97 speedster won't rev

[kappachampion]

Hi, new guy here. First I'd like to thanks everyone who contributes to this forum because it has given me (and I'm sure others) a wealth of knowledge.

I recently rebuilt the carbs on my 97 speedster, took it out to test it and one engine runs beautifully. The other idles beautifully but when I give it any gas it boggs down and eventually will die. Usually happens around 1/4 throttle, ~3000 rpms. It does this if I ease into it or just punch WOT.

Sounds to me like it's running too rich. But I'm not sure exactly what to adjust since it idles great. I'll check the spark plugs tonight to make sure they are wet and confirm my suspicions.

Other information:
High speed and low speed adjuster set to factory (0,1 turn respectively)
I don't have the equipment to do a pop off test, so i didn't adjust the needle valve arm. (that may be the problem, but I thought this would effect the idle)
Everything seems to be adjusted identically to the engine that runs great.

Could it be the acceleration pump needs adjusting?

If it idles great I would imagine the low speed jet is adjusted fine and the high speed jet isn't supposed to be adjusted. Correct me if I'm wrong.

If it sounds like I need to do a pop off test, is there a way to do this without the recommended tools, or a place where I can get the tools cheap?

Thanks,
Mark

 

[kappachampion]

I checked the plugs and they don't seem that wet. I also recently cleaned the fuel filters. I'm kind of at a loss as to where to check next. Any tests you can think of to give insight as to what may be causing it?

I might pull the carb off and double check that the filter is still clean.

Any advice is appreciated.

Mark

 

[timmyboy76]

Did you replace the springs, in n/s assy? If so, replace them w/ the oem ones, if you still have them. Make sure the "inline" filter has an o-ring in it/good shape, and that you dont have the inlet/return line on carb mixed up. Also, did you go thru the xcellerator pump, make sure those lines are installed correctly, it does have a check valve in it, also, the brass fitting protruding inside carb, make sure that "squirts" fuel into throat, while applying throttle.

 

[kappachampion]

I did replace the springs with oem ones that match what was there. the inline filter o ring was in decent shape but I didn't replace it. I'll check the inlet outlet line, but wouldn't that effect idle too? I did rebuild the xcellerator pump all lines are identical to the engine that runs great. I will double check the check valves to ensure that I instaled them correctly (I'm sure i did, but in the back of my mind I can't remeber how much attention I was paying when I put them in). When I apply throttle while the boat is off no fuel is squirted into the carb. Should that happen only when the boat is running or at all times?

A few things I thought of: could it be the valve on the under side of the engine that is daisy chained to the throttle? I'm not sure what it is called, I can look it up if you don't understand what I'm talking about. That cable seemed to be not as taught as the other engines.

I think I can swap the carbs and see if the problem persists on the same engine, that should let me know if the problem is with the fuel lines to the carb or the carb itself.

Do you think it could it be anything electrical? If so what should I check?

Thanks,
Mark

 

[timmyboy76]

the jetting in the carbs, coincide w/ having the xcellerator pump. It should squirt, while the system is primed...running or not. Think your referrring to the "choke" cable..right?, if so, its secured by the allen screws hidden inside tyhe brass "nut"..ok, after re-reading, that cable is your injection cable, make sure the alignment marks are aligned. You may have that, when taking carbs off, needed to "preload" it again, since when cable is removed, it spins all way around...

Install the oem ones. the ones that "look" like stock, aint the same "gram" spring.

 

[kappachampion]

The springs I installed are oem from a mikuni rebuild kit. The same spring as the one in the working engine, so I don't know that it could be the cause but I will try swapping it back with the original. The cable i mentioned is for the oil pump so I'm not sure that would cause this issue, but I will need to adjust that anyways. I'll take a look at the accel pump and see if I can get it to squirt fuel by adjusting it. I'll let you know what happens. If you think of anything else then please let me know.

Also, I wasn't following what you mentioned about the injection cable. Is that the same as the oil pump?

 

[timmyboy76]

cant "adjust" it, per-say. You'll need to clear out that fitting...carb cleaner, and if that dont work, along with compressed air, then use a lighter, heat it up, then blast with cleaner. Works for me. Trust me dude, install "stock" springs

Yup...oil injection/oil pump.

 

[kappachampion]

I took the boat out today and here is the update:

The engine that was running good is now acting similar to the other. So now both engine will rev to about 1/4 throttle and then bog down. I looked at the brass fitting where the accel pump gives gas and never saw anything come out when giving it throttle. This is true for both engines.

I took one of the carbs off and when I played with the accel pump i could get gas to squirt out if the other hose was not hooked up.

I will do some more testing to see if I can find where the hold up is. Please let me know if you have nay idea of things to try.

thanks

 

[timmyboy76]

you need to clear that unit out. Make sure you dont install those lines backwards, since they have a check valve inside them...

 

[kappachampion]

Update: Both engines are running now. I checked the fuel lines and there were connected correctly. I replaced the small fuel lines to/from the accel pump and it began functioning properly. Now the accel pump squirts fuel into the carb when throttle is applied. Both engines idle great, but the starboard one bogs down a tad at 1/4 throttle (3000 RPMs). It will rev upto 3000 just fine, when i go a hair past that it will drop back down to 2000~2500. If I keep going it will pick back up like it is supposed to and run fine.

I have also encountered a new problem. I have the RPMs but I'm not getting thrust. I believe this is caused by cavitation. I will have to tear into the jet pumps and see if I can find the cause. I will do some more research but does anyone know a good "checklist" of things to investigate when the boat is cavitating?

The engines don't hesitate (that I could tell) so I'm not sure what could be causing that blip at 3000 RPMs. Thanks.

 

[kappachampion]

Any body have any ideas or suggestions for the engine bog at 3000 RPM?

thanks