Interesting issue.. Wont rev until

[Quinc]

Superjet wont rev until pump comes out of the water... I can cruise around at around 4-5k rpms but it will not rev until I break the pump loose, then she will rev and hit the full rpm range/top speed. But as soon as I get below a certain rpm I have to hop or break the pump loose to get rpms up again.

61x ported and bored 1 over
bpipe
Single 46 155/130 24psi
boyesen reeds
stock electronics
hooker 10/16
170psi
-Cleaned carb, verified pop off etc.
-Replaced fuel line and fuel filter.
-One way valve is working
-Turning the screws makes no difference

I am leaning toward reeds are bad (only 2 season old...) but figured I would see if anyone else has had this.

 

[Baja 252]

I had a Raider that did that in the mid 90's. It was ported with SJ porting specs that just didn't work on the Raider. Is this a new build or did it run fine and just start doing this?

 

[Quinc]

I had a Raider that did that in the mid 90's. It was ported with SJ porting specs that just didn't work on the Raider. Is this a new build or did it run fine and just start doing this?

Been running great for a couple years now. Only recent change was going from 9/15 to 10/16 impeller.

 

[Nuklear6]

Reeds are likely candidate but before I did anything I'd throw a compression gauge on it. I know you don't wanna hear that but it's an easy check and a weak cylinder could be the issue.

If not reeds or weak cylinder its plausible to have a crank or drive line bearing tightening up.

Good luck cody

Chuck Palmucci
CPT Enterprise LLC
609 510 3062

 

[Quinc]

Pulled the intake off, the top reeds where not 100% sealed so I flipped them and now they are good, new gaskets with 1211 and cleaned the carb again. Also replaced orings in the head and checked compression (160psi), and new spark plugs. And the same damn problem!

Today I switched to a freshly rebuilt 44mm mikuni and she ran great all day. Time to toss the 46 into a bucket of chem-dip..

 

[kevbo]

I had a tiny exhaust leak cause the same problem on a couple of skis. Prop up the rear of the hood an inch or so and tape it in place. If it runs fine you will know the problem.

 

[bkillgore]

Did you ever do a leak down on it? Just went through this exact same thing on a buddy's ski and it ended up being bad crank seals.
His had the same symptoms as yours and we tried everything you did as well.


Sent from my iPhone using Tapatalk

 

[Quinc]

Did you ever do a leak down on it? Just went through this exact same thing on a buddy's ski and it ended up being bad crank seals.
His had the same symptoms as yours and we tried everything you did as well.


Sent from my iPhone using Tapatalk

Completely rebuilt the engine two seasons ago with new oem seals, gaskets, and 1211 on everything. I leak tested it then (10psi 15 minutes) and it passed.

Have you tried a new carb? I am surprised that my carb was the issue (completely rebuilt 3 seasons ago) and cleaned multiple times.

 

[orangefinger]

CDI/COILS/SPARK PLUG ITSELF

 

[Quinc]

CDI/COILS/SPARK PLUG ITSELF

CDI was next on the list. But I fixed it already.

 

[orangefinger]

what was it... ?

 

[Quinc]

what was it... ?

Post 5. New carb. Odd though since I thoroughly cleaned and pop off is crisp. Even changed the o-ring on the seat and put in a new needle..

 

[cookn]

Sometimes the tiny return restriction hole can get a piece of crud in it

 

[Joe Dart]

I had a similar issue when trying to use to small of a steering nozzle. Jet pumps are a delicate balance. Also, could it be engine/pipe temp? Over cooling a motor that doesn't need it like possibly you installed dual cooling with the new prop and didn't add water restrictions after the engine? Your plugs with look rich if that were the case but mine always do, I'm scared to go to lean. I'm running a similar set up here's where I'm at right now. Oh and maybe check valve on the gas tank?
61x ported with templates
Ported intake (cause for low pop off pressure)
44mm sbn
33cc domes ada head
Hs jet: 155
Ls jet: 120
2.0 n/s
12psi pop off
B-pipe
Custom waterbox
Wetjet flame arrestor w/ 2 of 3 screens removed
155mm pump w/ 9-? Solas prop and a Bored reduction nozzle to 88.5mm

 

[Quinc]

I had a similar issue when trying to use to small of a steering nozzle. Jet pumps are a delicate balance. Also, could it be engine/pipe temp? Over cooling a motor that doesn't need it like possibly you installed dual cooling with the new prop and didn't add water restrictions after the engine? Your plugs with look rich if that were the case but mine always do, I'm scared to go to lean. I'm running a similar set up here's where I'm at right now. Oh and maybe check valve on the gas tank?
61x ported with templates
Ported intake (cause for low pop off pressure)
44mm sbn
33cc domes ada head
Hs jet: 155
Ls jet: 120
2.0 n/s
12psi pop off
B-pipe
Custom waterbox
Wetjet flame arrestor w/ 2 of 3 screens removed
155mm pump w/ 9-? Solas prop and a Bored reduction nozzle to 88.5mm

That is a really low pop off for a bpipe. Most people run in the 22-26 range. I soaked the "bad" carb in chem dip for 30 minutes and blew through it with carb cleaner and compressed air. Going to give it another shot and see what happens.

 

[Joe Dart]

I tried everything from 19-35psi and never could get a hard hitting bottom end. I removed my choke, bolted all intake pieces together and used a flap wheel to match port everything. This might have increased the volume but killed velocity causing the need for low pop. I laughed the first time I tested that seat/spring getting 12psi, then decided to give it a try. Ended up working well. Would I advise doing this to your carb/intake? No but I found a way to make it work.

The only thing that has failed on an sbn for me is the plastic check valve on the block covering the jets and the diagrams. I would be more interested in looking for pump issues like a leak.

I was just reading on here an stumbled across your thread, sounds like some issues I have had in the past. I wish you luck my friend.

 

[john zigler]

Pulled the intake off, the top reeds where not 100% sealed so I flipped them and now they are good, new gaskets with 1211 and cleaned the carb again. Also replaced orings in the head and checked compression (160psi), and new spark plugs. And the same damn problem!

Today I switched to a freshly rebuilt 44mm mikuni and she ran great all day. Time to toss the 46 into a bucket of chem-dip..

Not a good idea to flip reeds. (Maybe ok just for a quick test in your case). I would get new reeds, or at least flip them back over..... You are now bending them the other way, and they will break off.