Jump to content

2000 Yamaha TDM 850 choke problem


Recommended Posts

Is anyone familiar with this? After 11 years VFR 750 I got a TDM 850, which behaves differently when it comes to cold starts. In warm weather it doesn’t require choke at all, that is, it won’t even start with the choke on. However, in cold weather it tends to cough and splutter with very erratic revs with the choke start and takes about 15 minutes to calm down. Is this a problem with the bike or am I doing something  wrong?

Link to post
Share on other sites

How long are you leaving the choke on for? I assume all the usual service items have been checked.

 

And is the fast idle set right?

 

I find that in cold weather I use choke to get it started, then hold the throttle at around 3000rpm for about 15-20 seconds, then ease the choke in halfway. By the time I've got my gloves on the choke is pushed shut.

Link to post
Share on other sites

Does the bike run normally when warmed up?

I have 4 bikes with manual choke and they all take some fine adjusting depending on engine and ambient temps.

On the R1, if its winter time cold I have to give it full choke and let it pick up by itself to about 2000rpm for 20 secs then it will start to race over 3000 and i back off the choke to maintain 2000. Once I've set off I'll shut off the choke after 1/4 mile and not need it again.

If its summer with a cold start, it will only need 1/2 choke.

The RGV needs full choke, summer or winter but have to shut it after 20 secs or it will over fuel it, start to choke up and cut out.

 

Have you been through all the usual;

plugs,

air filter,

valve clearances

Fuel filter

intake rubbers and hoses not perished

carb set up and balance, 

Is the thermostat working,i.e. running at normal temperature

 

Maybe you just need to get used to its cold running habits and regulate the choke accordingly.

 

And welcome

Link to post
Share on other sites

Thanks lads. And yes I am fairly new around here, sorry for forgetting introductions.


Having read your comments I can say that I have tried a few things so far: Half choke, full choke, before or straight after starting, hasn’t made a difference. it doesn’t happen every time but every second or third time.
Bike’s had a major service back in September by the way.
When it starts normally (on a good day) I shut the choke after about two minutes and all is well. Idle rev counter speed is around 1.3 - 1.4 when warm. 
When it decides not to play ball however, it feels as if opening the choke has caused the carbs to flood or something. It coughs, splutters, as if running only on one cylinder. When I rev it, it doesn’t respond immediately but suddenly jumps up 3/4 k rpm. When it happened the first time I thought it might go away if I just ride it and it nearly caused me to do an unwanted wheelie. When it’s idle for about 15-20 minutes, it then goes away.

 

I mentioned it to my mechanic and he said to try different variations of cold start until I get used to it, pretty much like what Bianco2564 said. If this is the case then I suppose I will have to work a little bit harder than on my VFR, which never had any problems of this kind.

Link to post
Share on other sites

Maybe there's damp around the spark plug caps. You could try a spray of wd40. Or it maybe there's rain water in the fuel. It collects in the bottom of the tank and carb bowls. It shows up on first start up after the bike has been parked for a while because the water has time to settle out of the fuel. You could try draining the bowls and see if there's water in the fuel.

Link to post
Share on other sites
32 minutes ago, WD-40 said:

Maybe there's damp around the spark plug caps. You could try a spray of wd40. Or it maybe there's rain water in the fuel. It collects in the bottom of the tank and carb bowls. It shows up on first start up after the bike has been parked for a while because the water has time to settle out of the fuel. You could try draining the bowls and see if there's water in the fuel.

This is not something I can do as I don’t have a garage but can certainly ask my mechanic to look into. Thanks for the tip.

Link to post
Share on other sites
On 02/01/2021 at 20:23, WD-40 said:

Maybe there's damp around the spark plug caps. You could try a spray of wd40.

Good call, but don't use WD40 for that. Use silicone 'tune up' grease instead. I use it on my outboards - never had a problem. WD40 will stop 'working' pretty quickly, silicone grease will last you a season.

  • Like 1
Link to post
Share on other sites

Arbitrary amounts of choke i.e. half or full rarely work. I've not had a choked vehicle that didn't need fine adjustment of the lever to make it not sound like a bag of spuds before it warmed up.

Try it next time you start up - set the choke off and engage the starter while slowly increasing the amount of choke. Once it fires up, gently decrease or increase the choke until it runs okay.

  • Like 1
Link to post
Share on other sites
10 hours ago, Jerry1111 said:

Good call, but don't use WD40 for that. Use silicone 'tune up' grease instead. I use it on my outboards - never had a problem. WD40 will stop 'working' pretty quickly, silicone grease will last you a season.

The reason to use WD40 first in this situation is because it is a dispersant. If there is damp in the ignition WD40 will drive it out. If that makes a difference that's the time to consider using something more long term.

 

Using something that could trap in moisture isn't what I'd try first.

 

But if WD40 does make a difference then the parts need replacing anyway because if they've deteriorated to admit moisture then they need replacing. 

  • Like 2
Link to post
Share on other sites
On 04/01/2021 at 08:23, Mr Fro said:

Arbitrary amounts of choke i.e. half or full rarely work. I've not had a choked vehicle that didn't need fine adjustment of the lever to make it not sound like a bag of spuds before it warmed up.

Try it next time you start up - set the choke off and engage the starter while slowly increasing the amount of choke. Once it fires up, gently decrease or increase the choke until it runs okay.

 

Trust me I’ve tried all that. Tried again yesterday with full choke, it got going coughing and spluttering, cutting out three times along the way so I had to rev it.
It took 20 minutes for the coughing to stop,  it warmed up, the normal idle speed returned and all was fine. But of course I can’t be doing this every time I need to get somewhere. 
 

So I’ve booked it in for Monday morning with my mechanic, who asked me on the phone if the bike was kept outside overnight. I’m assuming he was thinking whether it was a damp problem?  I’ll leave it outside his garage Sunday night so he has a cold engine in the morning. I’ll report how I got on after.

Link to post
Share on other sites

These things

* "it doesn’t happen every time but every second or third time"

* "it took 20 minutes for the coughing to stop"

make me think it's less likely the choke or the carbs, or anything to do with the fuelling, but more likely to be electrics. Damp and humidity can change make a bike with an electrical fault run lumpy one day and fine the next, and after 20 minutes heat from the engine can dry out a cable that is leaking charge through a pinprick hole. I'd be trying stuff like WD40 over the leads to the spark plugs to see if it makes a difference. If it does, then you're nearer finding where the problem is.

  • Like 1
Link to post
Share on other sites
On 10/01/2021 at 14:41, bonio said:

These things

* "it doesn’t happen every time but every second or third time"

* "it took 20 minutes for the coughing to stop"

make me think it's less likely the choke or the carbs, or anything to do with the fuelling, but more likely to be electrics. Damp and humidity can change make a bike with an electrical fault run lumpy one day and fine the next, and after 20 minutes heat from the engine can dry out a cable that is leaking charge through a pinprick hole. I'd be trying stuff like WD40 over the leads to the spark plugs to see if it makes a difference. If it does, then you're nearer finding where the problem is.

 

One cable was corroded once and left me stranded in the middle of Croydon waiting for AA. So it's quite posisble. It was one of the cables leading to the ignition from the relay, which I have no means of accessing because you have to remove the tank with the TDM. I am one of those bikers that do not have a garage unfortunately. 

Anyway it's been in the repair garage since yesterday morning but my mechanic hasn't been able to lok at it yet. He is snowed under with work, unusual for this time of the year I must say. 

  • Like 1
Link to post
Share on other sites

Update: Can’t completely get to the bottom of it. He said it started fine first time but wouldn’t the second. Opened up; carbs were a little flooded spark plugs were black apparently. He’s keeping it there until Monday morning to give it another go. Also burnt one litre of oil apparently having only done a few hundred miles since last oil change. Will

hopefully find out more on Monday.

Link to post
Share on other sites

He cleaned the carbs, reset the float heights and lowered the idle speed to 1000 rpm. It was in the garage for a week and he said it started fine every time after the work. That might have done it. I will see how I get on in the next few days.

  • Like 1
Link to post
Share on other sites

All good so far. Fired up with no problems this morning after a frosty night and runs like a dream. I treated it to a bottle of Redex to celebrate. 

  • Like 2
Link to post
Share on other sites
  • 2 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

Terms of Use Privacy Policy Guidelines We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.