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1970 AT1-B


dave62
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So here is my AT1, bought as a non running import from a local restoration business.

Story goes that it was only used to drive a mile up a track to the mail box and back again each day so never got registerd in the US for road use hence no title but it did have the C & E 386 to say all UK import duties paid.

Plan is to get it registered on an age related number but as I've never done this before I'm learning as I go. As far as I know I will need:

1, dating letter (yamaha owners or vjmc)

2, mot (on frame number)

3, insurance (on frame number)

4, dvla form v55

5, fee

6, tax disc

While waiting for the dating letter to come back I've got to get it ready for an mot. First job was to get the engine started, cleaned out the tank with some old nuts and thinners plus lots of shaking and stripped the carb down nothing too major in there apart from the float bowl is perforated in several places, bodged this for now with some JB weld but will need to sorce a replacment at sometime, Anyone?

Fitted a new set of points and pressed the starter....nothing! turns out the generator brushes are worn out so made up some replacements and....still nothing! good job its got a kick start so I give it a couple of prods and find that its to got issues as well, it does not always engage so reverted to bump starting and it finally splutterd into life and then it ate its crank seals! Got two replacments and they were thankfully easy to change. Starts dead easy now even with the faulty kick start.

Next on the list was new tyres. Had problems finding knobleys in the correct sizes (18 X 3.50 & 18 X 3.00) so opted for a pair of cheng shin road tyres for now. Sorted out a couple of blown bulbs ect and replaced the brake shoes front and rear.

So apart from a few minor adjustments I think its ready for the mot.

Heres a few pics and a vid (hope it works)

Cheers...Dave. ...... ps. Anyone know if bent handlebars are an mot fail?

th_P1000667_zps7c61daef.jpg

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Nice! :thumb:

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Nice work mate, dunno on the handlebars.

How bent is bent?

The tyres should be easy enough on the back at least, ive got conti tkc 80.

Vintage tyres or tyrefinder are both useful places to start.

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Thanks for the comments :thumb: Heres a pic of the original (bent) bars. Decided they were too bad and have now swapped for a better set that will do for the mot.

P1000661_zpsc3455c8b.jpg

mot booked for tommorow so fingers crossed.

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Good luck on the M.O.T davie" :thumb: yeh tyres are available,, you be wanting the classic trial [ block] tyres eh,,,

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Hey up John lad,

Yes the block trials types what I want, have tried Vintage tyres but they couldent help and will be having a look at Tyerfinder as sugested by busyeddie, any ideas where else to try?.....Dave.

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KH 250" :eusa_think: this ain"t Dwheel is it ? i"v just ordered 400x14 rear and 2.75x21, block pattern, Hi -level do them,, i think there Heudenue or summat,,,

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Yep dwheel on the Triples site mate :eusa_dance: How ya doin?

Problem seems to be the 18" front as most seem to only cater for 21" Thanks for the High Level tip will check them out...Dave.

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Hey Dave :wavey: , Airhead is also on here, you met him at Blackpool rally, your a DT man too now, i"l ask my mate to look out for an 18" tyre , see what comes up,,,, :icon_wink:

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Cheers John, Mot passed today so will start stripping it down now and sending a few bits off while I wait for my dating letter to arrive, then off to Dvla to register hopfully before any changes come in to force.

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Aahh well done on the mot. There will be tyres out there. May.be an obscure make though, but tbh the old dt wont be.pushing a tyre to its limits.

I think the bloke at tyre finder is called Mick. Very very helpful.

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Thanks busyeddie, will give tyre finder a call :thumb:

Been busy stripping the engine down so heres a few pics (and some questions) of progress so far.

Engine out.

P1000668_zps47ccec42.jpg

Scoring to bore and piston. Rebore?

P1000670_zps5a67dd69.jpg

P1000669_zpsc331a424.jpg

cases split

P1000671_zps455b65fc.jpg

I think this may be the cause of the kickstart problem? (intermitent not engaging/disengaging)

It appears that a lug is missing and allowing the kickstart tang to rotate. so my question is... Is this a common problem and is there a recognized repair? Im thinking maybe get a lug built up in weld and dress back? All opinions welcomed :thumb:

P1000675_zps7148dba6.jpg

P1000672_zps21a8fff9.jpg

P1000673_zps1614e7b1.jpg

Thanks in advance....Dave.

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Found a picture of a good crank case half on the internet. now at least i know whats missing from mine :icon_eek:

A couple of pics for comparison... first the good case, (kick start area)

KGrHqNHJCME-iH4Rc9BPrZnCuglw60_57_zps291

and second my bad case,

P1000675_zps7148dba6.jpg

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  • Moderator

Surely thats easy enough repair.

Ally welding or low buget, drill tap and use a set screw as the stop instead.

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I am investigating getting it welded first as a proper repair but will bear in mind your "low budget" idea if welding prooves to be a problem. Thanks :thumb:

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Its only keeping the spring in place and there is plenty of meat in that part of the case.

As to the bore. Depending on the depth of those marks. You could need to go up a full 0.5mm to get it clean and bring the bore back to round.

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Got a few bits done. Crank case Kickstart area has now been welded and just needs a tidy up with the Dremel.

P1000708_zps9d293a01.jpg

Had the Crank rebuilt with new bearings ect and had a chat with the guy regarding options for the rebore. Cant find a first o/s piston so followed his advice managed to sorce a standard piston which I will fit for the mean time until an o/s one turns up. Hes run a reamer through the bore to clean it up as much as poss so will be better than before.

P1000709_zpse855e46f.jpg

P1000713_zps56e06802.jpg

Got fed up searching for Generator Brushes so decided to try and make some. Time will tell if any good.

P1000715_zps53a52ff1.jpg

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From experience 1st oversize (0.25) is rare as boring to 0.25 normally does not remove enough metal to return the bore to true round. Its only removing an 8th of a mm from the liner.

The more common choice is. 0.5. Certainly what was reccomended to me on my dt. They would not do the bore (with my. 25 piston) untill they had measured the bore to make sure it could be done.

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Thanks for the tip, will look out for for a second (.5) o/size piston and keep on the shelf till needed. Good advice, thanks :thumb:

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Got a few more bits sorted, first job was to finish making some replacment carbon brushes by cutting down some larger ones. Ive used two different grades of carbon to see which will perform the best...time will tell :eusa_think:

P1000721_zps799d8b58.jpg

Had some luck on fleabay and bagged a Nos points cam (in the UK too) to replace my knackered one :thumb:

P1000718_zpsff24441e.jpg

Have now finished cleaning and inspecting the cases and gearbox internals and all looks good. Result.

P1000717_zpsd543aa3f.jpg

So should be able to start rebuilding very soon. Have got all replacment bearings chilling nicely in the freezer (mrs not too pleased though)

P1000722_zpsb3c4e6df.jpg

Cheers...Dave.

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