Keith Terry’s 118mph “road engine” Lambretta | FEATURE
Getting a genuine 100mph out of a Lambretta is a very difficult thing to do. It’s bound to be; let’s face it, a Lambretta isn’t exactly aerodynamic. Even with a cut down sprinter, it’s a struggle.
Yet there are an increasing number of foolhardy souls who set out to achieve this. With recent kit enhancements and decent “tuner friendly” casings around now, there’s never been a better time to try an attempt. Even so, there are still very few people who have achieved the magical ton, let alone on a sandy beach.
Who are these people? Well, Keith Terry (formerly of Kegra Racing in Southend) is one. He’s given SLUK an insight to his sprinting exploits over the past few months, on a veteran sprinting Lambretta with some bang up-to-date engine mods.
Indian cast origins
My sprint scooter, the Kursaal Flyer, has been around since its first build in 1991, originally using a tuned cast iron Indian barrel it has been quite successful and was developed over a few years. I sold the scooter some time in the late nineties, but I purchased it back in 2009 and decided to rebuild it chassis wise to as it can be seen today.
A few years back the big-end went at one of the Scooter Shoot-outs at Elvington and since then it had just been collecting dust in my garage.
CasaCase vs Methanol
At the beginning of this year the opportunity to try something different came along and now was a good a time as ever to dust the Flyer off. The opportunity was a chance to see what a modern fan-cooled tuned CasaCase road engine could achieve compared to my old methanol burning dedicated sprint lump.
High end spec
Well, let’s start with the basics, the engine we started with this year.
- Casa SS225 barrel kit
- Casa 64/120 crankshaft
- Casatronic ignition,
- 39mm smooth-bore Dellorto,
- Protti exhaust,
- Casa X44 chain tensioner
- Cyclone 5 speed box (added later in the season)
The engine was not brand new but had done very few miles, it was put into the frame and run up on JB Tuning’s dyno to give John a base figure and to see if he could extract more power with his own magic. By the time the first meeting approached John had released quite a few extra horses to push me up the runways we would be using at a greater rate of knots.
Straightliners, tarmac and sand
We would be attending Straightliners events and apart from a “one off” meeting to the famous Pendine Sands, all the meetings we would be attending would be at Elvington Airfield near York.
Windy first meeting
The first meeting was on the 20/03/2017. The scooter was fitted with a Pacemaker gearbox with a 21/46 primary drive setup. The weather conditions at the meeting were as good as we could get all year with a strong breeze in coolish conditions improving our push towards the timing gear. The meeting would not start till 1.00 pm due to early morning rain. All these non-record high speed meetings follow the same pattern; one mile from where you start there is some sophisticated timing equipment which will record the top speed over a small measured distance giving a read out down to three decimal places.
Five runs and a leg choke
We managed to do 5 runs at this meeting, the first four I experienced what I thought was either fuel starvation or flooding but I could not decide which, as the dyno figure jetting-wise had been very good. I managed to break the gearbox on the third run so we fitted an LI150 unit with a 20/46 primary drive. Regardless of the issues I could feel the potential in the engine but I was just unable to release it. The 4th run of the day was to be our best with a top speed of 112.168 mph even with a faltering engine. While waiting in the paddock for my 5th run, I sussed what the fuelling problem was. My old engine used piston port inlet where the new uses a reed valve, the newer inlet puts the carb a lot higher up and what I was doing during my run was to choke the carb with my leg when trying to tuck right in to the scooter.
With Mikey Bonett’s help we sussed a way round this and I would move my leg further back and rest my shin on the foot peg and leave my foot dangling by the tail pipe at the back. It was getting late and with building the foot peg up to do this we failed to think about the effect of my leg not choking the carb might have on the mixture!
Fifth run seizure
I think we had the cutting out sussed and the bike was really getting into its stride on the fifth run when at about 3/4 distance it seized, shame really that was going to be a quick one! That little mistake cost me a re-plate on the cylinder and another piston. This needed to be done ASAP as it was only three weeks until the next event. Another area I would have to work on was the brakes. The Flyer’s brakes have always been poor but the scrutineer was not happy with the thumb control front unit, so I had to fit the front brake back to its original design position and fit a left footed operated rear brake pedal unit.
Lighter side, biscuit gambling
There is always a lighter side to these sort of events. At any where Gav Watson is in attendance we wager packets of biscuits on the outcome. For this first meeting we had to predict our top speed before we started and it was placed into a sealed envelope and the rider nearest to their predicted speed wins. Even though my top speed was higher Gavin won because he was closer to his target speed.
Extra cog advantage
I knew from the first event that this engine had big potential for high speeds if everything fell into place on the right day. Now was the time to fit the 5-speed Cyclone gearbox. The engine came with the Casa close-ratio 4-speed box and even though the ratio changes into top are very similar, I thought tactically, it might be better to use the 5 speed.
Next meeting 11/04/2017
Barrel replated, dyno runs done, ready to go! We would get a good few runs in today as the conditions were favourable but not as good as the first meeting. We started the event with 20/46 primary on the 5 speed gearbox.
116mph…taller gearing needed
First run of the day a nice gentle cruise through with a top speed recorded of 116.348 mph. We decided it could pull taller gears so decided on a larger 100/90 rear tyre and fitting this would suffice for the second run. Even though there is plenty of clearance between the tyre and the casing, at speeds in excess of 110 mph the tyre grows and hits the crank case below the bump stop. I backed off this run as it felt like the back brake was on, but went through at 108.792 mph. To get round this we refitted the 350/10 tyre and upped the primary drive to 21/46 with a bigger front sprocket. With a few more runs we upped the top speed to 118.884 mph but I felt I could hear the engine pinking when working hard, we tried up-jetting and adjusting timing to cure this but was having little effect so we decided to call it a day and have a think about the issue. In less than favourable conditions, I was very pleased with the progress we’d made.
Chatting with John I think we came up with the solution to the pinking issue. With the stroked crank we have a 246cc engine and when revving quite hard, it pushes out a lot of hot gasses. These need to exit freely through the exhaust, or will cause unwanted heat build-up. We thought the solution lay in the tailpipe diameter. This was increased by a few extra millimetres to help the gases escape; a fairly easy fix from our local fabricator welder.
A run on the dyno showed no real loss of power with the wider tail pipe, which tuners might usually expect.
The next meeting was Pendine Sands on 13/05/2017. Run on the world-famous 7-mile long beach in Wales!
This meeting would require some special preparation as engines and sand do not usually mix well. After some investigation I fitted a Ram air filter over the carb to keep the sand out, but then covered this with a 4 litre milk container with the back cut out so it would pick up clean, still air (well that was the theory). I also manufactured a rear mud guard which ran from the engine to seat unit to protect the scooter from wheel driven sand. I left the same 21/46 primary on the 5-speed gearbox for this meeting.
Takes the biscuit
While lining up for our first run I am just behind Gavin, so there are more biscuits at stake. Another competitor informs us that’s its a bit loose down the other end! WTF that means I do not know, but I decide to take the first run gently to find out.
I can ride the Flyer in two positions feet forward but not with a very good tuck in, or feet back and get right down behind the screen. I decide on the former and see how I get on. Gavin was on his sprinter and as he went off he was having all sorts of handling issues – more like a motor crosser than sprinter and I was wondering what was in store for me.
Well I am pleased to say mine handled better than Gavin’s and I would describe the sensation as like aqua planing – I did not feel I was the only force controlling the destiny of my scooter. My terminal speed 86.995 mph on a standing start kilometre.
A ton on the beach
The bike was running rich so I down-jetted 5 points and decided to go for it on the second run with my normal feet back riding position. I was suffering the same issues as Gavin riding like this so reverted to feet forwards after about 150 yards. I pushed my speed up to 93.571mph. Two more runs and I was up to 98.516 mph but it was getting late and the tide would be coming in soon. I really wanted to be the first scooter to top 100mph on sand, given more time I would have put a smaller front sprocket in to compensate for the drag of the soft surface and the healthy cross wind. I lined up for my last run of the day and decided just to rag its arse in 4th to see if I could reach that magic 100 mph. Well, I’m pleased to say it did, with a terminal speed of 101. 441 mph and no pinking. Bonus, so the tailpipe mod appears to have worked!
This was a two day meeting but I could only stay for one but I got the biscuits from Gavin for highest top speed again! On Sunday Gavin changed to his full frame and over the longer mile distance he also joined the 100 mph club; well done mate.
Next meeting is the standing mile records meeting on the weekend of the 20th and 21st May 2017. This, like the previous meetings, is a one way west to east on the runway. We have settled into a pattern now and I am starting with the same primary drive 21/46 on the Cyclone five speed. The conditions were not ideal with a cross wind and clammy feel in the air; not the best for getting those high speeds I feel the scooter can produce. There were not that many riders at this one so we were able to do runs back-to-back apart from a fuel top-up and check, proving to me that heat build up is not an issue with cowlings on the sprinter.
The pinking, or what I thought was pinking has gone and the scooter is now able to flex its muscles a bit, but with the conditions as they were we got 114.842mph; a new standing mile one way record. We gave up with the conditions as they were I could not see us going any quicker.
Summer was now here and it’s not the time to go top speed hunting so its all on hold now till the next big event, the ACU @ UKTA records meeting on the 16th-17th September 2017 this is the pinnacle of the record hunter’s year.
Scrutineering and broken records
These records are based on two-way runs which will negate any wind assistance if it exists. The format here is to run groups of riders one way east to west then any in contention for a record are kept in an holding area then allowed to run west to east once they have changed the timing equipment. The return run must be completed within one hour of the first and apart from checking the bike over and refuelling, no adjustments are allowed. To qualify for ACU records the barrel must be sealed by a scrutineer and if successful he will check the seals are in place at the end, then the cylinder head is removed so a bore and stroke measurement can be taken to ensure conformity.
The wind this weekend was a strong cross-wind. This was slightly better on Sunday but Saturday it made riding the bike quite awkward. I started with the same set up as before 21/46 with the 5 speed gearbox.
The records for this meeting would be the standing start mile, flying quarter, and flying kilometer. The runway is 2 miles long and the distances are based around the halfway marker. Saturday was the flying quarter and the standing mile. There never seems to be any rush to get things underway and the meeting got going around 12.00. My first runs were not too clever with a slight seizure on a new piston on the return run which aborted that attempt. We cleaned the barrel up, refitted the old piston and we were ready to go again. The cylinder capacity was checked before the rebuild and resealed by the ACU official. The scooter was struggling in the cross wind conditions and not getting hold of top gear as I wanted it to and the way I know it can. Still not too bad with a new average speed for both directions on the flying 1/4 mile at 108.946mph, I must admit I was a little disappointed in the speed but this was still the fastest two-way scooter record on the books in the UK.
One of the mile markers failed to register a time so we did not register a speed, so no record but the mile would be in play Sunday so we would get another chance.
Assuming the conditions would be the same Sunday I discussed with Mikey how we would get round the wind issue, we decided that a subtle adjustment to the primary ratio should be enough, maybe sacrificing ultimate top speed if the wind came round to consistent top speed which is what we needed. We now have 21/47 primary with the 5 speed.
Because of my age I am struggling with the full crouch riding position so decide to start today with my feet forward style a sort of banker run, first run east west, mile 115.539 mph flying kilometer 111.333mph the return 110.599mph mile and 106.322 on the kilometer. Both were new records but ones I hope to improve later in the day. Then the rain came and to be honest I thought it was all over. With a cut off time of 5.00 pm I thought we were done, but in the distance the skies cleared so we hung on, it had stopped raining and the organisers were running vans and cars up and down trying to dry the course, even though not fully dry it was decided that the lower-powered bikes could have a go.
Bird feeder, now or never
I fitted my modified bird feeder on the carb (my anti-choking device) and we were ready to go, it was now or never. First run with full tuck 114.509mph mile and 111.285 flying kilometer; the gearing adjustment seemed to be working. Gavin made a big arrival in the holding bay, sort of sideways motor cross style! Something had broken in the rear end and the wheel was locked solid, this record-breaking stuff is not for the fainthearted! Time was marching on and only those with a real chance of upping a record would be allowed a return run, which was just four. My return run was timed at 17.00 and 42 seconds, giving me returning speeds of 115.266mph mile and 111.415mph for the flying kilometer!
New record, biscuit champions
My last attempts have set two new average speed records for others to try and beat in the future. 111.350mph for the flying Kilo and 114.887mph for the standing start mile. Team JB also secured the biscuits and I need to go on a diet now!
A massive thank you to John Balcomb and Mikey Bonett at JB Tuning and Casa Lambretta for building these engines to start with. Hope this will inspire others to get out there to give it a go.
Words: Keith Terry Pics: Keith Terry, Kelly Watson, Phil Evans & Steve McDonald
If you would like to see the Kursaal Flyer running, Keith is planning to take it to Santa Pod for a 1/4 mile event on Sunday 15th October 2017.
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