New Owner w/ Fuel and Overheating Problems

[rongbradshaw]

I need someone's help as I am a new owner of a 1978 GL1000 that is getting lousy fuel economy (about15 mpg) and is overheating after about 30 minutes of riding in warm but not hot conditions. I put it in neutral, the fan turns on, I turn off the bike and it won't restart until it cools down. Finally, there is a clunking sound upon accelerating from a dead stop in 1st gear. According to the prior owner, he recently had a new water pump, thermostat, valve job, new valve guide seals, head gaskets, rings and rebuilt forks. He said the clunking sound is somehing that the bike has done since he bought it a few thousand miles ago. It doesn't leak at all and the engine really sounds good. There is some intermittent white smoke coming out of either side of the exhaust pipes on an occasional basis. Any ideas of what could be going on or where I should start?

[2WheelBoy]

Congrads on being a new GL-1000 owner; however, it sounds like you have a lot of work ahead of you! I also own a '78 GL-1000, not the original owner, but have owned it for about 15 years now. I had never had any of the problems that you indicate. I get about 45mpg on mine and the cooling fan rarely comes on in any of my riding. White exhaust smoke generally indicates that engine coolant is being burned in the combustion chamber(s), a very bad thing as it can destroy engine bearings! I have never got any "clunking" sounds from my engine or transmission; not normal for sure. With the work that the previous owner indicated to you, should pose a "red flag". My thought would be; how competent was the person that did the work? Take a one mile ride, stop, and feel all three brake rotors; they should not be hot. Engine cooling is a serious problem, trouble shoot it just like if it was a car. Solve one problem, then go onto the next. I have about 45k miles on my GL-1000, and the only thing that I have done with mine since I owned it was to overhaul the carbs and brake calipers. Keep at it and good luck. Keep us informed here on how you are doing with it. Regards, 2WheelBoy

[rongbradshaw]

2wheelboy, thanks for the shout out and ideas to solve some potentialy serious issues. There is little doubt that the previous owner/s did a lot of tinkering as it has been altered to look like a cafe racer / bobber. Didn't pay a lot and not looking for a money pit either. The work described as accomplished seemed very practical items for 92,000 miles. If anyone else has any ideas on the poor mpg and overheating issue please drop me a note. Used to work for American Honda back in the 90's decade - in my opinion, the finest engine designers and builders in the world. Unfortunately this bike looks like it may have had too many hands being laid on her. Nontheless, I am commited to bringing her back to health but need all your help in fiding the right medicine. Thanks all.

[SteveB123]

I'd start with a new correct thermostat.

The wrong thermo can cause many of the issues you're experiencing, and they're cheap enough to replace. Even if it doesn't fix everything, as least you can rule it out in the future.

[bjatwood]

As steveB mentioned the thermostat already. I'll chime in and say make sure there is not a air pocket in the cooling system either. The white smoke might indicate a headgasket on it's way south. Also look at the plugs to see what color they are, and if they are all evenly black and sooty (15mpg like) and if one of the plugs looks alot different I would bet that cylinder has the head gasket issue.
Let us know what you find out in your troubleshooting.

[Old Fogey]

White smoke on start-up can be condensation in the exhaust system, should go away as the bike warms up. White smoke with it hot - head gasket(s) gone awol!
Check for fuel leaks. Remove the air cleaner and see if there is fuel pooling in the plenum. if so you will have to pull the carbs, renew the seals and set the float levels.
The clunking is most likely what we term the 'half turn clunk' caused by the shock absorber spring on the output shaft getting weak.
You might also be advised to check the universal joint for wear too.