1994 speedster 657x fuel return line

[hotrodssnova]

I decided to pull the carbs on the port side engine and clean them out. It stalled out on me and i have never cleaned this side. I noticed that the return line on the pto carb is non functional. this does not seem right, and i need some one with a spare carb to verify.

The 90* elbow will not flow air, nor can I push a wire thru.
any insight? should I drill it out? What size?

It does appear to have been replaced at some time. The cover has newer paint than the body.

 

[Dr Honda]

Post a pic of the fitting/hose in question.

 

[hotrodssnova]

I think I answered my own question. I pulled the return line off the other engine and gave it a good cranking, and sure enough, fuel came out.
So, I drilled a 3/32 hole in the return line cover so the fuel could actually complete the circuit. I will post a picture in a bit.

 

[hotrodssnova]

I have my finger on the return. I think it might be a casting or manufacturer error.
That section would not flow any air, or fluid.

 

[Dr Honda]

Well.....


you shouldn't have drilled it. There is a restriction in the return... and it's just like a jet in the carb. If it's too big, you won't build any pressure... it will all flow out. It was probably just plugged, and needed cleaned.


If it was a casting flaw... do you think it would have run for the past 20 years?


Anyway... get it back together, and see if you have enough pressure to run.

 

[hotrodssnova]

I did try and force about 50 psi of air thru it (with it off the carb body). I also tried welding tip cleaners, brake cleaner, bailing wire. Nothing would go through it. I've had the boat out 2 times last year, after getting it all back together, and it did foul the plugs at wot. It would idle and part throttle fine. It would foul them out after about 20 minutes of hard throttle. I just dismissed it as the premix I had in the tank last year. It did the same thing this first outing this year and that's when I decided to clean that side out.
The boat was bought not running and the previous owner said he went through the carbs. That part of the carb is definitely not the one that came on it. The paint is new, and the carb body paint is flaking off and dull.
I agree that it should have a restriction. I can add one to the outlet side hose until I can source another cover or a carb if it doesn't work.
I will take it out after I get the drive shaft bearing installed. It died on me this last time out.

 

[Dr Honda]

Brake cleaner won't touch the varnish of a carb. AND... compressed air won't push out junk when the hole is very small. Remember... pressure is in "Pounds per square inch." So, if you have a 0.040" hole... you are only putting a few grams of pressure on the goo.


But... if in doubt... just get a new (used) cover.

 

[hotrodssnova]

I wish I would have taken a picture of the inside. In the picture, you can see 2 'bumps', one has the return elbow and the other is just an extra. The extra has a small hole drilled into it, but doesn't have it drilled all the way thru. I used this hole to size my drill bit.
So the return has a 0.040 hole or was that just for reference for the air example. I could see through the supply side of the block and there was definitely no hole. If anyone has one laying around, I would love to know what size the restriction hole is, or close to the size of the hole.

 

[jimmaki]

I have my finger on the return. I think it might be a casting or manufacturer error.
That section would not flow any air, or fluid.

Just out of curiousity, how did you get a drill to go around that bend?

 

[jimmaki]

I wish I would have taken a picture of the inside. In the picture, you can see 2 'bumps', one has the return elbow and the other is just an extra. The extra has a small hole drilled into it, but doesn't have it drilled all the way thru. I used this hole to size my drill bit.
So the return has a 0.040 hole or was that just for reference for the air example. I could see through the supply side of the block and there was definitely no hole. If anyone has one laying around, I would love to know what size the restriction hole is, or close to the size of the hole.

Nevermind, I just saw this, I realize you drilled from the inside of the cover. My restrictors are not part of the cover so no holes there, I did find them in the carb body though. It's 1/8th" below the surface inside a bigger hole and I don't have any pin gauges, only a caliper. However I do have a small dill set, the shank of a #69 drill bit will just fit in the restrictor hole with a little slop. The shank of a #68 drill bit is no go, so the hole is somewhere between 0.0292" and 0.031". If I had to guess I'd say 0.030. YMMV since my carb is obviously different than yours.

 

[hotrodssnova]

Thanks for that information. Actually, I drilled thru the inlet side nipple. I could see the casting was solid just beyond where it entered the carb body. I will pull that cover and snap a picture in a few.

 

[jimmaki]

Thanks for that information. Actually, I drilled thru the inlet side nipple. I could see the casting was solid just beyond where it entered the carb body. I will pull that cover and snap a picture in a few.

My inlet nipple dumps into the cavity under the cover and flows by the pretzel oring to a hole that is a straight shot to the needle valve and also to the hole where the outlet restrictor is. Your setup sounds a bit different. You may not have enough pressure left to get by the needle valve at idle.

 

[hotrodssnova]

I will call 'A' factory bypass.
'B' is fuel inlet.

Here's my logic.
A is actually 5/64". I screwed up, I didn't realize I had that size, so I went a tad larger at 3/32".
A has no hole drilled to the out side of the casting. It is drilled into the lower hump in the previous picture, but the outlet of the hump is not drilled.

B is the fuel inlet for the pto side carb.
B also has the return elbow attached on the outside of the casting, top hump on previous hump.

I could look thru the hole on B and see light from inlet. I could also see a solid wall of casting on the outlet side of B. There was no hole to bypass the fuel.
I drilled a 3/32" hole from the inlet nipple just passed the hole. It was soft, and not very thick, maybe 1/8".
Hope this clears things up. I probably went thru 4 sets of plugs on this engine. I toss them after a foul. cheap enough to not worry about.

 

[jimmaki]

I will call 'A' factory bypass.
'B' is fuel inlet.

Here's my logic.
A is actually 5/64". I screwed up, I didn't realize I had that size, so I went a tad larger at 3/32".
A has no hole drilled to the out side of the casting. It is drilled into the lower hump in the previous picture, but the outlet of the hump is not drilled.

B is the fuel inlet for the pto side carb.
B also has the return elbow attached on the outside of the casting, top hump on previous hump.

I could look thru the hole on B and see light from inlet. I could also see a solid wall of casting on the outlet side of B. There was no hole to bypass the fuel.
I drilled a 3/32" hole from the inlet nipple just passed the hole. It was soft, and not very thick, maybe 1/8".
Hope this clears things up. I probably went thru 4 sets of plugs on this engine. I toss them after a foul. cheap enough to not worry about.

Hoperfully someone that has this carb or knows how it works will come to the rescue. Me, I have no idea what I'm looking at. Stands to reason B is the inlet since it is the bigger hole. The smaller hole to the other hump must be the outlet but I see no obvious path for it to get fuel to the outlet nipple, the curved one.

So there must be an internal passage from the smaller hole to the outlet nipple. I wouldn't think it would be accessible from the inlet nipple. Else why bother with the internal hole? I would expect there to be a casting wall between the inlet and outlet nipples to force returning fuel through the restrictor.

At this point you probably are best off just getting a new cover. Even if/when you figure this out, I think the holes you drilled probably made this part into a paperweight.

 

[hotrodssnova]

I would say the casting would fit multiple carbs, and depending on application, the fittings, and holes would be added as needed. There is no connection between A and B.
If you look at the first picture, you would see a casting hump if there was a passage way. Also, there would be a plug where they would have drilled it out.

I could always drill and tap the lower hump to accept a nipple if I have too. I can also pull the 90* nipple and tap that and insert plug. that would redirect the overage to that smaller hole, and back to the tank.

I will keep this updated with my findings.


edit.....
I did check the small hole with the air gun, it's a dead end.

 

[hotrodssnova]

Update. ......
I took a brass plug I had in my bucket of goodies and drilled it out to 5/64". I then took the plug and pushed it into the return line.

Took the boat out for testing, and the plug fouling is gone. I did multiple 180* turns, long sweeps, and short cut back and forth. I also did engine steering and full throttle to no throttle to full throttle.

I personally think it was either a factory defect or perhaps a part for a different carb? The engine has never been stronger and I couldn't kill it today. I also went through about 15 gallons of fuel today. I would mark this thread solved!

 

[jimmaki]

Assuming both engines are the same and that the starboard engine was working properly, I probably would have pulled the cap off the starboard engine's carb and tied to match it rather than making parts. But whatever works for you is great.

 

[hotrodssnova]

Assuming both engines are the same and that the starboard engine was working properly, I probably would have pulled the cap off the starboard engine's carb and tied to match it rather than making parts. But whatever works for you is great.

I actually was going to do that. Then I went to the local seadoo shop and talked with the mechanics there. They informed me that the 5/64" in the line restriction would be a good start. They also told me that the plate would fit other carbs, and if it was sourced on the Internet by the previous owner, he could have gotten the wrong one.

I pulled the plugs and all looks great. I will be sourcing a spare set of carbs to keep on hand and have them ready to bolt on. I will also investigate the restriction size of the return. Even if it means pulling the brass elbow and tapping in a new nipple. With the age of these boats, parts are going to be getting harder to find, and if we can do our own mods on other parts all the better.

On a side note, my thru the hull fitting was wasted, and I had to fab one up at the house. I run the boat in brackish water and that eats aluminum quick. My boat does NOT have aluminum fittings, it is a black abs type of plastic. It was cone shaped from years of owners tightening the clamp. If you're interested in a low cost repair, let me know. I took pictures of what I used and how I did it.

I realize some folks here are tried and true "gotta use the factory parts" crowd. I don't believe that is always the case. I successfully wired two aftermarket mpems in my boat, which I think is a better setup then factory. I will continue to improve on the factory setup where I see the need, and it's not a safety issue. This is a great board, and I will continue to contribute where and when I can.

This thread might just help someone in a pinch who just acquired a boat that has seen multiple short term owners who hacked this or that thinking it will get the boat going. My speedster was a mess when I bought it. It still has a way to go, but it's finally running like it should be, safe for the family, and it's paid for.

This might have seemed as a rant, but it's who I am, and shows my dedication to the boat and the community that drives them.
My 2 psi.

 

[jimmaki]

When fuel enters the carb it can only go two ways, 1) through the filter to the needle/seat and 2) through the restrictor back to the fuel tank. While pressures are not the same on the other side of both orifices, a return restrictor in the neighborhood of 2-1/2 times bigger than the original and possibly as big or bigger than the needle seat or either or both jets is not functionally equivalent to the original and could have unintended consequences. While it may work now, it wouldn't take much resistance from the internal filters to rechannel a lot of fuel from the needle valve back to the fuel tank with the restrictor providing so little resistance, not to mention upsetting the balance of fuel flow between carbs if your engines use duals.

Didn't your boat use the same carb(s) as the XP that year? Replacement parts are probably easily had.

 

[hotrodssnova]

Sure does. I plan on getting another set of carbs. I'm waiting on a reply for a set now. With college starting soon and the kids are going back to school soon, I had to get a good weekend in with the boat. This fix allowed us an awesome weekend. We spent over 80.00 in fuel for the weekend.

I am actually pretty dang sore from tubing and driving. The wife actually enjoyed the boat this weekend, lol! She and my son both drove it this weekend with no problems with hot starts, no stalling or bogging out. We didn't get back to the house till after 930 last night.

I fully understand about the fuel circuit. I have a built turbo car with a modified fuel system and forced induction system. These rotax engines are very simple and easy to work on. I need to start collecting parts to have on hand when issues pop up. I do have a spare coil, rectifier and solenoid. It's a start.
Now to locally source other goodies.
Thanks for the insight on this issue. It's a great place for all things doo!

 

[hotrodssnova]

Still haven't had a chance to pull the other side carbs and check the restriction hole, but in my search for a spare set, I found a 94 gsx for 40.00 and a polaris sl 650 for 20.00.
The doo has amazing compression and looks to be in decent shape for sitting in someone's back yard for a couple of years.

 

[hotrodssnova]

I pulled the plugs on the port engine and they were just about perfect. I didn't do a plug chop on the water, but it was running great, so I had no reason to do that.

I spent all day yesterday on this gsx. Still had the gray tempo fuel lines, and all the crud associated with them. Those carbs are a tough set to pull, so I pulled the the whole cover and intake, oil pump and carbs in one piece.

Those carbs are completely different and I can't compare the plates.