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  1. #1

    Speed or lack there of

    Hey guys,have a problem,question for everyone.I have a 2000 yamaha xl700 i've just bought,ski had been setting for a couple of years.Got a really good deal on it but have several things to do...Now,the problem is.when I go to the water and run,runs fine but only tops out about 25-30 mph.30 max.
    is there anything I can run in the carb to clean it,is is rebuild time,or could it be somthing other than the fuel.I have checked compression,its's 152 on both cylinders so i'm building pressure.What do you think,one more thing,is there an offering for a dual carb setup and would it be worth looking into for the $$$ spent.Thanks,Tony


  2. #2

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    Quote Originally Posted by tbrake View Post
    Hey guys,have a problem,question for everyone.I have a 2000 yamaha xl700 i've just bought,ski had been setting for a couple of years.Got a really good deal on it but have several things to do...Now,the problem is.when I go to the water and run,runs fine but only tops out about 25-30 mph.30 max.
    is there anything I can run in the carb to clean it,is is rebuild time,or could it be somthing other than the fuel.I have checked compression,its's 152 on both cylinders so i'm building pressure.What do you think,one more thing,is there an offering for a dual carb setup and would it be worth looking into for the $$$ spent.Thanks,Tony
    Hey Tony, and welcome to the forum.

    Something that a friend told me years ago that I've carried with me is something you need to hear. He said that 2 strokes are not very forgiving, and that if it was not running right, then put it back onto the trailer untill you could figure the problem out. Otherwise, a small problem becomes a bigger one. A bigger problem = more money and more down time. This nugget saved me many dollars through the years. Enough philosophy.

    You checked the compression (with a good gauge I hope) and that's a good thing. The first thing you should assume on a boat that has been sitting is that the fuel is bad. Not only that, the funk build up that the bad gas left in the gas tank is still there. You have to deal with the whole fuel system, unless there was some stabilizer put in.

    Clean the tank, inspect/replace the filter, and look at going through your carburetor(s). It is OK to use carb cleaner on these parts. Do not use carb cleaner in a running 2 stroke, because the cleaner wipes the lubrication off the walls of the cylinders, and you have no protection. Be sure to take note of your carb high speed and low speed adjustments if you take the carb apart. Put them exactly where they were and perhaps a bit more open.

    More than likely, this is your problem, but even if it is not, it is a good practice to do this when a boat is down for so long.

  3. #3
    Thanks for the input,I have cleaned out and put in new gas,eliminated all I know.NOW...In looking around i'm finding that the skis i'm looking at have two carbs on them,mine has one.I think the previous owner has replaced or stolen them from this ski,I don't know one carb from the other but I do know that two is better than one.I don't know if that single carb on this ski would be enough to move it or not...what cha think?

  4. #4

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    On a 701 engine, dual carbs will certainly make it quicker, but not much faster. It would also be more expensive to run. I do not think the problem is fuel delivery, or lack of fuel. I think the problem is fuel and exhaust gas flow. The 61X (701) cylinders are cast poorly, and IMHO if you had it cleaned up (ported) and add a little compression, then you should see better performance from top to bottom and still maintain reliablilty. It would also stay within the ability of a single 44 mikuni to supply enough fuel to keep it cool and running reliabily.

    Blasters and Raiders with this engine would do well with dual carbs, as they are performance minded. The 3 seater is set up for cruising. If you were to gain better mid range with an extra 3-4mph on top with a mild port and compression, I think you would be a lot happier.

    Check www.groupK.com Harry and Gerhardt are masters at making old school boats run reliably and better by working with OEM parts....the most bang for your buck.

    By the way, if you were to port and add compression, be prepared to get another impeller to deal with the extra power.

    Have you taken a look at your impeller. Any dings would cause problems.
    Last edited by salty; 09-03-2007 at 11:53 AM.

  5. #5
    Thats a good thought on the impeller.I had not given that much thought.I have been reading that the runner I have is suppose to run at about 45 to 50mph.I went to the water yesterday and i'll say mine is topping out at 30mph.that is about all.
    I didn't know if the dual carb setup would make the difference in what i'm getting or not,I have found a couple of good deals on them,just don't wanna go that way and be really disappointed.sounds like everything is a factor,little here and a little there.i'm going to go pull that grate and look at the impeller right now,any hints on a pitch change if I have impeller probs?
    Thanks again.

  6. #6

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    Quote Originally Posted by tbrake View Post
    I didn't know if the dual carb setup would make the difference in what i'm getting or not,I have found a couple of good deals on them,just don't wanna go that way and be really disappointed.sounds like everything is a factor,little here and a little there.i'm going to go pull that grate and look at the impeller right now,any hints on a pitch change if I have impeller probs?
    Thanks again.

    I seriously do not think that the duals are for you. You should think about the mild port. You will get the pep of the duals along with greater power and top end. It will have lots of pep all the way around.

    Carl at Long Island racing is the contact guy for your impeller.

    Remember that guys like Harry and Carl do things that have been tried and true. You have what is called a "developed" boat. Anything that has been done to it to improve upon it has already been done by those with tuneing skills better than you and I. It is just a matter of finding guys who know what is best practices on a particular issue. What you're looking for is kind of like a package where all components support each other in doing what you want. This way, you will not have to spend extra $$$$ and down time trying to figure out how to develope or improve upon a particular model. Harry and Carl are 2 such men. They know what is needed to get the most out of your model.

    I cannot tell you how much money I wasted trying a little of this and a little that. I call extra parts garage "ornaments". Most decisions were just bad mistakes. Contact someone who completely understands your problem. Wether or not you do business with them is another thing.

    For sure though, they will set you straight.

    I would have guessed the your boat would get you 40-42mph.
    Last edited by salty; 09-03-2007 at 01:43 PM.

  7. #7
    I just went to see the impeller,it has a small nick on all three blades,nothing looks bent or in really bad shape though.
    My wife and I took the ski out a couple of weeks ago,maiden voyage so to speak and when we left the marina it ran great,for about a half mile,then after that wouldn't keep it self planed out.Since i've done all the fuel things to it,and replaced the hose that runs to the head with the leak in it,it runs better but nothing like it ran that first half mile.That is more why I am thinking carb cleaning and rebuild.I don't mind the dual set up,but if what I have is sufficent then i'll keep it that way.Sure i'd like a rocket,but it's a 700 not 12 or 1300.i'll take what I get,just want what I can......Thanks..

  8. #8
    An idle thought. Is the engine overheat sensor defective. According to the manual, if the sensor thinks the engine is too hot it will limit your RPm to around 3400 rpm.

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