Triumph Twin twinshock trials bike.

The Llangollen trial is also on the same weekend as the Llanfest bike show, and one of the sections was to be in the arena of the show itself. There are 30 sections in total, but joined by some of the best green lanes the area has to offer, and was one of my favourite events of last year. This year didn't disappoint.
Section 1, which I got through clean.

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Not sure what number this is, but I do know that it was a lot steeper than it looks. I ended up with a 3 after I got off line immediately after the photo!

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And this one was a 5. My front wheel should have been a foot further right (as I am on the bike) to make the left turn up the bank. It wasn't, and I didn't.

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This was the last section of the day, launching the bike out of the stream with too much throttle, I very nearly overcooked it!

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A great days riding. The new forks were ready to go in, and I had picked up a few ideas from various people at the trial for little tweaks to improve the bike still further.
Mark
 
I tried my mates C15 with his new REH forks last week and it steers/rides very well
 
Very timely intervention there Tim. :D
After being away on holiday for a week with the family, I was eager to get the new front end sorted. The forks really are a work of art, and with them fitted I was pleased with how they felt bouncing it up and down in the garage. I nipped to the stables for an afternoon, with a mind to try and get the jetting better as well. The bike felt brilliant, the forks made the rear feel a lot better as well, the whole bike was now more supple over roots and such. I also got the jetting so that the hesitation I had just off idle was now further up the rev range, at about 1/8th to 1/4 throttle. At that point momentum took care of it so I was very pleased, I now had smooth control at next to no revs, and she pulled beautifully through the hiccup. My next problem might be fuel consumption, as it was very rich from mid to full throttle. Not my greatest concern, unless in a road trial......

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A better test would be at one of the practice grounds, so I rang around to see who was free for a couple of hours at Kynastons farm. Timolgra was keen to see how his hand would fare, as well as trying the Twin. Mark Newman had also been working on his Twin, so was looking forward to comparing notes. The photo Tim took shows three Drayton framed bikes, mine and Mark's Twins, and Tim's BSA C15.
My suspension felt superb over some of the rocky sections we practiced on, and the jetting meant I could find grip on snotty banks with ease. But Mark's didn't have the hiccup. :confused:
One theory put forward was that my timing might be a bit too advanced, and as that is fairly easy to change, I made a mental note to look at that next.
Mark
 
Thanks for taking the time to write that up, it's fascinating to watch a bike come together.

It's a beautiful thing too - I can see a few other folks drifting towards the pre '65 scene, the bikes are just so full of character. Enjoy it!
 
Just rediscovered this thread Mark. Looking and sounding good.

You mention a Kev Ellis, there was a Malcom Ellis riding when i was into Pre 65 and he was pretty good as i remember;
IIRC he rode a Royal Enfield, just wondering if their is a connection.

It's just come to me, it was Stan Ellis not Malcom.
 
The comment about the timing being a little out stuck in my head, and wanting things to be perfect, I set about adjusting it.

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Remember this picture? If you ignore the orange gasket and look at the three studs that the stator is mounted on. Notice that the stator is at the end of the adjustment in the slotted holes, and to retard the timing any more, the stator needs to be turned anti-clockwise. Not a problem, thinks I, the rotor is on a taper lock, not a woodruff key so if I loosen the nut slightly I can tap the rotor round. You can see where this is going can't you? I had taken the plugs out to turn the engine over earlier, and using my clutch holding tool to give me enough purchase, undid the nut holding the rotor on. I had a pair of vise grips set to a similar size to the hex on the rotor and tried to move it slightly clockwise, only 5mm or so........
Well the fu*king thing slipped, the rotor came off the shaft, and my pressure on the clutch holding tool was enough to put half a revolution on the engine. Bugger. Well and truly back to square one.

Mark
 
Bugger :blast that's your Saturday morning spoken for, see you Sunday for the trial?
 
The first thing I needed to do was to get the timing back to where it had been before. This accomplished, with the rotor and stator lined up so that there was adjustment available to save me going through the whole excercise again, I set about retarding the ignition a degree at a time. The old school measurement is apparently to check how many mm down the piston is from BTDC, which everybody told me should be 1.6mm. Mine is now at 1.2mm BTDC, and has softened the response some more.
One of the other riders who had taken the bike for a spin felt that a bigger pilot jet, and/or throttle slide would richen the lower end without making the top too rich. All of my previous experience with jetting off road bikes (admittedly two stroke motocrossers) has been trying for as lean as possible, to get that elusive "biscuit" colour on the plug electrode, and a sharp throttle response. All the advise I'm being given at the moment is to make the bike as rich as possible to soften the response. Makes sense, but goes against the grain!
Each of these adjustments have been made seperately, and then the bike used in a trial, to make sure I'm not confusing the issue. As this rambling report is not exactly linked to a timeline, I have done quite a few trials, with varying degrees of success, in between these posts. This shows up any other failings in either bike, or rider.
As I mentioned earlier, I was using a standard 520 chain, as there wasn't enough room for an x or o ring version. Given the conditions this is operating in, it soon stretched, and started to jump the rear sprocket. The first time this happened caught me quite by surprise at the top of a sharp bank, as I was preparing to turn right. The sudden loss of forward motion pitched me sideways down the bank, complete with a lump of hot, heavy British iron. Thankfully we parted company before the bottom! Once again I heard an metallic "ping" as I fell, and quickly scanned the bike for what had broken now.

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She'll never win a beauty pageant if I keep knocking chunks out of her!

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Lots of tinkering with a laser line and a straight edge confirmed that yes, I did have the sprockets lined up, but if I have one snail cam adjuster set a notch before the other, the chain stays on. Go figure? :nenau
A better fitting chain guide stops as much mud getting onto the chain, which also helps.
Bringing us neatly up to the present, two successive trials, and each one getting closer to what I want. I have gone back to the Intermediate route, so the sections are that bit tougher, but I now feel I have the bike performing more how I want. The deficiencies are now down to the nut holding the bars.........:D
Thank goodness Timolgra didn't have his camera with him for the last trial though, as section 5 could have produced a front page shot.
Mark
 
Thank goodness Timolgra didn't have his camera with him for the last trial though, as section 5 could have produced a front page shot.
Mark

Lesson learnt Mark:green gri, in fact considering using my GoPro so I couldn't miss such a spectacular dismount, unfortunately it would've also captured my two flights over the handlebars on Saturday :blast:D
 
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Mark Newman, of the maroon coloured twin fame, had just finished helping put together another twin for one of the club founders. He brought it to the last trial for a test run. I checked it over for things that might be useful on mine. :D

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This picture taken by Timolgra's wife, Ange, who was observing the section. Very brave of her, considering my history of launching bikes at observers!
The last couple of events have been marked by a considerable amount of smoke from my bike, getting steadily worse. A sweepstake of the various expert opinions all so common in classic trials came to the conclusion that the valve guides were shot. After the trial (April 1st) I set to with the spanners again.
Mark
 
The great thing about competing on the Pre 65 and Twinshock circuit is that you are rarely short of something to do on the bike. Some people might view that as a less than good thing I suppose. Even if you haven't broken or worn something out, there is always a new idea, or a rehashed old idea to try. We'll come to that later, but for now lets strip the top end off again and have a look.

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Tank and seat off.

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Taking the "silencer" off was harder than expected, because some muppet had fastened the chainguard over the bolt.

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And removing the rest of the exhaust system required some gentle persuasion.

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Carb off.

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Rocker covers.

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And this is what the cylinder head looks like inside! Ugh.

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I know the rings haven't done that much, but seems silly not to have a look while we are this far in.

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So with the pistons and barrel off and on the bench we can have a look at the ring gap and general condition.
Mark
 
Good job Mark.....did someone mention Tiger Cub low compression pistons? .......
 
More than one person Tim, and also machining 3mm off the standard pistons. I'm really not sure about that idea, so will keep it as it is for now.
Mark
 
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I was concerned to find that the rings were well worn, after what I would consider a very short time. One of the things that had been worying me about the bike was the state of the oil. There is only a mesh strainer in the sump plug, and despite me changing the oil regularly, it was often very dirty. One theory was that a modern oil would be washing the dirt out of the crankshaft sludge trap, but without splitting the cases I wasn't going to be sure. Rather than go to that trouble at this stage, I decided to fit an in-line filter.

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The head I sent to SRM engineering in Aberystwyth, who have an excellent reputation though are certainly not the cheapest. Whilst the barrel was off, I cleaned it up and painted it to smarten things up a little, then gave it a light hone ready for rings.

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New piston rings arrived within a couple of days, so without further ado they went in, and the barrel back on.

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Mark
 
SRM had the head back to me within 10 days, on a Friday, which I was pretty damn pleased about. Almost enough time to have it back on ready for Sunday's trial. If I spent all Saturday in the garage instead of going out on the road bikes with Denise.........:green gri

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With the time I had available I managed to get the bulk of the top end back together.

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Just the exhausts to slip on and we're nearly there.
Mark
 


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