SX Refresh

[nsaints]

I always enjoy projects folk document here, so here's my effort

Not wanting to take on any new scooters as projects, this winter I'm going to refurbish my SX. I have owned her for approx 7 years, originally being imported by Gran Sport in Birmingham. She'd changed hands a few times until I bought her, having to drive to Surrey from Oxfordshire in a rented van to collect.
When picked her up she was mostly original. original paint, cables (original set including cable oilers), ignition etc, however the 150 top end had been tuned by Ron Moss, there was an old Dellorto square slide carb fitted, and a original disc brake.

Since then I have fitted a Chris Sturgess fettled GT 186 top end , PHBL25mm, breathing through a modified standard airbox and a BGM ignition. I kept the original ignition and the fettled SX top end, and cables just incase. Incase of what I have no idea

2019 the wife rode her to the IOW for the rally. I was hoping I'd convert her to a Lambretta rider, so I didn't have to restore her P2.
Whilst she really liked the SX, I still had the burden of the P2 to restore (2019 winter project)

despite running generally well on really hot summer days some clutch drag occurred, & I was never happy with the 'italian chain' (Lambretta paranoia)
The occasional dragging clutch maybe down the the clutch pressure plate design, being the less desirable series three type without the central guide, prior to Innocenti changing the design to the GP variant
the cables were a bit of a mishmash, different shades of grey (my bit of OCD here)
and the wiring loom is a bit crispy with age

So...I'm intending to sort the clutch (whatever is wrong). replace the chain with better quality, renew the cables, and the wiring loom
Plus anything else I find wrong that needs attention. I'll document my efforts and findings here

[Storkfoot]

That’s very nice. Please continue to keep us posted.

Is that the original paint in the pictures?

[nsaints]

Is that the original paint in the pictures?

Yes, whilst the paint in the pictures looks almost 'perfect'
Close up it does have a fair share of dings, scraps, bashes, and welding plus touching up.
As you'd expect given it's age and use

I have found the colour match of the paint to be fairly good from Lambretta paints in Liverpool

[Toddy]

agree with Paul keep us updated you can almost guarantee you will find something else to upgrade once you start good luck with it looks a lovely scooter

[nickw]

Looks a tidy scooter. Good Luck with the refurb.

[Hat]

nice. having owned my SX150 for coming up on 3 years i'll follow with interest

[citydaz]

Nice pictures.
Me too!, it would really twist my melon if my cables were different shades!

[Scooterslag]

Looks lovely, looks great in the original paint. what was the Ron Moss tuned 150 top end like? cheers Paul

[coaster]

Looks lovely, looks great in the original paint. what was the Ron Moss tuned 150 top end like? cheers Paul

Way back in 1970/71 I had the loan of a mates Li150 which had a Royspeed (Ron Moss tuned) top end, Roys 50mm big bore and a 30mm VHB Delly and that was a very nice ride. It was straight out of the box and I thrashed it town and country as only a 17 year old can and it was brilliant.....quite dissapointed when his dad made him take it back

[nsaints]

what was the Ron Moss tuned 150 top end like?

It was too long ago and I was too quick to follow the crowd and put a kit on it to be able to give any appraisal

However a fellow club mate borrowed the barrel and took some rough port measurements to copy to his own barrel
everyone in the club comments how well it performs

[nsaints]

Stripped the body work to allow me to route and fasten the cables correctly, and then out came old cables and wiring loom
I'll reuse as many of the old fixings as possible

I've cleaned everything with Gunk, allowed to soak and then washed off
New cable set with dummy oilers ordered along with a simplified wiring loom and ali cable fasteners

[dickie]

That's lovely. I don't think many would disagree with your approach; it's certainly what I'd be doing with something as original as that. I'm not a massive fan if rustorations, but I certainly love a preserved bike.

A few years back, I had a Chris sturgess fettled gt186 with phbh30 and bgm clubman which was lovely to ride. Only 17bhp, but a real joy.

[nsaints]

Inspecting the frame with the legshields removed and I've found a cracked weld to one of the floor struts.

I'll need to make arrangements to get the scoot over to the person who does my welding to get this fixed
whilst I plan this I'll start on the engine, and see what other surprises I find

[nsaints]

So to the engine..

A dragging standard clutch after use on hot days, which I've already diagnosed the likely reason as using a non GP pressure plate without a guide. I'd already sourced a new pressure plate with a guide
I also wanted to replace the new, but, cheap Italian chain with an IWIS. Not expecting any issues with the chain, as it's a GT186 engine using a standard airbox (sub 15bhp) just correcting some Lambretta paranoia

predictably found other stuff wrong


1: Buy cheap buy twice: Broken chain shells
didn't expect to find the chain bust...flippin rubbish you can end up buying today..Grrrr


2: pissed clutch spring
I've found the surprising reason for this..will explain later


3: slack gear selector arm

4: Heavily worn cheap, Italian, drive sprocket. same age as the chain (same supplier )
I'll buy a Readspeed sprocket to replace the one made of cheese

5: Clutch wear between the rear sprocket and the spider. Will need shimming to correct when I reassemble

[nsaints]

Here's the cause of the deformed clutch spring. It took a bit of figuring out.
This clutch nut washer has been recycled dozens of times, just straighten in a vice and reuse.

what was happening was part of the washer was overlapping one of the recesses in the clutch spider that the spring locates in. Not by much, but just enough to fowl the spring locating correctly, and over time deform the spring...contributing to clutch drag.

Tried a new washer and the problem doesn't exist.

Either a washer that's been recycled too many times or a poorly made part to start with - who knows

[Storkfoot]

So to the engine..

3: slack gear selector arm

Having had a bad case of this in the past, I would recommend replacing with the one piece GP type selector arm

[Warkton Tornado No.1]

So to the engine..

3: slack gear selector arm

Having had a bad case of this in the past, I would recommend replacing with the one piece GP type selector arm

Hmmm. Undoubtedly the GP type eliminates any play that could exist if the splines of the lever & corresponding rod splines are not thoroughly cleaned & assembled correctly. However, in decades of assembling gearbox selectors, I have never witnessed the return of any play (or slop) if a methodical approach is taken.

I reason that the only reason that the change to a one piece design came about was due to cost cutting excercises, not to some form of 'Goodwill' to the tinkering, enthusiastic end user many years after manufacture. I'd even go so far as to say that the practice gained popularity through racing & is documented in Dave Webster's tuning book which came about in the 70's. Since then we generally have all gained unwittingly far more knowledge of good engineering principles compared to those times when torque wrenches were a rarity in anybody's array of tools! I recall having to 'metricise' Imperial hand-me-down spanners by filing them to fit......

The significance of this may be very little, but the consequence is worth considering, within the scheme of things.

The ideology of an original "unmolested" Lambretta, if indeed that is the objective, must vary from one person's interpretation to another's. An example is the fitting of Indian electronic ignitions. Anybody that continues to argue that doing so improves reliability over OEM points ignitions must surely be naive, yet it still occurs in large numbers. Some of those that change the ignitions do not even appreciate the sole function of the woodruff key, which is only a positional location device, not something to endure torque because the tapers are not matched by lapping! On the other hand, whenever I assemble a GP endplate/crankcase cover, why would I utilise the OEM internal kickstart engagement control if I have the earlier components to hand? Reverting to the previous design is an enhancement to my mind.

I guess many of us follow the herd, but I get mixed messages from what some people are trying to achieve.

I'm being Devil's Advocate, I'm sure you will realise, as the last thing I would advocate would be for anybody to continue to use OEM tyres. Nor would I personally wish to have any of the large frame or Luna line without front dampers fitted because they not only improve the ride, but are instrumental in improving overall braking efficiency, which is all part of the vehicle control process, thus a safety enhancement.

I'm enjoying following your process of the build, so please don't think I'm in anyway being negative toward that

[Fast n Furious]

I just weld the two together. 2 dabs from an arc welder. Problem solved.

[nsaints]

Post by Warkton Tornado No.1 wrote:
please don't think I'm in anyway being negative toward that

No, not at all, I appreciate everyone's comments

So, I initially used a flexi-head spanner (restricted access) to just tighten the gear lever pinch bolt, however reading the comments I decided to do the job properly to save it coming loose in the future:
Stripped the wheel 'n' hub to get access.
Ensured the lever position was marked with a centre punch
Removed the lever and cleaned the splines on both the shaft and lever.
Replaced the bolt with one of the correct length (the existing was too short and didn't utilise all the threads in the lever)
Ran a tap down the lever threads to clean up
Loctite on the bolt and torqued the pinch bolt up

[nsaints]

Rebuilt the clutch removing the excessive clearance between the rear sprocket and the spider by using a shim. Luckily one I had in the spare box was just the right size
Fitted the Readspeed front sprocket, IWIS chain and tensioned using a GT tensioner
Assembled the 4 plate clutch with MB springs and a pressure plate with a guide - hopefully no more clutch drag

Checking the clutch for operation
I use a method I read on MB site which works for me, compress the clutch 1.5 turns of the clutch compressor to stimulate clutch operation using the clutch lever
confirm the plates separate with nothing sticking. If the operations is OK then we should be good



I have replaced the Scootopia clubman with a MB V4



Now I'm at a standstill not being able to get to the welder due to COVID restrictions
I'll revert to fitting a mid-range tank to the TS