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Loss of Top Speed

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dmsva

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I have a 2014 GBR 2550 with a 250 HP Yamaha. My top speed is only 36mph lately, I don't run at full speed often so I don't know how long this has been going on but recall my top speeds were ~ 45mph when I first bought the boat. Does anyone have ideas on what to look at or can anyone with a similar setup share your top speeds. Boat only has 200 hours, runs well otherwise and the pontoons are free of water...
 
Are your pontoons clean ? Slime alone will take off 4-5 mph
 
I had this problem last year, speed was 6-7 mph low, as were revs. Noticed that the prop had some sort of coating that was like 80 grit sandpaper. Cleaned it off with a heavy duty scour pad, and speed was back to normal. Boat sits on a lift, but up till then I didn’t raise the motor out of the water. I do now.
 
Joeb14 said:
I had this problem last year, speed was 6-7 mph low, as were revs. Noticed that the prop had some sort of coating that was like 80 grit sandpaper. Cleaned it off with a heavy duty scour pad, and speed was back to normal. Boat sits on a lift, but up till then I didn’t raise the motor out of the water. I do now.
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wow, interesting. I haven't focused on the prop (except making sure it wasn't damaged).
 
You should be getting 5800 - 6000 RPM's . I have a 250 on a 23ft ( closer to 26 ) I hit just over 45 at 5900, full tank 2 adults . Prop is 16X14.7 Enertia.
 
that is very helpful. I will check my prop specs and see if that explains the lower RPM if not perhaps a tune up is in order. I appreciate the help
 
When I moved from a marina on a lake to a private marina on a river . I started fouling plugs every season . The tech at the marina where I bought and store my boat in the winter asked what I was doing different . I told him where I had moved . The river is a 40 minute ride in a no wake zone to the lake . He told me I needed to put the hammer down for at least 10 minutes when I got to the lake . I haven't fouled a plug since .
In your first post you mentioned you dont run "full speed " often . How long since your plugs have been changed?
You can also talk to Ken at https://propgods.com/
dmsva said:
I have a 2014 GBR 2550 with a 250 HP Yamaha. My top speed is only 36mph lately, I don't run at full speed often so I don't know how long this has been going on but recall my top speeds were ~ 45mph when I first bought the boat. Does anyone have ideas on what to look at or can anyone with a similar setup share your top speeds. Boat only has 200 hours, runs well otherwise and the pontoons are free of water...
Click to expand...
 
This feedback is great, i also changed lakes 3 years ago and I now traverse a channel that is a no wake zone of about 20 minutes in each direction. Its been 2 years since the plugs were changed.....the last 2 years I have not been able to use the boat much so less than 15 hours but I'll change the plugs and drop the hammer regularly going forward. Thanks!
 
Jack pretty much covered everything. But there could be one other possibility...... Water in your pontoons. Does it list to one side? While on the lift shake it to see if you can hear any water sloshing around. Worth a shot..... Disregard I just read that you said it was free of water.....
 
Jack M said:
When I moved from a marina on a lake to a private marina on a river . I started fouling plugs every season . The tech at the marina where I bought and store my boat in the winter asked what I was doing different . I told him where I had moved . The river is a 40 minute ride in a no wake zone to the lake . He told me I needed to put the hammer down for at least 10 minutes when I got to the lake . I haven't fouled a plug since .
In your first post you mentioned you dont run "full speed " often . How long since your plugs have been changed?
You can also talk to Ken at https://propgods.com/
Click to expand...

My lake is 90% no wake... so i'm just over idle most of the time.

I only have 90 hrs on my VMax 250, but been running ring free since break in finished. hopefully it'll help, but i run hard when i can...
 
On my Verado ,I don't know if it's fully broke in or when I changed the exhaust settings. This season it uses 21 GPH at wot vs 28 last season.
 
Funny part is that I accidentally found the exhaust settings.
 
Jack M said:
Funny part is that I accidentally found the exhaust settings.
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What exhaust settings are you referring to? something user changeble? I'm assuming it's specific to the Verado, but I had assumed the dealer retuned it for you. Now I'm questioning my assumptions! :)
 
It's on my simrad quite or sport mode . It had been set on quite . I could barely hear it even at start up .
 
Jack M said:
You should be getting 5800 - 6000 RPM's . I have a 250 on a 23ft ( closer to 26 ) I hit just over 45 at 5900, full tank 2 adults . Prop is 16X14.7 Enertia.
Click to expand...
Thanks for all the advice on this, wanted to report back on the cause of the problem. I had a recent tune up on the engine and went back to explore the low RPM issue, I pulled all the spark plugs and 5 of the 6 looked normal for plugs with ~10 hours. The 6th plugged looked brand new and had no signs of having ever fired. I replaced all the plugs and the boat is back to normal. Thanks again!
 
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