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600 VENTURE SMART CARB

31K views 27 replies 8 participants last post by  Timminz_small_engine_guru 
#1 ·
RECENTLY PURCHASED A 97 600 VENTURE SMART CARB AND IT RUNS POORLY (MISSING AND BACK-FIRING) AT RPMS OF LESS THAN 5000. I SEE THE MAINS WERE JETTED DOWN TO 156.3 (I THINK) AND PILOTS ARE NOW #60. ANYBODY WITH SOME EXPERIENCE WITH THIS SLED AND SOME ADVICE?
 
#2 ·
I own the same sled with the similar problems , low end loss of power, backfiring sometimes, runs rough low end until about 5,000 to 5500 rpms then it straightens out but I have also experienced a loss of power top end sometimes top rpms would be 7000, and with wide open throttle rpms would sometimes drop to 6,000 like the sled was starving for fuel, I have taken the carbs off cleaned and reinstalled, adjusted balance of throttle plates ,with little difference in performance
found two solenoids on each carb, I have disconnected all solenoids found this makes in run rougher and sets the diagnostic light flashing disconected the two lower solenoids ran rough backifred even worse, I then disconencted the two upper solenoids and top end is better than it has ever been,8,000 rpms now versus 7,000, and no loss of power at all, backfiring is gone , but still have low end rough running until about 5,000 rpms, just found this yesterday, and I am still working on the problem
better but not fixed right,by disconnecting stuff, so if anyone has any info it would be appreciated or maybe a website with diagnostic info, hints anything,
 
#3 ·
today we drove the venture and noticed a lot of smoke from the exhuast, checked the throttle cable adjustment and found over oiling, adjusted throttle cable so carbs and oiler come on at the same time, runs sweet, best it has ever run, reconnected solinoids we had previously disconnected and still loose power, top rpms drop from 8,000 to 6500
so we haven't figured it all out, but with carb solenoids disconected and throttle cable adjusted so oiler and carbs come on at the same time machine runs great, smooth power from clutch enguagement all the way through to max rpms, I will do further research to see how the solenoids are controlled to find the real problem, but we are making progress,
 
#5 ·
If this is anything like my 1998 MM600 smart carb...


Does the check engine light flash 3 times when you start the sled? Does it give any other series of flashes after it is running?


If the light works, and there are no codes I would think it would be something physical with the carbs. Perhaps try stock jetting and verify throttle free play, idle speed, clutch engagement etc...


I am surprised how certain things affect others. For example, I was having a bog problem when going WOT from a stop. Turns out my idle was 2-300 RPM too high. Lowered idle, hit WOT and it just moves out now.


One last question, this is under 5,000 RPM when the machine is warm right?


Jason
 
#6 ·
yes diag light flashes three times and yes problem occurs under 5,000 rpm if the upper solinoids are left unplugged , but if they are plugged in I still loose power, top rpms drop from 7000 to 6500 and with the solinoids unplugged I get 8,000 rpms I think I have two different problems,
 
#9 ·
GT-GADER

Make sure and check the air vent...

Per the book-

Poor mid

Clogged or loose pilot (clean or replace)
Lean Mixture (Overhaul carbs)


Poor normal speeds
Clogged air vent (Clean or replace)
Clogged or loose main jet (Clean or Replace)
Overflow (Clean the float and float valve)

Basically, like I said return to stock and make sure mechanically the carb is good. If that does not fix it start testing each sensor. If you need more information I can look in my manual. For example, you place the coolant temp sensor in hot coolant and measure resistance...

Well, I see you checked the sensors so I really think returning to stock settings is best. Have you checked the clutch/belt?

Jason
 
#10 ·
I'M NOW DOWN TO #55 PILOTS AND SAW A SMALL IMPROVEMENT OVER THE #60'S. IT WAS PRETTY WARM YESTERDAY AND THE SNOW WAS STICKY BUT THIS 100 MILES WAS BETTER THAN THE LAST DRIVE. I'M TEMPTED TO TRY #50 PILOTS NEXT AS THE 600 XT/XTC USES #45 BUT I DO APPRECIATE MY 600 SDI MORE NOW AS IT RAN CRISP ALL THE TIME.
 
#11 ·
First off, GT-GADER, please turn your caps lock off. When you type in all capital letters it gives the impression that you are yelling.
Now, about your issue. To me, it sounds like the TORS (throttle override sensor) is acting up. Its very common for Yamahas to spit, sputter, misfire and stall at low rpm when the TORS is acting up. Its a system that is designed to kill the engine when it senses the throttle sticking open. Its a fairly common issue. A lot of people just bypass the system, but you didnt hear that from me. I honestly dont know how to do it and even if I did I still wouldnt tell you how to because I dont believe in defeating safety systems. They are there for a reason.
 
#12 ·
I have 97 VT600A with same symptoms as GT and Scrossmans. I have tried bypassing the TORS with no improvement. I will try the other suggestions soon. I read the flashing diagnostic light as a bad thing. I then read my owners manual which explained that 3 flashes at start up means Smart Carb systems operating correctly. Good info gents, I will contribute if I find anything helpful.
 
#13 ·
On a 96 Mountain Max Smart carb, I have rough idle, and missing at top end. Tried bypassing the TORS, with no change. WHat does help the idle is to unplug the kill switch. Of course, you can't go, because the sled is in "safe mode", and you get the TORS light flashing. If I get a chance tomorrow, I'll put a jumper on the kill switch connector to see how the high end works without the kill switch. WHere can I get a shop manual for this sled?
 
#14 ·
On a 96 Mountain Max Smart carb, I have rough idle, and missing at top end. Tried bypassing the TORS, with no change. WHat does help the idle is to unplug the kill switch. Of course, you can't go, because the sled is in "safe mode", and you get the TORS light flashing. If I get a chance tomorrow, I'll put a jumper on the kill switch connector to see how the high end works without the kill switch. WHere can I get a shop manual for this sled?[/b]

Yamaha.com for the service manual $60
 
#18 ·
I just purchased a '98 VT600B with smart carbs and noticed the same roughness up till the 5000 rpm range. I get the correct 3 flashes after starting the engine. The roughness goes away for the most part after the engine warms up. I'm still waiting for my service manual so I can did a little deeper. For the two users that originally posted with the problem, are you sure your engines are getting to the correct operating temperature?
 
#22 ·
today we drove the venture and noticed a lot of smoke from the exhuast, checked the throttle cable adjustment and found over oiling, adjusted throttle cable so carbs and oiler come on at the same time, runs sweet, best it has ever run, reconnected solinoids we had previously disconnected and still loose power, top rpms drop from 8,000 to 6500
so we haven't figured it all out, but with carb solenoids disconected and throttle cable adjusted so oiler and carbs come on at the same time machine runs great, smooth power from clutch enguagement all the way through to max rpms, I will do further research to see how the solenoids are controlled to find the real problem, but we are making progress,[/b]

I had the identical problem and I followed your lead with the oiler and the solenoids with the same results. Sled is now running sweet as a nut. Thanks.
 
#23 ·
Just a couple of questions on the changes you guys did to get the mid range smoother...

1. I believe there are two solenoids on the carbs. Are you disconnecting the top solenoid?

2. As I glanced through the owners manual a few nights ago, I believe the process for adjusting the oil pump was lining up two marks on the throttle assembly (down by the carbs) when the throttle was wide open. Is this the same process both of you used for adjusting the oil pump?

Thanks!
 
#24 ·
Just a couple of questions on the changes you guys did to get the mid range smoother...

1. I believe there are two solenoids on the carbs. Are you disconnecting the top solenoid?

2. As I glanced through the owners manual a few nights ago, I believe the process for adjusting the oil pump was lining up two marks on the throttle assembly (down by the carbs) when the throttle was wide open. Is this the same process both of you used for adjusting the oil pump?

Thanks![/b]

Adjust your throttle cable first to spec (1mm free play). Then at WOT adjust the oiler cable to line up the hash marks, basically as you described. I disconnected just 1 of the upper solenoids and it smoothed out my low rpm pick up. I disconnected both but the diagnostic light flashed and it ran rough. I then tried them individually and found the one that was causing the problem. I also cleaned the jets and and adjusted the pilot jet to stock. (1 3/4 turns out). Pain in the butt getting the carbs off but I feel better knowing its clean and setup to stock. Before this work I checked my plugs and they were definitely oily. They are now a nice light brown colour and dry. My friend, an experienced rider, took it out for a blast today and feels it couldn,t run much sweeter. As you can imagine I am well pleased with results of a fairly simple fix. Kudos to Scrossmans
 
#25 ·
Adjust your throttle cable first to spec (1mm free play). Then at WOT adjust the oiler cable to line up the hash marks, basically as you described. I disconnected just 1 of the upper solenoids and it smoothed out my low rpm pick up. I disconnected both but the diagnostic light flashed and it ran rough. I then tried them individually and found the one that was causing the problem. I also cleaned the jets and and adjusted the pilot jet to stock. (1 3/4 turns out). Pain in the butt getting the carbs off but I feel better knowing its clean and setup to stock. Before this work I checked my plugs and they were definitely oily. They are now a nice light brown colour and dry. My friend, an experienced rider, took it out for a blast today and feels it couldn,t run much sweeter. As you can imagine I am well pleased with results of a fairly simple fix. Kudos to Scrossmans[/b]

Glad to hear its running so well. After doing the carb work etc, is your current mode of operation with the two top solenoids disconnected?
 
#26 ·
Glad to hear its running so well. After doing the carb work etc, is your current mode of operation with the two top solenoids disconnected?[/b]
Trails are temp closed right now. I ran with both sols. plugged in because I wasn't confident about any harm that would cause. I believe they cut fuel to the carb as soon as the engine is shut off so I dont think I can do any harm. Plugged in the sled ran fine right up to 8000 rpm. Unplugged the sled seemed to pick up off idle quicker but wasn't much of a difference. Once the trails reopen I will experiment.
 
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