December 2, 201213 yr Has anyone moved a triumph cub engine over to the left to give more chain,wheel clearance? I see the oil pipes on the bottom of the engine being a problem as theyd catch on the frame,do you lift the engine to get it across. Can anyone piont me in the right direction help me out regards Dan
December 2, 201213 yr Moving the motor will upset the left-right balance of the bike, which for most people is more important than gaining additional chain/wheel clearance
December 2, 201213 yr Has anyone moved a triumph cub engine over to the left to give more chain,wheel clearance? I see the oil pipes on the bottom of the engine being a problem as theyd catch on the frame,do you lift the engine to get it across. Can anyone piont me in the right direction help me out regards Dan The oil pipe union is easy to solve just cat away the frame. Then again the top cubs have the bottom engine mount removed and a new one welded on the rear of the gearbox then the bottom tube can be removed. Problem is if you move the motor too far over the exhaust stub on the head fouls the front downtube.
December 3, 201213 yr Dan, Look on the pre 65 forum. You will see some pictures of my Cub in one of my 'Tiger Cub' posts. I moved the engine over about 10mm (until the exhaust just cleared the downtube). I simply used spacers for the rear and bottom engine mounts. I also drilled the engine mount holes out slightly so I could use M10 bolts. You can bend the front mount over if you are careful but I removed mine and brazed 2 bushes in the downtube. I then made some ally engine plates and spacers to move the engine over. This looks a lot neater and makes removing the engine easier. Some people get away with just moving the back over a bit but you stand the risk of putting the chain out of alignment. Also, check the position of your sprocket as that may need moving over too! I made new wheel spacers. It's pretty tight but you can fit everything in........just! I also lengthened my swing arm to give more clearance for mud at the front, but that's another story! email me if you want some more photos. Bruce. Edited December 3, 201213 yr by brucey
January 22, 201313 yr Hi, I note the comment on disturbing the "balance" of the bike, speaking from personal experience with a B40 in an Otter frame, I have never seen an engine look so badly designed. There is no attempt at making the thing look balanced, I'm not knocking the performance of the lump, but was no thought given to making it appear concentric about it's centreline? Compared to my Honda tlr it looks ugly and lopsided. I knew there was a reason for choosing the Honda, it LOOKS like it was designed, not put together from spare parts. Could this go towards explaining the demise of an otherwise good industry? Sorry if this sounds like an attack on pre 65 bikes, but precious few appeal to me on design and construction grounds.
March 23, 201313 yr Hi Dan, Duncan Macdonald from Armac Design here. Not sure if you've solved this yet, but my advice is: all the extra effort to reposition everything is not worth the small gain you'd get by moving the engine. It is much easier and more efficient to offset the rear rim 3mm to the right which will give you the tyre clearance you need. Also you can widen the swinging arm on the right, if it hasn't already been done. Good luck!
March 23, 201313 yr Hi Dan, Duncan Macdonald from Armac Design here. Not sure if you've solved this yet, but my advice is: all the extra effort to reposition everything is not worth the small gain you'd get by moving the engine. It is much easier and more efficient to offset the rear rim 3mm to the right which will give you the tyre clearance you need. Also you can widen the swinging arm on the right, if it hasn't already been done. Good luck! Duncan so are you saying that keeping the wheels in alignment is not important?
March 24, 201313 yr Duncan so are you saying that keeping the wheels in alignment is not important? we are making compromises here, the fact is the cub sprocket is not far enough off the engine centre line to allow everything to be in the "correct" place an run a 4 inch rear tyre. Duncan's method is a simple solution, do you believe that triumph's frame alignment tolerances were better than 3 mm? moden superbikes are not much better, i really don't think a 3 mm offset when riding around at 3 mph with 5 psi in the rear tyre is a big deal.
March 25, 201313 yr Hi, Alan is exactly right: you can't notice the difference with a 3mm offset. A friend of mine (a wheel builder) had been racing a 650 Triumph Twin for a number of years and discovered that the rear wheel was 10mm out of line. He rebuilt it correctly, in line, and said he couldn't notice any difference. So with wheel alignment, although in theory is best equally spaced around the centre line of the bike, small offsets in reality make little difference, especially in low-speed pre-65 trials!. Cheers, Duncan
March 25, 201313 yr Interresting answer and contrary to everything I had been led to believe. I would hwve thought with the wheels out of line that the rear tyre would by definition be skidding to some extent instead of tracking in a straight line and I have enough problems making the tyre grip as it is without starting with a skid. Oh well you live and learn and the laws of physics obviously don't apply. Thanks Duncan
March 25, 201313 yr Interresting answer and contrary to everything I had been led to believe. I would hwve thought with the wheels out of line that the rear tyre would by definition be skidding to some extent instead of tracking in a straight line and I have enough problems making the tyre grip as it is without starting with a skid. Oh well you live and learn and the laws of physics obviously don't apply. Thanks Duncan Why would the rear tyre be skidding ? I know reliant robin's had many problems but although the rear wheels were a couple of foot out of line with the front, rear wheel skidding was not an issue....
March 25, 201313 yr Why would the rear tyre be skidding ? I know reliant robin's had many problems but although the rear wheels were a couple of foot out of line with the front, rear wheel skidding was not an issue.... ?? don't get you as on a 3 wheeler the front wheel and the two rear wheels all follow parallel lines. When a motor cycle has one wheel offset from the other for them both to track parallel lines the frame joining the two wheels would have to follow a diagonal line between the two parallel tracks of the wheels. If not and the frame followed a parallel or even same track as one of the wheels then one of said wheels must travel at an angle to the direction of travel and as such must scrub and skid. Just draw it out if you don't get it then you don't get it. Offseting the rear wheel would and could allow it to track parallel to the front wheel but it would have to be at an angle at the sprockets would then not be in line the rear would be at an angle to the gearbox sprocket and at the least would wear prematurely and at worst the chain could easily derail. Again sorry if you don't get it but try drawing it out and think it through.
March 25, 201313 yr Blimey, lot of chat about 1/8" ! The working centreline of the tyre must be wandering all over the place over different cambers and terrain, and the forks probably deflect more than that at the first sign of mud anyway
March 26, 201313 yr ?? don't get you as on a 3 wheeler the front wheel and the two rear wheels all follow parallel lines. When a motor cycle has one wheel offset from the other for them both to track parallel lines the frame joining the two wheels would have to follow a diagonal line between the two parallel tracks of the wheels. If not and the frame followed a parallel or even same track as one of the wheels then one of said wheels must travel at an angle to the direction of travel and as such must scrub and skid. Just draw it out if you don't get it then you don't get it. Offseting the rear wheel would and could allow it to track parallel to the front wheel but it would have to be at an angle at the sprockets would then not be in line the rear would be at an angle to the gearbox sprocket and at the least would wear prematurely and at worst the chain could easily derail. Again sorry if you don't get it but try drawing it out and think it through. Clearly you don't understand the term offset in relation to wheel building. What Duncan was suggesting was that you move the rim relative to the hub.The centreline of the rear rim will be slightly off the centreline of the bike but will track parallel to the front wheel. What you seem to inferring is that you misalign the rear wheel spindle so that it is no longer at right angles to the bike centre line. That is not what was suggested..
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