Carb adjusting during break in period

[SteveontheLake]

Tom in Pennsylvania rebuilt my 97 GTX 787. He was a stand up guy the whole time despite what I had read online from years ago. I rebuilt carbs with Mikuni kits. Due to the condition of the carbs I could tell someone had been in there before so I was very careful. The one thing I failed to do was the pop-off test. I'm buying the parts to make one but didn't see post that when I had the carbs on the bench.
I now have 7 hours on it and am still getting some sputtering/popping below about 4,000 RPM even though I have the low side about 3 turns out and idle at 1400.
Once it hits 4,000 or so it runs great. I still have not gone full throttle but am cruising at 30mph at 5,000 rpm.
What I'm curious about is this: Since I have had oil in the injector as well as in the fuel, the plugs are just black.
Since I had to go so far out on the low side, should I expect to have this same "way too lean at factory recommended 1 turn" on the high side? I dont mind buying more plugs but I want to make sure the high side isnt too lean and cause detonation.
I know some people say 10 gallons is enough to break in, since I'm new to PWC I'm erring on the side of caution and giving her 10 hours at ~50-60% throttle.

 

[SteveontheLake]

Clarification: Low side factory is 1 turn and high is 0 turns on Mag and 1/2 turn on PTO

 

[JeremyD615]

You should be running them at the factory settings if they are genuine Mikuni parts. Was the diaphragm nipple red when you had them apart? If so, just use the factory settings and let it rip. If not, you’ll need to go back through the carbs and rebuild with the correct kits. You’ll chase your tail all summer trying to tune them with junk rebuild kits in them.

 

[AKnarrowback]

http://www.groupk.com
Go to this web site and read their technical papers on carb tuning to get some insight into the theory on what is going on at various throttle settings. Really good material.

If you did not check your pop off pressure, after a full carb rebuild, I wouldn't go fighting things anymore until you are sure it is set according to factory specs. Three turns out on the low speed screw is too many. Read the tech papers to see how the two run motor.

Make sure you needle and seat are in good condition, they are the right size, the spring is matched to the needle and seat.

 

[SteveontheLake]

I definitely used real Mikuni kits when rebuilding. If I use settings anywhere near factory it falls on its face when I hit the throttle at all so I kept turning til it started working. As stated, someone had been in there before and had stripped the head of one of the screws holding down the plate inside. I had a machine shop extract it without touching the threads (best $20 I spent on this project). There was already a new needle in there and the springs in it were matte and grayish. I'll build the popoff tool and put them back on the bench. Thanks for the link, I will read up on it.
Still doesnt amswer the question though...should I be concerned running it til I get everything perfect? It really runs well around 5,000.
I live at the head-in of 2 rivers to the lake so I spend most of my time in the river at about 5k. Still havent run it at WOT but that's inevitable obviously.

 

[JeremyD615]

If it’s not running at the factory settings, I would advise against riding it until the problem is sorted out. Go back through the “carb rebuild sticky” at the top of the forum and make sure you’ve followed everything to the letter...

 

[dr00andrew]

There was already a new needle in there and the springs in it were matte and grayish.

i think you may have the wrong spring in there. i own a 96 gtx and its basically the same thing as a 97 engine wise. you need the 80 gram black spring and a 1.5 needle and seat. The PO put in a 2.0 needle and seat and my popoff was 23 which was "in range" but it was running way too rich at low throttle. now with a 1.5 it pops off at 38 and its night and day from how it ran before. let us know what size needle and seat are in there and what your popoff pressure is at

 

[AKnarrowback]

If it was my machine I wouldn't be running it unless I was sure the carbs were set right.

Seven hours is more than enough time to loosen things up and make it safe to run wide open. A full tank or two is all most people ever do before the motor is run hard, maybe 4 hours give or take.

 

[SteveontheLake]

I kept all the parts as I removed them and there were definitely no black springs. I ordered a couple and parts to make PO tester. Time to pull it back in and put the carbs back on the bench. I'm getting pretty efficient at doing this part of the job now so it shouldnt take too long.

 

[dr00andrew]

https://www.ebay.com/itm/Genuine-Mi...919577&hash=item284e9a408a:g:Vz0AAOSwVEFcFi89
just order these. people just seem to love swapping parts and putting random parts in the carb when they are "tuning" them. these are the correct springs for your machine and combined with a 1.5 needle/seat will get you the correct range for your popoff

 

[SteveontheLake]

Thanks for that. I searched but didnt find those. The ones I found are here...ended up ordering the ones from EBay, thanks!
https://www.amazon.com/gp/product/B002304IZI/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

 

[SteveontheLake]

OK so I built the popoff tool and with the silver springs it was 21 on MAG side. I ordered the black ones from Ebay (thanks dr00andrew for the link). Now popoff comes at 30. Book says 33+- 10 but seadoosource says 38. Since 30 is within spec at -3, is it critical to try and bend the arm to get it to 38 as so many others say is the correct pressure?

 

[JeremyD615]

No, as long as they are even between the carbs and in the specification range, leave them alone.

 

[SteveontheLake]

Wow! I checked PTO and it was 51!! Mag 21...no wonder it didnt have crisp response and I had to richen it to 3 turns to get it to run.

 

[SteveontheLake]

Thanks @JeremyD615 for the reply. I will leave them at current and see how it goes. The link arm plastic broke so I'm waiting for the new one to arrive to put carbs back on. Bought another set of gaskets to always keep one on hand!