In this video we look in to some possible differences between the 1971 Triumph tiger and a 1971 Triumph Bonneville and look in to a couple things to see why the Bonneville just doesn't seem to have the power like the Tiger has,
First step would be to set valve clearance, then compression test. You might get the extra PSI from that. There's a hole in the flywheel for setting the ignition timing and the bolt for it is just below the inlet pushrod tube/tappetblock (first hole is BTDC and second hole is TDC. Triumph has a timing tool for it but you can also use a centerpunch (or screwdriver). This hole makes it easy to find BTDC and set the Boyer ignition timing with the dots.
When I first rebuild and broke in my 1971 Bonneville. I had 170psi/cylinder. After many miles and a decade. I had 150psi/cylinder. Then 120. And just before new rings. 110psi/cylinder. My 650 had more power than my friends 650's. I ran 2" Bub Enterprises pipes and K+N filters. Jetted properly of course. I did a lot of research innold tuning books and the race track. Improving breathing on these bikes gives them a noticeable improvement in power. Much more grunt. If the 71 Bonneville was mine, I would thrash it. Not stupidly. But ride it a little hard. Go through the rpms. I'm thinking the rings haven't bedded in fully yet. I heard someone say 1000 km. If that's all, keep riding, and keep rechecking the compression. How did the cylinder wear measure on both biked? Unless there was a substantial difference, that wouldn't account for the difference. If the Tiger has slightly advanced timing, it will have more power also. Small differences that do add up. Especially with larger pipes, and better breathing pipes. Switch mufflers and try the Bonneville. Just for a short ride. It will be a little lean.
The only reason these bikes drip oil is because they have not been maintained or reassembled correctly. Ive been running them 40 odd years and all are drip free. A Bonnie that is dripping oil shows its been incorrectly serviced. No excuses.
The 1970 onwards the triumphs have a 3124 cam on inlet and exhaust. Unlike the original preunit Bonnie which had a 3124 inlet and 3325 exhaust cam. When you set the cams to T120 seting the inlet cam one tooth advanced that advances the cam 13degrees ahead and increases the exhaust -inlet valve overlap which is fine when the 3325 exhaust cam is used. So the not TR6/T120 setting is better and is hence making more power and torque in the blue bike. To rectify the Bonnie you need to use the vernier cam centers and time the Bonnie with 105 degrees exhaust lobe centres and then the bike will perform. My information of the cams comes from triumph twins by Roy bacon and I follow Mr Pete (Rip)on Brit bike forum 🙏🏻
It's getting pretty challenging 29:17 to get to dot dot dot dot to dot dot dot dot lined up. I did a top end on a Daytona and so fortunate never needed to get into the bottom. But you've both been... great! I'll look into more of your work ahead.
I've ridden bikes that were super easy to kick start, but had the same compression numbers as my 64 TR6 which takes a lot of force to kick. I tried out my friends 1957 TR6 and it kicked through so easily I thought the clutch was pulled in or it had crazy low compression.... but the bike started and ran great.. It had 140 or 150 PSI compression when I checked it. I'm still not sure why that bike kicks over with barely any force.
Your video is very interesting, but respectfully standard procedure is leak down test, by putting the cylinder in the top dead center, put 120 psi, check for leaks out of intake, exhaust and breather outlets to pin point the source of the leakage, no offense please.
Thanks, no offense taken, we can try that, we just didn’t try that because the rings, pistons, and bore on the Bonneville are less than 1000 miles but anything’s possible I suppose, thanks for your great suggestion
