Premium gas for 1980 GS1000s

[Billy Ricks]

Also interesting and pretty much what I knew is a new engine can get by on fuel 6-9 points lower than the same engine with 25,000 kms. They also recommend using the fuel recommended for you're vehicle at the high end of the range.

[49er]

gday 49er, that was a good read, note they said older motors with no engine maagement, i once broke a comp ring, because i down changed and gave it a handful, at the exact same moment my rear wheel hit a severe bump, because it failed to select the gear, all i heard was a big knock from the motor , this was on 91 octane, next day i fired her up and i could see this little smoke plume out the exhaust, instant shutdown, slip barrels off, and broken ring, this was on a motor that had done 90,000 kms, regards,

Gidday Mac. I haven't heard of comp rings being broken in this manner before. It's quite usual for big end bearings to fail during a serious over rev too.
In days of old, when English 4 cylinder cars (Austins/Fords/Morris's) were plentiful in Kiwi Land, first car buyers often sought out one owner high mileage cars. These cars were typically owned by little old ladies and their engines had never seen more than low rpms for their entire lives, usually in the 100,000 to 200,000 mile range. The teanagers who bought these cars started to thrash the motors and they suddenly started smoking, burning lots of oil. The reason was that these engines had soft bores compared to todays ones. They produced quite a lip at the top of the bores after high mileages. The extra revs produced more heat/expansion and the top rings would hammer on the lip until the rings and /or piston groves broke.
By the way, these engines happily ran on 83 octane.

[mac1170]

gday 49er, know the story, worked out because the stock shockers were ****, no damping, the gearbox did not select lower gear because i hit the bump from hell, when i turned on the throttle, it was still in higher gear 3rd, instead of 2nd, brutal use of right wrist, big rattling sound, from motor, instant shut off, too late, bearings were fine, infact 70,000 kays later full rebuild, told expect bearings on bottom end to be cactus, by reputable builder, gratuitous plug,[jim hanlon superbike performance] formerly jimhanlon race engineering, crank still spot on, probably due to, regular oil, and filter chganges, infact this motor has actually done 2 revs\, of the speedo, regards.

[49er]

gday 49er, know the story, worked out because the stock shockers were ****, no damping, the gearbox did not select lower gear because i hit the bump from hell, when i turned on the throttle, it was still in higher gear 3rd, instead of 2nd, brutal use of right wrist, big rattling sound, from motor, instant shut off, too late, bearings were fine, infact 70,000 kays later full rebuild, told expect bearings on bottom end to be cactus, by reputable builder, gratuitous plug,[jim hanlon superbike performance] formerly jimhanlon race engineering, crank still spot on, probably due to, regular oil, and filter chganges, infact this motor has actually done 2 revs\, of the speedo, regards.

Giday Mac, great story and highly plausable. I was interested in Billy Ricks's observations too.

I guess the reputation of the indestructable GS series has a sound foundation, but there will always be exceptions to the rule regarding over rev damage and these engines in stock form, mostly confirm that.

I was initially concerned that running higher than stock CR would reduce the life expectancy of my big end bearings and evenually it will!
I thought that day had come early 3 weeks back,after giving the engine a pretty severe test the day earlier. When I cold started the engine, an audible knock/rattle could be heard coming from the engine. I immediately shut her down. I checked the oil level and when I restarted it, the noise got louder and more constant. A quick shut down again. It took a fair amount of courage to restart it, but I needed to check the oil warning light for some confirmation/indication of the oil pressure status. The light went out as it should so I left it running and the noise level started to reduce as the engine got to running temperature.
Damn loose baffle?
I pulled the exhaust off, cut into the baffle area and there was the evidence. Whilst there, I did some slight flow improvement mods and zipped it up again. Voila, no more knocks. The mid and top end is even stronger now, but at the expense of slightly more noise.