787 backfire

[cunadomalo]

A 97 GTX with an SBT rebuild was brought in. It has been poorly installed and otherwise mishandled, so it is not an SBT issue. It stopped for the customer, then brilliantly towed BACKWARDS to the dock. It filled with water. Set for a few days and then brought to me. I had two MAJOR backfires before I got it running again. Now, it is hard to start and has something wrong with it that I cannot put my finger on, but it remiinds me like the motor isn't balanced. Do the counter balance shafts go out of sync? I get good spark output (smarttach) and compression is great. Perhaps the installer has the rotary valve mistimed? Front spark plug darker than back one.

[Technical Support]

Re: 787 backfire

It could have a damaged rotary shaft at this point and now is out of time, pull the R/V cover and check the valve timing.

[cunadomalo]

Re: 787 backfire

the valve was off a tooth or so amounted to about 1/4". would this cause hard starting and backfiring?

[Technical Support]

Re: 787 backfire

It can cause hard starting, possibly a back fire, reset it and see how it runs.

[cunadomalo]

Re: 787 backfire

runs great now but is the hardest starting ski in my 21 years of trying to repair these. might look to fuel and/or delivery, carbs something. timing great, spark strong and compression powerful.

[ashpapi]

Re: 787 backfire

seems like you're on the right track. where's dsolie? he would know. I've been away for awhile. can you tell if plugs are wet or dry when it doesn't start? maybe check the stuff coming out of either fuel line to test for water in the gas? oil injected or bypassed? was going to move to sumter, might still.

[Technical Support]

Re: 787 backfire

Hard starting could be from too high of a pop-off pressure, did you verify pop-off?

[cunadomalo]

Re: 787 backfire

I forgot. Have to dig out tool. Thanks.

[cunadomalo]

Re: 787 backfire

after putting "E-Zorb" in tank and always turning gas selector off in between uses, it starts easily. Always smokes alot. Could be water in gas (customer just bought ski, remember towing backwards incident) and/or carbs flooding. told him to monitor it and try to empty tank, hopefully fresh/good gas will help.

[cunadomalo]

Re: 787 backfire

still takes forever to start, smokes like crazy, hits and misses before staying steady like flooded condition and the brown goo flowing from exhaust is nasty!!!! not the black/oily/watery stuff I'm used to. brown slurry baby diaper remnants. needle and seat/flooding? awful junk in gas? you said pop-off?

[cunadomalo]

Re: 787 backfire

I modified pop-off, new needles and seats, slight adjustments. starts good rather easily.better battery. still has a different sound to it, hope it holds up.still think I haven't solved everything.

[Technical Support]

Re: 787 backfire

The brown mucky stuff was rusty water Hope it stays together for ya.