09-03-2010, 07:32 PM #1
- Join Date
- Nov 2007
Why is one VX110 slower then the other
I am working on 2 2008 Yam VX110 deluxe skis and they have a very strange problem. Both are totally stock but one is slower then the other. The faster one will pull 1-2 boat lengths in a drag race and it will read 55-56 top speed while the other sits at 51-52. i realize OEM speedo's are not reliable but run them side by side and it feels like a 4-5 mph difference. i checked the pump and all looks good (visual check only) and I replaced the plugs as I am doing a service on them as well. The boats have 55-60 hours each and are in excellent condition. I disconnected each spark plug coil lead 1 at a time to see if it had a dead cylinder but each one dropped the same rpm when I pulled them. The plugs look good as did the old ones that came out. I know there are a lot of good minds in this forum so I wanted to see if anyone has seen this before and have any ideas. BTW, it runs flawless just slow. If no one has any good ideas I will most likely pull the pump and inspect the impeller a little closer but it does not cavitate at all so I'm not sure.
09-03-2010, 08:36 PM #2
#1 cause of this is a contaminated partial air filter. you can not see if its dirty from looking inside with a flashlight. you must physically remove them and look at the intake side from the engine. just a small amount of oil at the bottom is enough to reduce speed.
best thing to do to verify this. take the air filters out. now go ride them. I'm betting they will run within a 1 mph of each other. if these skis were ever over filled with oil, some blew on filter at the bottom and it takes like 10% obstruction to result in a 4-8 mph lose of power.
also, some skis will just run 2-3 mph slower, there each there own, for whatever reason. happens in many things, cars, boats,etc... a spec within 2 mph is acceptable. it could have been many factory issues, or slight variations. if you check the manufacture date on the engine and hull, you may think you have 2 skis exact, but one could have been made 2-3-6 months later,
even the same year skis. I think there is a 4 month difference in our skis and there both 2007 model years, who knows what specs might have been slightly adjusted or not done correctly and exact compared to the other at factory weeks or days earlier. just like if you tighten a oil filter and then I do, they wont be the same, mine may develop a small leak. very slight variations can change the dynamics of a few mph, but almost never more then about 2 max. over 2 and something else is going on.
another factor here is were not comparing apples to apples are we??.
if one rider is 210 pounds and the other is 160, that will take from the top end, or if one has 9 gallons of gas and the other has 6, or maybe there is more weight in ones storage bin, this can reduce a few mph do to weight.
so an example for you:
rider 1 weight is 200 pounds with 12 gallons of fuel and 10 pounds in teh storage bin of stuff
rider 2 weight is 175 pounds, 10 gallons of gab and 3 pounds in storage. = 45-50 pound weight change total
factor in a slight factory variance, you could drop 4 mph top end in this situation, and if teh weight difference gets way more, even drop another 1-2,mph above that. plus wave and water conditions with hook up matters, cavitation,etc,
09-04-2010, 01:10 PM #3
- Join Date
- Nov 2007
Bulldog101 - Thank you for your insight. I am aware of the slight differences between same models and rider weights and I definitely factored that in. Mechanical tolerances have really increased a lot with the switch to 4 strokes and I don't believe engine wise there is much difference from model to model. I do believe that no 2 fiberglass/plastic hulls will have the same tolerances but again, I factored this in. I am very interested in your thoughts about the air filter. That does make a lot of sense and it will be the first thing I check. I was blown away when I saw these had air filters and even more blown away when I saw how expensive they are. I will pull the filter and take a look. I was a tech working at a full line dealer for 10 years but stopped about 5 years ago. I only work on skis for friends now and sometimes it's difficult to keep up with the changes. Thanks again.
09-05-2010, 02:26 AM #4
hi, yes these air filters can ABSOLUTELY 100% reduce and rob power, they are sensitive.
many people toss them and dont even use them, however my personal opinion is to have one in.
simply remove the old filterss, clean bottom of air filter box and go test ride them, wont hurt doing it. then tell me if you found the problem. you may very well have. in fact it may not even appear dirty to the eye but it can be, try above, u may be surprised
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