01 SRX with stock motor
I bought the sled almost 2 years ago. Finally got it a chance to run it this year. Ive been through a couple tank with it and I'm still chasing my tail to get it to run right around idle.
The previous owner had the carbs rifle bored. I looked down the bore today and there appears to be some offset large channel grooves going down the throat of the carbs.
I have went up 2 sizes in pilot jets from 40's to 45's with fuel screws out to 1.75 and it just seems like I'm chasing my tail.
I have checked all the boots for leaks and found nothing also found no leaks coming from the crank. I am gong to post pics of the throats tomorrow.
I'm thinking I might need a se of stock carbs to get this thing right.
Other then that, The sled really hauls the mail up top and amazed how well this sled performs.
I bought the sled almost 2 years ago. Finally got it a chance to run it this year. Ive been through a couple tank with it and I'm still chasing my tail to get it to run right around idle.
The previous owner had the carbs rifle bored. I looked down the bore today and there appears to be some offset large channel grooves going down the throat of the carbs.
I have went up 2 sizes in pilot jets from 40's to 45's with fuel screws out to 1.75 and it just seems like I'm chasing my tail.
I have checked all the boots for leaks and found nothing also found no leaks coming from the crank. I am gong to post pics of the throats tomorrow.
I'm thinking I might need a se of stock carbs to get this thing right.
Other then that, The sled really hauls the mail up top and amazed how well this sled performs.
If the carb throats were bored straight, meaning there was material removed from the floor of the throat where the needle jet seats, you will have trouble getting them to idle properly. The proper way to bore these if offset or oval bore them so there is no material removed from the floor.
What are the problems at idle?
What are the problems at idle?
Before I get started on this, these carbs are so clean, they shine, every circuit is perfectly clean. I would put them up for a clean carb competition.
The idle is rough and tractors yet still running on all 3 cylinders. There is still a slight bog when you wack the throttle.
In order for the sled to perform like it should, I have to get it up to atleast 2500 or better yet 3000 RPM's Then its perfect.
The idle is rough and tractors yet still running on all 3 cylinders. There is still a slight bog when you wack the throttle.
In order for the sled to perform like it should, I have to get it up to atleast 2500 or better yet 3000 RPM's Then its perfect.
mopar1rules
Active member
sideshowBob said:
why is that bob? could you please explain why?
I forgot to add that when the motor is at operating temperature, just a VERY SLIGHT adjustment to the idle screw makes the RPM's jump from 1500 to 2500 or 3000 RPM's whichever it decides to.
mopar1rules
Active member
tomseal6 said:
probably fromt the air zipping past the throttle slides on the right, just like we talked about on the phone. can't wait to see them pics.
If you remove material from the floor of the carb it does a couple things that can effect the idle as well as other areas:
-it increases the area below the slide substantially allowing more air to pass under the slide effectively leaning out the idle and low speed mixture
-the signal is lessened to the pilot circuit when the throttle is closed or barely open because of increased area
-the needle jet sticks up and is no longer flush with the floor effecting the signal to it
[even if you machine the needle jet to sit lower in the throat you have effectively enrrichened the needle position like raising the needle would do normally and you create more problems with securing the needle jet with the main jet as it may be too low to tighten up]
-the throttle valve may not be able to be adjusted low enough to reduce idle without machinig.
If you look at the back of a TM 31 like on the SX600s you will see that the bore is offset to the low side so when they machine them to 33s[they are the same carb casting] they offset bore to the top to centre the opening without touching the floor.
This is common in smaller bore carbs that share the same castings with larger ones.
See the last post by Mrviper in this thread as well.
http://www.totallyamaha.net/forums/showthread.php?t=42970&highlight=boring+carbs
Bob
-it increases the area below the slide substantially allowing more air to pass under the slide effectively leaning out the idle and low speed mixture
-the signal is lessened to the pilot circuit when the throttle is closed or barely open because of increased area
-the needle jet sticks up and is no longer flush with the floor effecting the signal to it
[even if you machine the needle jet to sit lower in the throat you have effectively enrrichened the needle position like raising the needle would do normally and you create more problems with securing the needle jet with the main jet as it may be too low to tighten up]
-the throttle valve may not be able to be adjusted low enough to reduce idle without machinig.
If you look at the back of a TM 31 like on the SX600s you will see that the bore is offset to the low side so when they machine them to 33s[they are the same carb casting] they offset bore to the top to centre the opening without touching the floor.
This is common in smaller bore carbs that share the same castings with larger ones.
See the last post by Mrviper in this thread as well.
http://www.totallyamaha.net/forums/showthread.php?t=42970&highlight=boring+carbs
Bob
Last edited:
Pics tomorrow. Maybe new carbs next week
bluemonster1
LIFE MEMBER ONLY ONCE!!!
betheviper had 2002 carbs for sale...
I'm looking more towards a set of carbs now.
There has to be air getting past the slides or an air leak in the slides from the bore.
Its not right, I cant remember who it was, yet to mention I forgot the carbs had been bored on it, but when I bought the sled, somebody told me I'll be dropping $100 on a carb rack to end a headache
There has to be air getting past the slides or an air leak in the slides from the bore.
Its not right, I cant remember who it was, yet to mention I forgot the carbs had been bored on it, but when I bought the sled, somebody told me I'll be dropping $100 on a carb rack to end a headache
mopar1rules
Active member
tom, i sent you a text message. check your phone.
That last picture of the slide really made me question these carbs.
mopar1rules
Active member
tomseal6 said:
see what i'm talking about?
In the mean time, I am contacting the previous owner and attaching a picture of the slides.
I am going to ask him who did the work on these carbs.
I am going to ask him who did the work on these carbs.
03viperguy
Moderator
interesting. I am just getting into some ice drag with a 95 mach 1 my father in law picked up cheap, has bored carbs and I am up to 660 and a 700 main jet on that sucker! pulls hard though 
let us know who did the work!!
let us know who did the work!!
Still no email from the previous owner, but its all beside the point anyways
I was suppse to call Mopar on the carbs but got watching a movie and forgot to. I dont think there going anywheres. I hope this discourages anybody from thinking about getting their carbs bored out. Its very hard to jet for these and have it be reliable as stock yet alone seems very easy to make a mistake which looks like the case with my carbs.
I was suppse to call Mopar on the carbs but got watching a movie and forgot to. I dont think there going anywheres. I hope this discourages anybody from thinking about getting their carbs bored out. Its very hard to jet for these and have it be reliable as stock yet alone seems very easy to make a mistake which looks like the case with my carbs.
mopar1rules
Active member
Don't worry tom, them carbs ain't going anywhere. They're just chillin' in a box in the attic.
03viperguy
Moderator
I think bored carbs work great. for a drag sled 
like I said, mine have HUGE jets in them, and really all that has to be right on since it is pretty much on or off. good luck tom!
like I said, mine have HUGE jets in them, and really all that has to be right on since it is pretty much on or off. good luck tom!