3000 rpm idle 1998 R850R

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M58
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3000 rpm idle 1998 R850R

Postby M58 » Sun May 13, 2018 8:33 pm

My bike was running well before I parked it up for a month,now it idles at 3000 to 3500 revs.I have checked the obvious things like cables, none of which appear to be stuck or wrongly adjusted.Anyone got any ideas?
1998 r850r

Jeff Highland
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Re: 3000 rpm idle 1998 R850R

Postby Jeff Highland » Sun May 13, 2018 8:54 pm

The only way it can be idling at 3000 rpm is if either the left(with throttle position sensor) or both throttle body butterflies are stuck partially open.
So check them where the cables attach to see if they go back to their stops and then check the cables again.

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Jaythro
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Re: 3000 rpm idle 1998 R850R

Postby Jaythro » Mon May 14, 2018 8:19 am

is yours a single cable to a splitter box or a single cable to left throttle and across the bike to the right ?

It has to be throttle "set up" / the Throttle position sensor

At the back of the throttle bodies are the "quadrants" that the cables pull These should rotate forward and hit the stops. Are they doing that?

My first test when I get one that is misbehaving is to flick the throttle and listen for the clack as both hit their stops, the throttle cables can get pulled out of the adjuster body and sit on it rather than in the cup and it can also get pulled out of the connector box (If you have the later type) Checking that the quadrants hit the stops negates messing about chasing cables


Are the BIg brass screws on the throttle bodies looking like they are disturbed ? They "Usually sit about 1 and a 1/2 to 2 turns out from fully in.

If someone has been messing and screwed these out that would bring the tickover up, My method is to count as you screw in and write it down I count in half turns It sounds daft but if you get distracted, you don;t remember that it was a turn or turn plus a half or a half turn Count the half turns as one side of the blades passes the outer side where you started turning!
So you screw one side in and if its value is way off the norm screw it back out 3 half turns from fully in and you can readjust this later with balance gauges
Are the rubber vacuum take off caps still on the small brass tubes underneath Sometimes they degrade and they allow extra air in! (The air is normally metered by the Big Brass screws to adjust the tickover)

N.B. NEVER adjust the small stop screws on the inner side of the throttle bodies These are factory set and it is a a hassle resetting them satisfactorily

N.B. Never Ever use WD40 on the Brass screws !!! The Rubber O ring swells and they are a total bugger to remove!! Use Back to Black spray OR Olive oil, combined with the heat effect from boiling water poured slowly over the throttle body Which helps to swell the alloy and start to break up the salt crystals that are most likely causing the difficulties¬!

When you are refitting? Use only a light SMEAR of rubber grease Or you can split the body I have seen the result!!!

Check the TPS by using a known good Multimeter You need to remove the rubber boot and insert a needle ir small probe into the rear most wire Usually its red with a white stripe BUT please check

Switch the multimeter to DC volts and the 20 volt range is good enough

Its a very small amount of movement to go off scale but you are looking for a value of 0.38 volt approx

When finished smear the inside of the boot with rubber grease and refit

Let us know how you get on!

P,S. Whereabouts in Ireland are you ?
"Put your Ass on a motorcycle and ride with an attitude and the "Grim Reaper" will ride in your shadow!"

Islandmagee in case you're interested?

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M58
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Re: 3000 rpm idle 1998 R850R

Postby M58 » Tue May 15, 2018 1:57 pm

Thanks Jeff and Jaythro, I fixed it (with your help).It just required giving the cables a good spraying with GT85. The throttle bodies were not quite closed when the throttle was closed. I will be replacing the cables soon as they seem to be stretched to the max.

Jaythro I divide my time between Fermanagh and Roscommon...
1998 r850r

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Jaythro
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Re: 3000 rpm idle 1998 R850R

Postby Jaythro » Tue May 15, 2018 6:06 pm

Jaythro I divide my time between Fermanagh and Roscommon...
Our Clan originates from Garrison :grin:
"Put your Ass on a motorcycle and ride with an attitude and the "Grim Reaper" will ride in your shadow!"

Islandmagee in case you're interested?

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M58
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Re: 3000 rpm idle 1998 R850R

Postby M58 » Tue May 15, 2018 6:34 pm

I`ll pm ya..
1998 r850r

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oldyam
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Re: 3000 rpm idle 1998 R850R

Postby oldyam » Wed May 16, 2018 9:43 am

Before you change the throttle cables just check it isn't the bowden box hanging up as this will give the same symptoms ( they get gritty & sticky inside )
Nigel
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M58
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Re: 3000 rpm idle 1998 R850R

Postby M58 » Wed May 16, 2018 10:35 am

Thanks oldyam, I`ll do that.
1998 r850r


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