GT150 Problems

[j_k_bisson]

Re: GT150 Problems

If you look over the back of te boat when you are up on plane, the top cavitation plate should be flush with the top of the water coming off the bottom of your hull. If you do not see the cavitation plate then raise again another bolt hole. I had to raise mine three times to get it right.

I would figure that boat/hull should be around 40-45mph (GPS) at 5600 rpms. Might want to up the pitch one size but it will drop your you RPMS 300-400 range.

 

[wtp]

Re: GT150 Problems

well we took the boat out and did the link n sync. Runs pretty good except it seems to load up at idle or low speeds. When you take off it kinda sputters untill you get going alittle. Should i try 1 hotter plug? Fuel is mixed 50:1 and using havoline outboard oil. There is no carb adjustments on these carbs, I have the floats set level when held upside down and turn them over the drop is set at 7/8. Timing is all set right. Any ideas?

 

[j_k_bisson]

Re: GT150 Problems

Have the same problem with mine. It's proped to much for the low speeds. That is my theory anyways. Other play witht eh jetting. My local dealer said to drill the prop and this would let the prop slip more at low speeds lower the amount of load on the motor. It makes sense but I don't want to start drilling my new prop. So I am just living with it.

I also drop the pitch of the prop and this also clear up some of it. Another Idea is you have money to play. I don't I was going to watch ebay this winter and pick up a used prop for cheap an play. If it worked I could do it to my good one.

If you find anythign out let me know. I would be interseted in what clears it up.....

 

[wtp]

Re: GT150 Problems

I did drill (3) 7/32 holes in mine. alittle better but not much. I'm gonna try some Ql16V plugs in it. I also readjusted my throttle cam so it advances the timing just alittle before it starts to open the carbs. won't beable to try it again until this weekend. I'll post results.

 

[wtp]

Re: GT150 Problems

put a new 19p prop on from iboats. super fast shipping, anyways put new prop on put ql16v plugs in and adjust the throttle linkange to advance a couple degrees before the throttle plates open. still has alittle shutter on take off. just can't get this thing set right. now i'm back to maybe a fuel problem. carbs have been redone a total of 5 times with 2 carb kits with the last one being oem. new jets, new fuel lines, new primer bulb and 2 pumps. float are set to 7/8 drop and level when held upside down. Top end is running fine. I did hit 40mph according to my speedo. best it has ever ran.

 

[j_k_bisson]

Re: GT150 Problems

So with the new prop what was your WOT rpm? This shuttering could be the motor loading up with fuel on take off. Also is your new prop drilled to allow for low speed cavitation? Will make a difference.

 

[wtp]

Re: GT150 Problems

So with the new prop what was your WOT rpm? This shuttering could be the motor loading up with fuel on take off. Also is your new prop drilled to allow for low speed cavitation? Will make a difference.

WOT is about 5000rpm
I'm also thinking it's loading up on take off also but not sure how to cure that problem. there is no carb adjustments i can do.
New prop is not drilled - did think about doing it though. I did it on my old 17P one but didn't care about that one.

Everything seems to work and run fine except loading up (I'm guessing ) on the take off. Sometimes it takes a bit to get going but when it does it planes right out other times planes right away.
I'm wondering if changing the float drop to 5/8 instead of 7/8 would do anything.

 

[j_k_bisson]

Re: GT150 Problems

I do not think that will help. It's an adjustment issue with the carbs in the idle/mid range. There has been alot of chatter here on Iboats about playing with the jets. I have never done it due to the fact that I run full out everywhere I can. I don't travel mid range. The days I did this year, I did have the shuttering you mentioned. I am always resistant to chaning carb jetting and leaning things out. Don't want to burn out the motor.

Might want to start up a new thread and ask about jetting and results. I'm no help in this depatment.