16 replies to this topic

[CrashTestDuffy]

Hi folks,

Just got bike back from garage after getting them to repair some corroded wiring and bike is idling at 2500rpm when warm. Usually idles at around 1000 when warmed up. Checked idle speed adjuster and it's as low as it can go.

Are there any electronic settings that could be causing it that may have been wiped with battery having been out?

It's a 2009 TDM900 non-abs

Cheers

[Nog]

Sounds like the good old fast idle mechanism is stuck.

 

Give it a knock with something to push the plunger back in and see if that drops the revs back down.  Might need a strip down/clean if it does.

[CrashTestDuffy]

Idle adjuster still makes it higher idle speed when tightened, just bottom end it's still sitting at 2500. Was idling fine before going into garage and they hadn't adjusted it as it was at the same position as normal which is what was making me think it may be a dashboard electronic setting that had been lost. I'll give it a whap though to be sure.

Edited by CrashTestDuffy, 04 January 2019 - 05:54 pm.

[Studley Ramrod]

I think Nog is referring to the Cold Start Mechanism (CSM)

[Nog]

I think Nog is referring to the Cold Start Mechanism (CSM)

 

Yep, that's the fella.

 

It's a plunger that sits on the throttle bodies with a wax filled barrel and coolant supply.  As the coolant heats up, the wax expands and pushes the plunger which moves the fast idle assembly and drops the rev's to the idle (set by the idle adjuster you've been moving).

 

The default position (i.e. when cold) is with the high rpm setting, so if the plunger gets stuck, it remains in this position and you have this problem.

 

I think the end of the mechanism can be seen when looking at the right hand side of the bike (as you sit on it) and you can nudge the plunger to push it back and drop the idle.

 

EDIT - there's a large write up on cleaning it it in the knowledge base although not sure if the pictures still work - http://www.carpe-tdm...?showtopic=5017

 

Also here's a picture of the TB's - the CSM is at the very bottom - see the two water pipes for the inlet and outlet, above that is the piston that operates the idle speed (with a small rubber gaiter on it) which is connected to the mechanism which is pushed by the wax plunger below it.  When you look at the side of the bike through the fairing, you can see the end of that piston.  Give it a gentle push as the engine heats up and if it's sticking it should move in and drop the idle.

 

Edited by Nog, 07 January 2019 - 03:46 pm.

[TKH]

If you do the CSM it's worth getting something to protect it from crap getting at it in the future. There used to be an excellent kit available on here (Mr Henty) but I don't know where the bits came from.

If you've never done the CSM I think it's worth stripping and cleaning as a preventative measure as it will cause problems sooner or later. It's easy enough to do if you have a few tools. 

Edited by TKH, 07 January 2019 - 12:45 pm.

[Rallyist]

When you have cleaned and lubed it fit one of these  filled with ACF50 grease then you can forget it.

https://www.ebay.co....4.c100903.m5276

Ebay item number 390923919216

Edited by Rallyist, 08 January 2019 - 07:52 am.

[spike240]

The item is not available (link above).

I did this job when I bought my 900. Didn't get fit a gaiter, but it has been ok since (about 18 months ago).

[CrashTestDuffy]

Thanks kindly chaps/chapesses,

 

I am a non-fettler at present as don't have the time available to reliably be able to start a job and finish it in one go and I use the bike daily for work. Took it back into the garage yesterday and they tweaked the CSM so that it now appears to work in reverse. Revs are below 1k on cold-start and I have to use the throttle as a manual choke to start it (or crank up the idle adjust), but, once it's warmed up, the revs climb and sit at 1.5k idle with the idle adjust at the bottom end of its limit. They've also slackened the throttle cable off a little which appears to have had the knock-on effect of the "throw you over the handlebars" engine braking disappearing that I'd gotten used to.

 

/sigh

 

I can live with this for now though.

Edited by CrashTestDuffy, 08 January 2019 - 09:17 am.

[trevini]

You'll need to get the CSM off to strip, clean and lube it. Easy enough job, but that's definitely your problem. It might be worth a try of liberally spraying the CSM with WD40 type stuff - you never know, it may loosen up and start working again.

[Nog]

It's easy enough to do in-situ to be honest, just a bit fiddly.

 

Get all the air box off etc and then you can expose the system and clean it all up and lube

 

You need a good day free to do it though really, so if time is an issue probably best to stick with it as you say.  I wouldn't have wanted them to disable the CSM though, just a simply knock once warm will push the piston out and could actually free it up.  It's so easy to do from the side of the bike without removing any panels and with the end of a screwdriver or something (wooden spoon handle if it comes to it).

 

Sounds like you have other issues though if even when warm you have the idle set to the bottom limit.  Sounds like the CSM piston definitely needs nudging home regardless.

Edited by Nog, 08 January 2019 - 10:24 am.

[fixitsan]

It sounds to me like the garage just turned the wax piston adjusting screw all the way so that no CSM action is involved. The reason the idle speed rises after warmup is probably just because the engine is warmer.

[chrisr]

With my bike the throttle bodies needed balancing as well, someone had been trying to compensate for the stuck csm and had adjusted the throttle bodies and the idle speed adjustment screw. It had been serviced up until I got it at dealerships, that will not happen anymore!

Edited by chrisr, 08 January 2019 - 04:07 pm.

[TKH]

With my bike the throttle bodies needed balancing as well, someone had been trying to compensate for the stuck csm and had adjusted the throttle bodies and the idle speed adjustment screw. It had been serviced up until I got it at dealerships, that will not happen anymore!

  Don't get me started on my dealer servicing....... fecking basads.

[AzzA]

When I serviced my stuck CSM: I used a gater from a push bike brake caliper, thingy that sits over the end of the Bowden cable/tube IIRC.

Had to cut it back a tad but was a good fit... and the push bike hasn't missed it...

[tr7dan]

I have a genuine original unopened Lee Henty kit which is yours for the cost of the postage.

 

It's basically 4 ss allen screws and spring washers to replace original crossheads and the rubber gaiter to cover the plunger. I ordered two at the time, one of which is fitted to my bike, and the other was to go on my mates bike but he has since changed for a Africa Twin, so no longer needs it.  

 

 

 

 

 

pm me if you wannit

 

Dan

[spike240]

Posted Yesterday, 12:44 pm

I have a genuine original unopened Lee Henty kit which is yours for the cost of the postage

I have a genuine original unopened Lee Henty kit which is yours for the cost of the postage.
 
It's basically 4 ss allen screws and spring washers to replace original crossheads and the rubber gaiter to cover the plunger. I ordered two at the time, one of which is fitted to my bike, and the other was to go on my mates bike but he has since changed for a Africa Twin, so no longer needs it.  
 
 
 

 
 
pm me if you wannit
 
Dan

If OP doesn't want this, I would be interested.