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Discussion Starter #1
I have not pulled the trigger yet, still very ambivalent about the reliability of a carbureted bike, but that's my issue.

I have a question: I've read about the brass plug that has to be drilled out in order to adjust the fuel mixture screw. Two turns counterclockwise I believe.
Does this adjustment have to be made regardless of the altitude the bike lives at or only for bikes that live at high altitude? Mine, if I buy one, will live in SoCal. Thank you for your time.
 

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Carburetors in general are very reliable. Carburetors last nearly forever. If you rebuild every couple years, they are cheap and easy to work on, and super reliable. Always drain the fuel system if you aren't riding for a few months (storage). This will greatly reduce the chances of varnish build up in the fuel/air passages. And replace the carb needle once every couple years in the float bowl and you're all set.

You can bump start of kick start the carburetor bikes. That's not possible on a fuel injected bike unless the battery and starting system is in good shape. A dead battery on a injected bike means it's NOT starting. Then you need a friend with jumpers at a minimum.

My bike is carburetor and I now carry jumpers, simply because I was on one ride where a guy on a 4 stroke killed his battery MANY times!! Something was seriously wrong on t hat bike, and two other riders played musical batteries for the majority of the ride when he stalled it or stopped the engine without thinking. No one had jumpers. And made me think about the hour plus I spent standing around while they removed seats and swapped batteries around to charge the dead one in a kicker bike until he killed it again. LOL....

I guess the take take away is regular maintenance is important. But it was not that guys fault really, he was on an unfamiliar rental.
 

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I have not pulled the trigger yet, still very ambivalent about the reliability of a carbureted bike, but that's my issue.

I have a question: I've read about the brass plug that has to be drilled out in order to adjust the fuel mixture screw. Two turns counterclockwise I believe.
Does this adjustment have to be made regardless of the altitude the bike lives at or only for bikes that live at high altitude? Mine, if I buy one, will live in SoCal. Thank you for your time.
Cali bikes come with the carb adjusted lean just so they can pass emissions testing. Once the plug is removed the correct setting is to run the screw all the way in to bottom it out and then back it out 2 full turns. some slight tweaking after this might be necessary but they must be done while the engine is at operating temps. Keep in mind that my advice is based only on the older style carbs between 1987-2000 and I am not all that familiar with the new model carbs. Others here who are out west could have differing advice. Adjusting for altitude seems to only be a necessity if you get above around 5,000 feet or more.

GaryL
 

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Discussion Starter #4
Cali bikes come with the carb adjusted lean just so they can pass emissions testing. Once the plug is removed the correct setting is to run the screw all the way in to bottom it out and then back it out 2 full turns. some slight tweaking after this might be necessary but they must be done while the engine is at operating temps. Keep in mind that my advice is based only on the older style carbs between 1987-2000 and I am not all that familiar with the new model carbs. Others here who are out west could have differing advice. Adjusting for altitude seems to only be a necessity if you get above around 5,000 feet or more.

GaryL
Thank you Toolman and GaryL, I appreciate your time. I’m thinking maybe I need to grow a pair, buy this thing and maybe learn how to adjust stuff, that would be a novel idea, wouldn’t it? One more question if I may: is this brass plug difficult to locate or can it be reached easily? Thanks again for your help.
 

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If the plug is there and has not yet been removed it is fairly easy to get out. On all of my Old Style carbs that had the plug there was a tiny hole drilled in it from the factory. I used a very sharp, pointed self tapping screw and turned it into the tiny hole just enough to get a bite and wiggle the plug out. On the old carbs the plug is located on the bottom and between the float bowl and cylinder and it is a PITA to get to if the carb is on the bike. You can actually loosen the boots on both sides and turn the carb without completely removing it. On the engine side the joint the carb goes into has an alignment tab at the top so the carb needs to be pulled out a bit before you turn it. Again, I don't know the new style carbs and if they have the same conditions.

GaryL
 

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The new style carbs have the same condition and same solution.
The brass plug is very thin and easy to remove. Many never make any adjustment though and just ride their bikes a little leaner than optimum, and thus a little weaker than they can be.
As far as elevation goes I have been pleased with stock California jetting with the mixture screw at 2 1/4 revolutions out riding from sea level to over 11,000 ft.
 

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Discussion Starter #7
The new style carbs have the same condition and same solution.
The brass plug is very thin and easy to remove. Many never make any adjustment though and just ride their bikes a little leaner than optimum, and thus a little weaker than they can be.
As far as elevation goes I have been pleased with stock California jetting with the mixture screw at 2 1/4 revolutions out riding from sea level to over 11,000 ft.

Thanks Fred and GaryL. Great help. Now I have a tarting point.
 

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As far as the pilot needle setting goes, it will be a little further out at sea level than altitude. At 6,000 feet I have mine out 2 turns. It is not all that sensitive as Fred points out, but the factory setting is usually 1.5 turns, way too lean for good running between idle and half throttle.

As far as reliability, I would NEVER trust a fuel injected bike when I go alone into the boondocks. The TW is the most reliable bike I have ever owned in 50 years of riding and really easy to maintain. I would ride it across Mongolia....alone. :p
 

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Discussion Starter #9
As far as the pilot needle setting goes, it will be a little further out at sea level than altitude. At 6,000 feet I have mine out 2 turns. It is not all that sensitive as Fred points out, but the factory setting is usually 1.5 turns, way too lean for good running between idle and half throttle.

As far as reliability, I would NEVER trust a fuel injected bike when I go alone into the boondocks. The TW is the most reliable bike I have ever owned in 50 years of riding and really easy to maintain. I would ride it across Mongolia....alone. :p

I bet they can probably fix it over there...haha
 

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+1 for a carburetor's simple reliability when away from civilization. Gravity always seems to work to supply fuel to carbs while fuel injected bikes absolutely need a working high pressure pump and clean injectors.
By bias is admittedly flavored by last weekend's FI fuel pump failure that left me stranded after dark in a neighboring state.

We did have a Mongolian TW rider for a while here, he explored the steppes from his home in the capital of Ulaanbaatar then disappeared never to be heard from again...
I did know an exploration geologist who worked far to the west and far from modern living...had no TW though...rode yaks, ate yak blood, yak milk, and yak cheese and really, really missed American hamburgers.;)
 

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My TW is a 2017 so it's the same as a new one. Remove the throttle cables and loosen the boots. I had to remove the intake valve cover for enough clearance to rotate carb without removing it for easy access to the plug. Not a tough job at all and well worth the results. I also shimmed the needle valve and changed to a 130 main jet all without removing the carb.
 

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Hi, new here to this forum and a new owner of a 2015. I just completed a jet upgrade and removed the idle mixture cap. I keep seeing people make reference to drilling a brass plug, but on my bike it was a silver plug.

I'm not sure if this is how it is on all bikes, but after reading a thread where someone drilled the cap under the choke pull by mistake, I wanted to point out that it is a silver plug on mine. Self tapping screw is definitely the way to go for removal.
 

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Good helpful observations larsfsu, we really don't need to drill that plug whatever it's color. Your self-tapping screw seems optimal.
I suspect some of those who have drilled had the bit penetrate and then turn the mixture screw in accidentally. No big deal, just might explain some of the reports of a fully seated mixture screw allegedly from the factory.
 

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Hi, new here to this forum and a new owner of a 2015. I just completed a jet upgrade and removed the idle mixture cap. I keep seeing people make reference to drilling a brass plug, but on my bike it was a silver plug.

I'm not sure if this is how it is on all bikes, but after reading a thread where someone drilled the cap under the choke pull by mistake, I wanted to point out that it is a silver plug on mine. Self tapping screw is definitely the way to go for removal.
Yup! I am sure that Yamaha probably saved a few pennies by going with an aluminum plug rather than the older brass ones.

GaryL
 
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