Javelin speed

[Crappieslayer76]

I have a 99 Jabelin Renegade 20 with a 225 Johnson. I have had the carbs rebuilt, new power pack, new fuel lines, compression is dead on for all 6 cylinders, renegade 4 blade 25p prop. I am only turnong 4900 rpms and about 54mph with 12 gallons of gas and about 600lbs on the boat. I feel the boat should be faster. Any suggestions for improvement?

 

[porthos33]

Yeah you should be able to get to at least 6000 rpm. I would probably switch to a 3 blade prop.

 

[churly]

3 blade 26p

 

[dryhorn2]

3 blade 25p

 

[jbh3]

If you have a hotfoot, I would make sure the stop screw is adjusted to allow you to achieve wide open throttle at the engine.

 

[Crappieslayer76]

I do have a hot foot. I know it ran faster when i first bought it. That is one thing i haven't ever messed with. Would it loosen up over time and not have the tension it needs?

 

[jbh3]

The hot foot uses a cable to the engine. The cable can stretch, but not enough to cause the decline you're describing. You stated the carbs had been rebuilt. That cable and the carb linkage on the engine was, no doubt disconnected in the process. Have someone hold the hot foot all the way down while you are looking to see if the carbs open all the way. Best of luck.

 

[Crappieslayer76]

I talked to the mechanic who rebuilt the carbs. He checked the hotfoot and said it was all the way open. We are going to take it out together and see what we can come up with. He recommended a different prop as well. I need to find a friend that has one i can borrow to test before buying one.

 

[Hook1]

Back when I bought mine at performance propeller they had some props that had been ran. He told me I could try one before I bought it. Maybe they do that regularly.

 

[porthos33]

Let us know what you figure out. I know you lose top end in the hottest part of the summer.

 

[Brock]

Who rebuilt your carbs and did they check to make sure the throttle roller outer shell had not come off it is on the stbd side top of engine its purpose is to make contact with arm on throttle plates to push them open sometimes the outer clear part comes of due to drying out this will allow the carbs to not open fully even though everything Else is adjusted correctly

 

[Crappieslayer76]

Local boat mechanic. He said carbs are opening all the way. I am adjusting on my jackplate. It was all the way down. I heard you can gain some by raising it.

 

[bluewingjb]

Oh yeah if your plate was bottomed out that definitely hurt the performance.. The rule of thumb is you want the centerline of the prop shaft to be about 3 and 1/2 inches below the pad, pad being the bottom of the lowest point at the back of the boat. If you do not have a low water pickup you might start around 4 and a 1/4 inches.. but being all the way down is definitely hurting you.. Let us know what you find..

 

[Crappieslayer76]

I raised it 2 inches for starters and in rough water it was even slower. I will raise it and measure like you are saying and try again. Thanks to each and everyone on here for their help.

 

[silvertalon]

Make sure you have a water pressure gauge. If not, watch your rooster tail-wide open full trim. It should not reach above the top of the engine by much. I'd try a 24" raker 3 blade. And check your wide open throttle timing. I'd bump it about 2 degrees advanced. Run some 93 octane with quality oil. Bow lift- Make sure you are not dragging in front. All your high speed testing should be done at full trim. A Raker will give good lift but, Quicksilver merc props fit on OMC so, a Tempest 25 should give you the best bow lift possible. Make sure there's not too much weight in the front of the boat. Change your lower unit oil too. Use a lighter weight synthetic oil like 'Amsoil". Check your hull and pad for deep scrapes and gouges too. Its usually a whole bunch of little things that add up to better performance. Weight is everything. Good Luck.

 

[silvertalon]

Also, a 4 blade 25" is equal to a 26" 3 blade. Thats about 2" too much for that set up. You need to turn about 5500/5600 R's min.

 

[Crappieslayer76]

Still no luck yet on better rpm's. Is there anyone willing that has a prop that would fit my boat be willing to meet me and let me try and see if that is the problem. I have also been told the driveshaft bearing could be going out.

 

[dryhorn2]

Take it to a prop shop and they should be able to help you find the best prop for your setup.

 

[Crappieslayer76]

I have been told that but I don't want to spend the money on a new prop without knowing that is for sure the issue.

 

[Crappieslayer76]

Tried a 24 pitch raker 3 blade prop and only picked up 400 rpms in the boat by myself over what I was running with 2 people and my 25 pitch renegade 4 blade.