'Blaster 61X weak bottom end power after rebuild

J

jpswift1

Location
Buffalo, NY
I rebuilt my 'Blaster with a Jet Maniac 718 ported top end, all new OEM crank seals, milled head (165 PSI), Riva Red pipe, Hooker 10/16 prop, new fuel filter, diaphragm, all new jets 120 low, 150 high, 2.0 N&S, pop off set at 25 PSI and I'm just not getting much throttle response down low. When I get past 1/4 throttle it pulls pretty well with no hesitation, but it just doesn't have the punch down low like it should. It runs fine, doesn't pop, miss, etc, but it just doesn't hit like it should, especially down low.

My SN Superjet has a stock 62T/61X with Factory (Limited) B pipe and it hits WAY harder down low and smokes my 'Blaster out of the hole and feels like it's a bit faster mid and up top too. Could you guys help me out with some suggestions on this.
 
catpower

catpower

Location
iowa
Wish I could help. I have two blasters. Both identical with Freeport and whole lot more except for the chambers the mod hits waaay harder on bottom than the limited. But...... I may have different jetting on the mod. Still solving that one.
 
J

jpswift1

Location
Buffalo, NY
catpower said:
Wish I could help. I have two blasters. Both identical with Freeport and whole lot more except for the chambers the mod hits waaay harder on bottom than the limited. But...... I may have different jetting on the mod. Still solving that one.
Click to expand...

Thank you for your input. Maybe the pipes do make a big difference. I was thinking about maybe selling my Riva Red pipe and getting a Factory B pipe and even putting my 61X cylinder on a 62T bottom end that I have......I'm just not sure what direction to go here.
 
SXIPro

SXIPro

JM781 Big Bore
Location
Here on the 'X' mostly
jpswift1 said:
I was running the stock 'Blaster prop previously. After I changed it to the Hooker, I noticed just a very slight bit better bottom end, but not very much at all.
Click to expand...

I own a B1 but have never changed props, but in an SJ with that powerplant I would have thought a 9/15 would have been a better choice. I didn't step up to a 10/16 until I put the 781BB in.
 
J

jpswift1

Location
Buffalo, NY
JC-SuperJet said:
Did you actually read 165 psi in a Compression test or is that the Nominal Compression Rating of the Cylinder Head?
Click to expand...

I actually read 165 PSI with a good compression tester.

I wanted a little bit of top end still, so I went with the 10/16 Hooker. I'd imagine that if I sent the prop to Impros they would probably be able to repitch it to 9/15 if need be, right?
 
bored&stroked

bored&stroked

Urban redneck
Location
AZ
Of course your superjet hits harder, it weighs less and has a much better pipe.
Your prop is a little steep for your setup as well.
 
fastgtfairlane

fastgtfairlane

Location
Charlotte, NC
instead of repitching the impeller, try a stubby cone or boring the nozzle to loosen the pump up a little on the bottom. you could also shim the impeller off of the stator section a little to loosen the pump a little. also a 781BB is probably not the best match up with a 61x bottom case
 
J

jpswift1

Location
Buffalo, NY
fastgtfairlane said:
instead of repitching the impeller, try a stubby cone or boring the nozzle to loosen the pump up a little on the bottom. you could also shim the impeller off of the stator section a little to loosen the pump a little. also a 781BB is probably not the best match up with a 61x bottom case
Click to expand...

I'll give that a shot and see if I can come up with those parts before I have the impeller repitched. I'm not running a 781 big bore, it's a ported 718. Sorry for the confusion.

Thank you everyone for the help so far.
 
Vumad

Vumad

Super Hero, with a cape!
Location
St. Pete, FL
You can also try a stubby pump cone or a larger reduction nozzle. They are easier to change than a prop. The main thing to consider is a repitch is a permanent change but a stubby pump cone can be resold if you don't like it. You should probably get the proper prop but you cant go wrong at least trying a stubby, especially if you have access to a 3d printer.
 
Quinc

Quinc

Buy a Superjet
Location
California
Post a pic of your water line routing. You may be dumping too much water into the exhaust. I would also try turning in your main screws on the carb down to half a turn out and see if it gets any better.
 
J

jpswift1

Location
Buffalo, NY
I would have had access to a 3D printer if I was still at work (I teach high school and our technology department has one), but we've been out since mid-March because of the Corona Virus.

I was wondering if I had my water routing correct. I have stock single cooling on it and a Riva pipe, but the water coming out of the pisser feels a bit warm. Compared to my 1100 triple 'Blaster with dual cooling it's about 20-30 degrees warmer I'd say. I'll post a pic of my cooling line routing, and then maybe add a flow control valve too.
 
Vumad

Vumad

Super Hero, with a cape!
Location
St. Pete, FL
jpswift1 said:
I would have had access to a 3D printer if I was still at work (I teach high school and our technology department has one), but we've been out since mid-March because of the Corona Virus.

I was wondering if I had my water routing correct. I have stock single cooling on it and a Riva pipe, but the water coming out of the pisser feels a bit warm. Compared to my 1100 triple 'Blaster with dual cooling it's about 20-30 degrees warmer I'd say. I'll post a pic of my cooling line routing, and then maybe add a flow control valve too.
Click to expand...

I have the XYZ printing Davinci Pro 1.0 and it has been exceptional. $300-$350, plug it in and start printing. Ordered mine through Amazon. I use Hatchbox brand PLA filaments for $20/kg. Fusion 360 is free for educational licenses.

The davinci 2.0 is not a newer version. It is a dual extruder. Good if you need that, but you sacrifice a lot of X-axis range which for most applications is not worth it.
 
Quinc

Quinc

Buy a Superjet
Location
California
Vumad said:
I have the XYZ printing Davinci Pro 1.0 and it has been exceptional. $300-$350, plug it in and start printing. Ordered mine through Amazon. I use Hatchbox brand PLA filaments for $20/kg. Fusion 360 is free for educational licenses.

The davinci 2.0 is not a newer version. It is a dual extruder. Good if you need that, but you sacrifice a lot of X-axis range which for most applications is not worth it.
Click to expand...
Have you tried printing the rski nozzle with it?
 
You must log in or register to reply here.
Top Bottom