HELP with 700!!!

Yes it will hit max RPM but not consistantly .....sometimes it breaks up so bad it starts to backfire! I had a 60 mile ride on New Years day and at the end of the ride about 2 miles from home it started running crappy again...... it ran normally when the throttle was barely applied....if you squeezed the throttle it would start to break up, but I limped it home! I recently put a new Yamaha stator on and its seems to run better but not quite right (see my post #32) I am starting to think this might be a coincidence and that its a needle and seat issue. I am still waiting for my needle and seat from Winnipeg Yamaha which was ordered in early January!!!! Brutal service!
 
that is bad service for sure.I e-mailed them guys for some prices and it has been 2 weeks and no reply..They are new ownership so maybe they won't be as devoted as the previous owners..Wildwood Yamaha used to always have my parts within a week of ordering..maybe go there instead.
 
Last year, the ONE time I had my 98 700 out for a ride, it started to cut out and backfire after about an hour. I put it back on the truck. When I finally looked into it I found that I had a broken wire to one of the coils. I fixed it and it's been fine ever since.
 
red6sx said:
at the end of the ride about 2 miles from home it started running crappy again...... it ran normally when the throttle was barely applied....if you squeezed the throttle it would start to break up, but I limped it home! I recently put a new Yamaha stator on and its seems to run better but not quite right (see my post #32) I am starting to think this might be a coincidence and that its a needle and seat issue.
Click to expand...

I just spent a month working on my 600 twin, did all of the same stuff you did trying to figure it out. A couple guys here on TY came through for me and suggested that I remove the needle valve and seat, I found a little piece of plastic (on my thumb in pic) sitting on top of my mag side seat :

image4_zpscc8b8d31.jpeg


Like you said, mine would run fine when the throttle was barely applied but when you got on the gas and fuel demand increased there wasn't enough flow. I wish I'd listened to sideshowbob when he suggested I check the needle/seats right away. Here's the thread I had running, might give you some more ideas on things to check :

http://www.totallyamaha.net/forums/showthread.php?t=90454

Oh, and I talked to Tony the other day for the first time, seems like a nice guy that knows a tonne about these sleds.
 
Yes I suspected all the needles and seats. I have removed them and blown air through all without restriction I even was able to find a rigid enough wire to run through from the inlet tube and no restriction found. One needle is suspect though, and I am going to change it. The raised ridges on four sides of one needle are polished and shiny suggesting the needle is vibrating and may not be seating during operation.....it seemed to seat when tested on the bench. The fuel pump was disassembled and inspected. It looked okay with some minor distortion of one of the diaphragms??? Not sure if this would cause an issue?
Wires look okay on the coils but I will check again.
 
Youve checked to see if the carbs are synced and that the throttle valves are all set to the correct idle height? And I know this is a bit basic but after doing all this and changing to the Yamaha stator have you changed to brand new properly gapped plugs?
Only thing else I could think of is, what type of gas are you running and is the gas brand new or out of a can?? If the gas was out of a can or if its regular, try running fresh 91 octane(minimum), just trying to think of things that can be easily forgotten as it seems youve checked everything else.

The one other thing is did you check your pipe and can to make sure there is no blockage or anything coming apart inside of either??
 
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issue

this is just a thought , haave ya gonein & confirmed the piolit & main jet sizes are all to spec , someone might have gotten into them & changed out the pto suspect cyl in attempt to fine tune ,If your rich on that one cyl bump your neddle clip up to "fine tune lean out" your rich condition?? maybe the ticket or confirm that the sizes are what tey appear to be

Good Luck
 
Yes carbs are synced....yes changed plugs and checked gaps......new gas and tank filter also....all jets to factory specs but will check again when I replace the needle and seat tomorrow.
Thanks to all for the suggestions! ......I will keep you posted of any results.
 
Pipe looks good but not sure about exhaust can so I will check that out..... and I did have the reeds out and checked them but it all looks good with reed petals resting properly on reed cage landings......just wondered if reed petals can get weak....I would think this would be very unlikely as fiberglass reed petals would either get frayed or break ....none of which I can find on inspection!
 
South St.Vital between St.Marys Rd and St. Annes......close to the perimeter.
 
GOOD NEWS....Took the Venture for a good ride yesterday and although it runs a little dirty at lower RPMs it ran fine for the three hour ride! Had it over 80mph and was running strong! Looks like the Stator was the bulk of the problem and after replacing the needle and seat on the one carb it seemed a bit better yet. Still does not run really clean at throttle transition from idle to higher RPM but that could be due to it being a bit rich as it was only -6 C yesterday. I will go over the carb settings again but at least I can go for a ride without it backfiring!
THANKS TO ALL FOR THE HELP!!!
 
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