43F carburetor tuning?
- Steffen
- Beiträge: 4719
- meble kuchenne Ruda Śląska Rybnik Tychy
- Registriert: Di 18. Mär 2008, 18:08
Re: 43F carburetor tuning?
Hello Jack.
Before you drill holes into your airbox try a short run without air filter (airbox closed) or even without filter and airbox cover.
Maybe the filter is not that good. Some new filters are too tight to support your engine with enough air.
Holes in the airbox are also known to me, "Wunderlich" even sold small filter caps for these holes some years ago. But I dont like this solution. First I would try a K&N air filter which gives a little more air to the engine without spoiling the air box cover.
You also checked the fuel? Does it get enough fuel?
Any possibility to check the generator?
Stef
Before you drill holes into your airbox try a short run without air filter (airbox closed) or even without filter and airbox cover.
Maybe the filter is not that good. Some new filters are too tight to support your engine with enough air.
Holes in the airbox are also known to me, "Wunderlich" even sold small filter caps for these holes some years ago. But I dont like this solution. First I would try a K&N air filter which gives a little more air to the engine without spoiling the air box cover.
You also checked the fuel? Does it get enough fuel?
Any possibility to check the generator?
Stef
Re: 43F carburetor tuning?
Took it for another ride today....seems to be doing alright for high speed after all however now it goes to the higher rev lacking a bit when going beyond 5000rpm today i realised that there's a slight cough so i'm guessing it's not getting enough fuel into the secondary or could it be the incorrect adjustment?
I had the generator check at the shop before assembly and it seems to be in good working order after a thorough check.
I will give the K&N filter a try however just in case. At the moment it has a dual element twin air foam filter in the airbox.
I had the generator check at the shop before assembly and it seems to be in good working order after a thorough check.
I will give the K&N filter a try however just in case. At the moment it has a dual element twin air foam filter in the airbox.
YAMAHA. The way it should be 

Re: 43F carburetor tuning?
Hi Jack
Before buying an expensive K&N give it a try without air filter or without cover. Maybe thats pointing in the right direction. A test ride without air filter wount damage your engine. You might also analyze the color of your spark plug after a full throttle ride (use kill switch, pull clutch and use brakes for stopping, then check the spark plug.
Not enough fuel: ensure that your fuel shutoff valve clean and working and pointing to "reserve". fill your gas tank a little (2-4 liter will be okay). Leave the fuel filler cap open (!) and make a test ride. Background: maybe there doesnt flow enough air into your gas tank when the gasoline runs to your carbs.
Not enough fuel (2): ensure that the floater in the left carburetor is in the right position. This floater regulates fuel for both carburetors. You have to deinstall the carb and open the float bowl. Then put the carburetor upside down.
1) ensure that both floater arms are parallel
2) shake the floater. If there is fuel inside than the floater is damaged and not working.
3) Now tilt the carburetor this far that the floater slightly touches the needle valve but does not press it down (angle ca. 40°). Measure the hight of the floater to the carburetor case (where the gasket for the float bowl is installed). The distance from the floater to the carburetor case should measure 25-27mm (see here). If it's more than 27mm than the carburetor closes too early and the bike doesnt get enough fuel. less than 25mm should be visible from outside because there will be fuel dripping out of the carburetor. You can adjust the floater hight by slightly bending the metal clip that touches the valve. Then measure again until you reach the correct distance.
By the way: do you have the "Clymer" repair manual?
I apologize if I explain things in detail that you might already know. It's not easy to guess how experienced you are or not.
Best,
Stef
Before buying an expensive K&N give it a try without air filter or without cover. Maybe thats pointing in the right direction. A test ride without air filter wount damage your engine. You might also analyze the color of your spark plug after a full throttle ride (use kill switch, pull clutch and use brakes for stopping, then check the spark plug.
Not enough fuel: ensure that your fuel shutoff valve clean and working and pointing to "reserve". fill your gas tank a little (2-4 liter will be okay). Leave the fuel filler cap open (!) and make a test ride. Background: maybe there doesnt flow enough air into your gas tank when the gasoline runs to your carbs.
Not enough fuel (2): ensure that the floater in the left carburetor is in the right position. This floater regulates fuel for both carburetors. You have to deinstall the carb and open the float bowl. Then put the carburetor upside down.
1) ensure that both floater arms are parallel
2) shake the floater. If there is fuel inside than the floater is damaged and not working.
3) Now tilt the carburetor this far that the floater slightly touches the needle valve but does not press it down (angle ca. 40°). Measure the hight of the floater to the carburetor case (where the gasket for the float bowl is installed). The distance from the floater to the carburetor case should measure 25-27mm (see here). If it's more than 27mm than the carburetor closes too early and the bike doesnt get enough fuel. less than 25mm should be visible from outside because there will be fuel dripping out of the carburetor. You can adjust the floater hight by slightly bending the metal clip that touches the valve. Then measure again until you reach the correct distance.
By the way: do you have the "Clymer" repair manual?
I apologize if I explain things in detail that you might already know. It's not easy to guess how experienced you are or not.
Best,
Stef
Re: 43F carburetor tuning?
Hello Stef,
That's all good thanks mate, you're only here trying to help anyway plus gathering other person's opinion is a good thing when comes to these diagnosis
Yes i do a have a clymer manual here but i thought i better get some more opinion just in case because i heard a few people that said sometimes the clymer's data may not be accurate on some models.
That's all good thanks mate, you're only here trying to help anyway plus gathering other person's opinion is a good thing when comes to these diagnosis

Yes i do a have a clymer manual here but i thought i better get some more opinion just in case because i heard a few people that said sometimes the clymer's data may not be accurate on some models.
YAMAHA. The way it should be 

Re: 43F carburetor tuning?
Also guys, while this thread is active i'm wondering if you guys would know the proper routing on the front brake cable for these 43F please?
YAMAHA. The way it should be 

Re: 43F carburetor tuning?
Would u pls ask this question in the responsive forum ? Thx.
Grüße, Henner
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