Hi everybody, i'm new to this site, joined just few days ago. i've got a sled i would like some opinions on. its a 2001 yamaha sx700r triple with 1000 miles on it and i'm the second owner since new. i bought this sled around 2010. like a lot of people i bought it as a project and with working all the time i never got around to doing anything on it till i retired which is now. i remember when i test drove it the choke needed to be half on in order to get any good response. the person i got it from never used it much so it sat a lot and thats why it only has 1000 miles on it. i figured the carbs would be a good place to start and so far this is what i did: i have a sonic cleaner so i cleaned the carbs twice each sprayed carb cleaner and air thru all the passages, bought new gaskets, jets, needle and seat w/screen, also replaced the fuel filter in the tank, replaced all the fuel lines from the filter to the pump and to each carb also replaced the line from the pump to the block that runs the vacuum for the pump. replaced spark plugs, pulled the boots off between carb and motor and made sure they were ok. checked the reed valves and replaced the gaskets between reed valves and the block. the gas tank was drained cleaned and refilled with fresh premium gas. i was also able to take the fuel pump apart and clean the junk out of it. i got it to start pretty decent and it does seem to idle ok but when you hit the gas its still the same as it was back in 2010 you need the choke on a little to get it to respond good. the pilot screw on bottom of the carb is adjusted 1&1/2 turns out. i do not have anyway to test the pump pressure but for the first start since all the lines, the fuel pump and carbs were all dry i poured some gas down the spark plug holes to help it start. it started first pull but since everything was dry of course it only ran about 2 seconds but in that 2 seconds the pump was able to fill the lines and put enough gas in the carbs to make it start right up again on its own. i do plan on checking the pump pressure but i'm not sure how bad its really going to be. while it was running i sprayed some carb cleaner around the carb boots and around the inside of the clutch but that did not have any change on the way it was idling. i have always noticed this has been hard to pull over with the recoil. i can barely get past the first compression stroke when trying to pull start it. i checked the compression and found each cylinder was even but at only 100 lbs each. i thought that might be a little low for only 1000 miles but i'm not sure what specs are and it does not have electric start so hand pulling was a little slower. besides for checking the fuel pump and maybe changing it on suspicion i'm running out of ideas on what could be wrong. oh, one more thing, i found someone that has a electric start setup for this that i am buying. so while i have the clutch pulled for that i'm going to take a little better look at the crank seal. other than that does anybody have any other ideas on what i can check besides for what i've already checked and replaced??? thanks
vent line to fuel tank is clear?
all the shelves are in the air box?
all the shelves are in the air box?
Simonsweden
Member
Have you checked your jetting ??
i have not checked the tank vent yet but i ran with the gas cap on then a couple times with the gas cap off and there was no change in how it ran.
i replaced all the carb gaskets, all the jets and the needle and seat. one of the jets i could not get clean so i just thought i'd replace them all. i replaced with the same size as was in the carbs when i took them apart. i live in central part of minnesota and i bought the sled from someone that lived in the northern part of minnesota. elevation between us is about the same so it shouldn't need any special jetting. the person i bought this sled from, his dad bought it brand new but passed away about a year later from a car accident. the sled sat and i'm not even sure if the kids ever tried to start it. so the jets in the carb should be factory.
this may seem like an odd question but let me ask this. i'm running this sled in my garage with the track off the ground and since i've been working on the carbs the air cleaner box is off, has anyone ever heard of these sleds not running right cause the air cleaner is removed? this may seem like an odd question but let me explain. i have a 2009 polaris sportsman 500 atv, last spring as i was doing maintenance on it i noticed the air filter needed replacement. i picked up a cheaper brand then polaris sells and thought that should work. well it did not, the machine ran like crap. to make a long story short, my wife drives a 2014 polaris sportsman 400 atv. i swapped air filters with hers and hers ran like crap and mine ran like a new one. i since went to polaris bought a new air filter and now all is right with the world again at least with atv's. has anyone heard of yamaha snowmobiles having this issue?
mod-it
Member
It could be because the air box is off, but I'd think if that was causing it to be lean on the idle circuit you'd also be seeing a high idle issue with it. It should be idling at 1600 rpm with the choke off.
Did you happen to double check what the main jets, pilot jets, and needle settings were in comparison to factory specs? What elevation are you at? This is what Simonsweden was getting at. Replacing the jets in the carbs didn't do you much good if they aren't the proper sizes for your elevation and average temps. There's quite a range of course, but if the previous owner always ran it at quite a bit higher elevation than you're at, then they could've had leaner jets installed.
I'd double check what main jets, pilot jets, and needle settings you have. I'll look up what factory was and post below this.
Did you happen to double check what the main jets, pilot jets, and needle settings were in comparison to factory specs? What elevation are you at? This is what Simonsweden was getting at. Replacing the jets in the carbs didn't do you much good if they aren't the proper sizes for your elevation and average temps. There's quite a range of course, but if the previous owner always ran it at quite a bit higher elevation than you're at, then they could've had leaner jets installed.
I'd double check what main jets, pilot jets, and needle settings you have. I'll look up what factory was and post below this.
mod-it
Member
2001 SXR 700 specs from the TY Tech pages:
Cylinder 1 main jet size is = 145
Cylinder 2&3 main jet size = 143.8
Needle posiiton = 3
Pilot jets = 45
Fuel screw is 1-1/2 turns out from lightly seated (where you already have it)
Cylinder 1 main jet size is = 145
Cylinder 2&3 main jet size = 143.8
Needle posiiton = 3
Pilot jets = 45
Fuel screw is 1-1/2 turns out from lightly seated (where you already have it)
You absolutely need to have the airbox in place for these sleds to run right
Simonsweden
Member
Air box in place when you run your sled.
Report back here what your jetting and needles setting are.
Elevation where your riding also.
Report back here what your jetting and needles setting are.
Elevation where your riding also.
the sled came from Bemidji Minn, elevation there is 1,350. minneapolis mn elevation is about 850. i am just a ways north of mpls and elevation here is about 950. i'm not sure how much variance there is in elevation but i assume there must be some. i would say bemidji's average is about 10 degrees colder then where i am at. i wouldn't think a person would have to change jets just for a couple hundred feet difference or 10 degrees temp. i'm going to take the carbs apart again and double check the jets i put in with what was in there and what factory calls for. the previous owner bought this new and since it was new it would have ran just fine so i wouldn't think he had any reason to re-jet the carbs but then i'm really not sure where he rode it he passed away before i knew the family. i'm working on this in my spare time so i'll get back to you in about a week or more. thanks
so spring is here in minnesota as i'm sure it is for all of you so i may be tabling this for awhile and pick it up later this summer or this fall. i have spring and summer projects coming up but here is what i've done just lately... rechecked carbs verified all passages clean, reverified floats set to factory setting, fuel screw 1&1/2 turns out, needle position is 3, pilot jets 45, carb#1 main jet 145 carbs 2 & 3 main jets both 143.8.. i did have main jets swapped on carbs 1 & 2 but corrected now so carb 1 has jet 145 but it made no change in running... i may have missed something while cleaning the carbs but while cleaning i went to the "Sled Tech Center" on this site and followed the "Carb cleaning 101 with pictures" to make sure i didn't miss anything. (whoever did that sled tech center did a great job). i put my vacuum gauge on where the tank line goes on the fuel pump then started the engine i had 5 inchs of vacuum. i don't know what specs are but i thought that seems decent. there is a local guy here that parts out yamaha sleds, i picked up a used fuel pump from him but that made no change. somethings like fuel pumps i don't care to buy used, i figure i already have a used pump why would i want another that may not work but he said his pump just came off a running sled and since it did not change how my sled ran i feel pretty confident its not the pump (unless his pump is weak also) and i saved some money not buying new. i put the airbox on and ran it but that didn't solve any problems. it idles fine when first started then when you try and move it bogs down and then idles higher. the only way i can get it to idle slower is put the choke on for couple seconds to choke it down then it will idle normal, at least till you decide to hit the throttle again. it seems like its sucking air somewhere. i've checked the rubber boots on both sides of the carbs and they seem ok. i also sprayed carb cleaner around the carbs on both sides and around the clutch seal with engine running but had no change. the only vacuum line that i can see is the one running the fuel pump and that's new. i have a hard time believing the cranks are bad with only 1000 miles on but i'm not sure what else to do. i have been thinking of trying another set of carbs but don't want to bear that cost if it doesn't solve my problem and feel i can't be to far away from solving this with everything i've already done. any other ideas would be appreciated. thanks everyone.
sounding like you need to raise the needles for the old mid range lean spot that i know the vipers had. the only way to get them to idle down quick was to flip the choke on quick.
Simonsweden
Member
Try open fuel screws to 1 3/4
Hi everyone, thought i'd update this and ask for little more advice. i got my yami running and it seems to run pretty darn nice. not exactly sure what fixed it but i took the carbs back apart and recleaned them. made sure the jets were all clean also. i watched some youtube videos and found some people say the tors could cause problems so disconnected that and connected the wires together to bypass it. took awhile to get it running but now it starts decent. i may have had the throttle cable to tight also but have it adjusted right now. but while it was running i reconnected the tors and its still running good so I'm not sure there is anything wrong with it. ohms readings are open at idle and with the throttle open ohms read 4 to 5. not able to find any specs on this yet. fuel screws are still at 1&1/2 turns. so i'm going to drive this for awhile but before i start going on to many longer trips is there anything else i should be checking? also i noticed at an idle the motor has a shake to it. i'm assuming thats somewhat normal since its a 3 cylinder...
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all sounding normal so far.
Hi, my yamaha is still running good and starting nicely but i have been trying to understand what the trouble was. it is sounding like i just had the throttle cable to tight but somehow that just doesn't sound right to me. i have been an auto mechanic for about half my working life so i can usually figure out how things work but i'll be honest 2 cycle sleds are a little different and i'm still trying to figure them out. i found 3 videos on youtube that i listed below in order 1-2-3 top to bottom. this guy has a 97 vmax and mine is a 2001 sxr but he has the same motor i do. the first video shows how his sled was originally running, the second video explains how the throttle cable being to tight wasn't letting the tors work proper and that was the problem and the third video just shows how good the sled runs now. if i could get someone to listen to just the first video and let me know what you think i would appreciate it. the reason i ask this is my sled was running exactly the same as his was, and i mean exactly. had the same idle, same backfire and same acceleration as his did. thanks to all for the assistance...
right ,you need to adjust the throttle cable so there is a lil slack in it and that should do it . just make sure your idle adj. screw is around 1500 rpm. no higher. unless ,of course you have the tors bypassed.