Shift Points for Bugsys 948 w Cooper S Head

[Jim_Gruber]

So I just realized that tach I'm staring at in Bugsy is a Jaeger with a Red Line that starts Yellow at 6500 and Red at 7,000 RPM going all the way to 7.500. Jaeger out of a Porsche perhaps. Gee Well I haven't pushed this 948 to Red Line I'm sure I've strayed over 6k on a regular basis. So the question becomes this is a generator driven speedo so I'm guessing it should be dead on. This engine makes power and breathes well all the way to 6500. a normal 948 redlines at 6k. I do have a CooperS Big Valve Head, HS-2's, and a not stock cam along with an LCB Header. Thoughts on how far I can safely push it? It sure likes to rev but I don't want to damage the engine.

Worked from home today. Two errands took me out in Bugsy sunny and 68 before snow over the weekend. A last gasp at Top Down Fall Driving. 70 tomorrow but it will be dark before I get home tomorrow from work. Who schedules a Team Meeting at 4:00 PM on a Friday. Not me. BTW the drive was fabulous Front Discs and Suspension Rebuild and MC Change will happen soon.
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[HealeyRick]

I think the important part in determining a rev limit isn't at the top end of the motor but at the bottom. In other words, if you have a standard 948 crank and rods you're probably safest by sticking to the stock red line. My 948 seems pretty similar to yours and I regularly shift at 6,000 (I have 4.55 gears so that comes up pretty quick). I might hit 6500 in an autox. It's held together well.

 

[twas_brillig]

On a similar note: I had a 1980 Yamaha RD400 two stroke twin a few years back with expansion chambers, and it loved to be shifted about 1000 rpm above the red line until the pressed together crank became wider. Got the engine rebuilt and watched the red line, but out on a late fall run in the foothills keeping up with the big bore boys at 150/160 km/hr on a cold day: pistons very hot get bigger; cylinders very cold get smaller. Rear wheel momentarily locked up as the engine seized on a long sweeper but fortunately the engine broke loose again and a rode a very rattly motorcycle home, for another rebuild. Until you've talked to someone like Winner's Circle and maybe upgraded rod bolts and added bearing caps, it's probably better to stay out of the stock red zone. Doug

 

[Jim_Gruber]

Maybe time to swap the Jaeger for a spare BE tach in the back of my garage. Well maybe not as the time I got in yesterday was likely Bugsy's last trip out thus year. Weather gets nasty and possibility of snow flurries on Sunday. Speedhut GPS Speedo and Matching Ejectronic Tach are coming. Thanks.