During the last few track days in riding the 2020 Daytona 765 moto2, I was having trouble getting the bike to start, both cold and warm. When it finally started, it sounded like it was missing a cylinder for the first 30 seconds or so and I thought I was seeing a tinge of white in the exhaust for that first 30 seconds. The bike ran fine and did not seem down on power, my top speed was actually 1mph faster than what I’d seen before on the front straight (though I was braking slightly later too).
I’d already scheduled my bike to go to my local mechanic (P&M Motorcycles in Petaluma) when I brought the bike home for the Fall and Paul was going to do the valve inspection and a once-over on the whole bike. I described the symptoms and he and I had the same suspicion–a leaky head gasket. A few days later after doing a leak-down test and compression tests, they had the engine out of the bike and the head off and it was very apparent that there was leakage into cylinder #2 from both cylinders #1 & #3 and there was even residual coolant in the cylinder.
Okay, so obviously a head gasket is called for. Since we’re in this far, let’s do a new camshaft tensioner, cam chain, rings, and pull the cylinders and get them checked, as well as the head of course. By the way, all the valves were in-spec. Right next door to P&M is Engine Dynamics, an esoteric specialty shop that blueprints heads and engineers solutions to motorcycle heads that breathes some more magic into things. Since the head is off, may as well get it checked out for opportunities. As it turns out, ED has done work on 675 & 765 heads, and with some porting and polishing, they have seen up to +5 bhp out of the bikes. This is a nice kind of power because you’re not using special fuel, thin head gaskets, etc. that place a lot of additional strain on the engine. This is just power by helping the engine breathe better. What the hell, maybe I can hit low 140-ish mph on the front straight at The Ridge Motorsports Park…
After the initial cleanup and check on the cylinders, it turns out that there appear to be imperfections in the casting. There are a couple of options now: 1) replace the cylinder assembly and *hope* that the replacement is perfectly cast -OR- 2) try to fix the existing casting by cleaning it out, filling it with aluminum-friendly weld, and re-honing it. We are going to try for option 2. If ED can successfully repair the cylinder assembly, then that will significantly reduce the probability of this occurring again. If they aren’t able to repair it, then we’ll order a replacement set of cylinders from Triumph and hope for the best.
So in sum, yeah, I’m bummed that Triumph had a poor casting for these special, limited edition bikes. On the other hand, it’s done nearly 7,000 track miles (11k km) at A group pace and most maintenance has just been consumables. If anyone from Triumph happens to read this, maybe put a message to your casting group and QC to check for the cylinders a little more closely. I love my bike but it was really the first manufacturing disappointment I’ve had and the head gasket failure could have been prevented.
20230919 Update
ED was able to weld and hone the cylinder assembly so that part is good and likely better than stock so that’s encouraging, also considerably less expensive than purchasing new jugs.
ED has also begun the blueprinting process, brief video showing the start of it below. Now lets see if the rest of the parts arrive in time to get the bike back together for my late September track days!
2023-09-21 Update
ED has finished the cylinder assembly and the head is coming along with the blueprinting. I had a fascinating discussion with John who is doing the head work. No photos that I can take with my phone capture what is happening with it but any lips and roughness is being cleaned up. The difference is staggering as he had finished two exhaust and intake areas and had one that was untouched. You can very noticeably feel the ‘lip’ between mating surface areas, as well as how smooth the intake and exhaust chambers feel. It’s a labor intensive process and they also have the ability to ‘flow’ the differences (though that won’t be necessary with mine as they’ve done enough of these, they can tell right off hand what’s going to make a difference). John showed me the valves and they’re all in good shape and they’ll test the springs before reassembling as well but so far everything is looking good.
Mike and John operate Engine Dynamics and since all of this is new to me, I had lots of questions but these guys are terrific and put up with all of my questions. I have no intention of getting into this business myself but I like to know how this stuff works and learning about it. It’s got a kind of old-world feel inside the shop with lots of parts, raw materials (they can make valves for antique vehicles if need be) but they both have oodles of experience that they can verify. There aren’t a lot of shops doing this type of work any longer but they are on the high-end of this sort of work with as much or more experience than most. They can verify their work and they take a keen interest in why something might have failed initially and working to prevent it in the future. They fully understand that there are ways to develop maximum power but that’s always a balance between keeping it working as long as possible and know how to weigh that. As I mentioned earlier, this is the kind of work that’s attractive to me because it puts less strain on the engine as compared to increasing compression (higher compression pistons, thinner head gaskets, etc.) and it’s done in a way that overcomes mass production shortcomings. Granted, OEM manufacturing has come a long way in the last 20 years or so and the benefit of this type of work isn’t as great as it was when tolerances weren’t as tight as they’ve become recently but there are still gains to be realized. I also take a degree of pride in supporting this type of work. While it seems like an art to my uneducated familiarity, they have this down as a science.
2023-09-28 – Head Work is Complete
John and Mike at Engine Dynamics have finished up the head work and have reassembled the valves into the head. At this point we’re just waiting on Triumph parts, some may be coming from England yet. This would include gaskets, rings, camshaft tensioner, cam chain, etc. While there, Mike & John let me know their recommended coolant–Evans Coolant for Powersports. Apparently one of the ways that engine damage happens is when the coolant boils, at which point it turns to steam. Steam is a poor conductor of heat so consequently those areas in the engine get hotter and can lead to failure. Evans is apparently used in Nascar to deal with extreme heat so that’s what I’ve ordered up.
