48 replies to this topic

[fixitsan]

 

...and another one.....

 

Almost. That's just my usual fat-fingered mistake, the U is next to the I on a UK keyboard (and others....).  I've been making those bloopers since forevet !

[dmmsta]

 

Almost. That's just my usual fat-fingered mistake, the U is next to the I on a UK keyboard (and others....).  I've been making those bloopers since forevet !

Thats almost as good as Les Dawson playing a piano.

[fixitsan]

Thats almost as good as Les Dawson playing a piano.

 

Steady on, he was a legend wasn't he.

 

And now RIP Jim Bowen, surprisingly funny at times !

[dmmsta]

Surprisingly difficult to play the piano badly...

[fixitsan]

Surprisingly difficult to play the piano badly...

 

 

 

You have never heard me play yet, it's completely effortless ! 

Edited by fixitsan, 16 March 2018 - 09:11 pm.

[RobinHood]

The ht lead mod sounds like it may be a bit beyond me, i may have to have the mechs help again.. I've been so busy over not been back on this thread to check for about a week. I just had the plugs replaced as this has only been an issue since the new ones were fitted. And the first ride was awesome, really felt like it was back on form. Now it feels like a drunk pig again. Very cheesed off. So I guess I need to check the coils and leads. Possibly the throttle system?? I don't know anything like enough and don't have the time to tinker or make and rectify mistakes. So its just weekly visits to the garage for me. Until I roll the thing into the f'ing sea! Can't wait to have it back on form and not just to tease me again.

[RobinHood]

How would adjusting the idle tell me anything? Pardon my ignorance. And what is a csm?

[PICARD]

Sounds like you need a bit of help fella. Where are you ??

CSM is cold start mechanism. (bit like the choke on medieval machines).

[fixitsan]

How would adjusting the idle tell me anything? Pardon my ignorance. And what is a csm?

 

Back in them olden times, when we had manual chokes for cold starting, the choke mechanism did two things. It enriched the mixture, the air/fuel ratio of the carbs, and also increased the idle speed, by changing the throttle arm backstop position a little bit, to keep the engine from stalling.

 

With the 900, the enrichment is automatically controlled through the fuel injection system, but as there is no electric actuator on the throttle to raise the idle speed Yamaha added a cold start mechanism which raises the idle speed by pushing on the throttle arm (just like an old cable operated choke lever would do)

 

The csm  contains a water jacket and a thermostatically controlled plunger (waxstat), which works in a similar way to the thermostat in the cooling circuit. When the water is cold the waxstat is in it's extended position and raises the idle rpm to stop the engine from stalling when cold.

 

As the water in the jacket warms the csm has less of an effect and eventually when the csm actuator is fully retracted the idle speed is then controlled by the idle speed set screw.

 

If you suspect the csm is to blame you can turn up the idle speed (because that is all the csm does) by using the idle speed adjusting screw, and then if the bike starts fine when it's cold you know the csm is faulty

 

Another way to tell a faulty csm is to just run the bike from cold and make no changes. A cold bike will have an idle of say 2000rpm which will drop down steadily to about 1200rpm (ballpark rpm figures) once the temperature gauge needle is reading about halfway. If this automatic reduction in idle speed is not observed at all from a cold start then the csm is almost certainly inactive

 

There are a lot of info pages on this site about it, it sits just below the throttle bodies on the right hand side of the engine (when viewed from above, bike right side up (!) )

[PICARD]

That's what I said....

[dapleb]

Lolzio

[RobinHood]

Cool thanks for that. The cold start mechanism seems to be working like it always did, firing up first time every time, and running at 2k until warm then at 12-1300 and steady. Sometimes when running, particularly when the bike is warm or further into a journey, the revs can go funny and sometimes audibly wrong. Its basically going lumpy and unsteady when riding, mostly in lower gears. When accelerating or in higher revs all seems fine. I do need some help I think, I'm in Hove East Sussex

[dmmsta]

It sounds like it could well be HT leads.
If they've never been replaced then it may be just that the copper core is finally getting old.

I've get a meter of Magncor 7mm (i think) and start there...it's really easy to do.

I'm a bit of a trek...

[fixitsan]

it sounds like it only happens when the engine is running slowly, which is the same problem mine had when the alternator stator was failing. Basically, at idle there wasnt quite enough alternator output.

Check battery voltage when the bike has been idling for a couple of minutes. It should easily be 13.5-14.0V.

Failed stators are a known problem with the 900....do the lights brighten up significantly when revved, or dim noticeably when the engine slows to an idle ?

Edited by fixitsan, 20 March 2018 - 08:39 pm.

[dablik]

That's what I said....

 

 

I had an issue long ago with my 9r, similar situation but mine became unridable, problem turned out to be the cam position sensor (top left on rocker cover) you can switch it out with the speed sensor (behind the sprocket covers) which is an actual limp home aid, was long ago so it's a bit murky and it's a long shot but certainly worth checking. The swapping of sensors will limit speed but you never know, it could at least determine if it's part of or the issue, long shot but you'll be kissing me if it turns out to be the problem

To be sure you swap the right sensors they actually look identical.

 

Btw, the crazy french man will be familiar with the knowledge about it so have a look on his site,

[RobinHood]

Thanks again, the bike now has 50500 on the clock, would that fit with the ht lead idea dmmsta?
As for alternator, the bike always seems happy to start and warm up and i can start with the lights switched on, and put the heated grips on straight away. Ramo fitted battery indicator lights and these read a happy green for 12v charging and 12v charged at all times. I will test the battery when i get home.
2 questions: what does ht stand for?
And how I would I source replacement cam positi0n sensors? Any ideas? I'll try everything. And if all else fails I'll buy an fjr!

[fixitsan]

HT = high tension. It's old nomenclature but still accurate. High voltage is the modern term, because they feed the spark plugs with a very high voltage impulse.

 

The cam position sensor probably won't be a cheap part so the ability to swap it with the speed sensor is a godsend. It means a little bit of work, but only by removing screws and a couple of plastic covers. Download and refer to an online manual if you're not sure about location. You might get a sensor cheap on ebay and sell it again for the same amount after you're done checking ?

Edited by fixitsan, 21 March 2018 - 08:40 am.

[dablik]

Just to be clear the swap is not a permanent fix as the speed sensor is a limp home aid, but it would simply rule out the cam sensor being faulty if that's the case, thought i would throw it in the pot as a possibility, dont know for sure that's the problem, if all else fails take a look at it.

 

In my case i was able to ride the bike for a short while up until the point i needed the AA, took forever to find the problem and the speedo sensor got me started and idling which proved a faulty cam sensor.

 

I bought a used sensor on ebay, but best to check against returns if you end up needing one.

[dmmsta]

Its possible - some still have original leads.

Its the cheapest triage option I would suggest....

 

 

Thanks again, the bike now has 50500 on the clock, would that fit with the ht lead idea dmmsta?
As for alternator, the bike always seems happy to start and warm up and i can start with the lights switched on, and put the heated grips on straight away. Ramo fitted battery indicator lights and these read a happy green for 12v charging and 12v charged at all times. I will test the battery when i get home.
2 questions: what does ht stand for?
And how I would I source replacement cam positi0n sensors? Any ideas? I'll try everything. And if all else fails I'll buy an fjr!

[RobinHood]

So... I went for a diagnostic sesh at the garage and after a test ride the bloke removed my throttle aid clip and the issue has become far less severe, but still present. So it seems its not misfiring but the suspension has gone pretty soft and floaty which messes with my throttle control. Particularly noticeable between 3-5k rpm. Which is apparently where the secondary jet comes in at. I'm not entirely satisfied with the solution as i notice when i hold the throttle is a steady position while off the bike at 2k, the revs still wander a bit above and below 2k by up to 200rpm. So I think I need to adjust and setup my suspension and stiffen things up a bit, and potentially tune her up a bit. Am I right? I've never adjusted preload and rebound before so I could use some tips on how to set this up right. I weigh about 100kg with full kit and need the bike to handle a further 20kgs for some long trips i have coming up. Can anyone direct me to a good thread or page or offer some tips? Much appreciated