Backfiring through Carb after Carb rebuild

[gajipr]

I have just got done rebuilding my carb well I actually purchased a new OEM carb and now I have a small issue with my engine it backfires through its single carb when at just over half throttle. On the water it cant get oven 10 miles per hour when it backfires. Will backfiring keep me from going faster? I have heard that my rotary valve timing might be off and the cause of backfire. I would appreciate it if anyone can explain to me how I can adjust the rotary valve so I can stop the backfire.
MODEL: 1997 GTI
ENGINE: 717 TYPE
SINGLE CARB

THANK YOU ALL

 

[timmyboy76]

did you pull the RV plate off, when removing carb?, if not, and it wasnt backfiring before, than timing is ok. Need to go thru carb, make sure jets are, what supposed to be in there, pop-off is right for that ski???

 

[gajipr]

First of all I appreciate your prompt response timmy.

Well I am not exactly sure If i did pull the RV Plate but I will tell you what I did pull besides the carb, underneath the carb I removed the oil injector to fix the spring on it, it was loose now I am not sure when I removed the oil injector I removed the rv plate. It was not backfiring before I removed the carb. Well the main reason I removed/rebuilt the carb was because I had problems accelerating it would not go faster than 15miles an hour then it would rev back down all while I was holding down full throttle. So i figured the carb was the problem so I removed it and rebuilt it the filter was not dirty, once it was put back in I cranked it and and held down the throttle and it backfires at just above half throttle, So I wanted to see what it would do on the water, and well it of a course kept backfiring and I could not accelerate past 10 miles per hour while holding throttle down.

 

[gajipr]

I looked through the shop manual about how to time the RV and its not very detailed, I would appreciate it if a anyone has better instructions on how to do this. It a 717 engine

Thank you all in advanced.

 

[gajipr]

OK I found out how to time the RV but I was wondering if it could be timed with a regular school type PROTRACTOR? thank you

 

[timmyboy76]

Yep...from center, have imaginary line running from center, past unde the mag hole, to edge of RV case. Thats your "0" mark. then go counterclockwise, 147* and mark there.
Then from center, imagine line from center to edge of RV, passing top mag hole mark there "0". from there, go clockwise 65*.
With RV, you want edges to line with those 2 markings, if not line'n up, flip RV over....:cheers:
top marking should be roughly 1/4in past the "arrow notch" on case...,also, make sure mag piston is TDC

 

[gajipr]

timmyboy I FOUND A DETERIORATED O-RING ON THE ROTARY VALVE DO YOU THINK THIS COULD BE THE CAUSE OF MY BOGGING AND BACKFIRING AN AIRLEAK? !

ITS PART NUMBER EC-6 AT THE LINK BELOW.

http://partsfinder.onlinemicrofiche.com/seadooforums/Seadoo_oem/Seadoo_PWC.asp?Type=13&A=50&B=19

 

[timmyboy76]

Hey stud, not a bad place to start, along with part #1 on same link. If you need one, I have one i'll mail yah...pm if interested.:cheers:

 

[gajipr]

Hey stud, not a bad place to start, along with part #1 on same link. If you need one, I have one i'll mail yah...pm if interested.:cheers:

Timmyboy I sent you a PM! I hope you got it i greatly appreciate your help so far. :hurray:

 

[gajipr]

Bad Rectifier??

Well I have never been more frustrated in my life! I got the two O-Rings from Seadowarehouse put them in and set the RV Valve also and and she fired up but It backfires at halfthrottle and up and also bogging down. I now decided to test the Rectifier and I found out it is not giving charge to my battery:ack:
So my question is can a BAD rectifier be the cause of my troubles? Think my rectifier could be bad, I only did one test which was place a voltmeter on the battery and rev it up and see if It was charging and no go.

Thanks for your time and help

Joey

 

[timmyboy76]

The rectifier/regulator box does two things. It recieves AC voltage generated by the stator coils through the yellow wires. It then converts that AC power to DC power using the rectifier portion. The red wire sends back to the battery, regulated DC voltage to keep your battery charged while riding the ski.
When the rectifier quits working, that red wire is sending AC voltage to the DC battery. Your ignition runs off DC power as it is a DC CDI ignition. When AC is sent, it interferes with the DC CDI. If you can picture the static your car radio has when under high power lines you can understand how the AC effects the ignition.

A magneto produces very little voltage at lower rpm and more voltage at higher rpm. That is why the motor will start and run decent at lower rpm, but run very ragged at higher rpm when the rectifier is shot.
...Hey, you still need the o-ring, wuz shoot'n out today???

 

[gajipr]

The rectifier/regulator box does two things. It recieves AC voltage generated by the stator coils through the yellow wires. It then converts that AC power to DC power using the rectifier portion. The red wire sends back to the battery, regulated DC voltage to keep your battery charged while riding the ski.
When the rectifier quits working, that red wire is sending AC voltage to the DC battery. Your ignition runs off DC power as it is a DC CDI ignition. When AC is sent, it interferes with the DC CDI. If you can picture the static your car radio has when under high power lines you can understand how the AC effects the ignition.

A magneto produces very little voltage at lower rpm and more voltage at higher rpm. That is why the motor will start and run decent at lower rpm, but run very ragged at higher rpm when the rectifier is shot.
...Hey, you still need the o-ring, wuz shoot'n out today???

Yes Timmyboy I still probably need that particular O-RING that one has not been changed thank you so very much.

Hey I want to test the rectifier, how do you remove the RED wire without damaging it??
Timmyboy does this sound like an electrical problem, I can send you a video of what it is doing!! let me know how much you want to the Shipping thanks. OH as of know do you have any other suggestions to what I can test to find the problem.

I've done compression test.
I've had all my hoses replaced.
I've gapped the spark plugs correctly.
I've got a very clean and rebuilt carb.
I've replaced a couple O-rings one more from you!

I have not

Checked fuel selector,
Pulled red wire from rectifier,
ANY OTHER SUGGESTION GREATLY APPRECIATED CHEERS :cheers:

 

[timmyboy76]

Scratch the cash, homey, already shot it out...
Disconnect the red wire from its own male/female connection, or remove it from the solenoid post. If carbs are in tolerance of being clean, pop'n off correctly, no leaks, then another source of bogging is a bad rectifier.
I'd pull carbs again, wait'n for my o-ring, double check pop off,..etc, usuall maintinance, then install everything with new o-ring, and if still bogg'n, disconnect wire/s...:cheers:

 

[gajipr]

Scratch the cash, homey, already shot it out...
Disconnect the red wire from its own male/female connection, or remove it from the solenoid post. If carbs are in tolerance of being clean, pop'n off correctly, no leaks, then another source of bogging is a bad rectifier.
I'd pull carbs again, wait'n for my o-ring, double check pop off,..etc, usuall maintinance, then install everything with new o-ring, and if still bogg'n, disconnect wire/s...:cheers:

Thanks a lot timmyboy you don't even know I really appreciate all the assistance especially for sending me the O Ring, you know I have actually never performed a POP off test on the carb, I don't know which tool or device to buy can you let me know what tool or device and where is the best place to buy one cheers. :cheers:

 

[timmyboy76]

check out JPX sticky, on carb problems. You'll see pop-off tester, rigged one up from manual bike pump. insert the pump hose in where "little filter" is installed. Leave the n/s(needle and seet) assy in carb. Here's setting for ur ski...

1997 GTI 717 270500297(carb #) BN-40I (SB) MAIN-175jet PILOT-67.5jet 1.5n/s 23psi - 43psi LOW(lsa)- 1 HIGH(hsa)- 1-1/2.

You'll have to rig adaptor, preferrable, extra set of hands, to hold in place in filter hole, to achieve po-off. Should pop with'n 23-43psi. If you rebuilt carb, and didn't remove the float-arm spring, then you might be ok, make sure the float arm is level with'n the carb body...or if time is not relevant, then parkeryamaha.com, has tester for 40buks or nuther source to see picture of device...:cheers:

 

[gajipr]

check out JPX sticky, on carb problems. You'll see pop-off tester, rigged one up from manual bike pump. insert the pump hose in where "little filter" is installed. Leave the n/s(needle and seet) assy in carb. Here's setting for ur ski...

1997 GTI 717 270500297(carb #) BN-40I (SB) MAIN-175jet PILOT-67.5jet 1.5n/s 23psi - 43psi LOW(lsa)- 1 HIGH(hsa)- 1-1/2.

You'll have to rig adaptor, preferrable, extra set of hands, to hold in place in filter hole, to achieve po-off. Should pop with'n 23-43psi. If you rebuilt carb, and didn't remove the float-arm spring, then you might be ok, make sure the float arm is level with'n the carb body...or if time is not relevant, then parkeryamaha.com, has tester for 40buks or nuther source to see picture of device...:cheers:[/QUOTE


THANKYOU THANKYOU THANKYOU!:hurray:

I will go ahead and try the Bikepump method here I did remove the float-arm spring. Maybe I am getting to much fuel through the cards causing backfire?

 

[gajipr]

Victory

:hurray::hurray::hurray:VICTORY

I have found my problem and It was right under my nose, dam it I feel stupid:stupid:

It was the end of the MAG cylinder Spark cable that was not making contact with the mag spark plug which means I was running off of only one CYLINDER:ack:

I trimmed the Spark cables and she purrs like new!
NO BACKFIRING NO SURGING, BOGGING I AM SO GLAD IT WAS THIS SIMPLE
I could not have done it without this forum thank you all so very much all of you for all of your tips and suggestions.

CHEERS:cheers:

 

[kustomkarl]

Sometimes the simplest things cause us the most aggravation. Glad you found the problem.

Karl

 

[gajipr]

OH NO! I got the same thing happen today, i cannot believe it this is so frustrating I am now getting backfiring again! I though it was the ends of the spark cable but apparently not
I have owned the Seadoo for only 1month and have ridden it only 4 times I really have no clue where to look now, does anyone have any suggestions PLEASE

 

[timmyboy76]

OH NO! I got the same thing happen today, i cannot believe it this is so frustrating I am now getting backfiring again! I though it was the ends of the spark cable but apparently not
I have owned the Seadoo for only 1month and have ridden it only 4 times I really have no clue where to look now, does anyone have any suggestions PLEASE

Pull the intake/RV plate off, and with the "mag" piston TDC, see where/take picture and post, where its lining up. Wait for my o-ring to be delivered to you before reinstall'n everything....

 

[gajipr]

Ok timmyboy I will do that very soon thanks so much for the help I got the O-Ring today!

 

[gajipr]

Pull the intake/RV plate off, and with the "mag" piston TDC, see where/take picture and post, where its lining up. Wait for my o-ring to be delivered to you before reinstall'n everything....

Timmyboy I could not get a photo of the plate, but i know for a fact it's timed right and the o-ring looks great
well to no surprise still get backfire starting at half throttle so I did a second carb rebuild today and once I put it back in I will see whats happens, if it still happens maybe I will change all fuel out, because this started to happen once I put fuel in it one morning.

CHEERS

 

[timmyboy76]

By chance, we should look up the word "patience", in the dictionary,..if not already there, should be a picture of your mug..:cheers:

Noticed when, I mentioned about "pop-off tester", that your following thread, was you found problem, and it was plug wires. Following that, was, that wasn't it.
Hav'n 2 ski's, along with your ability and patience, if you havn't rigged up a tester, maybe, since season over, pretty much everywhere, is to order a "Mikuni" pop-off tester, from parkeryamaha.com..$50 buks.

Not only, you'll get an accurate reading on pop-off, also, you'll be able to perform "leak" test with it, on the carbs and "case" as well...:cheers:

 

[gajipr]

By chance, we should look up the word "patience", in the dictionary,..if not already there, should be a picture of your mug..:cheers:

Noticed when, I mentioned about "pop-off tester", that your following thread, was you found problem, and it was plug wires. Following that, was, that wasn't it.
Hav'n 2 ski's, along with your ability and patience, if you havn't rigged up a tester, maybe, since season over, pretty much everywhere, is to order a "Mikuni" pop-off tester, from parkeryamaha.com..$50 buks.

Not only, you'll get an accurate reading on pop-off, also, you'll be able to perform "leak" test with it, on the carbs and "case" as well...:cheers:

Very True, I am just trying those free test first. But I will have to get a popoff tester indeed I am at the moment trying a few things here and there.
I am just not so sure If my carb has something to do with because....This all started when I put new gas in it and changed the battery I am baffled why these two things can cause such a problem...thanks timmyboy I greatly appreciate all of your assistance to this moment.

Cheers

 

[gajipr]

By chance, we should look up the word "patience", in the dictionary,..if not already there, should be a picture of your mug..:cheers:

Noticed when, I mentioned about "pop-off tester", that your following thread, was you found problem, and it was plug wires. Following that, was, that wasn't it.
Hav'n 2 ski's, along with your ability and patience, if you havn't rigged up a tester, maybe, since season over, pretty much everywhere, is to order a "Mikuni" pop-off tester, from parkeryamaha.com..$50 buks.

Not only, you'll get an accurate reading on pop-off, also, you'll be able to perform "leak" test with it, on the carbs and "case" as well...:cheers:

ALL right So this goes especially to timmyboy, I rebuilt the carb for the heck of it ok, and I purchased a Pop-off tester and that is good it poped off at 35psi pop off. I also emptied the tank and put fresh fuel in it today. SO...I got it started and noticed i HAVE A WATER/AIRLEAK !! On the exhaust manifold where it bolts on. It was leaking alot ! enough that water was spraying out..SO i took the exhaust manifold off and found that the gasket was well on its last leg, it had a bad tear in it right where the water and air i suppose was leaking. So I am confident after all I have troubleshooted on this thing, This is my true source of my problem..I posted pictures to give you an idea of the condition of the gasket. Please give me an opinion on this. thank you, cheers :cheers: