Engine Differences?
- Thread starter Biiim
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Just about any carbed Triumph 900 triple should fit your frame. The differences between those motors is most likely internal, not external (possible exception transmissions). When Bloor took over Triumph he wanted his engineers to create 'bin' bikes that had interchangeable motors and frames as a starting point to get into production. That said there may be subtle differences between model years.
I have a 98 Trophy 1200 whose motor could bolt right into a 98 Daytona 1200 frame. The Trophy has about 98 HP and the Daytona about 147.
I have a 98 Trophy 1200 whose motor could bolt right into a 98 Daytona 1200 frame. The Trophy has about 98 HP and the Daytona about 147.
Biiim
Well-Known Member
Thank you ! They look the same externally so this makes a lot of sense. Part of me wants to do more research the other pert of me wants to pull the trigger and order this damn thing !
According to Hermys parts the engine case kits for the 1998 Thunderbird fit:
You can check their website and see if the model engine case you have is the same for different models. The basic difference would be if the transmissions are the same (5 vs 6 speed). Since it's a carburetted bike there isn't any injection mapping issues to deal with, just whether it bolts into the frame. If you can swap out like for like it's ideal but you may have to adapt some stuff if that's not possible. Good luck.
| Triumph Adventurer > 71698 | 1996, 1997, 1998, 1999, 2000, 2001 |
| Triumph Thunderbird Standard | 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 |
You can check their website and see if the model engine case you have is the same for different models. The basic difference would be if the transmissions are the same (5 vs 6 speed). Since it's a carburetted bike there isn't any injection mapping issues to deal with, just whether it bolts into the frame. If you can swap out like for like it's ideal but you may have to adapt some stuff if that's not possible. Good luck.
Biiim
Well-Known Member
Well I bought the legend tt engine. If I have to modify the mounting bolt hinges I will. Good thing I’m a fabricator !
Don't forget to post up pictures of the engine swap and any problems you encounter. Inquiring minds want to know.
triple trouble
Member
Going by memory (dangerous I know) all the engines were the same. Cams are the same on the Trophy, Sprint, Daytona etc. The intake rubbers are of smaller internal diameter on the “classic” bikes restricting the flow and increasing midrange torque but losing 10-15 horsepower.
Biiim
Well-Known Member
My buddy is visiting and the legend TT will be shipping out Monday so hopefully ina week we’ll be swapping! I’ll for sure post pics
Biiim
Well-Known Member
The legend and the sport engines look identical same w the mounting points. I’m 98% sure it will fit ! Not sure about the carbs but we’ll see! Might need to upgrade carbs
JCooper
Member
Oh, the carbs should be the same, too. Both had Keihins. Jetting is the same. The reduced intake rubbers were only on the early bikes with Mikunis. The only thing different is the TBS exhaust has a crossover tube. Supposedly this accounts for the advertised increased power output.
I think the output sprocket is the same on both, but I could be misremembering that.
You could just toss in the whole Legend package, trans and all, but you'd have to learn to shift one up and 4 down. Or mount the shift lever directly on the shift drum shaft and have to move your foot forward off the peg to shift.
I think the output sprocket is the same on both, but I could be misremembering that.
You could just toss in the whole Legend package, trans and all, but you'd have to learn to shift one up and 4 down. Or mount the shift lever directly on the shift drum shaft and have to move your foot forward off the peg to shift.
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The shift drum rotates in the opposite direction? First I've heard of this. After spending MANY hours in the FACTORY dealer service/workshop manual the only difference I could find in the first series Hinckley 3/4cyls transmissions, (mine is 1996 Thunderbird), is that in the "cruiser" models like Thunderbird they put a blanking sleeve in place of the 6th gear- why?- who knows! Without an extensive part number search- and now that you've aroused my curiosity, I'm going to do just that. The specifications info in the factory manual shows that (IIRC) with the exception of the Tiger model, gearing is virtually identical.
And...the stock engine in a Legend will be down in HP from a TBS- from memory about 15HP- due to intake boots, exhaust differences, likely camshafts, etc, etc, and the BIG one- the igniter, or ECU. Different part number, likely different ign timing, etc. Just how interchangeable ECUs are- I don't know. But a failed pick-up coil last season led me a way down this path and ECUs are $$$$$$!!!!
I would REALLY like to know more on this- I bought a complete Sprint 6 speed transmission, (same year, 1996), to address issues with my Thunderbird; weak 1-2 gearchange, (bent/worn fork?), and that feeling of always needing 1 more gear at highway speeds- 80mph+. So please keep us posted!
JCooper
Member
Between the Legend and TBS, cams carbs, boots, igniter are all the same. (Even the black cylinders.) The only difference is the exhaust. Put that Legend engine in the TBS and it will magically have more power, or at least that's what the marketing department says. All Legends and all TBS have Keihin carbs. Your (early) Thunderbird has Mikunis. All Mikunis used a different boot with a restriction. Not sure why, or if you can use the later boots on the early carbs.
If your Thunderbird has a 5 speed then adding the Sprint transmission without changing the shift drum will net you a 5 speed. Five speed drums don't have the 6th position.
The TBS has a remote shift linkage and it makes the shift drum rotate the opposite direction. Lever up rotates drum CCW. The 6 speeds have an extra position on the drum, regardless of the direction of rotation. The TBS drum is unique within the Classic series. I recall the Thunderbird is also a 6 speed, but different drum and direct shift lever on drum. Lever up rotates drum clockwise. Regardless, you can use the parts in your current TBS transmission. The spacer was to save the cost of the unused gear in a 5 speed.
TBS 6th gear is very close to Adventurer 5th (IIRC) because they have different front sprockets. Legend 1-5 is the same as TBS 1-5. I went up one tooth on my Legend front sprocket, same as Adventurer. (I thought all the Thunderbirds were 6 speeds.)
All the gearing stuff is from memory, so I could be confused about which models are which, but the TBS is a 6 speed with CCW drum and the smaller front sprocket, for sure.
If your Thunderbird has a 5 speed then adding the Sprint transmission without changing the shift drum will net you a 5 speed. Five speed drums don't have the 6th position.
The TBS has a remote shift linkage and it makes the shift drum rotate the opposite direction. Lever up rotates drum CCW. The 6 speeds have an extra position on the drum, regardless of the direction of rotation. The TBS drum is unique within the Classic series. I recall the Thunderbird is also a 6 speed, but different drum and direct shift lever on drum. Lever up rotates drum clockwise. Regardless, you can use the parts in your current TBS transmission. The spacer was to save the cost of the unused gear in a 5 speed.
TBS 6th gear is very close to Adventurer 5th (IIRC) because they have different front sprockets. Legend 1-5 is the same as TBS 1-5. I went up one tooth on my Legend front sprocket, same as Adventurer. (I thought all the Thunderbirds were 6 speeds.)
All the gearing stuff is from memory, so I could be confused about which models are which, but the TBS is a 6 speed with CCW drum and the smaller front sprocket, for sure.
Good info! I worked as mechanic in Triumph dealer- 1995-1996, so no experience after early '97 model year. Quite a few changes were made in 1998 model year, including the addition of the TBS with the 6 speed. The early 1995 Thunderbirds had the square section swing arm with the eccentric chain adjusters (maintained wheel alignment!), and the access panel to sprag clutch, (deleted for 1996 model year), and ALL Thunderbirds up to end of 1997 M.Y. had the 5 speed transmission- a blanking sleeve was fitted instead of the 6th gear. Using "Hermy's" Triumph part listing- the following; changes were made starting at engine number 156499,- shift forks are the same for 5 and 6 speed, (all use same part number), shift drum for 6 speed TBS is T1190355- T0301, earlier 5 speed shift drum is T1190460. Selector shaft is different- up to engine number 156498-part number is T1190035, starting with engine 156499 shaft number is T119091.
I can see now that I need to spend more time looking up part numbers!!
My 1996 Thunderbird, (engine #T033843), is a 5 speed- bought as a wreck with a weak, but usable 1-2 gearchange. Be gentle- works fine- be rough- sometimes misses 2nd. Figured it was bent or worn shift fork. Bought complete, VERY low miles, near zero wear '96 Sprint 6 speed transmission for a song- since 2nd/4th shift fork NLA, figured use for parts, fix 1/2 gearchange, possibly swap in 6th gear. Not 'broke enough" yet, (about 3-5k miles year for about 5+ years now!) to warrant the BIG PIA to fix it.
Biiim
Well-Known Member
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Triplet
Member
You can literally drop in a 4-cylinder 1200. The only issue might be sorting kickstand from a Daytona? It’s been done before. Imagine bolting in 147 hp!!
The 4 cylinder is almost identical +1 jug. Almost all parts are interchangeable less obvious like head gaskets etc
There have been two others I’ve seen who have done this. I came very close to doing it myself. If I come across another TBS or High Spec Daytona w damage cheap enough I’m likely doing the same thing.
The 4 cylinder is almost identical +1 jug. Almost all parts are interchangeable less obvious like head gaskets etc
There have been two others I’ve seen who have done this. I came very close to doing it myself. If I come across another TBS or High Spec Daytona w damage cheap enough I’m likely doing the same thing.
Biiim
Well-Known Member
That would be fun as hell to
Ride !
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