Over heating need advice

Bush said:

Not aware of any system in our bikes that shut it down during overheating?? That sounds more like a momentary seizure of the engine to me.

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I went through the wiring diagrams to see if indeed there was any connection between the temp sensors and traction control.( the traction control detunes the engine on the abs model) unless it's internal in the ICU, which I doubt. It was a thought which I had to check out. Or if there was something like the bank angle sensor that shuts the fuel pump, and kills the coils via the ICU. Nada.
There was another issue unbeknownst to me at the time. After my overheating incident, the bike seemed to run rough, the odd time it would seem to miss, a slight backfire on deacceleration, it would make the odd "schutz" sound like gasping or letting out air. Did I have an electrical issue with a coil, as suggested here on this thread? I described my issue to my mechanic, he thought since I had the Tupperware off and on the past view days I may have disturbed something, possibly vacuum related. So, off came the plastic again, inspected the vacuum hoses (that are used to sync the carbs) BINGO! A check valve had come apart allowing air to be drawn into a carb. I use three carbs to draw vacuum for my cruise control, each line has a one way valve installed. I replaced the valve and it's running smooth again. Is there a co-relation with my vacuum issue and overheating causing my engine not to fire I have no idea. So far there hasn't been a problem of the engine not firing. The PAIR system has been removed on my bike, and from what I read that too can cause a slight popping sound on deacceleration.

A vacuum leak will cause a pretty lean, thus hotter combustion...

The PAIR system has been removed on my bike, and from what I read that too can cause a slight popping sound on deacceleration.

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Don't believe everything you read on the web. The PAIR system has nothing to do with the normal ST1100 decel burble. I know of only only one PAIR failure in 18 years on the ST forums. Nor has there been a vacuum leak in the PAIR vacuum hoses. Please do not perpetuate this erroneous 'fact.'

John

John OoSTerhuis said:

Don't believe everything you read on the web. The PAIR system has nothing to do with the normal ST1100 decel burble. I know of only only one PAIR failure in 18 years on the ST forums. Nor has there been a vacuum leak in the PAIR vacuum hoses. Please do not perpetuate this erroneous 'fact.'

John

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I stand corrected. Thank you

The test of the PAIRs (secondary air supply system/air suction valves) is so simple it's ridiculous (p.5-17). You don't even need to have a vacuum pump, just suck on the tube and if it holds, the valves are fine. Sheeesh!

I think a lot of folks rationalize removing the valves. If you want to take them out, just do it.

John

John OoSTerhuis said:

The test of the PAIRs (secondary air supply system/air suction valves) is so simple it's ridiculous (p.5-17). You don't even need to have a vacuum pump, just suck on the tube and if it holds, the valves are fine. Sheeesh!

I think a lot of folks rationalize removing the valves. If you want to take them out, just do it.

John

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I did nothing with the PAIR system, I didn't use it for my Audiovox cruise control. I took the vacuum off of the sync hose from the carbs. ( Something I had checked with you a few years ago because my 1990 didn't have a PAIR system from the factory and you said you thought it would be OK to use it instead of the PAIR vacuum for the ACC) What failed was a $7 part from NAPA, an inline check valve, it came apart. When I purchased the 97 last fall The PAIR system was already sealed off. A bonus I thought.
On the 1990, the cruise wasn't that strong, it would always drop a few km/h when engaged. Doing some research I saw that the Valkyries were using 5 carbs' vacuums, each with a check valve before going to the canister which also had a check valve. It also had a different setting for a dip switch to be more aggressive. So when I transferred the cruise from the 1990 to the 97 I took the vacuum off of three carbs, changed the setting and in my case the cruise works very well. Over the winter I may change the source of vacuum to the PAIR line as per your method.
By the way I'm very grateful for that tutorial, very well documented with excellent photographs.

What I didn't specify in my original post was, when the vacuum leak was mentioned as a potential problem, my mind went to the connections I had made via the carbs, and that one of the connectors came loose.

Thanks John for your guidence
Cheers
Robert