Specification first. @Paul Weeding took my very worn 1700 Type 4 and did a full refurb on it as follows: Keeping the original stroke, the case was line bored and the crank reground. 1800 heads polished and ported with new valves and guides. Eurorace II cam. 96 mm barrels and pistons to raise the capacity to 1,911 cc. Twin Weber DCNF 40s + K&N filters (used, supplied by me). 400 miles after rebuild, this gave 102 BHP (corrected at engine) at 5,000 rpm. The power and torque curves were quite steep with not a lot going on at the lower end of the rev range! I ran in this configuration for about 6 months and 2,000 miles. The good point was strong acceleration especially if revved a bit, but fuel consumption was a disappointing 18 mpg, it tended to run hot (115 degrees when cruising gently in cool weather) and wasn't happy at less than 2,000 rpm. I also had a strong smell of petrol from the vents, suspected to be the carbs. With a few oil leaks as well as the oil temperature, the van went back to Paul. He sorted out the leaks and installed a secondary oil cooler in a scoop under the van. To go with the extra length of cooler pipework, he also uprated the oil pump to 30 mm (from standard 26 mm). The carbs were rebuilt to solve the petrol leaks. At the same time, I got a used gearbox refurbished with a longer (2 litre) final drive and longer 4th gear as cruising speed was very noisy with the original ratio giving around 16 mph / 1000 rpm in top. The new setup has not been in that long, but with a trip to Italy thrown in, it has covered over 2,000 miles in not much over a month. Performance: Even with the longer box, the engine pulls 65 mph easily on a hill and was only a problem on some of the long steep hills we encountered in the Alps this summer, especially as the performance did drop off a bit at high altitudes. The big issue is that if forced to slow down due to other traffic, it can be a struggle to get back up to speed on steep hills due to the lack of bottom end torque. This was 5 up with luggage. Gearing: Although the gearing makes the 3rd - 4th gap quite big, it has made a huge improvement in noise when cruising, raising the ratio to around 20 mph / 1000 revs. Fuel consumption: Sorting out the leaky carbs and raising the gear ratio has improved the fuel consumption to an average of nearly 24 mpg over an 1,850 mile trip with multiple large climbs and at a cruising speed of 65 mph. Oil cooler: The additional oil cooler means that the temperature now sits at around 90 degrees cruising at 65 mph. Long uphill spells raised this to 100 degrees and I saw just over 110 degrees on a few occasions on steep climbs at high altitude when the engine was really working hard. Drawbacks: The engine does not pull well below 2,000 rpm, but that's hardly surprising for a short stroke motor in this state of tune. Adding the longer ratio box has shown this up even more and any future improvements will be directed at this area. I'm not convinced that the rolling road set up was a great job and maybe a better state of tune would help.