'92 907ie ... high idle when warm
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Author:  Leftfield [ Thu May 30, 2019 5:25 am ]
Post subject:  '92 907ie ... high idle when warm

Hello ,

My recently 'awoken' 907 is doing great and over all I am more than pleased .

One thing is a bit baffling however --- at cold start-up she will fast idle at about 1,400 until the "choke" is removed , then it drops to about 1,150 and all is well . When the bike is being ridden normally , the temp is about 150 ish and at a stop , it will idle at 1,150 to 1,200 .

I have a very long driveway that is gravel and sloped and we take our time and travel slowly . When leaving the house and going downhill ... when we reach the road the temp is about 175 or slightly more and the idle will be around 1,600 . When we come home ... going uphill , temp are around 190 to 200 and idle is around 2,000 and the fan will run for maybe 1 minute or so .

It almost seems that the bike is trying to protect itself from overheating by having a high idle . I am likely so far wrong , it's laughable on that one . A complete sync was done and balanced nicely .

It has been 20 years since this bike was used ( please hate me for that , I certainly do !! ) but we sure do not remember any similar behavior . Although , we never saw it get this warm either ???

The fact that it will go back to a normal idle after being ridden has to be a clue of some sort .

As a side note ... this bike was bought new for my wife and she has put almost every mile on it ( 25,000) ... she was present when I started it for the first time about a month ago ... and she cried , as in great big 'ole alligator tears . Yes , these things are special . Soooo grateful to still have it !!

Any idle ideas ?

Thx , JD

Author:  nickta [ Thu May 30, 2019 9:04 am ]
Post subject:  Re: '92 907ie ... high idle when warm

Hi JD.

I'm going with you did a full service and clean out before you hit the start button? With the service you drained and replaced the coolant etc!? The coolant system is a bit odd in that it is pretty easy to get air locks in it. The other thing to check would be the temperature sensor in the coolant. There is the one that the gauge runs off and there is one that the ECU uses. It could also be something's as simple as badly routed high idle cable.

20 years is a long time between drinks with the 907. And it still brings out tears!



Author:  Leftfield [ Thu May 30, 2019 2:51 pm ]
Post subject:  Re: '92 907ie ... high idle when warm

A long time indeed . Shame shame .

I did a very thorough service which included the 'radiator filler neck CBR 600 re-do' mod . I don't believe that I have an air pocket . The rad shows full when cold and the tank shows low when cold and about 1/2 when warm . All cables are as they should be .

I keep coming back to the fact that ... as the bike is ridden and the temp goes down ... the idle returns to normal . Really the only time that we seen the elevated idle is when we are either leaving or arriving home . Our driveway is just over 2 miles long and is gravel and has a bit of a slope to it . We go real slow . For the life of me , I can't imagine any reason for this to occur .

The temp sensor appears to be healthy , as the fan will turn on for about a minute ( or 2 ) when temps reach around 190 . Seems about right to me .

Thx !! JD

Author:  duc907 [ Fri May 31, 2019 10:56 pm ]
Post subject:  Re: '92 907ie ... high idle when warm

check the upper rad hose, it runs up against the throttle cable. it may be expanding and holding the throttle open.

Author:  higgy [ Sat Jun 01, 2019 3:38 pm ]
Post subject:  Re: '92 907ie ... high idle when warm

+1 on cooling hose hanging the fast idle cam :thumbup:

Author:  Leftfield [ Tue Jun 11, 2019 2:09 am ]
Post subject:  Re: '92 907ie ... high idle when warm

Ding Ding ... we have a winner !!

The upper hose was pressing against both the high idle screw and also the nut on the end of the throttle shaft . I made a little radiused sheetmetal piece that allowed me to pull the hose out of the way using some zip ties . Works great !! Great job guys ... huge thanks !!

When I did the CBR filler neck mod , I was a bit baffled at where I am to ' cut a slot in the i.d.' ... the only id of any kind is in the tank itself . So , a hacksaw blade to create a slot which will go past the o.d. of the relief valve in the cap ?? I am confuzzled .

Thx !! JD

Author:  Leftfield [ Tue Jun 11, 2019 3:12 am ]
Post subject:  Re: '92 907ie ... high idle when warm

Hi ,

Just after writing the last post , I had the rad cap in my hand and I was able to completely unscrew the check valve assembly from the cap .

It would seem that I could use the cap as-is (without the check valve ) and it would accomplish the same thing as the 'cut the slot' approach . If correct , do I use the gasket on the cap ?

Again Thank you !!! JD

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