I'm working on an SP1000 that belongs to a friend of mine who tells me of a few odd symptoms as well as loss of power at freeway speed. He also tells me that he got stuck in traffic on a 100-degree day and left it idling while stopped for a couple of extended periods, like 20 or 30 minutes.
When I regained my composure after a brief spell of verbal diarrhea, he also noted that it was reluctant to return to idle between shifts. Sure enough, as I rode it onto my lift, when I blipped the throttle, the engine would speed up and very slowly begin to idle down.
We ran a compression test and found that the readings were down on both cylinders compared to a few weeks ago when we did an oil service, valve adjust, and carb sync here. Previously we saw 165 and 155 compared to the 150 and 135 readings more recently.
He had previously spoken to another mechanic friend who thought that he should test for a vacuum leak, so while it was idling, he sprayed a little WD40 on the intakes where they meet the cylinder head. Sure enough, when he sprayed the left one, the idle speed increased. Below is the picture of what probably was causing the vacuum leak. As you can see, the Delrin manifold has melted into the intake port and into the cylinder fins!! The picture is the left one. The right one has some melting but not as much.
Obviously, we need to replace both intakes, but what else is likely to need checking and/or replacement after such a severe overheating event? Is it possible that the carb return springs have been weakened by the heat? Could the rings have lost their tension? How about the valve springs?
The bike has over 83k-something miles on it and was running really great when he left here a few weeks ago.
ADVthanksANCE
-Jack (horrified in steamy central Texas)
When I regained my composure after a brief spell of verbal diarrhea, he also noted that it was reluctant to return to idle between shifts. Sure enough, as I rode it onto my lift, when I blipped the throttle, the engine would speed up and very slowly begin to idle down.
We ran a compression test and found that the readings were down on both cylinders compared to a few weeks ago when we did an oil service, valve adjust, and carb sync here. Previously we saw 165 and 155 compared to the 150 and 135 readings more recently.
He had previously spoken to another mechanic friend who thought that he should test for a vacuum leak, so while it was idling, he sprayed a little WD40 on the intakes where they meet the cylinder head. Sure enough, when he sprayed the left one, the idle speed increased. Below is the picture of what probably was causing the vacuum leak. As you can see, the Delrin manifold has melted into the intake port and into the cylinder fins!! The picture is the left one. The right one has some melting but not as much.
Obviously, we need to replace both intakes, but what else is likely to need checking and/or replacement after such a severe overheating event? Is it possible that the carb return springs have been weakened by the heat? Could the rings have lost their tension? How about the valve springs?
The bike has over 83k-something miles on it and was running really great when he left here a few weeks ago.
ADVthanksANCE
-Jack (horrified in steamy central Texas)
