[JWA]

I retired last spring and spent the first months doing all sorts of catch up maintenance on the LT with plans to drive around the country for the coming years. I had hauled the bike to Florida in February and caught a snowstorm on the way back that had me have to clean up the bike and replace several corroded bolts along the way. The to doo list was 25 items long and I did most of it except replace the clutch and oxygen sensor which I postponed till the following season.

When I took the bike out for my first long ride in late May the bike was behaving like it wanted to ride and gobble up the miles. I had the sidecar rig attached and drove around 300 km when the bubble burst on the way back home: the motor started to lose power and the exhaust was making a distinct popping sound. No white or blue smoke, but definitely a motor problem at 235000 km (145 k miles). Fortunately, my problem occurred within a few kms of Sailor’s home so I went there, and he graciously agreed to plug his computer on it and we could not find any listed problems. I limped back home and tried to diagnose the problem (changed spark plugs, spark wires, switched injectors but cylinder #2 exhaust never heated up on short start). Finally bought a compression tester, mine was on the island with my older bikes, and found I had lost compression on cylinder #2! Woe is me!

I had planned a road trip on the north shore of the St-Lawrence for June and ended up doing it in the PHEV SUV which was a blessing in disguise as the windshield washers were running for most of the trip. When I got back home, I bought a used 1999 motor in NH with 60k miles and drove down to pick it up before I left to spend the summer in the Maritimes as I now do every year.

When I came back in September, I took the damaged motor out and replaced it with the salvaged unit. I took the motor apart and found an exhaust valve on #2 cylinder had broken.

Every cylinder also had damaged sections on the inner linings, the largest being on cylinder #2. Broken valve and cylinder damage seem to point to detonation problems. The motor was burning a bit of oil (1 liter/qt per 4000 km/2500 miles) but I thought that was normal for the mileage.

When the motor failed it was relatively hot (30 deg C, 86 deg F) for our neck of the woods and the temperature gauge was sitting very high but no warning lights. I also had a booster module on the airbox temperature sensor that I removed after the failure thinking it might have had an impact. While changing the motor I replaced both radiators with refurbished units that Sailor had available to avoid any further overheating. While discussing potential detonation issues with Sailor he mentioned possible air intake from the lower seals on the throttle body that would create lean burn/detonation conditions. I did not change any as they looked good on inspection.

The new motor was installed and ran well when I rode it for over 2000 km before winter set in. It was quoted as having 60k miles and there was no sign of oil around the clutch so I left it there and it worked fine. No smoke except for the initial start-up and no oil consumption. Temperature was at the middle mark and gas consumption was good. Compression test showed all cylinders in the 210 psi range. I changed the oxygen sensor before the end of the season.

I hauled the bike down to Florida again this winter, this time timing my travel to avoid any snowstorm issues. Filled it up with high octane gas in Florida as I always do, took it out for a few short rides and all was fine. I then took it out for a longer ride around lake Okeechobee in 75 deg weather. Halfway around the lake I feel some hesitation on the motor and potential knocking symptoms. I limp back home having done 450 km (265 miles) on the gas tank which is right on average for me without the sidecar and check it the next day: good spark on all cylinders but cylinder #2 exhaust hardly heats up on short start. I bought another cheap compression tester and #2 has 2/3 the pressure of the others. Woe is me again!

The bike is on the trailer waiting for me to return up north at the end of the month as planned. I found a used motor with transmission, injectors and starter in Melbourne on sale and drove up to pick it up. It is also on the trailer, and I will make the switch when I get back.

What else should I be looking out for? Air leaks, plugged exhaust, bad injectors, other?

 

[JWA]

On the first failure the temperature was high for two reasons: the original radiators were opaque to light when compared to the ones I replaced them with and I had left the left hand radiator fan unplugged on my spring maintenance routine. I did not realize that until I dismantled it later, and decided to replace them with some clean ones. When I replaced the motor, I ran it until both fans kicked in and the temperature never went above middle until it conked again 2500km later.
Bad cooling was certainly a contributor on the first failure but not so much on the second. I too wonder if there is something in the #2 cricuit that might be another source of the problem, hence my question to the group above: air leaks, partially plugged exhaust, bad injectors, blocked catalitic converter, other?

 

[JWA]

Since you gave me more info during your visits here (and a few emails exchange) , I taught I would post this addition... please comment if my understanding is incorrect.

Besides the radiators, I think you need to specify a few other jobs / repair that have been done just before (or at same time) as you installed this new engine.
By a process of elimination, I believe these items are important to help pinpoint WHY this 2nd engine would fail again:
1) Your 4 injectors have been checked and cleaned by a reputable local injector shop a bit before this used engine was installed
2) I think you had replaced the Oxygen sensor - but I cannot recall when this was done timewise


IMPORTANT QUESTIONS... some I may have asked in our previous exchange, but I cannot recall all the details:
A) Do you have the Motronic version of your ECU ? This can be read using a GS911 -or- by removing the ECU to read the label on opposite face.

B Do you have a GS911 to check if the air-box temp sensor is working properly ? This is is important as you said you have removed the "cheater" device that was connected to it. You can make a rough check using a Multimeter OHMS function on the 2 male pins with connector removed:
- at 8 celcius (46 F): should read 3800 Ohms
- at 20 celcius (68 F): should read 2500 Ohms
- at 40 celcius (104 F): should read 1000 Ohms (you may use a hair dryer at "low heat" to warm up the tip)

C) have you ever tested the fuel-pump running pressure ? I have the needed gauge and adapters here but you need to have the right side fairing removed to connect "inline" between fuel tank quick connectors. On the K1200RS forum (and probably here too) we had at least 1 case where a pin hole / crack on the short hose connected to fuel-filter (inside tank) would cause a lean mixture. Total running pressure was not proper as per specs at 51 PSI.

1) Yes the four injectors were refurbished before the first failure.
2) Oxygen sensor was replaced in december, after fall rides and before Florida trip.
A) No Gs911 and don't have info on chip but believe it is original 1999 fabrication date.
B) Will try to check temp sensor but it may be when I get back in two weeks
C) never tested pressure but I do hear the pump start/stop when turning the key. Changed gas filter and hoses last April in the catch up maintenance before first failure

 

[JWA]

I bought the bike in 2004 with 14k on the odometer from a friend that was not very power motorcycle minded so I don't think he changed the chip but I will check when I get home in a few weeks. I do have the special torx bits for the cover.
I will want to borrow your gas line pressure setup though to test the injector infeed pressure. I should be travelling your way around Easter.

 

[JWA]

What John said. Premium fuel for sure and you indicated the same but what oil weight and formulation are you running in it as a curiosity and people, don't make this an oil thread please. Just want to make sure it is up to spec.

I Always used premium gas.
I also always used Castrol Edge synthethic oil either 10W40 or 10W50. Pistons showed no damage of the rings but did have some scuff marks on the skirt below the rings..

 

[JWA]

Are you lugging the engine with the side car ?. The more weight you have the more you would like to keep the engine rpm's higher. Your final drive gear ratio in the 1999 K1200LT is 2.75. I just sold a 2.91 gear ratio final drive to a member hear in Florida with a K1200LT side car and he likes it much better. If I had a side car I would use a 3.09 ratio.

Not sure that low RPMs are more of a detonation risk. I do find myself using 4 th gear more often when hauling the sidecar as It will need more revs/hp to accelerate, particularly when climbing hills, and first gear is a bit tricky if fully loaded. The temp gauge was running hot (above center line) without the sidecar before the failure, but really topped out with the sidecar in hot weather. The bike works harder with the sidecar. My clutch did not seem to mind the sidecar as it was still the original on the first failure at 235k km (145k miles) having pulled the rig for close to 50k km (30k miles) and measured up to 5,4mm which I believe is slightly more than half worn.
I also changed my final drive 75 k km ago for a 2005 unit (34/13, 2,62). It replaced my original which was a 35/12 (2,91) and had had to have its bearings replaced 3 times, every 30k km or so by the dealers until Charly in VT finally took out one of the two shims in it. No sign of failure yet on this one, which came off a trike conversion and already had 75k on it. I drive less now and change the oil every year/ 6-8k km.
Although my driving may have changed a bit with less cross country tours with the rig recently, average fuel consumption has improved slightly 4-9% with the final drive change. My average fuel consumption without the rig before the change was 4,73 l/100km (50 m/usg) and 5,84 l/100km (40 m/usg) with the rig vs 4,54 l/100km (52 m/usg) and 5,34 l/100km (44 m/usg) after. The motor works 18-23% harder with the side car, and thus hotter.