Speedster fuel issues.

[ESaddler]

So last two trips out after an hour or so of running the port motor would surge between 4000 and 5000 rpm. So today I cleaned the carbs and replaced the gaskets. I left the needle and seat alone only cleaned it. I reinstalled everything and it now blows air out of the carb instead of sucking in. I pulled the carbs off again just to double check the gaskets and everything looks good. So now i'm stumped.

Thanks in advance,
Eddie

 

[mikidymac]

You need to replace the needles and seats and carb kits with new genuine Mikuni.

 

[ESaddler]

Yes I used the Genuine Mikuni kit but it didn't have the needle and seat in it. So this morning I switched the carbs from the other motor, and it did the same thing spitting fuel out from the carbs and no start. When I pulled them off there was a piece of what looked like a piston ring in the intake port so I did a compression test and it's now at 125. Now Sunday when I got back I did a compression test it was at 145 so I'm thinking the broken piston ring is the cause of the blow by and spitting fuel.

 

[mikidymac]

It probably ruined the rotary valve and gear causing the rotary valve to not turn.
Your job just got bigger.

 

[ESaddler]

I pulled the rotary valve cover off and it still turn when I spun the motor by hand. Can the rotary valve gear jump timing like a car. I think I'm going to pull the head to inspect for cylinder damage.

Is it cheaper to buy a remain motor or just rebuild it. I've built drag racing motors and diesel motors in the past these don't look to complicated or am I missing something?

 

[mikidymac]

The rotary gear has a brass gear that runs on the crank and is designed to break first so make sure the engine turns over all the way really smooth.

These are simple enough to rebuild yourself. But some like to order a fresh engine with a warranty and drop it in.

 

[ESaddler]

So the rotary shaft pulls out from the side of the block with the brass gear?

 

[ESaddler]

Well I think I found the problem. Now the only question is what caused it?

 

[mikidymac]

Running lean from a dirty fuel system and/or carbs.

 

[ESaddler]

Is it possible to clean the bottom end out and put a piston kit in it? Or should the whole motor come apart and cleaned?

 

[mikidymac]

The entire motor and your crank has a 99.9% of being shot from the debris.

 

[ESaddler]

That’s what I was thinking. So who sells the best remain motors?

 

[mikidymac]

Best is probably full bore online but they have gotten extremely slow on delivery. If you want one fast for summer your only option is SBT.

 

[ESaddler]

Thanks for the help.

 

[ESaddler]

So do you have to pull the pump out in order to get the motor out of the boat? I have been pricing parts to rebuild the motor top and bottom end and it seems after parts and gaskets its roughly a hundred dollar difference from the rebuild to a remain motor?

 

[mikidymac]

Yes, pump has to come out but make sure you remove the clip/o-ring retaining the stainless hat on the driveshaft seal first.

 

[ESaddler]

Ok so I got my SBT remanufactured motor in, and when figuring out the rotary valve timing something don’t look right. If I Line it up on the 130 it’s no where close to the 65 degree. The rotary valve itself appears not to be flat is this normal or do I need a new one.

 

[mikidymac]

You need a new valve. Also make sure you are using the correct degrees for the valve your engine uses.

 

[ESaddler]

The manual says 130 with the 360 degree on the bottom one the mag side intake port And 65 with the 360 at the top of the port.

 

[JeremyD615]

Your 65 degree mark doesn’t look like it’s in the right place to me. Put your degree wheel back on it and double check your measurement...

 

[mikidymac]

Your 65 degree mark doesn’t look like it’s in the right place to me. Put your degree wheel back on it and double check your measurement...

Agreed, your rotary valve cutout should match both timing marks so you have either the wrong rotary valve or the wrong marks.

 

[ESaddler]

I ordered a new one and I’m going to recheck the alignment today.

 

[ESaddler]

Ok new development I installed the new motor from SBT and I had rebuilt the carbs minus the needle and seat due to the screw being stripped by the previous owner. I took it out on the water and started the break in process after an hour when I would bring it up to 4000 it would stay there for a min then it would drop of like it was running out of fuel.
So any recommendations on where I can get another carb to rebuild or is it possible to fix the stripped screw if I drill it out.

One last thing what are the low speed settings and high speed setting on the 657x.
Sorry for the lengthy post.

 

[JeremyD615]

I wouldn’t give up on the carb just yet... First, get about 6ft of fuel line and a 1/4 tee. Take the fuel line off of the reserve nipple on the fuel tank baffle and run a short piece of that line to the inlet of the tee. Then take two pieces of line and run them from the outlets on the tee to the input of each water separator. This will bypass the fuel selectors and eliminate the possibility of any air leaks there.

If that doesn’t fix the issue, remove the carbs and pull the fuel pump cover plate and reseat it making sure to get those screws good and tight. Sometimes that plastic diaphragm just doesn’t seal well and you have to reseat it to get it to stop leaking pressure under load.

Carb settings on the ‘94 and ‘95 Speedsters are 1-1/4 turns out from closed on the low speed and 0 turns out on the high speed screw, although I like to leave the high speed screw just barely cracked open. (Like 1/16 of a turn). Pop off should be 16-21psi.

 

[ESaddler]

So the first set of carbs that I rebuilt will run all the fuel out of the filter but it won't suck fuel in to keep it full. the other carb works fine. I ordered new check valve disc and installed them with the blue line up and still no fuel. Have you guys ran across this problem before?