Ski wont rev up!

[norcal ex]

One of my skis will not rev up. I had it running perfect but then i

The ski has
-Protec mach 2 exaust
-Ported cylinder (701)
-61x electronics
-stock cdi


I had it running perfect but then i,
1. switched hulls
2.took off the water injection
3.put a stock head on (used to be protec girdled
4.put dual 38s on (used to be dual taper bored 46s)

It will not rev up, when i pull full throttle it has no bottom end and feels like it fat. ONLY WHEN IN THE WATER
Outside of the water it seems fine, but today when i pulled full throttle and it felt like it was missing at top. this is sooooo weird and i cannot figure out what the problem is!


I have changed the flywheel, stator and cdi and it still has the same symtoms.
I also put on the 38s and it did the smae thing. WEIRD!

Anyone know?!

 

[Matt_E]

sounds like a potential jetting issue. You have also lowered compression and removed water injection. That will kill some bottom end.

 

[Mark44]

From 46 to 38 I am sure you have jetting issues like Matt said. What jetting is in there now? what pop what N and Seat?

Mark44

 

[norcal ex]

i reallly do not know the jetting. in my past experince, i have never jetting dual 38s. that has been with a 760 and a 701 and both ran like champs. i should check the jetting, but the possibility of it not running any better with completly differerent carbs is low....right?

 

[Matt_E]

The possibility of it running equally ********ty with throwing on two sets of carbs you don't know the jetting of is pretty high, actually.

 

[norcal ex]

i guess, seriously, i have never messed with 38 jetting OR tuning, i have never had to tune 38s before. i guess i have just been lucky

 

[Matt_E]

That may mean that you have stock jetting in those carbs - I am not surprised then that a ported cylinder with a dry pipe won't run very well.
Before anything else, you need to figure out what the jetting is right now.

 

[norcal ex]

yea, im going away till sunday, but sunday or monday i will for sure do it! i know that those cylinders were on a heavily ported 760 before my ski

 

[keefer]

Maybe the exhaust ports are so high that the new combo of pipe and lowered compression has just killed the engines ability to make power at low end and rev out when under load.

 

[Matt_E]

I doubt it would be that ********ty, but it's possible. I would start with the carbs first.
Once you're sure those are tuned right, you can attack other angles.

 

[Waterdawg Kustomz]

It sounds like you might have a water leak in your head. After running it in the water, you can carefully pull the spark plugs and check for water. Look at the outside ring of the plug, around the electrode, and you may see tiny little droplets of water. Gasoline will not leave this, only water. Just a thought. Good luck!!!!!!

Jeff

 

[keefer]

Yup, I agree, get the jetting right and try to clean up the bottom end if it is too fat and go from there.

My previous post relates to a guy in this area that had a B1 with a "ported" cyl he had bought and installed on his ski. This cyl had been hacked by a local guy that was known for going overboard with porting. The boat ran exactly like what is being described here and was setup similar. Recently a friend of mine that has a shop did some work on this boat and he found that the exhaust port height and the near stock compression was the problem. He fitted it with a more mildly ported cyl and it made a night and day difference. The bad combo of pipe, porting, and head just added up to an engine that could not pull itself out of low end. Runs like a champ now.

 

[Mark44]

g

i reallly do not know the jetting. in my past experince, i have never jetting dual 38s. that has been with a 760 and a 701 and both ran like champs. i should check the jetting, but the possibility of it not running any better with completly differerent carbs is low....right?

Right! Take those carbs apart and let us know what the jetting in now. We can give you a good starting point. check pop also. :biggthumpup:

Mark44

 

[norcal ex]

It sounds like you might have a water leak in your head. After running it in the water, you can carefully pull the spark plugs and check for water. Look at the outside ring of the plug, around the electrode, and you may see tiny little droplets of water. Gasoline will not leave this, only water. Just a thought. Good luck!!!!!!

Jeff

i thought of that already, i put it in the water and disconnected both water lines and it ran the same. RIGHT when it comes out of the water it runs fine

 

[norcal ex]

the main jet is 135 and the pilot is 70, shouldnt it rev up with those?

 

[norcal ex]

those are what i am running in my main boat with a STOCK 701 cylinder and that things pulls hard!

 

[Matt_E]

And now you have a ported cyl with a drypipe - that's why it doesn't run worth a damn with those jets. You need to richen up the pilot to 77.5 and the main to 140.

Those are stock 701 jets in there.

 

[norcal ex]

my other ski used to have a PORTED 760 with those same jets, a Bpipe and everything else you can think of and pulled hard.

 

[norcal ex]

And now you have a ported cyl with a drypipe - that's why it doesn't run worth a damn with those jets. You need to richen up the pilot to 77.5 and the main to 140.

Those are stock 701 jets in there.

I am pretty sure that the mach 2 is a wet pipe, but i am not sure.

 

[Matt_E]

I recommend you richen up the pilots to 77.5 and the mains to 140 and see how it runs.