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Hey guys,

This is my first post, but I've been reading up on this forum for some months already.

I wonder if you guys can help me out with some advice for my 1985 BW200N. Maybe someone has had a similar experience with his/ her TW.

I got the bike around two months ago, but it did not have an air filter. So I rode it a bit just to test it and it ran LEAN. It would backfire, hesitate when opening the throttle past half way and the spark plug would come out white. It made a rattling sound which I assume was pre-ignition (pinging) and when idling when warmed up it would die. Also when having the throttle slightly opened (like 1/8) the rpms would go up and down, without changing the throttle position. I attributed all of this to the lack of air flow restriction because of not having an air filter.

So the filter finally arrived. I installed it but nothing changed :huh. It still lacked a lot of power.

So yesterday, I changed the needle setting to the first slot (richest), and the bike runs pretty good, but still has the rattling sound coming from the engine. Here is a video so you can hear it:



It still dies while idling when it is warmed up (I have adjusted the rpm screw but it still dies) and when having the throttle at 1/8 it still goes up and down on rpm's without changing the throttle position.

I have:

Checked the gas cap for flow - OK
Checked the fuel filter for obstruction - OK
Cleaned the Carburetor throughly twice
Checked Airbox and Carburator Rubber Connection for Leaks - OK
Checked Spark Plug Gap and used a couple of new ones for reading
I am using Premium Fuel
Oil Filter is clean / Air Filter is new
I am using Yamalube 10W-40 Mineral Oil

The original owner almost did not use it. It has very low hours. The main jet is stock (#108) and I have the pilot crew at 1.5 turns from the closed position.

I closed the pilot screw almost completely to make it run rich. It felt like it was running on choke, but it STILL had the rattling sound from the engine. So I don't know if the pinging sound is actually because of running lean? Or could the timing be off? Could it be the valves? Even if the bike has been used very very little.

Here is how the spark plugs look right now. They have a white tip, but tan color on the lower part. Does it look like it is still running lean?






Any advice will be greatly appreciated.


Many many thanks.
 

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If your carb is the same as the TW you need to open the pilot screw around 2 1/2 turns out to start. You have a lean condition now, check for air leaks at the carb intake by spraying WD40 or starting fluid onto the boot.
 

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Discussion Starter #4
Go the other way with the air/fuel screw to richen it. Try 2 1/2 turns out and go from there. Did you oil the air filter? Also, use regular not premium gas in it.
Hi littletommy thanks. I almost closed it completely to richen it the most I could. It felt like it was running with the choke on and you could smell it running rich. It still had the rattling / pinging noise. I tried different positions with the pilot screw, and it runs best at 1 1/2 turns out (which is also what the manual states). Any other suggestions?
 

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Discussion Starter #5
If your carb is the same as the TW you need to open the pilot screw around 2 1/2 turns out to start. You have a lean condition now, check for air leaks at the carb intake by spraying WD40 or starting fluid onto the boot.
Thanks RBM.

I did check for air leaks with WD40 on the boot and carb intake. The bike did not go up on rpm's when I sprayed it.

I tried different positions with the pilot screw, and it runs best at 1 1/2 turns out (which is also what the service manual states). If I went out further, or went less it runs very poorly.

Any other suggestions?
 

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I would try going out another turn for a total of 2 1/2 out from bottoming out, then if nessesary adjust the idle screw so it is within specs. Did you oil the new air filter? Do these things first, then if it is still rattling and making noise, it could be the chain tentioner or valve adjustment, but I am assuming that those are ok, since it has low miles. Never hurts to check them though so you have the peace of mind that they are right.

I am assuming that it is the same engine as the TW. Perhaps do as they say with the 1 1/2 turns and adjusting the idle, oil the filter, etc, first. Then try the 2 1/2 turns out..
 

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Discussion Starter #7
I would try going out another turn for a total of 2 1/2 out from bottoming out, then if nessesary adjust the idle screw so it is within specs. Did you oil the new air filter? Do these things first, then if it is still rattling and making noise, it could be the chain tentioner or valve adjustment, but I am assuming that those are ok, since it has low miles. Never hurts to check them though so you have the peace of mind that they are right.

I am assuming that it is the same engine as the TW. Perhaps do as they say with the 1 1/2 turns and adjusting the idle, oil the filter, etc, first. Then try the 2 1/2 turns out..
OK littletommy will do. Just to make sure, I close it completely (clockwise), then open it 2 1/2 turns (counterclockwise)?

Yes I oiled the filter and yes it is basically the same engine.

Question: If the chain tensioner is out of adjustment, would it advance or delay the timing? Or what effect would it have?

Many thanks again for the pointers!
 

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OK littletommy will do. Just to make sure, I close it completely (clockwise), then open it 2 1/2 turns (counterclockwise)? correct. lightly seat it, then 2 1/2 out. Did you try it as the manuel says? 1 1/2?

Yes I oiled the filter and yes it is basically the same engine. OK>

Question: If the chain tensioner is out of adjustment, would it advance or delay the timing? Or what effect would it have? Noisy rattling.

Many thanks again for the pointers!
Glad to be of help.
 

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Try some Lucus Deep Fuel Cleaner or Seafoam in it too. It would be better if you had regular gas in it too. Was the gas fresh that you have in it at least? Just for peace of mind, I would go ahead and check the valves and chain tensioner, then you know it's not them.


*they are kinda rattling little engines anyway..so take that into consideration.
 

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Discussion Starter #10
Try some Lucus Deep Fuel Cleaner or Seafoam in it too. It would be better if you had regular gas in it too. Was the gas fresh that you have in it at least? Just for peace of mind, I would go ahead and check the valves and chain tensioner, then you know it's not them.


*they are kinda rattling little engines anyway..so take that into consideration.
Yes it is now set on what the manual said 1 1/2 turns, but I will give it a try with the 2 1/2 turns.

Yeap the gas is fresh. I emptied the old gas when I got it.

OK I will check the chain tensioner and the valves. Thanks again for the pointers littletommy!

I will keep you guys posted.
 

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Discussion Starter #11
Here are some pictures of the bike.

It had the original factory tires but they were cracked, so I put new ones on it. Ordered new graphics form ebay, and bleached the plastics. I think it's looking pretty good. Too bad I haven't been able to adjust it properly :nightmare:






 

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Here are some pictures of the bike.

It had the original factory tires but they were cracked, so I put new ones on it. Ordered new graphics form ebay, and bleached the plastics. I think it's looking pretty good. Too bad I haven't been able to adjust it properly :nightmare:






Great looking Big Wheel!

I am curious, how did you bleach the plastics? They look great.
 

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Idk, but I wash trying to hunt down the same noise on mine! But mine is way different. In 5th gear at like 40-50MPH at WOT. The engine will "clack...clack clack...clack clack...clack clack clack" Like nowhere near as fast as the RPMs or even regularly. I figured it was piston slap cause I have a rejet and plug chops show I'm very dead on with my jetting. Please keep me posted on what it is.
 

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Idk, but I wash trying to hunt down the same noise on mine! But mine is way different. In 5th gear at like 40-50MPH at WOT. The engine will "clack...clack clack...clack clack...clack clack clack" Like nowhere near as fast as the RPMs or even regularly. I figured it was piston slap cause I have a rejet and plug chops show I'm very dead on with my jetting. Please keep me posted on what it is.
Sounds normal to me for an engine which is under load trying to go faster but can't do it quickly due to speed & gear it is in, wind, hills, weight of rider, etc. I wouldn't worry about it. The noise sounds like it comes from the top end of the motor, timing chain, valve train, etc. It's just a small engine rattling under a load. Change gears so that the rpms are higher and the motor is working easier and you probably don't hear it anymore.
 

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Discussion Starter #18
Idk, but I wash trying to hunt down the same noise on mine! But mine is way different. In 5th gear at like 40-50MPH at WOT. The engine will "clack...clack clack...clack clack...clack clack clack" Like nowhere near as fast as the RPMs or even regularly. I figured it was piston slap cause I have a rejet and plug chops show I'm very dead on with my jetting. Please keep me posted on what it is.
Hey Kdick91,

I will keep you posted when I find the cause.

Mine will go off and on, even if I down shift.
 

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Discussion Starter #19
Anyone think it could be the CDI going bad? Or would the symptoms be different?

I won't be able to check the valves or timing chain until the weekend when I have some time to work on the bike.
 
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