Triumph Twin twinshock trials bike.

I still have a Whitehawk 175, which will be pressed into service this weekend. The Pre 65 bit of the Twin is just the engine, and bits of that are brand new! One of the engine specialists whom I was discussing my plight with claims that modern piston rings (made for classics) are made of cheese, and he replaces them after six months/when it starts smoking, whichever is sooner. My engine is being collected today, so hopefully will know more soon.
Mark

I recently bought a whitehawk 175 and im just not getting on with it, It possibly is too modified, I prefer my 250 twinshock, which is a lot heavier but maybe just suits my riding style better.
 
Proper soft dab in the second clip. Well done
 
Proper soft dab in the second clip. Well done

Yes Steve, my sentiments exactly. That was the first section of the day, and where I had that dab there was a deep wheel sized cleft just to the left, which was playing on my mind. Got a bollocking off my mate for that too.
Mark
 
A gentleman by the name of Bill Beveridge, well know in the trials world, agreed to rebuild my engine. He collected it on his way to Wales for the weekend, with the promise that by Monday evening I would have a full breakdown of what he had found, and what was likely to be the outcome. He had asked for the engine complete, so he could investigate for himself the problem. When he collected it, he asked what I had filled the distributor hole with. I told him I had made it into the breather, with a metre length of tube with a swan-neck in it. "But did you know that it can suck when you are engine braking?"
"Erm, no", says I somewhat sheepishly. This explains the grit and such that I have been finding in the oil. Bugger.

True to his word, Bill rang me at 9.00 on Monday to tell me that the head, barrel and pistons were off, but he was currently struggling with the timing gear which was stuck on the crankshaft. The rings were worn again, the little ends were loose (in fairness, they weren't that tight when I put them back last time, I didnt realise they were a press fit. :blast) The timing gear bush, and the big end on that side were all worn. So far, so expected.
At 1.00 he rang to say he had got the gear off, and that I was very fortunate, as the crank was good. A new gear was needed, as the threads inside were stripped, but the crank threads only needed dressing.
At 6.00 he rang to say everything was apart. I had a crack in the clutch case, and it was also the wrong one. This explains why it was so difficult to seal. he is going to fix that. There were also two old cracks in the bottom of the crankcase, which he is also going to repair. He has a couple of options that he is exploring regarding which pistons to use in the reconditioned lump, and is seeing someone on Tuesday to finalise that. A different breather, the same as the other three twins that he has worked on, will be added. He expects to have it all back together for me in a week to ten days, depending on parts.
Not expecting the final cost to be cheap, but I will at least know the engine will be as good as it gets.
Mark
 
A selection of photos from the engine rebuild.

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Mark
 
After numerous phone calls to discuss his findings, and my options, Bill dropped the engine back last Thursday night on his way to North Wales. The bottom half has been rebuilt with all new bushings, numerous cracks welded up and bolt holes helicoiled. The distributor hole has been plugged and a new breather positioned to exit through the clutch casing. If you look back to post #6, this was how the engine breathed when I got it. :blast
Bill has lowered the oil drain hole to save having too much sloshing around the clutch case. He has done some welding work on that also, repairing a couple of cracks and trying to give more overlap to help it seal.

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The lump ready for refitting.

Sadly for me, Friday night and most of Saturday were taken up with domestic duties, moving furniture and boxes out of Denise's place. I did however get an hour on Saturday afternoon, so made a start.

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Almost in.

With some slit hosepipe on the frame rails, I lifted (!) the engine into the frame and let it rest in the cradle. The front and rear engine plates help lift the engine up, but it is the bottom bolt that is the most difficult to get in, as it lines up two bosses on the frame, the centre lug of the crankcase, and two spacers, all with a nine inch long length of threaded bar. Now it is a lot easier to get the threaded bar in if you have previously removed the gash bolt that the engine builder has used to hold the crankcases together for transit! Tossing my pry bar aside in disgust, it bounced off the trolley jack, which gave me and idea.....
Loosening the front and rear plates enough to give me clearance, the trolley jack between the rails lifted the engine allowing me to remove the offending bolt, and then lower it into position to slide the threaded bar in easily. Then it was back to furniture removals.
Mark
 
Next day and straight into the garage! With the bottom bolt in place, the remaining engine mounts could be tightened up. Reconnected the oil pipes and positioned the filter, which I had renewed and changed the O-rings in whilst the engine had been away. The carb slipped back on, the rocker oil feed then the exhaust. My new secret weapon for exhaust instillation is visible in the photo, a soft plastic dead blow mallet helps things go together easily. :D

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The stator was next, taking off the clutch cover and setting the timing as I last had it. Bill had reminded me that the clutch and tappets would need checking as he had just put them in loosely, so I tightened the springs up to roughly where they had been and went through the tappet adjustment procedure. Shiny new drivechain and that side is done. Round to the other side and refit the clutch cable, starter return spring and the outer gearbox cover, carefully adjusting the clutch pushrod at the same time. Gear lever, kickstart, air filter all bolted back on and time to put some oil in. Tank back on and filled up, and outside for a try, fingers crossed!

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After flooding the carb I barely leant on the kickstart and she burbled into life as though she had never been touched! I was somewhat surprised, as I had expected some reluctance. Quickly checking around for leaks, I was pleased to see the oil return flowing strongly after a few seconds, and cracked the rocker nuts to make sure oil was getting up to them. There was a slight leak from one of the oil filter unions, which stopped with a nip, and a couple of weeps from the clutch casing. I had put this together with a paper gasket for the moment, once timing and clutch adjustments have been finalised I will seal it with Loctite 510. Very pleased, I rang Bill to tell him the good news.

Mark
 
And here is a video clip off FB, which sounds a bit rattly to me. It doesn't when you are next to the bike.



The pistons and the bores were surprisingly well within tolerance, so Bill polished them up and put new rings in. He has suggested that I might be running a bit too rich, and the fuel is washing the oil off the bores, accelerating the ring wear. I will be trying to address that this Saturday (hence not sealing the clutch cover yet, in case the timing needs a tweak) before entering Gresford Club's Llansilin trial on Sunday.

Mark
 
As it was dry when I got home from work, I took the bike out for what was supposed to be a five mile spin to bed things in. Turned out to be a two mile spin followed by a two mile push. :(
The loss of tune, followed by glowing header pipes, followed by loss of spark, had me very concerned :eek:. The push back gave me plenty of time to ponder, until I realised what the symptoms were pointing to. I hadn't, had I? :nenau
Whip the clutch cover off and lo and behold, I had. Some muppet hadn't tightened the rotor nut on properly when he set the timing. :blast
Anyway, the oil needed dropping, and at least now it was warm. :augie
Pillock.
Mark
 
As it was dry when I got home from work, I took the bike out for what was supposed to be a five mile spin to bed things in. Turned out to be a two mile spin followed by a two mile push. :(
The loss of tune, followed by glowing header pipes, followed by loss of spark, had me very concerned :eek:. The push back gave me plenty of time to ponder, until I realised what the symptoms were pointing to. I hadn't, had I? :nenau
Whip the clutch cover off and lo and behold, I had. Some muppet hadn't tightened the rotor nut on properly when he set the timing. :blast
Anyway, the oil needed dropping, and at least now it was warm. :augie
Pillock.
Mark

Wish I'd been there :D
 
I had two jobs to do on Saturday, one was sort the jetting on the Triumph, the other was to try to talk some sense into a teenager. Hmm. :augie
After my ill fated test run earlier in the week I had reset the timing to where it should have been.

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This picture shows the new drain holes in the crankcase to allow the oil that gets into the clutch case to flow back to the sump.

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With the bike running as it was set before the rebuild I went to the old stables with my Amal box and a notebook, along with aforementioned teenager and the Beta.

Imagine the scenario. You are rolling down a bank, off the throttle and on the brakes, then at the bottom you have to make a full lock turn and back up the bank (without planting a foot and pivoting around it on full throttle, wrong sport!) This is the test, too sharp and you push the front past the turn, any hesitation from the bike and you stall and fall on your ear. Smooth transition from nothing all the way through the range is the idea. The "science" of Pre 65 fuelling defeats me. My original problem had been that the bike was too sharp at initial throttle opening, which was almost like a modern bike in its delivery. Modern bikes have a clutch that you can soften the delivery with one finger though, whereas the Triumph clutch needs two hands! I had tried to richen the mixture to achieve this, by putting in a bigger pilot jet, lifting the needle, and changing the slide cutaway, to little effect. One of the old hands said to put a bigger main jet in, but this to me should make no difference to the fuelling at the point where I was struggling? As usual, I was wrong, and to get the off idle response I was looking for I went up to a 160 main. This left the plugs looking like they had been dipped in tar, and the left side shock with a black sooty stain every time I rode it, but the bike continued to run, and the throttle was very gentle. But.....
With Bill's warning about the longevity of piston rings ringing in my ears, I put the next size down main in and tried it out. Finding that I could probably manage a bit more, I dropped to a 140. This gave me a slight stutter, but lifting the needle a notch cured that. All this over a couple of hours gave me the confidence that I needed. It helps that I have been riding it for a while now and have grown less terrified of it! :D


Beauty and The Beast.

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Which one is which depends on the day. :green gri
Mark
 
The perils of ebay. :blast
The gearing is ok for closed course trials, but for a road trial I struggle. The bike is revving its tits off at 30mph, which worries me greatly. There is lots of talk about "wide ratio" gearboxes, and how they are the Holy Grail as far as this type of application is concerned.
They don't come up very often though, and getting new ones made seems to be something of a hit and miss affair. Imagine my delight when a set came up on ebay, advertised as wide ratio, with a helpful diagram showing the number of teeth on each cog. No one could tell me the right number of teeth though, but as my bid of £250 was the highest, I became the proud owner.
Last weekend I found myself with a couple of hours to spare, so set about pulling the gearbox out. As it is what you would now call a cartridge design, it is a relatively simple job, and within a short space of time both main and layshafts with their associated gears are on my bench. Comparing them to the ones I'd just bought, they looked identical. So I carefully counted the teeth on each cog, then counted them again. Then counted the teeth on the ebay set to confirm that they were the same as the drawing.
Bollocks. They are identical. :mad:
One of the Pre-65 lot comes up with a page from a parts book that shows the teeth number on the standard cogs, which (both of) my gears are not.
Seems I have (two) close ratio gearsets.
Perfect.
Mark
 


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