dont know what they make them out of but when it corrodes it goes deep down into the alloy structurally fucks it, I had to cut where the tire bead sits off with a cutting wheel, looked fine once the tire was on but wasn't much rim anymore.       

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  • 2 months later...

Lockdown enthusiasm, looked at sorting the old seat...
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Screwdriver and pliers got 90% of staples out, just tapped in the broken off bits pliers would't grip...
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Not too bad underneath but a few holes in the foam...
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So I levelled them out with roughly shaped bits contact glued in...
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And put a layer of smoothing foam over the whole thing...
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Looks like the cover I bought will fit...
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But stalled there cos I've only got 14mm staples, and you can feel them through the foam at thin points. Had an 'Aha' moment this morning though, cutoff disc, staples in vise and some gentle application and you can trim blocks down... :thumbleft:
9i1F0JS.jpg

So will have a go at stretching the cover over when I get a chance, never really done this before so will see how we get on with my Lockdown Barrying... :grin:

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Decided to wait till I can get some s/s staples, so put the forks together today.. Had a hell of a job remembering how they went together, surprisingly had taken bugger all pics when I pulled them apart...
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But got there with parts manual pics, some scribbling and some logic. Used a plumbing fitting to press the top bush and seals in...
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Added the correct amount of oil (533mls) although it seems very low in the fork legs...
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And done, the bushes aren't available so pretty much a clean and new copper washers/seals/fresh oil...
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Glad to get these bits out of the way, were taking up a bit of room...

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Managed to buy the correct shielded lower taper bearing over lockdown, so bunged the steering stem together. Stem in freezer, bearing under the hot air gun for a few moments and drove it on with old bearing shell...
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And glad I painted it, looks good, just got to figure out a way to torque up the locknut under the top yoke for correct clearance...
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And looked at the tank, just been sitting there cos I couldn't be bothered cleaning it...
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And of course one bolt on the side covers wouldn't undo, felt like the whole thing was spinning, so no option but to drill it out...
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And after grinding it flat and trying to drill out the bolt, the whole thing came out when it got hot, was nervous drilling in case I drilled through the plastic but thread had a blind hole so that couldn't happen...
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So re-tapped the square brass fitting...
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And cleaned the hole and epoxied it back in...
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I cut some slots in the brass fitting to help retain it in the plastic, should be ok if I don't gorilla-install the bolt. When that's set I'll move onto the tank cleanup...

 

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Barried up a tool to tighten the steering locknut tonight, couple of big washers, a big nut and bolt, and some drilling and tapping...
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Will it work? Fuck yeah...
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Just managed to torque to 27 ft-lbs to seat bearings without it failing (shouldn't have used brass screws in retrospect) before backing it off a full turn and re-torquing to 7.2 ft-lbs. Feels tighter than I would have set it to by feel, so good to know it's to spec. Job done...

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Got my lockdown s/s staples so had a go at stretching seat cover on. Went ok but wished I'd warmed it up first, ran the hot air gun over it halfway through and made it much easier to work with. Still got to pull the YAMAHA lettering even with the bottom edge and finish stapling, but looks ok...
El60cRM.jpg

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  • 4 months later...

Took a break from other projects to look at this again today. The white tank was pretty scody, have heard a few methods of sorting this, but tried first scraping the powdery stuff off with a razor blade, went ok...
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Then tried some cutting polish, made it shiny but bugger all difference, so tried some wet and dry sandpaper with a bit of this instead of water, started with 240, then 400, 1000 grit on a flat test section...
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And can definitely see where I've done it...
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But it's pretty labour intensive, so I tried making a paste out of bleach and baking powder. Brushed it on and left in the sun till it dried...
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And blasted it off with great excitement...
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To see it's done fuck all... :grin:
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So looks like sanding is the go. Interesting exercise anyway. Won't be too bad if I take it a section at a time...

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