20 replies to this topic

[toddyboy]

I bought a 2005 non ABS 900 recently from my son in law who simply wasn't using it. It hadn't been ridden for a few years but had been dry garaged.

The mileage is just under 50K

It has the standard exhaust system

The airbox mod has been done

The air filter is clean.

I haven't checked the plugs

It starts on the button and the engine is strong, pulls well and appears to have no issues.

The only annoying thing was a high tickover (1800 - 2000 rpm)

The idle adjustment knurled screw on the right hand side of the frame didn't appear to be doing anything so I flipped up the tank and found it'd completely screwed itself out (or someone had).

I refitted it, spring n' all and it now turns in and out as it should, but the tickover is still high.

I then adjusted the small adjuster screw just above it thinking that would do the trick but that only reduced the idle to about 1600rpm.

I then checked the air intakes and found they were exactly balanced. 

Can't think of what else I can do to reduce the idle tickover. I'd like it to idle at 1100-1200 rpm.

It's not the end of the world but it's annoying that I can't adjust the idle. I used to be able to do it on my previous 900

What am I missing?

Edited by toddyboy, 29 May 2023 - 05:03 am.

[Favs]

CSM?

[toddyboy]

What's CSM?

[fixitsan]

CSM?

+1

 

The cold start mechanism sits alongside the throttle bodies. It's a temperature based actuator, with 2 small water pipes connected to it. In normal operation as the water warms up the throttle/idle speed is steadily reduced.

These can become sticky and hold the revs high. The plunger sticking out of the end can seize with only a small amount of contamination, and they usually free up with the application of WD40 and pliers.

Once free, a good blob of grease and adding a new rubber boot to protect it usually sorts it out for another couple of years

Edited by fixitsan, 29 May 2023 - 07:29 am.

[toddyboy]

Might be a problem with the TPS (Throttle Position Sensor) maybe, though the idle isn't irregular, it's just high and I can't seem to mechanically adjust it any lower than 1600rpm.

My CSM appears to be free but I'll take a closer look.

+1

 

The cold start mechanism sits alongside the throttle bodies. It's a temperature based actuator, with 2 small water pipes connected to it. In normal operation as the water warms up the throttle/idle speed is steadily reduced.

These can become sticky and hold the revs high. The plunger sticking out of the end can seize with only a small amount of contamination, and they usually free up with the application of WD40 and pliers.

Once free, a good blob of grease and adding a new rubber boot to protect it usually sorts it out for another couple of years

[toddyboy]

Problem solved! There's a spring loaded screw accessible from the left side which adjusts the CMS. I turned it in about five clicks and the idle is now at 1100rpm. RESULT!

Edited by toddyboy, 29 May 2023 - 08:27 am.

[Catteeclan]

Prob have no fast idle when cold now unless someone has messed with it before.

[toddyboy]

Prob have no fast idle when cold now unless someone has messed with it before.

You're right! It still idles over at 1100 even when cold.

So that probably means the CSM is stuck internally.

Well at least I know now. Good job Summers here. I prefer the lower tickover speed.

Won't be a problem for now. I'll hoik it out and clean up the internals at some point before it starts getting cold again

[fixitsan]

You're right! It still idles over at 1100 even when cold.

So that probably means the CSM is stuck internally.

Well at least I know now. Good job Summers here. I prefer the lower tickover speed.

Won't be a problem for now. I'll hoik it out and clean up the internals at some point before it starts getting cold again

 

1400 is a good place to set the idle because it eliminates some slow speed roughness and possibility of stalling

[toddyboy]

 

1400 is a good place to set the idle because it eliminates some slow speed roughness and possibility of stalling

I'll test it out on the road tomorrow. The engine seems happy ticking over at 1100 and responds well to blips on the throttle. At least I can adjust it now, albeit with the CSM adjuster!

[leehenty]

Fix the CSM it will all work as Mr Yamaha San intended

[fixitsan]

Fix the CSM it will all work as Mr Yamaha San intended

 

I never found the standard rpm the best, but I have a bike with the 'throttle wiggle stall' problem, or it did until it was remapped

 

I think there's a low speed transition between open loop to closed loop for higher revs, and if you wiggled the throttle between these two modes quickly it seemed to make it stall.

I'm not sure if the change between the two modes happens so low down in the revs to be honest, I think it's more common for it to happen at higher revs.

 

I could have just learnt not to wiggle the throttle as much I suppose ....

 

 

This is what mine could do, even after applying 'fixes'

 

 

Edited by fixitsan, 30 May 2023 - 06:12 pm.

[toddyboy]

Road tested it today. Fired up from cold at the touch of the button and idled at 1100 no problem. No stalling when blipping the throttle or anywhere along the route. Doesn't crunch into 1st gear at the lights anymore and gearchanges are smoother. Didn't stall when changing down to a stop either. I like the low speed idle. All in all, pretty good result seeings as the CSM is stuck internally. It'll do for now.  

[toddyboy]

Bike has been starting up at the touch of the button from cold with no throttle and idling smoothly at 1200rpm since I screwed the CSM adjuster a couple of turns. Then a couple of days ago the tickover started playing up. The bike wouldn't just start with the button anymore, it needed a little throttle to start, hot or cold, and when I stop after a run the engine either cuts out or continues idling ok and then a few seconds later the idle starts to falter intermittently, then picks up, then falters again,then the engine cuts out. It'll start again but requires a little throttle and the idle is intermittent.

Still runs fine out on the road, lotsa power as before.

Almost feels like an electrical problem or I'm wondering if that intermittent idle phenomena could be the CSM trying to kick back in again? 

[fixitsan]

Bike has been starting up at the touch of the button from cold with no throttle and idling smoothly at 1200rpm since I screwed the CSM adjuster a couple of turns. Then a couple of days ago the tickover started playing up. The bike wouldn't just start with the button anymore, it needed a little throttle to start, hot or cold, and when I stop after a run the engine either cuts out or continues idling ok and then a few seconds later the idle starts to falter intermittently, then picks up, then falters again,then the engine cuts out. It'll start again but requires a little throttle and the idle is intermittent.

Still runs fine out on the road, lotsa power as before.

Almost feels like an electrical problem or I'm wondering if that intermittent idle phenomena could be the CSM trying to kick back in again? 

 

Might be the csm, but all I've heard about them is once they've stopped they rarely start to work again by themselves, in other cases a good spray with a thin penetrant, and moving the plunger in and out (once it has been removed off the waxstat element), with pliers, and then a good daub of antiseize grease to protect it. It's worth doing, you almost certainly don;t need to buy a new one.

 

There can be a few electrical gremlins but unlike many bikes the connected components are usually completely reliable, and the failures come in the form of poor connections to those components. Every year I open up every connector, spray them with a contact lube and re-mate them in and out a few more times to ensure a good connection.The connectors under the tank, behind the headstock and behind the dash can corrode more than most, and once they start to corrode and gain a high resistance they start to overheat and corrode even more quickly. It's worth the 2 hours per year to do it I reckon. It also gets you to look in places of the bike where the harness might be rubbing against metalwork that eventually can cut through the insulation.

[chrisr]

As Mr H said - fix the csm, fix the problem

[toddyboy]

Hoiked the CSM out. The outer pin was jammed solid. Got it out and cleaned it all up. In the process of doing that I cleaned up all the electrical connectors beneath the airbox. Put it all back together and turned on the ignition - nothing! Dead as a dodo. Ignition wouldn't turn the bike on.

Took off the airbox again and checked all the connectors and found that the positive wire connector from the ignition had broken due to corrosion and probably me messing around with it to clean the connectors. Fixed the broken wireI and also cleaned up the coil connectors and put it all back together. Bike fired up and with a bit of adjustment idled correctly. No intermittent faltering on idle any more.

First ride out and it feels a LOT smoother and feels like it has more low down torque

[fixitsan]

Hoiked the CSM out. The outer pin was jammed solid. Got it out and cleaned it all up. In the process of doing that I cleaned up all the electrical connectors beneath the airbox. Put it all back together and turned on the ignition - nothing! Dead as a dodo. Ignition wouldn't turn the bike on.

Took off the airbox again and checked all the connectors and found that the positive wire connector from the ignition had broken due to corrosion and probably me messing around with it to clean the connectors. Fixed the broken wireI and also cleaned up the coil connectors and put it all back together. Bike fired up and with a bit of adjustment idled correctly. No intermittent faltering on idle any more.

First ride out and it feels a LOT smoother and feels like it has more low down torque

That's the way.

 

A few of us had a problem with that, or similar, red wire, where it attaches to the fuel pump relay.

 

Happy riding !

[Snowbird]

At least that has found a leccy issue before it happened away from home.
I'd call that a win.

[toddyboy]

At least that has found a leccy issue before it happened away from home.
I'd call that a win.

Definitely a lucky find, as you say, if that had happened on the road I'd have been n the s**t.