Transalp Engine Swaps
From GummyCarbs
Swap Candidates
The following engines should swap in with no modifications to the frame:
- Hawk NT650 (known as the Honda Bros outside the US market)
- Honda Africa Twin XRV750 (RD04 or RD07)
- Honda Transalp XL650V
- Honda Transalp XL700V
The Honda NT650V and NT750V Deuville motor will not swap in, because it's shaft drive. It may be possible to put the head and cylinders onto a Hawk engine. The Deuville EFI throttle bodies may be usable on a 52-degree Honda EFI conversion.
The Rotax-made Aprilia 60-degree V-twin engines might' be made to fit, but will require frame modifications. To my knowledge, this has never been done. One person on the Hawk GT Forum has swapped a Tuono engine into a Hawk and only mentions modifying the front engine hanger, but there are no additional details or photographs.
Engine Swap Details
Hawk NT650
Exhaust
- This post shows the difference in front exhaust port angles between the Transalp and Hawk engines.
The latest Two Brothers Racing exhaust 1-1/2" at the exhaust port, 1-5/8" through the curves, 1-5/8" at the collector, to a 2" tail pipe to the muffler.
Modification
The Hawk 650 still has great aftermarket performance support. Hord Power is the best known supplier and modifier in the US. Hord Power commented on the Hawk GT forums:
The order of building hp into a Hawk goes:
Stock 47hp
Pipe/3.0 kit/pods 52hp
700 kit/cams 62hp
Stage 1 heads 67hp
Stage 2 heads 72hp
Flatslides +5hp
Stage 3 heads 80+hp and $$$$$$$$$$$$$$$$$$$ and other $$$$$$$ stuff to make it "reliable."
XL650V
- Thunder Dan's engine swap. He put a 2003 XL650V engine into a 1988 XL600V.
EFI Conversion
Rather than trying to source and/or tweak carburetors, it's probably best to use one of the aftermarket EFI systems that are now on the market.
EFI Systems
- Megasquirt
- Microsquirt
- Ignitech
- EcuMaster EMU
Throttle Bodies
The 2003+ SV650 uses 39mm throttle bodies. The 2017 model's throttle bodies are redesigned and "slimmer", according to Wikipedia.
The NT700V was sold in the US. It had 81x66mm bores with a 10:1 compression ratio, producing 65hp at 8000 RPM and 48.8 lb-ft of torque at 6,500 RPM. It's in the same 52-degree V-twin family as the Transalp, Hawk, and Africa Twin. Its throttle bodies are 40mm with 12-hole injectors. It appears that the NT700V used a fuel pump that provided something like 45 - 50 psi.
Specification Comparison
| Displacement | Horsepower | Torque | Bore x Stroke | Compression Ratio | Induction | |
|---|---|---|---|---|---|---|
| XL600V | 583cc | 50 hp @ 8000 | 39.1 ft-lb @ 6000 | 75x66mm | 9.2:1 | 2x32mm Keihin CV |
| NT650 | 647cc | 56.1 hp @ 7897 | 43 lb-ft @ 6053 | 79x66mm | 9.2:1 | 2x36mm flat slide carburetor |
| XL650V | 647cc | 52 hp @ 7500 | 40 lb-ft @ 5500 | 79x66mm | 9.2:1 | 2x34mm flat slide CV |
| XL700V | 680.2cc | 59.1 hp @ 7750 | 44.3 lb-ft @ 5500 | 81x66mm | 10.0:1 | EFI 40mm throttle bodies |
| XR750 RD07 | 742cc | 62 hp @ 7500 | 46.2 lb-ft @ 6000 | 81x72mm | 9.0:1 | 2x38mm flat slide CV |
| Aprilia ETV1000 | 997.6cc | 98 hp @ 8250 | 71.5 lb-ft @ 6250 | 97x67.5mm | 10.4:1 | EFI 47mm throttle bodies |
Transmission Gear Ratios
| 1st | 2nd | 3rd | 4th | 5th | 6th | |
|---|---|---|---|---|---|---|
| XL600V | 2.571 | 1.777 | 1.380 | 1.125 | 0.961 | |
| NT650 | 2.769 | 1.882 | 1.450 | 1.174 | 0.965 | |
| XL650V/XL700V | 2.500 | 1.722 | 1.333 | 1.111 | 0.961 | |
| XR750 RD07 | 3.083 | 2.062 | 1.550 | 1.272 | 1.083 | |
| Aprilia Tuono | 2.26 | 1.63 | 1.3 | 1.09 | 0.96 | 0.88 |
| Aprilia Caponord ETV1000 / Falco SL1000 / Futura RST1000 | 2.5 | 1.75 | 1.368 | 1.091 | 0.957 | 0.852 |
The XRV's first gear is 20% lower, second is 16% lower, third is 12% lower, fourth is 13% lower, and fifth is 12% lower.