twinshock giles

Just watch out if you are ordering an ebay bargain from the States that some of their bikes used a fine spline that I have never seen over here in the UK. Don't ask me how I know this

Looking for a bit of info as to what it is really, I thought it was an Amigo 80 Now I've got the bike looking at images online I'm not sure exactly what it is. I have front disc and rear drum, 21 & 18" wheels, its fitted with a Franco Morini engine but the bore size is marked as 39mm which I think makes it a 50. Unsurprisingly it needs a new rear mudguard, I've tried the one from my Skywalker and its a spot on fit, which seems to rule it out being a Alevin as i found a reference saying they were close but not right. I've messaged Harglo to see if they have any engine spares remaining, if not does anybody know anybody else who may have spares or what else used this engine, I've found a T4 cast into it which seems to be the Morini engine model code. Anyway the main thing is No.1 Son and Daughter are most impressed and its nice and light so should be easy enough for them to get the hang of riding once its done,

Look carefully at the frame top tube from the head stock back, it should be straight, I had one bike for breaking that had had the bashplate spaced down previously that had a dog leg in the top tube.... That said its far more likely to be a bent bash plate and a weak or sticking detent spring - the wear can be difficult to spot though, I resorted to fault finding by substitution. The Ossa box (and the whole engine really) is tough in my experiance, I very much doubt you would have done any damage to it running it low on oil for one trial unless that trial included a lot of road work.

The frame number is the format that would be allocated by the DVLA when the original number is lost or not present, so probably not going to be a lot of help. It will be road registered though probably on a Q

I think there must be more going on than is immediately obvious here, if you haven't already got it booked in somewhere and it still doesn't want to rev out is it possible to try it without the final silencer to see if it might be clogged internally. Other than that could it be a wiring issue - filth in connections causing issues?

Well I would, but then again as I'm buying a Mecatecno I'm probably not the best person to answer that....

IF (and its a big IF) the plating on the barrel is ok - I couldn't make up my mind from the photos and you are on a tight budget, I would be tempted to smooth out the chips and try to get hold of a used piston and stick it in with new rings, they shouldn't catch the rings where they are. It would probably be ok for a good while as long as you don't let it scream out or try to do the SSDT Check the edges of the other ports for any sharp edges too. Also check the bottom end for any broken bits of piston, most of the time stuff just goes out the exhaust port but there is always a chance...

What tolerance did you go for in the end?

The Maxi was last out of tax July 1984, so probably is earlier.

Embarasingly there was movement in the flywheel end of the crank when I took the casing off.... Yes condensors just fail with no warning

Well i'm up for taking Nigels advice anybody wants to sell an Ossa or 2 cheap either down South or up Derbyshire way I'd be up for buying

Does the Alpina run a motoplat electronic ignition like the Pursang, the only time my Pursang let me down (surprisingly in everybody elses opinion) was after quite a lot of trail riding the main bearing on the flywheel side had developed enough play in it to mess up triggering the spark, It didn't get noisy or seem to loose compression but would only spark randomly. Otherwise if it has a conventional ignition system and it runs ok when cold my vote is for a faulty condensor

Has PJ1 changed formula does anybody know for definate? Its the only stuff I had ever found that stayed on and still looked good on barrels and heads Normal cellulose seems to work fine on crankcases/ clutch covers but its not realy rock resistant..

You don't need an Ossa specialist - anybody who is used to working on 2 strokes should be able to split it and rebuild it for you, probably your best bet would be to find someone who rebuilds MX engines. The Ossa engine is about as simple as it gets to work on and split, the only tricky thing to remember is that there are shims everywhere and you really don't want to mix them up when you take it apart. I think the only special tools you are likely to need is a clutch holder so you an undo the centre nut (or just use an impact wrench) and flywheel (magneto) puller. An impact driver is usefull to loosen the screws that hold the casings together. Other than that there may be a special tool for holding/ dismantling the cush drive on the end of the crank but i've never had one. While it is apart you may as well fit new bearings and seals they are only a few extra £/$

Could it be a broken kickstart shaft? I've never seen or heard of it happening on an Ossa but I can't think what else it could be. The only thing I have had close to it was a 350 which only started to engage after about 2/3rds of a rotation of the kickstart shaft. I think that was down to mis matched parts and needing reshiming though, it didn't just suddenly happen.

Isn't the new Ossa recommended to run at 120:1? That sounds a frighteningly little amount of oil but if thats what it takes not to upset the system. That may account for the fouled plug?

Sorry to drag this thread up from the past but does anybody have a photo of a Gori rider on LCN 43X, the last time it was taxed was for the 1982 Scottish and it still has parts marked up Thanks

Just a quick question for Woody, was a decompressor factory fit? I've had bikes with them, but also have some with a blanking bung or an undrilled space where the decompressor usually fits. Not that it makes any difference to anything I was just curious.

The CG gearbox is very close ratio, it may be possible to fit the TL gear set but i've never tried. I had a good one in an XL and although on paper they both develop about the same amount of power it always felt down on power compared to the OHC engine and if you geared it for slow stuff you were flat out on the road at about 45 /50 ish and I mean absolutely flat out - on the positive side they are very hard to kill!! The overbore might address the power issue and make it significantly more torquey (sorry about the spelling)

Well I've sent it off with 200 Trials as the model type so I'll wait and see in 6 weeks time, fingers crossed they can find a reference to the frame number

That looks a nice thing, personally I would say its a very reasonable price, If you get it don't paint the plastics - they'll never be right, you can use various products to improve the look of them.

Trying to get a DVLA search done for the reg number of my Fantic. Can anybody tell me how they have it recorded originally? Is it FM whatever or 200 Professional or Trials? Thanks very muich Giles

You've probably got this sorted now but the only MAR I had difficulty starting had the same symptoms as yours, the previous owner had started it with ether for years to save messing about kicking and kicking and once it had been run it would start reliably all day even if it was stood several hours. The problem was piston rings that were so worn they were less than a 1/2 of the thickness they should have been. A new set of rings (the bore was still ok(ish) and it started from cold no problem with just the tickler to flood it. Incidentally it didn't really feel down on compression when turning it over on the kickstart. If you have checked everything else then I would have a look at them, or even borrow one of the screw in compression testers with a flexible pipe to test the compression accurately

Just as a follow up have now got the reg number for my Gori, originally registered 11 September 1981 and the last tax ran out March 1983, has a nice short reg number ending 43X - Does anybody remember doing the Scottish on it? Only showing the digits as the frame number - none of the prefixes

I would try riding both if you can, in standard trim they both have a very different feel. I would say that if both are unmodified the SWM was always going to be more powerful and competitive. I have no idea what they are like on the road as my experiance with quick riding on both has been limited to between section dashes I'm happy to be corrected but my experience of the rotax engine (as fitted to the SWM) is that they will run quite well and reliably even when pretty much worn out and don't tend to get noisy like they TY's do when wear becomes excessive. Shame the SWM clutches are an aquired taste