I know this sounds dumb, especially coming from me but I have been told too many things. When adding riva/k&n flame arrestors to my gp1200 should I change pop off? GroupK says yes. Riva said no(i didn't speak w/bubba), Island Racing, Long Island says yes. Take a look at what is done to my 97 gp1200 and let me know your opinion about pop off. What pressure should I go with? I was also told to get the protec jetting kit, which re-routes the fuel lines to the carbs to allow fuel delivery more consistant for all 3 carbs. I am not doing the motor this year so jetting will stay the same - except adjusting the high speed screw. I want to do this right - but don't want to spend money 2 times, so all answers will help. next winter i am going to get the motor done, and the carbs have to come off to get rejetted, chokes out, and bored to a true 44mm.. so if I don't have to take them out now I won't(hence that is why the chokes are still in). Thanks for everyones help!!

fatten up high speeds 1/4 turn, you'll be fine. mooky #926

When installing flame arrestors your carb signal decreases so yes you should lower your pop-off but may get away without it. The only way to find out is to try it.

I personally would call Bubba and follow his recommendations. Tell him exactly what you plan on doing and what you have allready done in addition to the elevation you will be riding at.

It is funny that group K says to change the pop-off pressure because when they did my carbs on my GP1200 and ported the cylinders they did not change the pop off pressure????? They only changed the high and low speed jets??? This resulted in a expensive Fed Ex bill one summer because I had to continually ship stuff back and forth due to several piston seizures. I changed the jetting to Riva's spec for pump gas porting and never had a problem after that.

thanks... i will call bubba tomm. i will post the riva solution on the thread to end any questions that others may have.

NJ,
I got almost the same setup with my 99. Riva Flame arrestors and adaptors with a primer kit. The only thing I did was adjust the high speeds a 1/4 turn and the boat has been running great ever since. And this was done 2 years ago. 150 hours on the motor since I installed the flame arrestors.

NJ,

I would go with Joe on this one. If you have hesitation off the line and can't bring her in by fattening the lows then you need to adjust popoff. I would definately fatten up the high speeds a 1/4 turn. You can always adjust them later.

NJ--if your only doing the f/a you would prob. get away with the stock 1.2ns .I recomended for u to go to the 1.5ns,dont forget,the 1.2 were designed for the restrictive airboxes. dont foret the old saying--better safe than sorry--easy enough to do-- you could always go back.

Carl is right

I'm no carb whiz...

If you decrease the restriction on your intake you will change the manifold pressure and thus the pop-off. You may get by with the stock pop-off, depending on how much the manifold pressure changes.

Having just read the Mikuni manual and Group K stuff while dialing in my SuperJet carbs, I'd be worried about the "tourque peak" seizures that Group K mentions. Sounds to me like you can have the ski running well and have lean midrange that you might not notice (until you seize). They don't specifically say it is related to pop off, but that it is related to lean midrange and pop off has a lot to do with that...... They also talk about the 80% or 7/8 throttle seizures... All kinds of stuff to lose sleep over

got the email back from riva and they said not to change pop off (from bubba himself). gonna go with mooky and have him set me up. thanks everyone

you may want to check the yamaha specs on a micro fiche..I think you find that the needle/seat were different on the 97 GP1200 in comparison to the 98 or 99.