Faults:

Mine was a courier bike, I worked for City Link out of Camden Town '89 through mid '99. Only major issue was I cracked the exhaust bumping down a high a curb in Regents Street which the workshop replaced with a (better sounding) 4-1. This may be hard to believe, but once the workshop only finger-tightened the sump bolt which then dropped out along London wall. Kept it upright (somehow) as the engine drained itself. After a re-fill it was fine. When not trying to kill the riders the workshop ran the whole fleet (yellow and green GT550's and GT750's) on Mobil1 which was replaced every 2 or 3 thousand miles. Came out pretty much looking the same as it went in. Zero mechanical issues, had to have a few clutch overhauls but that was to be expected. Rock solid bike.

General Comments:

Handled pretty well, very predictable, not huge on power, good brakes, hard to wheelie but possible, heavy but could handle being ridden hard all day as long as the oil was changed regular and topped up to the high line in the sight glass. Did 108k in the year I had it and these were pretty much pushing the bike hard all the time; it never faltered.

Faults:

Nothing, except put a new battery in.

Very reliable; goes all day without problem. Had these bikes many years ago, and they will do 150,000 miles if you look after them well, or 100,000 miles if you do not look after so well.

Sound bikes; the couriers can't all be wrong.

General Comments:

Solid, reliable, dependable, and mine is G9. I think 59HP, so quite good performance for what it is.

I forgot; very comfortable bike for long distance.

Faults:

My clutch springs went at about 60,000 miles, causing the clutch to be very stiff, and made it difficult to change gear. The cable was also a little stretched. Replaced the springs with heavy duty EBC parts, and also replaced all the plates with EBC items while it was open; the old plates were still within spec though.

Standard exhaust rotted through within the first two years of owning the bike, because I ride all year round, so I'd say by 30,000 miles the system was replaced with a stainless Motad 4-1 that's still going strong.

General Comments:

Since owning the bike I've covered over 100,000 miles with virtually no problems, rebuilt the clutch and have changed the exhaust. I ride all year round and don't baby the beast. I don't thrash it through the gears, but all day cruising is 80/90mph with blasts up to 110mph when the urge hits me. I commute daily, and also use it for touring holidays and long weekends quite often, covering 1000 miles in three days.

The longest trip taken on her was two up through Europe, covering 8000 miles in three weeks; not a single problem!

This however is what I believe to be the secret to its long trouble free life so far; REGULAR preventative maintenance!

I change the oil and filter every 2000 miles religiously, and NEVER go more than 3000 miles without changing the oil. I use fully synthetic premium quality oil and good filters.

The diff oil gets changed at the same time.

New spark plugs every 10,000 miles along with cleaned after market air filter and balance the carbs. Balancing the carbs should not be skipped, they go out pretty quickly; 10,000 mile intervals I find to be just right for how I ride.

The valve shims get checked/adjusted every 20,000 miles.

Also I've made a habit of keeping her well cleaned, polished and lubricated. I use a lot of WD, and any rusty bits get rubbed down and Hammerited! For an old bike with high mileage, she looks fantastic. All those that say they rot quicker than you can say "Salty roads kill bikes", obviously never clean their bikes. The tail light bit on the rear guard is only showing signs of rust bubbles this year!

If looked after, I believe this bike will cover another 120,000 miles with nothing more than what it's received already.