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1971 GP125 bare frame and engine bitsa rebuild

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1971 GP125 bare frame and engine bitsa rebuild

Postby Pompeydave » Sun Jun 01, 2014 7:43 pm

Hi all, here's my 1971 GP125 frame and engine purchase again, from start to finish, in a few posts. This came from Jonski up in Pudsey, West Yorkshire last August, cheers Jon. It was a marathon weekend. I left my job in Fareham, Hants at 21:30 on the Thursday night, and drove overnight to Inverness to pick up a load of stuff for a cousin who'd temporarily moved in with us in Pompey. Got there at 05:30, had about two hours kip in the car, and then loaded the wife's Honda Civic up to come back.

I stopped in Catterick around 3pm on the Friday and bought an Indian GP150 unfinished project that had loads of new Indian parts with it. I somehow got it all in the car and then shot across the M62 to Pudsey to buy the Italian GP125 frame and engine you see below from Jonski. By this time, it's about 5:30pm and I've had two hours sleep in the last 48 and I still have to get to Accrington for about 7pm :? . Anyway, the frame and engine were well and truly shoehorned into the Honda, and I went over to Accrington to a nice b&b outside the football ground. A quick shower, and off out for a few beers before returning to the b&b around midnight. God knows how I was still awake, but needless to say, I slept well that night!

Next morning began with a leisurely full english followed by a slow wander across the road into the pub owned by the club. Couple of pints and out the back door and into the ground. A cracking 2-2 draw ensued, followed by a nightmare drive home where I really struggled to stay awake all the way :shock:. Thank god for Pro-Plus! Finally made it home around 7pm, and unloaded everything the next morning.

So, what I ended up with was a bare Italian GP125 frame and engine case, a fuel tank and a chrome rear mudguard + a complete new set of Indian bodywork, GP150 engine, frame, forks, headset, hubs, tank, toolbox and good quality Ancillotti seat. There was also a new Indian electronic kit, a complete new rubber kit, several Indian wiring looms (all with yards and yards of indicator wiring), new tyres and inner tubes on new chrome rims. A couple of boxes of odds and ends, (mostly fit for the bin only) completed the inventory.

I kept all the new bodywork plus the gearbox, barrel and head, the forks, wheels and tyres, rubber kit and seat. The rest, I added a few bits to that I had lying around, and sold it all on as a project. After which, what I had was a nearly complete bike in bits that just needed a few parts, spraying and rebuilding.

Here's some pics....

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First thing to do was to strip out the tank and rear mudguard. The mudguard being chrome, wasn't what I wanted, so it went into the Indian project I moved on. I measured the frame and found the front cross member to be just slightly out of alignment. I heated it up and used a heavy mallet to persuade it back into place. Once I was happy with the geometry, I did a quick dry rebuild. Most of the Indian panels fitted very well actually, with only minor fettling.

I didn't want to keep it metallic blue, so I decided to have it resprayed in Yellow Ochre, and after stripping it down again it all went off to Mike, my trusty retired sprayer.

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Whilst the bodywork was all away being prepped and sprayed, I tackled the engine. On closer inspection the case I got from Jon was a belter, with no repairs and nothing needing to be done apart from a good clean. The engine number was some way out though from the frame, and althought it was the correct Li125S designation, it was clearly from a much earlier bike. I managed to find a case with a number only a hundred adrift from the frame, but it needed a few repairs doing to make it a good 'un. As shown above there was a side casing stud at the bottom that had split, and the top one on the left hand side had sheared off completely. These two were rewelded by a mate over in Waterlooville and the exposed upper repair is shown after filing back to it's original shape...

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The rim underneath the layshaft housing bearing was split, and Rog welded this back into place also...

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Side cover was ok, apart from the kickstart wear as shown here. It was a good cover otherwise so I was happy to live with it. It doesn't stick out like a sore thumb anyway...

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The mag housing was from the Indian engine, and was perfect. All the threads were spot on, and I don't think it had ever been apart before. Haven't seen one as good for a long time, so this was a result. That's it for now, I'll add more pics shortly to show the build progress...
Last edited by Pompeydave on Mon Jun 09, 2014 1:09 pm, edited 1 time in total.
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby Rich Oswald » Sun Jun 01, 2014 8:48 pm

Looking good so far Dave,

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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby Pompeydave » Tue Jun 03, 2014 12:56 pm

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Underside of the engine showing the repair after a broken off stud was removed and new metal was added. I didn't retap it as I've never really found they make much difference to the exhaust mounting.

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Just a blob of new ali here as it doesn't show. I just drilled it out and retapped the thread.

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This was the top thread that was broken clean off. Here's how it looked after the repair.

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And the underside, showing the repaired split at the bottom of the brake lining area.

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There was an exhaust stud here that was broken off flush to the casing. Roger managed to get it out and fill it full of new metal. I drilled it out and retapped it.

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And here's the bare case, side cover and mag housing after all the repairs and bead blasting...

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The last job I did was to helicoil one of the rear hub bearing plate cover studs. It all came out quite well in the end I think 8-)

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Ok, so with the case all repaired and cleaned, it was onto the engine build...
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby scooterstu » Tue Jun 03, 2014 1:02 pm

looking forward to following this one
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby Toddy » Wed Jun 04, 2014 12:23 pm

Me too, you have made a good job of repairing the casing
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby Pompeydave » Thu Jun 05, 2014 5:18 pm

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Thanks Toddy. Here's a few more engine build pics. The above one shows the helicoiled and rear hub bearing cover plate stud.

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Same again, but after fitting one of Broady's top quality rear hub bearings. This was quite hard to track down actually. All the usual suspects had sold out, but thankfully Torbay Lambretta eventually came up trumps. Not only was the price good, but I ordered it at around 4pm one day, and it was on my doorstep in Pompey by 10 am the next! Well impressed with that kind of service :D

Anyway, a good dollop of gas hob heat allied to the bearing being frozen overnight, and it just dropped into place.

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Cover plate added. The new stud was a touch longer than the original for some reason, but doesn't make any difference.

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I used the original Innocenti layshaft as it was in such good nick. Although you can see where the gears have sat on it, there's no wear step at all, it's just been slightly polished over the years. I treated it to a new O-ring though. The sliding dog pictured was going to be used, but on closer inspection the edges of the prongs were a bit borderline, so I used a different one I had lying around that was virtually new. I could have got away with the one pictured, but I hate a sloppy gear change, ooo-err :shock: .

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With this in mInd, I renewed the brass gear arm bush in the case to give more precise movement.

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And again with regard to gearchange feel, I used new fork gear selector pawls. At a couple of quid each for good quality ones, it's a false economy not to really.

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Ok, here it is with the box all in place and endplate added. The endplate is SIL but it's as good as the Innocenti flavour one. A new SKF endplate bearing rounded it all off. I just hoped I'd got the right thickness gearbox shim :?

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Rear hub came back from my sprayer first, and here it is fitted. Painted in Fiat 690 Silver, it came up a treat. The hub lining was almost new in appearance with very little wear and no scoring. I fitted a new set of Makino shoes at the same time, and the good news was that the gearbox shim had left just the right amount of clearance as per Sticky's book, so happy days :D

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Here's a few of the new internal parts, before fitting.

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Note the condition of the clutch spider- and that's straight out of an airtight SIL plastic bag :o . I think it must have been packaged literally in a sweat shop for it to have rusted like that in the bag :shock: . Anyway, once cleaned up it was AOK.

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Onto the top end. A new SKF drive side bearing went in first, followed by the plate with a new Rolf oil seal, and loc-tite covered screws. A new Mec-eur road/race crank followed as seen above. Engine mounts had been fitted at this point too.

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And here it is with the piston added. Again, a new SKF bearing and Rolf oil seal were used in the mag housing and it fitted prefectly. I used a new SIL electronic ignition kit, and the stator plate was resistance checked before fitting, and was found to be a good 'un.

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...and the chaincase cover fitted. I used a new MB front sprocket bolt, and standard good used Innocenti chain guides. A new 46tooth crown wheel, chain and Surflex clutch plates were fitted. The clutch steels were good enough to re-use. The original gearcable block was cleaned up and re-used, but I added new stainless/chrome adjusters. A new chrome clutch arm also went on and a new stainless tie bar was fitted. At this point I could test the gearchange action for the first time, and the effort of renewing anything that could have worn was well worth it as the change was very smooth and precise 8-) . The chaincase cover had a good brass kickstart bush in it , so that was left in place. The spring was good, so re-used but a new shaft was fitted, with a new piston kit. The clutch arm assembly was rebuilt with new o-rings, and a shiny chrome kickstart finished it all off.

So, that was much of the engine work done. I started to get bits of bodywork back next, starting with the freshly painted frame....
Last edited by Pompeydave on Mon Jun 09, 2014 1:12 pm, edited 1 time in total.
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby Pompeydave » Sat Jun 07, 2014 1:56 pm

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First frame pics. Stand and splash plate added first. No problems apart from the usual shenanigans trying to add the spring at the same time. Not easy to do, and I ended up going back to it later to do it properly, so a lot of patience was required. but I got there in the end, and the spring is shown fitted in later pics. I used a new Indian stand to get the footboard bump stop they thoughtfully added.

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I offered up the forks next to check the new steering bearings. I later rebuilt them used progressive springs and new buffers. The GP type are so much easier to fit rather than the earlier bolt in flavour :)

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With the stand in place and the forks added, I could move onto the under panel bodywork..

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Rear mudguard, stainless panel springs and the electronic mounting were next up. The mudguard holes lined up correctly as per the dry build which is a bonus. I've had several before that were drilled in the wrong place.

Rear frame badge, grille, blanking buffers and side panels rubbers. I always use Tutto remade ones as they're thicker than the fit-for-the-bin-only Casa type which are far too thin and ripple really badly.

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Wiring loom went in next. I know a lot of people use cable ties these days, but I just think they don't look right :? . I prefer the original ali strips. The tank wasn't too bad inside, and before painting it was pre cleaned and hoovered to get any remaining loose stuff out. I'm not a fan of Petseal, so I finally put some fuel in it and shook it around before draining it out. I repeated this three times to get the last of the dregs. Once back from painting, it was a bit of a struggle to get in place without scratching the paint, but again with patience paying dividends, I got it in place with the straps facing the right way in the end!

I went for a new rear exit fast flow tap and it sealed correctly first time. Finally the fuel tap lever was connected and the tap adjusted to bring the lever just up against the rubber buffer. The airscoop was offered up ready for the toolbox later on..

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Rear light added. This is a remade Bossata unit by Casa.

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I managed to get hold of a NOS plastic toolbox from a guy in Italy. Expensive, but well worth the extra to get a new one. The only part not A1 was the brackets, so I took them off and had them chromed.

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And here they are refitted again. Whilst the chroming makes it not strictly original, I wanted a finish that would resist atmospheric corrosion in the future. Hoefully, this'll do the trick.

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A new Tutto rubber finished it off. 8-)

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Toolbox, airbox and air scoop fitted. The toolbox rubber buffers were a nightmare and incredibly fiddly to fit. Horrible job :x

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Cables and wiring loom in place towards the front of the frame. Sticky's book in invaluable here and each time I've followed his pics the cable action has been spot on once finished :D .
Next up, headset...
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby Pompeydave » Sat Jun 07, 2014 2:16 pm

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Rebuilt headset. Pretty much everything here was renewed including Casa lights/horn switch and a new ignition switch. The plastic gear and throttle wheels may not look that good, but they do work well once any movement in them is taken out with very snug fitting pins which will help to gve a smooth, precise gearchange and throttle action. I always have the headset clamp chromed as they corrode really quickly if left with the mild steel finish.

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New gearchange tube again showing a tight fitting roll pin.

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Forks, headset and horn fitted. Levers connected up to the cables. I used an oversized lever pin on the gearchange side as the original opening had ovalled over time. Speedo cable was fun as usual, but went in ok in the end.

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More bodywork back from the sprayer....

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Rear hub and exhaust came up well in Fiat 690 silver..

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Nice finish to the paint I think 8-)
Last edited by Pompeydave on Mon Jun 09, 2014 1:17 pm, edited 1 time in total.
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby pazwaa » Sat Jun 07, 2014 3:21 pm

Great looking scooter and great build thread. I'm new to scooter restoration and this type of thread is incredibly helpful, so cheers :)

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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby Rich Oswald » Sat Jun 07, 2014 4:03 pm

Lovely paint, looking forward to seeing this one finished.

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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby Pompeydave » Sun Jun 08, 2014 11:02 am

Cheers for the kind words chaps. Makes it all worthwhile, and it's nice to get some encouraging feedback :D .

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Fitted the legshields loosely. I used Scootopia supplied Tutto plastic strips as they come out of a new set of mouldings and are absolutely perfect 8-) . Tutto legshield rubbers used also, with Casa sharks teeth. When it came to fitting the ali strips I realised I'd bought Li/SX/TV flavour by mistake, :roll: . Allstyles to the rescue for the correct GP type, cheers Gary!

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Leggies, horncasting and front mudguard fitted, with just the rubbers to add. All starting to come together now...
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby Pompeydave » Mon Jun 09, 2014 1:46 pm

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Floor strips finished. Lots of time spent adjusting these to get the correct fit.

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Headset in place and wiring connected up. I had an issue here with the main loom connectors being too small to fit the headlamp wiring block so I had to refit larger terminals to get a good 'click in' fit.

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Bodywork nearing completion.

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And the front end is finally starting to look like a scooter again :D

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It all still fits! :D Next up, engine fitting.....
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby Pompeydave » Fri Jun 20, 2014 11:11 am

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Engine in! Couple of tricky bits were trying to line up the engine with the tube and cones, and doing it alone doesn't make it any easier :? . The other problem was avoiding contact with the rear mudguard as the engine went in. All ok with patience, but there were a few heartstopping moments...

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I'd already run the engine in a custom made test bed I recently bought, and it started within a few kicks and ran well. A good investment is the test bed- so many times in the past I've had to fit engines into a bike before being able to run it and when somethings not right the whole bloody lot has had to come out again :evil: . Once the engine was in I connected the wiring up and away she went first time. Unbelieveably, all the lights and horn also worked first time- I might just be starting to get the hang of this :D .

So, a quick ride up and down the road, and straightaway I'm brought back down to earth- no fourth gear. Bugger. I've had this problem before when rebuilding an engine as per Sticky's book. In it, it's suggested that the gear arm needs to be directly in line with the chaincase stud when the bike is in second gear. Every time I buiild an engine this way it's wrong, i.e. when the gear arm gets to where fourth gear is next up, there's no swivel room left to allow it to go into gear. When I move the arm back one notch on the spline (yes I'm using the earlier type two piece arm) it give enough additional movement to comfortably select fourth. It might well be that I'm at fault here in as much as I had to grind the swivel slightly to clear the pivot block it sits on, which doesn't sound right. Either way, once this was all done, all four gears were fine. I'd like to know what the answer is on this though? No amount of cable adjustment seems to work, it's always a case of moving the arm one spline back before it will work in all four gears. Maybe the extra flexibility I'm after by fitting the two piece arm is a mistake and they're machined differently? Can't really see that as the case and internals didn't change throughout production.

Anyway, seat next, then side panel stripes, and badges. It's then headset top, footboards and a final alignment check of all the panels. Check torques all round and hopefully she's done 8-) .

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Here's a couple of 'before' pics again....

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....and 'after'. All finished. I ran her over to Scooter speed shop in Farlington, and she passed the MOT 1st time. I put just about 10 miles on her with some gentle around town riding and found that the fuel mixture was running a little weak. I richened it, and she burbled away quite happily after that. As a precuation I changed the gearbox oil just in case there was anything in there from the rebuild that shouldn't be. All ok on that score, so fresh oil added and a trip to the post office for some lovely free historic tax was the last job to do.

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Bit miffed here that I didn't get the HT lead tag re-welded, but it probably doesn't make that much difference...

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So, that's it. Sadly, due to me temporarily working part time, a bit of an overdraft built up at home, so she had to go almost straghtaway unfortunately. Hopefully the new owner will have a good few years riding pleasure out of her 8-) . Now then, what am I going to build next? :D
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby Rich Oswald » Fri Jun 20, 2014 1:06 pm

One word...........Fantastic.

Rich#
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby Pompeydave » Sat Jun 21, 2014 7:53 am

Cheers Rich :D
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby lammydave » Sun Jun 22, 2014 7:20 am

Beauty, Dave, well done....

That has motivated me to get on with the "Performer" I got from you a few years ago..

She's currently in bits as the rust got a bit too much.... :cry:

Apart from that, the electrics were playing up (they did a bit when I picked her up if you remember)... turns out that the wires from the switch on the gearchange side had all been sliced through by the action of said gearchange...common problem as I understand...

Anyway, as I said, a great Job on your GP, and brilliant to see all the photos!
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby Pompeydave » Mon Jun 23, 2014 10:55 am

Hi Dave, good to hear from you, and thanks for the kind words! I agonised over what to do with the Performer. I liked the fact that it was all original and untouched and with such ultra low mileage, but the fact that it looked like it had never been kept out of the elements was so frustrating. If it had been kept in a garage it would have been like new. Still, hopefully you can now bring her back to her former glory now! Take care...
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby steveiow » Tue Jul 15, 2014 8:36 pm

That's a beauty mate. As Tina Turner would say "Simply the best" :D
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby nickw » Fri Jul 25, 2014 7:31 pm

Great looking scooter. You've obviously got some talent. Andy says can he have his stepladders back.
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Re: 1971 GP125 bare frame and engine bitsa rebuild

Postby wellerchap » Fri Jul 25, 2014 10:00 pm

That's a thing of beauty - you should be very, very proud
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