few questions about a Riva piped 701...

[Al//gsx//sj]

picked up my first modded ski and wondering if these numbers sound right for a 701

94SN, 701 Riva pipe, Riva F/A, milled head with 175ish compression and a few handling goodies...it's been set up like this since 1998 by a performance shop in Maybank, Tx (that is now out of buisness). is that the correct spark plug and is it normal to have almost 3 turns out on the low speed circuit?

high speed jet 147.5 high speed screw turned 1 1/4- 1 1/2 out
low speed jet 115 low speed screw turned 2 7/8 out
n/s 2.5
dull silver spring
B8HS spark plug gapped @ .028

 

[Mike W]

How is it running? If its running well than I would leave it alone. One thing I have learned over the years is if it aint broke don't fix it.

 

[Al//gsx//sj]

it starts and idles great, out the hole it seemed slow/sluggish, kinda like loading up in a no wake zone, mid throttle is very responsive. the carb. was very clean, no trash in the filter or signs of rust inside. it's been in storage for 5 years and i was paranoid of a seizure so i limited the test ride for only 15 minutes with very light throttle (just enough to get on plan). guess i'll need more water time to know for sure. just thought if the set-up was not right, i could catch it before i do damage to the motor... also, he was running Amsoil 100:1, of coarse i mixed this tank at 50:1...

 

[tor*p*do]

pull the plugs in a dark garage
use a fiber optic bore sight to look at the top of the pistons
and read the piston wash.
That will tell a lot!:fing02:

 

[Al//gsx//sj]

lol...sorry the best i can do is a straw and a mini mag light...hummm that might actually work though...

 

[onesojourner]

could it be a pump issue? are you sure its just not hooking up right?

 

[Al//gsx//sj]

very good possibility, i found the threads on the prop broken. before i removed it, there was enough play that it would hit the sides of the wear ring and i noticed cavitation burns on the cone, so the problem has been there a while. the 15 minutes was just long enough to make sure the motor could run with a load placed on it, ran very smooth, no backfiring, stalling, popping,etc...

http://www.x-h2o.com/threads/35737

Solas SS YB-SC-A

 

[Al//gsx//sj]

Wow, all these years working here and our shop mechanic had a SeeSnake borescope, :banghead:...anyway, took a look and the piston tops, they were black with no piston wash. Fattened up the high speed screw to 3 turns out. spent about 2 hours on the water this weekend. trailered the ski, brapped the throttle a couple times to clear out the water and shut it down for the day. later that night i checked and this time pistons were light black/dark gray, but still no piston wash. I checked out my co-workers old GP800 that has a fresh rebuild of 18 hours and his piston wash looks perfect. I guess jump up a jet size? Maybe 2 hours was not enough run time? Any thoughts?

 

[Al//gsx//sj]

Well…after reading what seemed like a thousand pages on pipe routing and carb jetting, I decided to change mine. Most everyone is running 1 or 2 exits off the head, mine has 3 for some reason. with some help from Paul, below is where i'm at today.

water routing
rear cylinder OEM exit feeds the lower pipe
front cylinder exit to a "t" straight to pisser, other feeds the stinger
top of pipe is exited outside the hull
2nd rear cylinder exit is going outside the hull also

carb jetting
changed N&S from 2.5 to 2.0 LS @ 1 3/4 turns out
changed pilot from 115 to 120
pop-off changed from 17 to 22
main jet is still 145.7 HS @ 3 turns out (changed to 155 HS @ 2 turns out)

test ran for about 30 minutes and ski ran great and much better snap off the bottom, mid to top felt the same. plug chop was grayish/tan. still not good.trailered the ski and changed main jet to 155 HS @ 2 turns out. ski has perfect throttle response, pulls harder on the low end and has a little better mid to top. ran 3 gallons of gas thru it and am very happy with this "feel" but encountered some problems.

doing tricks, as long as i'm on plan the ski rev's and pulls, but if i fall off or the nose gets buried, it can't pull itself out no matter how much gas i give it.
with the engine warm it starts and idles but dies unless throttle is applied
will then only idle for 10-12 seconds
after sitting for 15-20 minutes is hard to start
on the trailer it will idle indefinitely

i'm seeing a little more piston wash on the edges (about the size of a grain of rice), still not what it should be. now that i'm hooked on the low end power, next step is a 125 pilot and 160 main and adjust accordingly. if it takes more than a 160, something's gotta be wrong with the motor...

 

[itismejoshy]

this is a good story! i'm on the edge of my seat here!! whats gonna happen next????? really??? your killing me!!

 

[ATS_Aaron]

I like your water routing.

I always measure my pop off instead of going by the chart.

A waterproof tachometer with peak/hold is better for tuning than piston wash.

Aaron

 

[Al//gsx//sj]

I like your water routing.
I always measure my pop off instead of going by the chart.
A waterproof tachometer with peak/hold is better for tuning than piston wash.
Aaron

my next water routing will look even better. good points about the pop-off and tach. idea thanks,

i was talking with a board member and looks like i've been tuning with a not-so-good water routing. it should've been closer to the picture at the bottom.

working with the routing i have now, he suggested i plug the extra exit line on the rear cylinder and i think that did the trick. spent an hour tuning and once i was sure of my adjs., i came in and re-attached the line. took it for a test spin and the bottom end was slower, not so good throttle responce.

so after plugging the line again, the rest of the day went a lot better. plug chops were good, idles forever at about 1180, throttle response was really quick/almost instant and great pistonwash. i know the #'s below won't mean squat when i change the water routing next season, but it was nice to finish out today's testing on a positive note...

before
115 pilot @ 2 7/8
147.5 main @ 1 1/4- 1 1/2
2.5 n/s
95g spring
17 psi pop-off
max rpm ???
top speed 49.8

after
135 pilot @ 1 3/4
160 main @ 1
2.5 n/s
95g spring
18 psi pop-off
max rpms 6720
top speed ???

 

[ryan]

way to much jet. you almost at superstock size jetting. is the cylinder ported? 2.5 needles my god talk about no fuel control. how long dose a tank last ya? check the cranks seals?

 

[Al//gsx//sj]

lol about a hour of non-stop riding. when i got this ski it had no signs, not even a hint of pistonwash. i figured i'd work with the n/s that was already in there and start changing jets. i have no idea if any internal mods were done. had to check my timing about 2 months ago to see if was correct and noticed this.

 

[Talsivar]

replace that seal, and bring that jetting down!

 

[ryan]

should be around 117.5 low 140or 145 high 2.0 needle 95gram spring. 2 turns low speed ajuster 1 1/2 on the high.

 

[Al//gsx//sj]

well that's not good news. it's such a small leak, i figured it was normal for a 14 year old ski, guess not.