Bad Running 900

[Doggy]

Hi All

 

My 900 has a hunting - sensation between 2500 & 3000 rpm. When i started it this morning it was running really rough, sounded like it would cut out at any second. As it warmed up a bit it seemed to settle down as normal. However riding it it hunts and is very jerky between 2500 & 3000. Above that it seems to rev alright but feels a bit down on power but seems to tick over ok

 

It was recently service by myself and the great Mr.Henty, having new plugs, air filter, airbox mod done, cold start mechanism cleaned and a Mr. Henty kit fitted, HT leads wrapped in self amagamating tape and new coolant.

 

It ran beautifully since up until today.

 

It had a new battery over the winter.

 

Any advice or pointers as to where to look would be much appreciated.

 

Cheers

 

Doggy

 

 

[Trevini]

Might be worth having a look at the co settings on the dash. It has been known for them to reset to zero if the battery was a  bit low when turning the engine over to start. 

 

 

 

[attachment=o15211]

This post was last modified: 03-05-2023, 03:13 PM by Trevini.

[Catteeclan]

Might be worth having a look at the co settings on the dash. It has been known for them to reset to zero if the battery was a  bit low when turning the engine over to start. 

 

 

 

Screenshot 2023-05-03 at 16.12.45.png

Or in the case of my blue 04, reset one side CO to -128 I think it was.

[chrisr]

Wouldn’t be that if it was running ok till today

[Trevini]

Could be if it did it when he went to start it Chris. Usually only happens if the battery is low on charge or knackered. It’s a new battery, so maybe just low if it’s been sitting a while since last run.

[Doggy]

Rode it a couple of days ago and it was fine, battery has an optimate connected when not being used.

[MArk2]

Revisit ht leads plug end i managed to dislodge one of mine pushing the cap back  

[Doggy]

Hi Guys

 

Just checked my co2 readings, engine cold, C1 25 & C2 11. Played with them, but didnt seem to make any difference.

 

Have set them both to 10 will take it for a spin and see if feels any different.

 

Should i readjust once warmed up?

 

Cheers

 

Doggy

[fixitsan]

Hi Guys

 

Just checked my co2 readings, engine cold, C1 25 & C2 11. Played with them, but didnt seem to make any difference.

 

Have set them both to 10 will take it for a spin and see if feels any different.

 

Should i readjust once warmed up?

 

Cheers

 

Doggy

 

I think if it makes no change and doesn't help you to find the problem then set them back to 25 and 11.

 

The adjustment is designed to fine tune the open loop low speed/low load mixture. When the throttle bodies are made they have slight differences due to manufacturing tolerances, not to mention, that in the airbox each throttle body has a different length rubber snorkel .

I would be surprised if under those conditions many bikes left the factory with both settings at the same value, due to the inherent differences between intakes, of each cylinder.

 

The better approach, imho, is where there is a difference between them to start off with, keep the difference the same by increasing both, or decreasing both, by  the same amount.

 

By all means adjust them, I find I got a smoother idle by increasing them both, but retain the units of difference to keep them balanced.

 

If it hasn't fixed the problem, anyway, I would go on to rechecking the ignition system again as mentioned above, but check the simple stuff too, such as vacuum hoses coming off the manifold. The vacuum pipe to the airbox flap is a good place to get a vacuum leak too

[Doggy]

Many thanks 👍

[LAURENCEAUX]

Poor idle - corrupted fuel? Inconsistent spark? Tank breather blocked?

[Doggy]

Hi All

 

Just taken it for its mot, it passed no advisories, but the problem appears to be intermittent.

 

From  cold its starts but is all over the place, then settles down to an even tick over. However on a run through town it is practically unrideable at times, surging and and dieing. then appears to be fine for a bit.

 

Help please, i have no idea where to start but i do need to get it sorted.

 

Cheers

 

Doggy

[Snowbird]

Sounds like a check and clean of all electrical connectors may be in order, a corroded wire can be hard to spot and give intermittent issue like you describe so give them all a little tug as you go, a good looking wire may just came apart with a minor tug.

[LAURENCEAUX]

Is oil creamy? - perhaps caused by coolant ingress to combustion area that is inhibiting good sparking and correct air/petrol ratio?

This post was last modified: 12-05-2023, 07:23 PM by LAURENCEAUX.

[dablik]

Lift the tank and have a good poke around, look for a RED wire from a connector block, has corroded on a few occasions, could be your problem...

[chrisr]

Having spoken to Mr H about this when I went to see him today he too thinks it will be the multi connector under the air box, or a dodgy connector somewhere, so its off with the plastics and up with the tank and pull them all apart and acf 50 or servisol contact cleaner and you should be sorted

[Doggy]

Thanks Chris, will have a go tomorrow.

[dablik]

Your welcome 

[Doggy]

Thank you, red wire hunt starts tomorrow

[MArk2]

Thank you, red wire hunt starts tomorrow

The red wire lives on the big relay 5 EA-81950-10  its live to fuel pump.  Also try the red on the reg rec, known to corode. Best Mark.