had one cylinder burn up BAD in the middle left side.(93 fast strike carbed motor) the one below is reasonably scarred but not bad. seemed it was lacking fuel on that cylinder,but ive found no restriction anywhere in that cylinders carb or fuel feed line or anything. had fuel in all bowls on that side too. anybody ever seen an ignition problem that could do that or is there something i havent looked at here? right side looks really good.
Modified by bottledgt at 3:50 PM 6/27/2011
Inspect the reeds, intake gasket and O ring on the carb side of the intake.
thats one of the first things ive looked at. nothing is out of place whatsoever there.
Did you check both sides?
for sure. but the problem has to lie in that carb and cylinder if its fuel related.. 6 separate carbs for each cylinder. heres a nice pic of the piston...ouch!
Modified by bottledgt at 9:05 AM 6/27/2011
Hole in piston initially, sounds like too much WOT timing. Have a shop check the timing now-can be done on this motor. Might help you hone in the problem and avoid the same issue after a repower or reinstall of replacement powerhead.
im definately gonna check that when i get it all back together. i dont feel that would be it though,since the rest show no signs of detonation. im gonna go in and check out the waterpump now. may have an issue there.
well, water pump looks ok, but this missing gasket is a bad deal.... and also, water alarm had been going off at random for a few years.
also, totally forgot to mention ,but the main jet in the carb was real loose,but every carbs jets were loose,not just that one. that doesnt surprise me since theyre plastic. do they make anything to keep them in better?
well, update. i originally had ruled out it being an oil issue, but i went back and drained the whole starboard side carb bowls. found the gas did not look mixed whatsoever. the left side in the pic is a 50:1 mix from another boat to compare. not sure why it would only destroy one cylinder and another not quite as bad and leave the other 4 alone,but this sure dont look like mixed fuel to me!
If the orifice was totally out of its seat and it let loose on a high speed run then you leaned that cylinder out. You need to check the hose that feeds that side's throttle body for obstructions if no oil was seen coming out of the drains. The mix comes out the VST into the VRO then back up and is split. There are new style drain plugs that have a "tit" on them to keep the HS orifice in place. But that from the looks of that piston, this problem had been brewing for a while and looks like detonation to me. When was the last time that thing was decarbed?
none of the jets were all the way out,but all were between 1.5-3.5 turns loose,and the burnt up one wasnt but about 2 turns or so from tight.the hose was one of the first things ive been through. clean and clear everywhere. i thought the gas didnt look mixed when i first drain the port side carbs, but actually checked the other side today, and its definately not mixed fuel. dont you agree?i agree that look s like detonation also, but not sure why only one is doing that.and like most people,the decarbing had probably been forgotten ,lol. but ive looked through all the ports on the block and lower unit. theres no excess or blockage of carbon anywhere. all is pretty normal there.
On the burnt piston was the carb to throttle body gasket messed up? Something caused the lean out issue. Usually if it isn't a bad reed then a bad intake gasket or pinched spaghetti O ring on the intake leads to that condition. It is possible that a recirc hose is split.
im going back through it all now. i hate when theres something obviusly wrong but no signs like this. all gaskets are perfect. what exactly would cause the main jet falling out to make it lean. that should be immersed in fuel,which to me would make it too rich with the jet out,unless it somehow blocks the hole . but the jet wasnt all the way out anyway,lol.
cant find any plugging or cracked hoses or anything of that nature whatsoever. BUT i did find this in the lower cowl panel on the same side as the burnt piston. i dont see any hole anywhere thats missing something of this size that shoudl have an expansion plug in it. its 7/8 diameter. ever see one of these anywhere?
That is the welsh plug and the numbers are the serial number of the block. Compare it against your serial/model number tag on the mounting bracket.
thats not anything to do with it then. but numbers arent even close. and where were you talking about oil running out of? and does that seriously look like mixed fuel to you?
<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by bottledgt »</td></tr><tr><td class="quote">thats not anything to do with it then. but numbers arent even close. and where were you talking about oil running out of? and does that seriously look like mixed fuel to you?</td></tr></table>
The oil mix should be coming out of the drain plugs in the carbs. Each side should show the same color to the mix. Is this your motor or are you fixing it for a customer?
its a buddys. i know they should have an oil mix coming out of the carbs. thats my point. they all look the same and its whats in that glass on the right in the above pic.lol. i can see why it blew up with gas like that,but with only 2 cylinders showing that sign, its a little bit weird to me. they should all be like that.
whoever made plastic carbs should be shot.lol
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