Honda GL1000 K3 crankshaft disaster.

[bstenrod]

Some years ago, I bought a 1978 GL1000 from a man in Minnesota. It was a very nice bike with only 25000 on the counter. I knew when I bought it, that the engine had a strange knocking noise. While I have some other bikes to repair, this Honda has been stored in my garage without any time to repair it. But now I decided to repair it.

I took out of the engine of the bike and opened it. When I took the crankcase apart, you can see on the photos what I found. The inside of the engine, pistons and everything was in good condition, so why this has happened, I don´t know.

I bought a spare crankshaft two years ago, just in case. The price of these crankshafts is low, so this thing doesn´t happened often.

[joecoolsuncle]

burnouts? my first guess is it was caused by some nasty harmonics.

[Rambozo]

I would guess a manufacturing defect combined with lugging the engine.

[khspe2]

That’s the Displacement on Demand version of the motorcycle.

[joecoolsuncle]

That’s the Displacement on Demand version of the motorcycle.

well, it worked just as well as GMs version. lolol

[LAB3]

The old timers would lead you to believe that there's NOTHING that can't be fixed with JB Weld and Marvel Mystery Oil. I'm a little more modern in my approach and would add duct tape, zip ties and super glue to that list. Give it a try, it certainly can't hurt!

[WingAdmin]

Wow, that's not something you see very often with these bikes.

It doesn't look like structural failure to me, and the way you see the break on two different journal web interfaces makes me think mechanical shock. You might want to closely inspect the transmission as well for damage.

[SteveRand]

It's broken at the front end of the crankshaft, which only drives the cams via the timing belts, so there shouldn't be any mechanical shock here. My guess would be a manufacturing defect. Interesting...

[Bryanj]

The colour of the metal in the front break suggests metal fatigue to me, only othe possibility is using an impct wrench on the front bolt or if the engine was hydrauliiced of frozen and somebody put a long bar on the bolt to try and turn it.
Never seen a broken crank on a wing and ,m old enough to have worked on the first ones in the UK

[Truckintom]

The 3 be thing I can think to f would be towing in overdrive and or lugging{low speeds) with trans is n high gear.It's not that it can not be done, it's the great strain that is applied to the engine and trans in high or overdrive. I have one now that will be torn down that has problem with 5th gear, it has a trailer hitch on it, high miles,this ole girl has been rode hard and put away wet a lot,Thru at least one odometer trip over 100,000 miles. I am hoping that the case is not scrap.

[DenverWinger]

Really surprising when considering how robust these engines are.

My GL1100 which I resurrected from dead (sitting for 15 yrs) in 2005 has a nice knock when first starting which goes away when the oil pressure comes up. Sounds like a rod knocking. When I first got it running I figured I'd just run it until it gave out and search another engine for it. That at 53000 miles. After the first year and probably 3000 miles I decided it wasn't a rod bearing, that would have been gone by then. So I'm pretty sure it is a loose wrist pin.

In 2010 I bought a camper trailer, we made three cross-country trips pulling the camper, probably 550 lbs loaded, engine still knocking on startup.

I bought the 1500 in 2017, it now has the trailer pulling duty. The 1100 is still knocking, now with 102k miles! So that's going on 17 years and 50,000 miles, probably 10,000 of them tough-duty miles pulling camper that I've put on a knocking engine.

It is now to the point you can hear the knocking some at certain RPM and load, so it is probably closer to letting go. So I have delegated the 1100 to just commuting and rides in the local area. We'll have to see how long it lasts... Surprised it has lasted this long. By the time it finally gives up will probably be hard to find a replacement engine!

[grahamlanghorn]

The colour of the metal in the front break suggests metal fatigue to me, only othe possibility is using an impct wrench on the front bolt or if the engine was hydrauliiced of frozen and somebody put a long bar on the bolt to try and turn it.
Never seen a broken crank on a wing and ,m old enough to have worked on the first ones in the UK

I have replaced three broken crankshafts on gl1000 in the 70s/80s. i worked in main multi franchise japanese dealerships from 71 till 2007

[Bryanj]

That is a good reply, i do know that here in the uk mileage is nowhere near as high as in the US
we did have a "shop" gl1000 that did 50,000 in 4 years and apart from a sliding coupler on the drive shaft(it was a VERY early one with no grease nipple) plus rear tyres every 5,000 miles it had nothing but routine servicing.
Perhapsthere was a "batch" of incorrectly treated cranks.

[grahamlanghorn]

That is a good reply, i do know that here in the uk mileage is nowhere near as high as in the US
we did have a "shop" gl1000 that did 50,000 in 4 years and apart from a sliding coupler on the drive shaft(it was a VERY early one with no grease nipple) plus rear tyres every 5,000 miles it had nothing but routine servicing.
Perhapsthere was a "batch" of incorrectly treated cranks.

possibly, the customers picked up the bill as they were out of warranty. i have a 77 k2 with 70,000 on it. cant remember milage of the ones that broke, it was a long time ago.

[mickydint]

That is a good reply, i do know that here in the uk mileage is nowhere near as high as in the US
we did have a "shop" gl1000 that did 50,000 in 4 years and apart from a sliding coupler on the drive shaft(it was a VERY early one with no grease nipple) plus rear tyres every 5,000 miles it had nothing but routine servicing.
Perhapsthere was a "batch" of incorrectly treated cranks.

My 75 GL1000. Is also an early GB model ( Oct 75) no grease nipple on transmission tunnel.

[Rambozo]

Some people are extremely hard on equipment, too.
I've heard them described as; "He could break an anvil in a sandbox".

[rfluharty]

I worked in public schools for 11 years and that's exactly what we said of students. Our joke was Johnny telling the teacher, "Teacher, my anvil broke!".... Notice they wouldn't say they broke it, but that it mysteriously broke by itself.