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The MB Developments gallery of scooter horrors!!

With the engineering experience and back up MB Developments have we are often called upon to examine the remains of some scooter parts that have had a very hard, tragic life.
Some have just been used in vast excess of their expected limits but some have been born into a world of bad engineering.
As with other sections of this site, this section contains Marks opinion based on 20 years in the scooter trade and his engineering training.
It is not intended to upset anyone but it probably will!!! We all make mistakes sometimes, but at MB Developments we are the first to put our hands up and say we have made a mistake.

Anyway, on with the horror show.......

As before click on a thumbnail to see a bigger version of the picture.

Phil Dalgleish is a regular customer of ours and is the owner of the "forks that seemed to melt" further down the page.
This picture shows his mates helping him change his clutch plates on a the recent Yarmouth rally.
They didn't have a clutch compressor so they had to use this piece of wood they found in the shed of the bed and breakfast they were staying in!
Note the careful use of several coats to protect the scooter.
I'm sure there's a "how many scooterists does it take to change...." joke to be made.
Here are the offending clutch plates, well and truly cooked.
Nothing you can really do on a TS1 apart using the best clutch plates (Surflex B) and gearbox oil (ST 90).
This engine mount came out of an engine we were asked to change the mounts on.
It had developed a bit of a wobble, when we took the mount out we found out why!
Only one small piece of the rubber in the mount was still attached to the inner metal part.
We were sent this Rapido barrel with a view to repairing it.
As you can see the iron part where the exhaust studs go has come away.
It is unlikely we can do anything as it is difficult to weld where it is half Iron half Alloy.
So it's basically scrap.
We weren't sure whether to put this in the horrors or the gearing section!
It was sent to us by Howard Chambers, the renowned Lambretta restorer.
We are not sure where he got it from.
The sprocket has 28 teeth and looks well made.
It weighs just over 700 grams which is a lot of weight to have on your crank.
It looks like you would have to modify your casings to use it.
We calculate that, in theory, if you used this sprocket with a 46 tooth crownwheel and a TV200 gearbox you could get your scooter to do over 230 miles per hour.
That is of course impossible bearing in mind wind resistance and the fact that any engine would struggle to pull that gearing, even in first gear!
These forks have had a hard life.
What you can see is the surface that the headset yoke bolts onto.
Apparently all was well until our customer sent his forks away for chroming.
When he got them back this section was "deformed, like it had been melted" so our customer has had a go at building them up with weld and grinding down again.
Now he can't get the yoke on so has brought the forks to us to sort out.
Ian came across this in a Series 1 Li125 he had picked up.
At first glance he thought it had just had the plate on the back ground off to do something with the springs but on close inspection he realised a severe bodge had been perpetrated.
Someone had removed the springs and replaced them with pieces of metal rod which had been welded in.
So this falls between a bodge and something that Innocenti started doing nearly ten years later on the GP range.
Unfortunately the way it had been done meant that the crownwheel was really heavy.
The new dismantable engine mounts from Italy.
Only joking, these look really nice - a lot of atttention has gone into them.
This one lasted 200 miles before it went leaving the scooter with a strange leaning sensation - not nice when it suddenly happens at 70mph.
Our advice - use the Indian ones. They may not look as nice but they last longer.
Ouch!! Taffy rear shocker had done only 100 miles from new. The customer came to us for a quick road test before going on to a rally. Mark was riding the scooter and felt a bump like he had gone over a pot-hole. When he got back he put the bike on its stand the front was really high in the air and he discovered what had happened. No damage only a dent in the petrol tank. Could have been MUCH worse!
Oooops!! This customer goes from one dealer to another and back again.
He cuts corners to try and save money but he must have got through 6 ts1 pistons and 3 cylinders in the last couple of years.
He obviously has a big problem but some people will not be told!
Look at the size of these inlets and exhaust ports.
Tuned by a dealer famous for making exhausts (near Blackpool).
Both MBD and RS tuning checked the cylinder and both said to throw it in the bin.
No said this customer, it's got to be run.
So we gave him the first prototype SR200 piston for testing with the comments "If it lasts more than 500 miles in that barrel without breaking then it's a good piston".
The piston actually lasted around 3000 miles.
The rings or piston didn't go, he ended up putting a hole in it.
He'd tried a new AF asso piston but that hadn't lasted 5 minutes.
Based on this result we had great expectations for the SR road/race pistons.
Over-tuning inlet ports usually causes pistons to crack. Over-tuning exhaust ports mean the rings drop and break or on good pistons the rings pop into the exhaust port then the top of the piston comes off!
With a TS1 piston both go wrong but the SR piston survived.
MB Developments normally do inlet widths of 44-48mm, this cylinder was 55mm.
We normally do exhaust widths of 46-50mm, this was 55mm.
On a 66mm piston it is no wonder it eats pistons, classic case of overtuning!
Now come on Indian manufacturers, theres no need for this to happen but it does!
Totally beyond our control!
For some reason in 2002 we are getting a lot of comebacks on Indian GP Kickstart shafts.
It turns out about 6 different places make these shafts in India.
This problem become more evident on 6 plate conversion where the shaft needs extending, this adds more leverage to the problem
We have tried various methods to get to the bottom of this problem.
We can cure it with some welding to strengthen the weak area.
This is not a new problem, Innocenti knew all about it but there is little room to improve the thickness.
A "rivet type" crownwheel.
Note the bottom two rivets are missing.
These were found in the gear-box.
Apart from this the rest of the engine was it top order when we stripped it down.
Sometimes all the rivets shear and the clutch stops working.
This is why we recommend the solid GP type crownwheels.
Melted and cooked big end bearing failure from a Suzuki Katana.
An expensive outcome from nor using any oil to lubricate the engine. It also took out his cylinder and piston.
Even Vespas seize up!
This is an SS180 piston, there is not a part of the piston that hasn't seized.
Perhaps it was run on chip-shop oil, who knows?
Jason from Absolutely scooters brought us this barrel so we could put it on this page.
It came off a non-running 200 import Jason had got hold of.
It is a classic example of what over-tuning can do to a barrel.
Some of the work is OK but most of it is not. This is a totally butchered cylinder!
The inlet port has been ground away so much that it had to be brazed back up.
Not knowing the history of this cylinder we don't know if it ever even ran.
The inlet port size seems to have a timing close to 200 degrees, so it probably didn't even start!!
The boost port fingers running up the bore actually do work, we have done them in the past.
Why there are holes in the transfers ports inside the bore we do not know.
In the back of our mind we seem to think a certain Italian who made his name with exhausts and seats may have had something to do with this barrel.
If run today with a modern race piston it may just work, but in the sixties when the pistons were crap it wouldn't have lasted 5 minutes.
Some of the thing we come across are beyond belief!
This was on an imported Series 2, from what we could see of it the cam was not worn, they never do - the brake shoes do.
It looks like the cam was brazed up to take out the play in worn brake shoes - strange but true!!
Mark had been writing an section on Lambretta electrics for the website, stating that it has been known for the Indian flywheels to come apart.
He was saying had been many years since he had seen one let go.
th_horror2.jpg - 12718 Bytes The next day a customer phoned to say his flywheel had exploded, taking out his mag housing, dust cover, head cowling and flywheel cowling.
Luckily it was in his garage and not on the road!!
th_horror3.jpg - 12412 Bytes A totally burnt out 4 plate clutch.
Absolutely cooked and black.
Most of the cork had come off the plates.
Shows the power of an MBD TS1 engine!
The only cure is a 6 plate conversion.
On the right are the shiny new plates.
This gudgeon pin came out of a running TS1 engine.
It's rare for us to come across this problem.
The hardened surface is breaking up which eventually causes the small end bearing to fail.
th_horror6.jpg - 10256 Bytes This picture shows what can happen to a high mileage TS1 piston.
If the transfer feeds were rounded off like Japanese pistons this problem would disappear.
It has been a fault in all Lambretta designed pistons.
This piston came out of a 22bhp touring tune top end. The engine had done over 10,000 miles with regular pistons changes during that period. (Just for safety).
It has toured all over Europe 2 up. Mark clocked the scooter at 85mph with the rider sat up whilst following in his van on the way for a dyno day.
In the 10,000 miles the scooter never broke down once. The cylinder and piston were brought in just to be checked. The customer hadn't even seen the cracks.
th_horror16.jpg - 10424 Bytes This picture shows the the next step of what would happen if the cracks in the TS1 piston hadn't been spotted!
th_horror17.jpg - 10397 Bytes It's obviously someone elses piston as we'd never knowingly let someone use a piston with cracks in!
This picture shows seize marks on a TS1 piston.
If they seize it's always at this point on both sides.
3 views of a GPM 3 ring 200 Lambretta piston.
This is why we never use them. The windows have broken off and it is seized everywhere. The skirt has cracked at all four corners.
This came out of a running scooter.
It has been known for the skirt cracks to go right across leaving you with a short piston!!
It has been known for Suzuki piston to do this also.
A customer rode his bike to us saying that it wasn't as fast as it normally was.
We revved it up on the stand to hear all sorts of ungodly noises, there was something terminal going on.
The exhaust was removed to look in the exhaust port, we found no piston skirt below the gudgeon pin.
It had all been spat out the exhaust without the customer noticing! The problem was caused by 18mm-16mm piston bushes wearing out which is why we don't recommend them anymore!!
We've only seen this happen 3 times.
It must be a fault in the forgings.
The scooter was still running - just!
This is the first time we've seen this, a crack through the gudgeon pin area of the piston.
Came out of a running bike, the customer caught it before it let go!
A GPM piston with seize marks all over as usual. We don't use them as they are constantly seizing. This is a Lambretta 175 conversion piston.
Ouch, the usual consequence of running weak!!
Sometimes Japanese pistons go wrong too! This usually happens with excessive piston to bore clearances.
This is (was!!) a genuine Yamaha piston.
th_horror16.jpg - 10424 Bytes Something we've seen many times before on Honda pistons but never on a TS1 piston. One of the ring pegs has been pushed over and one looks like it has been pushed in.
th_horror17.jpg - 10397 Bytes The customer (who also races a group 4 Lambretta) noticed a lack of power compared to normal so he stripped down his top end to see what was going on.
If he had left it the rings could have spun and jumped into the exhaust port destroying the piston and damaging the barrel.
Looking at the piston and knowing the customer we are confident in saying this was a faulty piston - there were no signs of any other problems with the engine.

Please E-mail us with any questions or comments.