I think unfortunately you lose the kickstart ...
If you are prepared to take the engine apart, last (best) version of the Triumph 5-speed gearbox are available new and used.
Multiple Bent Pushrods
- Thread starter Woollybandit
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Lordmac
Well-Known Member
Dang! I looked at the folder I have of this gearbox and have no links to the source. Probably an internet search would produce something. I tell ya, the other photos are also amazing to look at. This thing has its own custom castings and everything. A real beaut! As I recall, this thing cost more than my Triumph when I bought it new.
Lordmac
Well-Known Member
THAT looks to be true . . . looking at the gearbox outer cover which has a PLUG where the kickstarter aughta be. But that makes no sense; what, a guy is sposed to push-start the bike? Still, the idea of a six speed is cool by me.
I think unfortunately you lose the kickstart ...
If you are prepared to take the engine apart, last (best) version of the Triumph 5-speed gearbox are available new and used.
Well, two things:
First, does the 5-speed tranny fit in the 4-speed case?
Second, are there different ratios available, so you can have a true overdrive 5th?
Lordmac
Well-Known Member
T140V General Data says: Gearbox (5 speed) Internal ratios 5th (top) 1.00 : 1
Not overdrive. But if yer cruizing around at 10 miles an hour in 5th gear, yer engine is turning 627 rpm . . .
Yes. History is: first made by Rod Quaife during the 1960's for racers to replace the 4 speed; Triumph used it in the 650 production racers; fitted to the triples built for the 1970 Daytona 200; 71, AMA stipulated any engine part for racing, at least 200 must be made available to the general public, Triumph interpreted that as it must make 200 Tridents and 200 Rocket 3 (originally used the same 4 speed gearbox as the 650); Quaife was not then geared up for mass production so BSA bought the rights; intention had been to use triple engines for all types of US racing but they proved unsuitable for any off-road racing; factory riders reverted to 650 4 speed twins for off-road racing; mid 1971, Triumph made 200 T120RV to homologate the gearbox in twins to reduce the deficit for factory riders against other teams; 72, Triumph fitted the 5-speed to triple and 650 twin road bikes on/off while they debugged it, finally fitting it as standard from about March 1972 afaict.
No. 5 speed first is lower than 4 speed first so, if you are gearing up and still have good acceleration in first, overall gearing in fifth will be quite high?
The 6 speed is intended for racing, racers push-start.
Nova? If so, it will not fit a 650 (or triple).
Bummer. Well, ultimately it doesn’t matter, as I’ve got the R100RS for freeway duty. But would’ve been neato…
Lordmac
Well-Known Member
Agreed. That is strange. I might have thrown-in for a stuck valve, or two (which I have had happen before, in a Honda) but three? I am scratching my head on that one. I am still, however, betting on stuck valves because that would explain the bent rods even if the adjustments were correct, and, the engine would still run (poorly) whilst the rods are being bent until they finally become disengaged. I don't know, it's weird . . .
speedrattle
Well-Known Member
side note, on ratios think about the gearshift sprocket. stock on my 1972 T120 was 19/47, which is a buzzy ratio that doesnt allow for freeway cruising at modern speeds.
i have cut three T120 chaincases for 21-tooth gearbox sprockets, and love them. the 21 will force you to use the gearbox through the lower speeds, but first gear becomes something useable in traffic, and high gear allows you to cruise along at 75-plus.
on a five speed, first gear does nothing except move your the first twenty feet. a 21-tooth sprocket is the way to go, unless you are running on dirt or in green lanes.
i have cut three T120 chaincases for 21-tooth gearbox sprockets, and love them. the 21 will force you to use the gearbox through the lower speeds, but first gear becomes something useable in traffic, and high gear allows you to cruise along at 75-plus.
on a five speed, first gear does nothing except move your the first twenty feet. a 21-tooth sprocket is the way to go, unless you are running on dirt or in green lanes.
So: more detail on this operation, please, because you’ve got me a little excited. I am running a 20-tooth up front with a standard 47-tooth at the rear. It’s better than the 19/47 stock combo, but you’ve got me going here!
First - are you talking about just opening up the hole shown in this picture a smidge to be able to slide the 21-tooth in there, or is there more to it than that? If it’s just opening up this hole, will I have to do any mods to the cover and gasket, or just seal it up as usual?
Second - what is the part number for a 21-tooth sprocket that will fit the ’71-72 T120R? The only one I can find is 57-4782, which KM Jones indicates is for the 5-speed. Will that fit my T120R 4-speed, or is there a different number?
