TW200 Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
363 Posts
Discussion Starter #1
Hello Guys,

Can You check this short recording and try to help me what is that strange "noise" at some points?
The idling is like thump thump thump thump, very regular but a couple of times in these 10 seconds there is a sound like: thump thump thump thu thump thump thump thu
 

Attachments

·
Super Moderator
Joined
·
5,325 Posts
Ear plugs …..

The TW runs a “wasted spark” – eg every time the crank comes up to TDC you get a spark, even on the exhaust stroke

The inlet valve “should” block fuel flow to the cylinder at the appropriate exhaust stroke, but if even a little is getting through it would explain the noise you’re hearing. Now, I may be talking out of my own personal exhaust pipe here, but the first thing I’d do in your circumstances is double check the inlet and exhaust valve settings.

If your valves are set correctly, there shouldn’t be anything getting through at the wrong moment, so it’s unlikely to be your carb jet settings.

The only other thing that “could” be upsetting your valves are the seating arrangements – but as that involves a full top end tear down, if it ‘aint broke, don’t fix it – just keep an eye on it and get a set of ear plugs …….

(If you put your year of TW and the mileadge in your sig line, it’ll help to diagnose things like this)
 

·
Registered
Joined
·
363 Posts
Discussion Starter #5
Ear plugs …..

The TW runs a “wasted spark” – eg every time the crank comes up to TDC you get a spark, even on the exhaust stroke

The inlet valve “should” block fuel flow to the cylinder at the appropriate exhaust stroke, but if even a little is getting through it would explain the noise you’re hearing. Now, I may be talking out of my own personal exhaust pipe here, but the first thing I’d do in your circumstances is double check the inlet and exhaust valve settings.

If your valves are set correctly, there shouldn’t be anything getting through at the wrong moment, so it’s unlikely to be your carb jet settings.

The only other thing that “could” be upsetting your valves are the seating arrangements – but as that involves a full top end tear down, if it ‘aint broke, don’t fix it – just keep an eye on it and get a set of ear plugs …….

(If you put your year of TW and the mileadge in your sig line, it’ll help to diagnose things like this)
Tw200
1993
52984km

What I have to touch to fix?
Is something I can fix modifing the idle screw or the mixture screw at bottom of carby?
 

·
Registered
Joined
·
363 Posts
Discussion Starter #7 (Edited)

·
Registered
Joined
·
363 Posts
Discussion Starter #8
Nearly 53000km huh? Are you the only owner? Had any work done to the engine recently?
Nono I am not the first owner, its an used bike, I purchased like 3 months ago
I never noticed before because You know there were other things to do like install a brake disc, fix the electric circuit (because the front light was intermittent) etc so I didn't really paid any attention to it
But after three months of daily riding You start to get "a feeling" for the bike so You start to notice very small details that You never noticed before
So probably this was there since I purchased the bike

No recent engine work, as far as I know it was never touched
 

·
Registered
Joined
·
13,810 Posts
I've listened to your audio file numerous times. What I'm hearing can best be described as "the engine is skipping a beat".

I'm with purple in that you may want to verify the valves are set within specifications.

If they are: You can actually perform the below in any order I just put them in this order but not a requirement.

First, increase your idle speed and see if this "skipped beat" or "thumping in your words" goes away at the higher idle setting.

Second, decrease your idle speed and see if the mentioned sounds become more pronounced or disappear.


I'm not engine nor engine tuning expert, not even close but my thought is this sound should, could, most-likely will decrease or disappear when the engine idle speed is increased. You suggest or are asking if the pilot screw adjustment is needed. If you know how to adjust the pilot screw, you could make slight adjustments in or out with the screw and see if this makes a difference in the sound. Should you do this, you may want to make sure your engine isn't running too lean (white ish color or too rich (black sooty). Heck, you might want to check the condition of your spark plug now to see if it's adjusted correctly and not dirty or worn.

This next week I'm going to listen to my TW engines and see if they make a similar sound as yours does. I'm not probably giving you the real help you need but thinking (writing) out-loud to try and give you some ideas.

Keep us posted. Thanks.
 
  • Like
Reactions: Badgerflorida
1 - 9 of 9 Posts
Top