lean or rich...hesitation or bogg?

[russianphil18]

I was breaking in my '97 xp and it starts bad while cold because of the oil mixed with the gas im guessing. I premixed the first tank. It idles well as soon as its warmed up. The idle is a bit high (cause the speed is about 5-6 miles an hour) but ill turn that down. I dont know what the rpm is at cause there is no gauge.

These things i can do but the problem is that when i try the second step of breaking in the engine (ride around varying the throttle up to 20% for 30 minutes) the ski doesnt go past about 10% throttle. I cant tell if its rich or lean. I dont really know what it feels like. the low speed is set at standard 1 + 1/4 turn and the high speed is at 0. what could be wrong and what can i do. could it also be cavitation in the impeller?

I thought maybe it hasnt worked itself in enough and the compression is bad but both cylinders show 150 exact. The engine was rebuilt by SES

 

[Dr Honda]

If you pull the throttle... dose it sputter... or does it try to die? Sputting is rich... die = lean.

 

[russianphil18]

well i dont pull the throttle past 20% and from that it seems like its dying but i dont know what thats supposed to feel or sound like. is there any video of those situations? I tried to find one but couldn't.

i took off the exhaust pipe to get a new freeze plug and it had white liquid inside. im guessing thats from unburnt gas mixing with water, right? so that would me its running rich?

 

[JJinSC]

Did you rebuild the carbs too? How is the accelerator pump working? It will cause the engine to die when transitioning from idle to speed if it is not working properly.

 

[russianphil18]

yeah i took them apart and cleaned every part. they were pretty clean already though. no sludge or buildup of any kind.

the accelerator pump, i think, works fine. it sprays when i pull the throttle down, even when the engine is off. its supposed to do that though.?. how can i check if its working properly without buying some special tools?

i have a feeling that this is just the carb tuning which i need to play with when i put the jetski back in the water. does it make a difference if i run it a lil without the air box on. the flame arrestor will stay on but that plastic box ontop...can it be off? or will that mess with the air pressure?

 

[- BiRkS_]

You wont be able to tune a carb by using 20 % throttle. Thats still running on the low speed. an easy way to check if its rich or lean is when it feels like its about to die, blip the choke and see if the engine picks up speed or dies. If it picks up speed, your carbs are lean, if it dies, its rich. Only tune the carbs when the engines warmed up. as long as the engines warm, pull the throttle quickly, and you will really hear a bogging sound if its lean. Rich is more rough and choppy, smelly, more like 4-cycling.

Hope this helps..

 

[russianphil18]

That's a good idea. Simple and logical. But the choke lets in air right? So if the ski picks up speed when I use the choke a lil, doesn't that mean I'm running rich cause now it'll work with a higher air/fuel ratio. Or am I thinking about it backwards?

 

[russianphil18]

Wait I am thinking about it wrong. The choke restricts air cause the butterflies close. Ok thanks a lot for the tip. I'm deff gonna try that

 

[- BiRkS_]

The choke restricts the air, allowing more fuel than air to enter the engine. I was able to diagnose carbs on my '90 GT the same way.

Once you get the engine running decently, for the break in period, i would recommend you keep the carbs slightly rich. engine will run cooler and wont work as hard. Once you've broken it in, slowly tweak the carbs until it runs at its best. For the last bit of fine tuning, you need to run it at full throttle (after its warmed up) for about 3-5 minutes, then pull the lanyard while at WOT. let the ski come to a stop on its own and pull the spark plugs and read them. you want a light tan/brown colour on the insulator. Black is too rich, white is too lean=BAD. There are plently of threads in regards to carb tuning, but this will get you started.

 

[russianphil18]

yeah i read the carb tuning posts i just didnt find on there, how to tell if your running rich or lean while still on the break in period which means no WOT. the choke check is perfect though. thanks

 

[russianphil18]

so i finished tuning the ski and now it runs fine and picks up speed well. i read somewhere in this forum that seadoos usually have a hesitastion in mid throttle and then they get up out if the water. is that really normal? cause i try to slowly increase the throttle and it seems like the jetski is really loading up but when i go up to 10% then 90% and back to 30-40% to cruise it is fine. so why do i need to almost floor it for a second to get it out of the water?

i drove yamaha before and i remember it being a smooth acceleration. like if i slowly increase the throttle it will slowly increase speed.

 

[mikidymac]

That is perfectly normal, I had the same ski. The 1997 XP was the first hull of it's kind and there is a lot of wetted surface and weight for that 787 to get up and out of the water. You need to gass it to get it up on top of the water then you can back off. My opinion is that seadoo knew the engine was a little small when the ski was introduced but they were still haveing issues with the new 950 so they waited until 1998 to add it. Also would explain why it had the 787 for only one year. I still loved my 1997 and with a little work was just as fast as a stock limited. Go have some fun on that bumble bee.