Superjet runs funky again

[Galaitoto]

I picked it up from the shop today, I had a stock head put on. It's a 760 engine, but I really don't know to much about it, I am learning as I go. It has aftermarket air filters, and pipe. The shop said the carbs are good and don't need a rebuild. Today was a rainy day, but I went out for a ride. It started up no problem and ran strong, until I released the throttle. When I would stab the throttle wide open, it would not rev past a certain rpm, and it wouldn't accelerate. If I left the throttle half way open for 2-5 minutes, it would finally accelerate again and run strong, until I let off the throttle again, and the same thing would happen. I checked the plugs, they had a brownish color. My mechanics said, since it has an aftermarket pipe and air filters, the rainy day and cold weather was most likely causing the problem. What do you dudes think ? Edit: after reviewing the mukuni site, it says meteorological conditions most certainly affect the carbs.

 

[88kawi5fiddy]

the pipe and air filters dont do poop different on a flippin rainy day. if it was cold, making it leaner, and raining, making it richer, i.e. it aint the weather. skis dont run poopty because of weather. its definitely a fuel issue. did they go through the carbs and actually take them apart piece by piece?

i.e. back filter plugged, line plugged, just tuned straight wrong, leaking N/S, wrong popoff pressure. what flame arrestors are you at and what popoff PSI are you at? And what carbs? stock dual 44's, single?

 

[jetx]

Is the stock head install the only thing the shop did? Are u 100% sure it was a 760 head and not for a 701.

 

[TLR67]

I would have told the shop your only going to pay them a third of the Bill since it was rainy too... What a Joke... Typical service these days...

 

[88kawi5fiddy]

My mechanics said, since it has an aftermarket pipe and air filters, the rainy day and cold weather was MOST LIKELY causing the problem.

also, there is no correlation between pipe and filters, and rain and cold. he's just "MOST LIKELY" blabbering shonet at this point.

for the OP, my riva motor is damn near what an open class 2 cylinder would have been like 10 years ago. it ran great in 100'F temps nad 80Fwater. I took it out for an end of year ride last weekend at 50Fair and 55F water temps. all i did was turn my needles a quarter on high and low speed and it ran near perfect.

 

[Galaitoto]

Thanks everyone for your help. I have a lot to learn about the engine. I can't even tell you guys what you would need to know in order to help me, so in that sense, I am useless. I went out today and it ran better. The only iffy thing it does, is after releasing full throttle, sometimes it takes a few seconds to pick back up. My plugs are slightly black, a hint of oil on them, not very much. Other than that it was ok. He told me to mix the oil/fuel 40:1. Does that sound ok? And besides burning up an engine with not enough oil, what other symptoms would the engine have, being used with an insufficient amount of oil?

 

[Galaitoto]

Is the stock head install the only thing the shop did? Are u 100% sure it was a 760 head and not for a 701.

He told me what to order, so I got it off eBay. Now that you mention it, he might have asked me to buy the wrong one. It's a 61x 701 head

 

[Galaitoto]

the pipe and air filters dont do poop different on a flippin rainy day. if it was cold, making it leaner, and raining, making it richer, i.e. it aint the weather. skis dont run poopty because of weather. its definitely a fuel issue. did they go through the carbs and actually take them apart piece by piece?

i.e. back filter plugged, line plugged, just tuned straight wrong, leaking N/S, wrong popoff pressure. what flame arrestors are you at and what popoff PSI are you at? And what carbs? stock dual 44's, single?

I'm sorry, I don't know what flame arresters I have, nor do I know what the pop off psi its at. All I know at this point, is that it's a dual carb setup. I hate not understanding this engine, but I will. I have been busy with work, but I am going to pick up a service manual, or something like that, and try to get up to speed. So next time, at least I'll be able to tell you guys the info that you need to better help my situation.

 

[jetx]

If you have a true 760 or even a bigbore 61x...that's the wrong head...61x is for 81mm bore and 760 is for 84mm bore...I'd try and confirm what cyl you are running and that you have the right parts...sounds like u need a new head to start.

 

[Galaitoto]

If you have a true 760 or even a bigbore 61x...that's the wrong head...61x is for 81mm bore and 760 is for 84mm bore...I'd try and confirm what cyl you are running and that you have the right parts.

Ok thanks, I'll find that out. This thing is driving me mad. I bought it for 2k, and between July until now, I put another 2k into all kinds of repairs. I love it, and hate it.

 

[Galaitoto]

Would this head possibly be what I would need? http://www.ebay.com/itm/Yamaha-760-..._Watercraft_Parts&hash=item1c498fb16d&vxp=mtr

 

[Lighthouse13]

What area are you in? Best bet is to meet up with someone local who knows superjets and they can take a look and help you out.

I'd think itd be rare you would need a 760 head.

 

[Galaitoto]

What area are you in? Best bet is to meet up with someone local who knows superjets and they can take a look and help you out.

I'd think itd be rare you would need a 760 head.

Well that's refreshing, thanks. I live in Rancho cucamonga, ca. Do you know anyone around here that is a superjet wizard?

 

[eastcoastjumper]

The link you posted that head is no good. The one dome is all pitted from a previous engine failure.

 

[Galaitoto]

The link you posted that head is no good. The one dome is all pitted from a previous engine failure.

Thanks man, I was just using that particular link for an example..but I wont buy it now for sure, good eye. Do any of you guys sell used parts that I could buy for mine, for the next time it breaks?

 

[Lighthouse13]

Well that's refreshing, thanks. I live in Rancho cucamonga, ca. Do you know anyone around here that is a superjet wizard?

I do not, but there are sections on this site that probably have local riding groups around you. This site is the biggest group of standup riders on the net. Once you get to know a few local people, they likely know the rest of them. You'll want to find some local people that you can trust, because esp with used parts, a lot of people sell polished turds for parts.

 

[Galaitoto]

I do not, but there are sections on this site that probably have local riding groups around you. This site is the biggest group of standup riders on the net. Once you get to know a few local people, they likely know the rest of them. You'll want to find some local people that you can trust, because esp with used parts, a lot of people sell polished turds for parts.

Ok,I'll look here for local groups. I didn't know that this site was so popular for standups, thanks. When it comes to buying stuff, I tend to believe people a little to much. I get burned often.

 

[Lighthouse13]

Ok,I'll look here for local groups. I didn't know that this site was so popular for standups, thanks. When it comes to buying stuff, I tend to believe people a little to much. I get burned often.

Definitely now that you know, keep that in mind. Of course not every seller is like that, but it happens more often then not. Feel free to shoot me a PM if you second guess something until you get to know some local people.

 

[Galaitoto]

Definitely now that you know, keep that in mind. Of course not every seller is like that, but it happens more often then not. Feel free to shoot me a PM if you second guess something until you get to know some local people.

Very cool, thanks for offering to help. I posted in the group section, like you mentioned, and I already found a group to ride with !

 

[Lighthouse13]

Very cool, thanks for offering to help. I posted in the group section, like you mentioned, and I already found a group to ride with !

Awesome, time to get that SJ ruining and get some tray time in.