Loose Jet at launch

[J C Gordon]

Well boat run extremely well sunday on the motor still having problems with the holeshot, David is getting me a loaner to try in an A/B instead of the aluminum B I have. It pulled the B to 6600rpm and never cavitated the pump. Runs strong as soon as it loads pump. Problem being is that it takes a second that I dont have for it to load.. Boat ran very well in Oct outta the hole and now it doesnt, my thinking is that maybe the water was a little thicker due to the lake rolling over. I'm thinking a bowl bleed and a pre-impeller.. ANy thoughts out there?

 

[KONA77]

well over all i am still learning about jets and how they actually work,  but i would say your thinking is right on, don't need any air in the bowl, and the more water you can get in there the better off you are, that's my .02

 

[duanehydro]

I thought this was gonna be a video of a boat sliding off the trailer... :smile29:

 

[Devilman]

When you say "bowl bleeder" you talking about one of them little checkvalve deals some peeps put in the top of the bowl? I was under the impression that was to "burp" the pump, helping to eliminate the formation of air pocket in the pump upon launching... Not sure if it would do anything to load the pump on holeshot though. I mean, if you are already cruising around & making passes, kinda doubtful you'd still have air in the bowl right?

For the launch thing, probably an inducer/pre-impellar is more of what is gonna take care of that. heard some peeps using a stuffer plate to help in that situation too...

Thats my uneducated opinion, just based on what I've read here, there, & yonder...

 

[jetboatperformance]

Well boat run extremely well sunday on the motor still having problems with the holeshot, David is getting me a loaner to try in an A/B instead of the aluminum B I have. It pulled the B to 6600rpm and never cavitated the pump. Runs strong as soon as it loads pump. Problem being is that it takes a second that I dont have for it to load.. Boat ran very well in Oct outta the hole and now it doesnt, my thinking is that maybe the water was a little thicker due to the lake rolling over. I'm thinking a bowl bleed and a pre-impeller.. ANy thoughts out there?

Hi JC maybe some more info I dont recall how much HP (and maybe where the motor makes it) assuming your tach is right 6600 is alot of "turns" for a A/B or a B for that matter (depending on power of course) Tom

 

[J C Gordon]

Tom the engine has never been dynoed, So HP is a guess. but it should be all over 750hp. And I think the Tach is a lil off, its a autometer 10k tach but i think its going bad. I did hit the rev chip at launch  at 7k and the tach showed 7400 so its 400 off for sure. Still got me wondering why its slipping now when it didnt in Oct. and changed nothing. Gonna do some tweeking and try and get back to do some testing in two weeks. As far as the bowl bleed it just takes it easy on the new equipment coming when ya first start up..

 

[jetboatperformance]

10-4 on the bleeder , prevents the potential for air lock at launch and possible Impy/wear ring "clash" , I'm still amazed at the Numbers however, I'd like to see yo go big on the impeller , say to a AA and work from there  just my 02 Tom

 

[sturat]

Stuffer will not really help your holeshot (i think) You need an inducer to help with that. I have one on my ride and it leaves real hard and i have nothing close to 750hp

 

[J C Gordon]

Found a used inducer today and went ahead and ordered it, Or I didnt but my bro-in-law did its on a rent to own type deal I guess.. :smile30: And David is gonna let me try his A/B Bronze Aggressor and an ultimate wear-ring..

 

[jdf]

10-4 on the bleeder , prevents the potential for air lock at launch and possible Impy/wear ring "clash" , I'm still amazed at the Numbers however, I'd like to see yo go big on the impeller , say to a AA and work from there  just my 02 Tom

ding ding we have a winner floks .........tom i have been beating my head on a wall ..

 

[J C Gordon]

10-4 on the bleeder , prevents the potential for air lock at launch and possible Impy/wear ring "clash" , I'm still amazed at the Numbers however, I'd like to see yo go big on the impeller , say to a AA and work from there  just my 02 Tom

ding ding we have a winner floks .........tom i have been beating my head on a wall ..

David we have been thru this before, My motor needs to turn between 6000 and 7000rpm to let the camshaft do its deal.. I'm just scared its gonna slow it down if we pull the motor out of its sweet spot.. And even on the spray I'm not sure I can pull an AA up there... Maybe I'm wrong but thats my outlook on it..

 

[jdf]

i know jc i m just pulling ur chain ...........go to bed grumpy

 

[sturat]

Now it's time to pull and machine your shaft, that is if it is not cut for the inducer already.

 

[J C Gordon]

Yep my dad is a machinist so he's  gonna cut a few for us probly next week...

And David I get that transom plate built I will try a big impeller just for you... And I agree a big impeller will bite harder just my motor is set up like a drag car motor built to spin up....

 

[3boatpaul]

Yep my dad is a machinist so he's  gonna cut a few for us probly next week...

And David I get that transom plate built I will try a big impeller just for you... And I agree a big impeller will bite harder just my motor is set up like a drag car motor built to spin up....

load thet puppy up , it may suprise you .  :smile17:

 

[J C Gordon]

[/quote]
load thet puppy up , it may suprise you .  :smile17:
[/quote]

We gonna try it. :smile29:

 

[badblood]

You know I think every jetboat should have an inducer, and you should replace your rope seal, if it leaks air it will never take off hard. Start there and then I will talk you into the big impeller. Do you wanna bring back a big number on the gps or beat then boat beside you like a rented mule on take off.  The latter is where I can help you... come see us.

 

[J C Gordon]

Gps numbers don't really impress me, I just want it to leave like a drag car. Thanks for the shaft seal tip makes alot of sense and is probly on of the most overlooked items.

 

[jetboatperformance]

JC ,Although time consuming and arduos IMO the idea of starting out with a big impeller is to establish sort of "bench mark" in this type situation  I can see that the motor might likley want a smaller Impy to work in its power band But agin we try to start out big (cut for inducer but inducer not added right away) Test and then cut/tune from there Every set up differs a little , everything is an expiriment to some degree  :wink:

 

[J C Gordon]

Inducer is here, gonna tear down on next day off and install. Also boroughing an A/B aggressor from David.. Think this should give us an idea if we going in the right direction....