Blaster 760 in b1 is slow?

Waveblastermaster

Waveblastermaster

Location
Leland, NC
I put a 97 760 motor in my wife blaster 1. I also installed pro tec head, pipe, reeds, jet kit ect...it has a stock b1 pump and prop. It runs great but it's slow, runs same speed as my buddys 701 with a pipe only, and also won't pull me out of the water when trying to side mount. I was thinking it was cause of the stock prop? But had a couple people tell me that's not the problem although obviously it would help. Thoughts? Thx

When this motor was in my blaster 2 without the head, pipe, ect...it was prob 10 mph faster than my b1, so I don't understand why this thing isn't hauling ass.
 
Waveblastermaster

Waveblastermaster

Location
Leland, NC
Size of pump I know would effect it but 760 with my mods should have like almost 40 more hp than a 701. I would think it would haul ass in a little b1 especially on top end.
 
WB1994

WB1994

Location
Amherst NH
I remember my B1 with Factory Mod pipe and head and impeller used to slightly pull from idle straight through top end on my friends B2.
 
Waveblastermaster

Waveblastermaster

Location
Leland, NC
Humm, I remember my b2 being a lot faster than my rockered blaster. And my rockered blaster is quite faster then that motor in this b1. Possible 1 of the carbs might not be working proberly?
 
mxr181

mxr181

Location
California
I just put a 760 in my b1 temporarily for a houseboat trip (its getting an 1100 now). I had a very clean 760 out of a raider, removed base gasket (run thin bead of 1211...this slightly lowers port timing and bumps compression), ran a blaster mod Bpipe, stock head, 115 / 135 jetting w/ stock 44s, and a 10/16 hooker prop. Ski hauls ass, bottom wasn't bad but mid to top rips hard! Sounds like something isn't right with your ski. I wanted to try my Ada head to bump up compression but couldn't get domes in time
 
Waveblastermaster

Waveblastermaster

Location
Leland, NC
I put a solas 14.5/18 prop in it yesterday and it definitely helped top end and bottom end a little. It later fouled the plugs so i think it's just some tuning issues now. Friend of mine is going to put a tach on it and see what the rpms are. Anybody have a simular setup can tell me what prop your running? I have a 9/15 in my rockered blaster was thing of doing that or a 10/16 in this one.
 
cegpcola

cegpcola

Location
Pensacola FL
Tuning will be a pretty substantial change from the B2 to the B1. Not only for the head and exhaust change, but the 144 pump isn't going to put the same load on the 760 that the 155 pump did in the B2. Are you running the 760 electronics? If you are you might want to switch the CDI over to a 701 CDI. I remember reading that the timing on the rear cylinder was retarded on the 760 CDI in the B2 because the amount of load the 155 pump would put on the engine would twist the crank and cause advanced timing in the rear cylinder. If you aren't putting the load on the crank to twist it like it was in the B2, then your rear cylinder is just going to have a retarded timing. Just a few things to look at. I have not done this swap myself, but based on the Group K findings with the B2 this would be my thoughts.

Kurtis
 
Waveblastermaster

Waveblastermaster

Location
Leland, NC
That's kinda the answer I was looking for, so I can put the 61x cdi in it and that's all, nothing else to worry about or change? Thank you

cegpcola said:
Tuning will be a pretty substantial change from the B2 to the B1. Not only for the head and exhaust change, but the 144 pump isn't going to put the same load on the 760 that the 155 pump did in the B2. Are you running the 760 electronics? If you are you might want to switch the CDI over to a 701 CDI. I remember reading that the timing on the rear cylinder was retarded on the 760 CDI in the B2 because the amount of load the 155 pump would put on the engine would twist the crank and cause advanced timing in the rear cylinder. If you aren't putting the load on the crank to twist it like it was in the B2, then your rear cylinder is just going to have a retarded timing. Just a few things to look at. I have not done this swap myself, but based on the Group K findings with the B2 this would be my thoughts.

Kurtis
Click to expand...
 
cegpcola

cegpcola

Location
Pensacola FL
Should help your issue out a good bit. The 760 in the B2 had the retarded timing in the rear cylinder fixable by CDI swap, and they also had a staggered compression Should be corrected by the head swap. You will still have some carb tuning to do, as the engine is under different loads then when it was in the Larger hull and hooked to a bigger pump and prop, and as such would hit different load/rpm cells if you looked at it in a graph form. You might have to play with the low and high settings, but it might actually want a pop-off change to transition better due to less load. This is just might thoughts based on my Automotive tuning knowledge, so I might be a little off on the carb tuning as 2 stroke and marine application is a little different, but at the least make sure your carbs are tuned right to keep it happy.

Kurtis
 
mxr181

mxr181

Location
California
I also ran 61x flywheel (.5lbs lighter) & stator. As far as jetting I ran stock 115 pilots, 1.5 N&S w/ lightest spring I could get (I want to say 60g), 135 mains and it ran absolutely perfect. Plugs were perfect. I read several 760 jetting threads and that looked like a good baseline
 
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