Motorcycle Repair: No compression in No4 cyclinder, suzuki bandit 1200s, interval times

Question
Hi Mark,
I have a Suzuki Bandit 1200S (UK registration March 2003). It has had regular services at or very near to interval times, and to date no problems in any respect had been reported.
The last service was a week ago at a mileage of 24,000. I asked them to investigate a problem with the choke, it appeared to not operate at all meaning I had to hold the throttle open for a while till the bike warmed up. I had allready checked the choke slide and could see no prob. At service they could not find the problem, the only thing they noted was the oil level was low at one and a half liters, but that it was not at "critical" so after draining and top up was told it was ok.
After just 200 miles riding I began to notice the engine running rough. Above 3000 revs it was fine but below that in any gear it "chugged" and sounded "fluttery", it also cut out a few times when stopping the bike at lights etc. The engine would just drop to 500 revs then die.
The choke still does not operate properly under any conditions.
I took the bike back to the service center and after more checks they tell me there is little or no compression on No.4 cyclinder. Having checked the valves to see if any were sticking and finding them to be ok they reckon it's either a damaged piston or rings.
I would have expected to see other indications of this type of damage i.e blue smoke, black deposit on exhaust, rough running particularly "above" the 3000 rev mark, but have not seen any of these.

I'm told this is an almost unheard of problem with the Bandit engine so I would greatly appreciate any comment or info you could offer.

Regards
Roy

Answer
Hi Roy,

Compliments on a well written description. Thanks!

Cylinder failures can happen with any engine. The problem is not common with any engine brand that I know of. If so, the factory's existance would be short lived.

A couple things you can do:

1). Measure cylinder compression.
2). Perform a leak-down test.

Both tests will indicate the integrity of the combustion chambers sealing properties (condition of the engine). A leak-down will indicate whcich part(s) are defective.

If you need more intel on these tests, send me an email address as requested. I return tech files via email.

Visit "www.banditalley.com" and inquire with other Bandit owners.

Respectfully,
Mark Shively