Went Riding Today after I did the Valves and ....

[Rampage]

Well they where calling for 6 to 8' waves today, so we decided to go wave jumping for a while. Ski runs great out hitting waves or playing around, but at WOT and pretty much max RPM...it still drops 1k to 1500 very often. Im just not convinced that this is a Carb prob...but I have been wrong before. I serviced the Rave's...cleaned fuel filter...fresh plugs. Ski starts very easy and accelerates very nice.

 

[Bills86e]

Try cut back the plug wires 1/4" after removeing the boots. BR8ES gap .021.

 

[dsw222]

did you adjust the spring pressure on the raves at all?

 

[Rampage]

I set them all flush with the top of the cap

 

[dsw222]

I set them all flush with the top of the cap

were they screwed all the way in the last time you went riding?

 

[Rampage]

They where about half way down...It it did the exact same thing when I rode back then too. I also changed out the fuel lines...but even the inside of the Tempo lines did not look bad yet. The best way I can describe it, would be if I was riding wide open and touch the kill switch for a quick second....crossing wakes seems to make it happen also I think....but jumping big waves and starting, and accelerating its great. This only happenes when it reaches high RPm for more then 10 seconds or so....and if you keep holding it wide open it pretty much will do it constant.

 

[dsw222]

They where about half way down...It it did the exact same thing when I rode back then too. I also changed out the fuel lines...but even the inside of the Tempo lines did not look bad yet. The best way I can describe it, would be if I was riding wide open and touch the kill switch for a quick second....crossing wakes seems to make it happen also I think....but jumping big waves and starting, and accelerating its great. This only happenes when it reaches high RPm for more then 10 seconds or so....and if you keep holding it wide open it pretty much will do it constant.

my boat did the same thing at the end of last season. i would be going full throttle, then if i turned or hit some wake (or even just after 10-15 seconds), one engine would stumble to 1500-3000 RPM or so.

i'm almost positive that its related to the RAVEs. in my case, I think that i shaved too much off during the engine rebuild, so now they aren't maintaining the proper pressure to stay open regardless of spring setting. i never was able to get it sorted out because my other engine blew... but i ordered fresh raves to have properly shaved for next season

my thought on RAVEs is.... if the spring pressure is too tight, then they will not open at the proper RPM and will snap shut too easily if you turn or hit wake (anything that causes a change of load on the impeller/engine). if they are too loose, then a wake/turn load on the impeller could cause you to stumble a little bit because the valve could be open more than it needs to be which gives a loss in power, and that effect is then amplified until the rave closes again. just a theory... but all i know is that my boat wasn't running right with the raves too tight OR when they were too loose

 

[Rampage]

they are set flush with the top of the cap...wonder if I should put them all the way in and see if there is any change. I have spair plug wires and coils...do you think its worth swapping them out.

 

[Rampage]

Took my carbs off...took one look and I dont recognize a dang thing on these and frankley they scare me...so I put them in a plastic bag and dropped them off at Capt Scales house, so he can go through them for me. :cheers:

 

[Dr Honda]

Yep... pressure carbs aren't anything like your typical Holly, but it all works the same way.


On your main carb, you have a fuel pump. Simple. It uses pulses from crank case to drive the diaphragm back and forth pump the fuel. It has a couple check valves, to keep the fuel flowing in the right direction, and there is a return line with an orifice (jet) to keep the fuel pressure at the target level.

Next... you have a needle and seat to control the fuel coming it. (you should recognize that) BUT, instead of a float, there is a diaphragm. That diaphragm holds pressure on the needle, and the "Pop-off" pressure is the same as adjusting the float hight.

After that is (normally) a main and pilot (idle) jet. The only differance here is that there will be a check valve by the main jet to keep the idle cuicut from sucking air back though the main jet.

Simple. :cheers:


After seeing the hot engines you posted... I'm surprised you wouldn't tackle some simple little carbs.

 

[Dr Honda]

Almost forgot... it seems like most rebuilt engines like to have the RAVE screw turned the entire way in. Not sure why, but it probably has to do with the blade clearance.

 

[Rampage]

yeah but thats like asking a old school Ford Tech to work on a new Audi!! LOL..nothing looks right. I might try and screw those valves all the way in and see what happens