84 tt600 carb probs

[thumpertt600]

well im having probs with the carbs on my 84 tt600 if i rap the it it will rev really nice but wen i roll it on and it craps out and sputters and it seems like its just dumping fuel, it runs really fat and i have no idea what to do with those carbs :coocoo:

 

[matt-itude]

Has it always been this way or did it just start doing it one day?

 

[thumpertt600]

i just got the bike , and it didnt run , so i pulled the carb and cleaned it really good about 4 times , im either thinking that its valves or ignition or the carbs suck really bad on theise bike it has a special 2 barrel carb on it so im pretty lost wen it comes to that set up

 

[matt-itude]

I had an 83 yamaha it was a 550 but very similar i am guessing the same carb setup. It had a somewhat standard primary side with a small slide on a linkage. I don't recall if the needle had adjustment to it or not (I think it had 3 groves and standard was in the middle) When I got mine it ran but barely. someone had swaped the pilot jet with a plug that should have been in the secondary side where the pilot jet would have been if it had low speed circuits. After I figured that out it ran half decent. The rest was jetting which nobody could get jets for it. So I had to grind the end down on a standard mikuni jet (the threaded end) then used a tap to cut the threads further down the body to fit. thats what I had to do for the primary side. The secondary side is easy (assuming it is the same setup as my 550) There will be a small fuel line that goes between the float bowl and the other half (secondary half) of the carb. You just stick the size jet you need inside of that small piece of fuel line (also used standard mikuni jet). this worked for me because i needed leaner than the factory jetting (so the jet i installed limited the fuel even more than the jet already installed which is the nipple assembly that the hose hooks on to). If you study it the secondary side of the carb works like a 4 barrel on a car in that it doesn't open up until you give it enough throttle for the linkage to open the butterfly valve on the secondary side. Check the choke to make sure it isn't stuck part way on and try playing with you mixture screw. It sounds like your problem is probably on the primary side (assuming that it is a carb prob) and should be in the mixture and needle range of motion since it sounds like it is at smaller throttle openings. I hope something here has helped. Mine ran smooth and crisp once it was dialed in i loved it.it was heavy though.good luck!

 

[thumpertt600]

that just sounds like alot of crap , im just ganna sale the bike

 

[matt-itude]

I hope you mean alot of crap as in a pain in the but. It is hard to explain but once you understand the carb its not that bad. There seems to be a couple other threads right now talking about some 600 yamahas that sound quite similar. sorry if I have discouraged you.

 

[thumpertt600]

what about putting raptor 660 carbs on it i think that mite help and you can jet to what ever you want

 

[matt-itude]

I dont know the bore sizes of the two different carbs. When i fixed mine it cost nothing but a few jets and TIME. It may b worth it to find something that has comparable sized carbs. Definiately easier to find jets and parts for.

 

[thumpertt600]

but i still dont under stand y it would run like that from factory

 

[matt-itude]

What elevation etc. do you ride? Mine didnt run bad under load (while riding) but did sputer if i hammered the throttle in neutral with the stock jetting. That was at 4500 ft. Check your valve adjustments. Also some guys were saying that the carbs secondary side would stick (picky about any kind of debris). mabey it is stuck open or partially and when you open the throttle slow its causing this problem. Im guessing you have checked and or replaced the plug and did it look black wet white what is it showing. just a few ideas. Mine ran really bad until you got it reved up you could barely ride it around the yard. Some one (not even me this time) had taken the carb apart and when they reassembled it there is a small plug and a pilot jet that are the same thread pitch and they swaped them. it would kind of idle but just ran like crap. once i figured that out and swaped the pilot jet into the right hole and the plug in the other it ran much better. ridable. I fine tuned it from there. It ran before i figured that out like it was out of time or the valves were to tight it would back fire seemed to run a little hot I dont know if yours runs that bad does it?

 

[thumpertt600]

mine runs the same way i have put 2 plugs in it , it revs nice and idles nice but if you role on the thottle it spitter and sputters like and puffs out black smoke like its just dumping gas , thier has to be another way to fix it , i dont know y yamaha doesnt have jets for it , im just ganna take it to a shop and see what they can do , and if they cant , then the bike is for sale

 

[matt-itude]

I dont think it will be as easy as unscrewing one jet in and putting another in and if you arent comfortable building parts there are people out there that know exactly how to dial these in. You should probably spend some time on the phone (if you are going to take it somewhere) and find some one that has experience with this setup before you take it there and spend money on someones learning on your bike. You dont live close to me do you I'm in Orem Utah

 

[thumpertt600]

well guys i fixed the prob, its the hole tt600 carb , its junk , i went out and got a xt550 carb and bolted right up ,and it runs perfect now , so if anyone is having a prob with their carbs try out the 550 carbs much better set up , less crap on the 550 carbs, works much better

 

[Jon K.]

Just saw the post, so I'm a bit late.

The '83 TT600 carb system is one of the finest I have run across. Not sure about the '84. Not sure about the 550.

The system uses one and a half carbs. The left hand carb is a real carb with idle circuit, mid circuit, main jet. . . the whole nine yards.

The left carb runs the left intake valve. It is not connected in any way with the right intake valve.

The right carb runs the right intake valve. It is not a complete carburetor. It has a main jet only, and is vacumn operated. No float even. It pulls fuel from the right float bowl. I would call it elegant.

The two are connected with a link that is position sensitive. The right carb doesn't open until the throttle is turned past 1/4 or so.

This allows the engine to run on one intake valve, and one small carb up to 1/4 throttle or so. Runs good too; lots of air velocity, lots of response, cranks really good.

Once the throttle is opened up further; the second carb kicks in and all hell breaks loose. Quite an engine for 1983.

Loooong stroke engine with tremendous torque. Nothing compared to the engines of today. More like a Gold Star. A true thumper, not like the high revving four strokes currently offered.

Thumpertt600; there is no telling what was the problem with your carbs. But I can assure you that if you had taken the time to get them right; they work really well.

I've got a TT600 right now. Runs like a charm. I call it "Thunder"

Now that you have yours running right; you have GOT to find a better set of forks. If you can graft a late model fork to it (I have a '90 model YZ fork on mine . . . . hmmm . . . . I suppose it is getting a bit dated) you will have a completely changed bike.

The rear suspension is pretty good. Try to find a nitrogen resevoir with a compression damping adjustment. Mine is off of a KDX and screwed right on the hose no problem. Even works with the original bracket.

Happy trails;

Jonny

 

[thumpertt600]

well the carb i got is off of a 83 550 bike , and yes its a mutch better carb , runs perfect smooth throttling from idle to wide open , i love it , the bike loves to be on one wheel , the only thing is thats its alittle heavy , im glad i finely fixed it .

 

[thumpertt600]

the bike still runs perfect, so if anyone has this prob look at this post the 550 carb is the carb to go with