TW200 Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter #1
Hi. This my first post, but have enjoyed the great variety of topics covered here. There are many posts here about carbs and I guess I am going to add to that. My 88 has about 3500 miles and runs great. The problem is that is that if it is cold enough to have to use the choke. When using the choke the bike will start and start to idle up, but immediately starve for fuel. Fortunately the bike will usually start and run without the choke. The carb has been cleaned and rebuilt. The valves are adjusted, the air filter is clean, and the carb intake is in good shape. I have sprayed the intake when running to be sure there isn't an air leak. I saw one post that hinted at the slow jet, but doesn't the choke circuit by pass the slow jet? I've had the carb apart several times but must be missing something. I'm starting to get envious of the people whose bikes will only idle with the choke on. Also I live in Colorado at about 8000 feet.
 

·
Super Moderator
Joined
·
5,299 Posts
How many turns out is your idle jet ?

And when you say “starve for fuel” – the only way your bike can “run great” except at starting / idle, is if the idle jet is blocked somehow, or the choke (which is an enricher) is malfunctioning somehow

At altitude, if your bike will run fine in warm weather (thin air), it should run better in cold weather, as the air will be slighter thicker

There are two components that tends to do better when it’s warmed up - and that’s the spark plug, and the condition of the battery …..
 

·
Registered
Joined
·
7 Posts
Discussion Starter #3
The bike runs normally except if you try to start it using the choke. The spark plug is new and the battery is charged. I guess I am thinking that if the idle jet is plugged, it wouldn't idle at all. I'm confused about how the choke functions. I did rebuild the carb. The choke had the same problem prior to the rebuild. My idle jet is a 40 and I am 3 turns out on screw.
 

·
Super Moderator
Joined
·
5,299 Posts
Then the problem is likely to be with the choke assembly

I’ll be the first to admit that I have no more than a passing knowledge of carbs in general, so I’m in no position to answer your question of how the choke works – but have a quick read of this thread, only the first post is relevant - http://tw200forum.com/forum/technical-help/6448-carb-choke-issues.html

Although the thread concerns the ’06 CV carb, some of the other parts such as the choke have a lot in common, and in this case, your symptoms are similar (unless I’m misreading this)

If you look at the relevant ’88 part here - https://www.partzilla.com/catalog/yamaha/motorcycle/1988/trailway-tw200u/carburetor-non-california-model - you will see that there is more to this part than you’d think, and taken in conjunction with what that thread suggests, the smallest of bits missing could result in what you’re experiencing

At this stage, were both shooting in the dark here, but I’d remove the choke assembly and check it against that schematic

Hopefully, someone else will be along later to shine some more light on this …….
 
1 - 4 of 4 Posts
Top