Jetting - small silly question

[Polish jet pilot]

Hi all,

I am trying to dial in my old pp 550 kawi with practicaly all the goodies. It has a westcoast Works pipe, 44sbn, ported cylinder, hi comp head, 15 skattak, bored nozzle by 2mm, etc...

The ski runs well up top but it takes time to get there... I think the problems are or could be:

1. not running a pisser from headpipe to stinger (I guess a lot of water gets to the w/b)
2. popoff? (hard starting under load - e.g. in water). Outside water starts fine.

To fix these:
1. run a pisser
2. change popoff? Now the spring is quite "stiff" - should I change it for better starts and throttle response?

I know these are silly questions but they make a world difference to me ...

Thank you

 

[Polish jet pilot]

Nobody? Come on, I was thinking that lighter spring will open the needle more easily (with less pulse during cranking...) Am I right on this one??

 

[SUPERTUNE]

Piston port engines are fussy with starting hot and in water.
Starters, battery and electrical conditions, and healthy crankshaft seals play a big role in this starting problem with 550 PP engines, might not be the carb at all.
Turn the idle screw all the way out (check cable slack too) so the throttle plate completely closes, start and run briefly on the trailer under load backed into the water with the flame arrestor off, hit stop button and close throttle at the same time and look with a flashlight into the top of the throttle and look for any fuel puddling on top of the plate, if so, there's your big problem with the carb and or needle valve/setup.

Your taking me back way too far with my memory!!!

 

[tom21]

yeah- but it least its in there somewhere Chuck!

 

[Polish jet pilot]

Chuck,

Thank you for your insight. Let me provide some info for better assesment:

1. Engine rebuilt just 10 tanks of fuel or so with all new parts (including seals)
2. No known electrical problems, starter was rebuilt recently... but yeah it was a problem before...
3. Simple fuel system (fuel in, fuel out, pulse line, no filters, restrictors, etc). I setup the ski for a beginner so I installed OEM kawi 550 intake (with the pumice filter)- so he does not drown the motor
4. In water engine turns, but no fire - I take the pump out of water and starts with some throttle.

I was thinking that the spring is too stiff - and it needs to much pressure to "pop open" the needle...

BTW, I bet you can adjust the Kawi with your eyes closed, after a 6 pack of beer

Thank you!

Andrew

 

[SUPERTUNE]

Chuck,

Thank you for your insight. Let me provide some info for better assesment:

1. Engine rebuilt just 10 tanks of fuel or so with all new parts (including seals)
2. No known electrical problems, starter was rebuilt recently... but yeah it was a problem before...
3. Simple fuel system (fuel in, fuel out, pulse line, no filters, restrictors, etc). I setup the ski for a beginner so I installed OEM kawi 550 intake (with the pumice filter)- so he does not drown the motor
4. In water engine turns, but no fire - I take the pump out of water and starts with some throttle.

I was thinking that the spring is too stiff - and it needs to much pressure to "pop open" the needle...

BTW, I bet you can adjust the Kawi with your eyes closed, after a 6 pack of beer

Thank you!

Andrew

Andrew,
1. The trick with crank seals on 550 engines, is to buy a extra rear seal (one next to crank bearing) to use in the front, this gives you a double lip seal for for the front which the stock seal is a problem single lip seal. Being new helps, I hope you used OEM seals, as aftermarket seals IMO are junk.

2. Sometimes rebuilding starters doesn't repair them if they have a weak armature or stator magnets.
IMO new only, not worth the time spent in most cases.

3. I can't give a lot of pacific advice with jetting using SBN carbs on a 550's as they came out with SBN carbs after I was with 650 Superjets to race with. I used the BN 44's with the 3 adjuster screws with the fixed drilled main plugs for high speed jetting.

4. Maybe the porting is contributing to this with a possible weak cranking speed with the ski in the water. Aggressive intake port timing is very critical on piston port engines, just like the rotary valved Seadoo Rotax engines. These engines are a different breed compared to reed inducted intake engines.

 

[Polish jet pilot]

Chuck,

Do you think that I could try to change the spring, if all of the above are OK? The porting can be wicked, as this is an old L&S cylinder - I have no clue on the numbers, etc. I just want that thing to start in water...

 

[SUPERTUNE]

As long as it passed the flooding test I spoke of earlier, does the ski start easy in the water with a squirt of fuel from a primer? This would indicate it's lean when starting, then yes, you can go to the next lower gram spring for lowering the pop off.

 

[ger87410]

Supertune, you're freakin' awesome!!!

If the primer doesn't help, is that an indication of too much fuel?

 

[Polish jet pilot]

Great. I will do the testing and see what happens. I tested it with primer before and it was hestitating to start in water, then It felt like its flooding...once the pump was out it produced much smoke but it did start. Those PP engines are a pain...unless you know them by heart..