James Guillaume
New member
- Joined
- Dec 24, 2024
- Messages
- 2
Hello,
I recently picked up a 98' Venture 600 with only 880 original miles. Overall its in good shape. I have always had Apex's and Attaks but I have never owned a non power valve 600 or a Yamaha 2 stroke twin. I have worked on countless engines and cleaned countless carbs filled with junk. I used to do it as a job at an independent shop but this one has me baffled.
The sled started and ideled great when I got it, but had a terrible bog once you got past quarter throttle. I cleaned the carbs and there was not much change. I cleaned them again and found that one of the pilot jets reclogged itself. I put it back together and it seemed much better. I ran it on a stand and it had some hesitation and then came out of it and would rev out no problem multiple times.
Today we got some snow so I took it out. Overall it runs good, it idles great, starts very quick and pulls hard wide open. It just seems to struggle to get going on hills where it can't get too much speed after the secondary engages. You half to give it like half to 2/3's throttle to get moving up hill. The only other symptom when going slow on flat ground between 5500-6000 it just kind of sounds like it is going between one and two cylinders, or sounds and feels like when a Yamaha triple fouls a plug and drops to two. There is a change though when pulling spark plug wires off at idle so both are sparking.
I noticed the belt was sitting low in the secondary so I added some shim to the back plate and it seemed to take off a little better but its just not as peppy down low as I thought it would be. Am I missing something? Is this typical for a non power valve 600? for reference it feels about the same in the mid range as my old Indy 440 liquid but not as smooth, but pulls up top like any 583 or mid size motor.
It is just something we will use to ice fish with and sometimes ride two up on. I know its not new and nor a power house. Should I go back to the carbs? They are the smart carbs and I tested the solenoids with a 12v source and they all click. The oiler looks to be at the correct mark. I also made sure the air screws were at 1 3/4 turns out. There is no difference during the hesitation if I flick the choke on or off. I feel stuck on this one as I am mechanically inclined and usually can find the smoking gun of a problem but this one I cannot put my finger on. Maybe it is just how it is?
Any input would be great.
I recently picked up a 98' Venture 600 with only 880 original miles. Overall its in good shape. I have always had Apex's and Attaks but I have never owned a non power valve 600 or a Yamaha 2 stroke twin. I have worked on countless engines and cleaned countless carbs filled with junk. I used to do it as a job at an independent shop but this one has me baffled.
The sled started and ideled great when I got it, but had a terrible bog once you got past quarter throttle. I cleaned the carbs and there was not much change. I cleaned them again and found that one of the pilot jets reclogged itself. I put it back together and it seemed much better. I ran it on a stand and it had some hesitation and then came out of it and would rev out no problem multiple times.
Today we got some snow so I took it out. Overall it runs good, it idles great, starts very quick and pulls hard wide open. It just seems to struggle to get going on hills where it can't get too much speed after the secondary engages. You half to give it like half to 2/3's throttle to get moving up hill. The only other symptom when going slow on flat ground between 5500-6000 it just kind of sounds like it is going between one and two cylinders, or sounds and feels like when a Yamaha triple fouls a plug and drops to two. There is a change though when pulling spark plug wires off at idle so both are sparking.
I noticed the belt was sitting low in the secondary so I added some shim to the back plate and it seemed to take off a little better but its just not as peppy down low as I thought it would be. Am I missing something? Is this typical for a non power valve 600? for reference it feels about the same in the mid range as my old Indy 440 liquid but not as smooth, but pulls up top like any 583 or mid size motor.
It is just something we will use to ice fish with and sometimes ride two up on. I know its not new and nor a power house. Should I go back to the carbs? They are the smart carbs and I tested the solenoids with a 12v source and they all click. The oiler looks to be at the correct mark. I also made sure the air screws were at 1 3/4 turns out. There is no difference during the hesitation if I flick the choke on or off. I feel stuck on this one as I am mechanically inclined and usually can find the smoking gun of a problem but this one I cannot put my finger on. Maybe it is just how it is?
Any input would be great.
bird
New member
- Joined
- Feb 28, 2022
- Messages
- 26
You've listed off three things.
Carbs/Fuel supply.
Secondary Engaging
Electrical Gremlings.
I would check your stator coils resistances. A high speed miss/bog is usually electrical. Make sure your coils don't have any loose or open wires frayed.
Carbs/Fuel supply.
Secondary Engaging
Electrical Gremlings.
I would check your stator coils resistances. A high speed miss/bog is usually electrical. Make sure your coils don't have any loose or open wires frayed.
Almost certainly the main nozzles, which I don't think can be found anywhere.
totallyamaha.net
6 mpg problem solved.
I am one of several owners on this site of 90's yamaha 600 twin motors that are/were getting poor mileage. It was frustrating to me because when new the sled got 12 mpg. Tried a lot of fixes over the years but none had any affect on mpg. Finally heard of something new(to me) and it sounded like...
bird
New member
- Joined
- Feb 28, 2022
- Messages
- 26
What makes you think its the nozzles?Almost certainly the main nozzles, which I don't think can be found anywhere.
6 mpg problem solved.
I am one of several owners on this site of 90's yamaha 600 twin motors that are/were getting poor mileage. It was frustrating to me because when new the sled got 12 mpg. Tried a lot of fixes over the years but none had any affect on mpg. Finally heard of something new(to me) and it sounded like...
High speed BOG, not lean is from a bad coil.
High speed miss is from a bad stator.
Because you said it was a midrange running issue.
You should check the rollers and weights in the primary clutch.
If it isn't one of those issues, then I don't know.
check the flywheel for rust as it can cause spark issues.
i would swap out the primary spring for a new one as that one is probably too weak from sitting/age.
have you checked the crank seals with quick start or flammable brake clean? they tend to dry out when they sit.
those carbs can be a curse or a blessing. seen/heard of a few leaning themselves out and popping motor. as soon as guys had carb trouble, if they swapped out to the xtc 600 twin carbs, it would straighten out and run better.
i would swap out the primary spring for a new one as that one is probably too weak from sitting/age.
have you checked the crank seals with quick start or flammable brake clean? they tend to dry out when they sit.
those carbs can be a curse or a blessing. seen/heard of a few leaning themselves out and popping motor. as soon as guys had carb trouble, if they swapped out to the xtc 600 twin carbs, it would straighten out and run better.
James Guillaume
New member
- Joined
- Dec 24, 2024
- Messages
- 2
I seem to have figured it out. Ultimately it was just super rich, gas dripping out of the boost bottle and reeds after inspecting them. I set the idle fuel screws at 1 1/4 turns out, cleaned behind the solenoids and took the needle and seats out and cleaned the seat and needle. They were set a little low so I made them level with the carb body. That helped things and gave it better idle and much better top end and let it rev out fully. The midrange would no longer bog but still sounded poor / hesitate.
I dropped the needles down a notch and now things seem proper. Drives great around the yard and and runs smoother. Need more snow to really see how it performs after a while. Plug electrode is now nice and tan.
I dropped the needles down a notch and now things seem proper. Drives great around the yard and and runs smoother. Need more snow to really see how it performs after a while. Plug electrode is now nice and tan.