96 xp

[VaDeerHunter]

Thank you for your thoughts. I think I inadvertently found the problem that precipitated this whole mess. I took the ski in for gas tank recall and they swapped the tank. Last night I was actually starting the process to check the lines I installed to make sure they were connected to the right spigots. Ends up the vent line and return line were swapped. With the return line correctly installed it appears there is some back pressure on the return line created by it being below the gas level of the tank. I would expect that that could cause the fuel pump to exhibit low pressure symptoms in the carbs at high speed, causing them to empty. I would expect some back pressure on the overflow line helps balance the amount of fuel in the reservoir in each carb. Also it would create an open loop that would cause the fuel line to empty back into the tank when the engine is off. As for your Ideas, I did blow pressure back through the fuel line and I can hear the tank bubbling. I also pinched the line before the tank and could not feel any pressure drop. I "pulsed" the fuel pump and was able to get draw from the tank. Also by placing transparent filter in the line I can see fuel coming to carb. I guess my question would be, once the "pulse is gone" should the fuel stay in the line or would it siphon back to the tank or filter? I have to wonder if the vents are clogged and creating a vacuum in the tank which might reduce fuel flow. My main concern though is the air coming back out of the intake. Maybe one side sucks while other exhales in the system since its an open crankcase system. My concern is the valve plate is out of time because it got stuck. The oil pump is working as I can see oil coming out of the injectors. I am going to go check the vent line and make sure it is working, I assume no or clogged vents could also cause a low fuel feed too. I am slowing this process down and going to take a few days off and attack it again next week. Thanks for the pep talk!

Pat

 

[VaDeerHunter]

Vents are working! Happy 4th!

Pat

 

[VaDeerHunter]

I thought I would give everyone an update after all this time. Being a cautious person after causing my own problem I took to the ski to a dealer over near my other home. Nice folks but as of $750 later getting carbs rebuilt, fuel system cleaned and set up correctly, fixing oil leak, they got it all back together. During the process they discovered it had jumped time and reset it to the correct timing, something I had suspected since day one. I think the quick squeal I heard was the rotary disk sticking causing damage to the brass gear. So now of course they want to split the block etc. This is going to take to a point where I have more money in repairs invested in the ski than it is worth.

This brings me to a question...should I pick it up and do the shaft replacement myself using the sight comments? Some folks say you need to split the block to get the brass out of the block and others say since its brass it won't hurt anything and just pull the shaft assembly and replace it. So my question is can you pull the intake off and get to the filings with out pulling the engine out? Should I wait and see until I get the shaft out to see how much damage actually was done? When the dealer got it back together it ran for about 3-4 minutes before it got out of time. Can you see the crank gear through the hole once the shaft is out for inspection? I don't want to put a new shaft assembly back onto a bad or out of line crank gear.

Getting kind of frustrated here and could use any advice.

 

[Sportster-2001-951C-Stock]

During the process they discovered it had jumped time and reset it to the correct timing, something I had suspected since day one. I think the quick squeal I heard was the rotary disk sticking causing damage to the brass gear. So now of course they want to split the block etc. This is going to take to a point where I have more money in repairs invested in the ski than it is worth.

This brings me to a question...should I pick it up and do the shaft replacement myself using the sight comments? Some folks say you need to split the block to get the brass out of the block and others say since its brass it won't hurt anything and just pull the shaft assembly and replace it. So my question is can you pull the intake off and get to the filings with out pulling the engine out? Should I wait and see until I get the shaft out to see how much damage actually was done? When the dealer got it back together it ran for about 3-4 minutes before it got out of time. Can you see the crank gear through the hole once the shaft is out for inspection? I don't want to put a new shaft assembly back onto a bad or out of line crank gear.

Getting kind of frustrated here and could use any advice.

If the service dealer removed the rotary valve shaft to reset the timing, they should have seen the condition of the brass gear and if necessary, replaced it. Maybe they decided it didn't need to be replaced, but if the RV timing had jumped than it would be because the gear was damaged or worn, I would expect. It baffles me why they didn't replace the gear while they were in there?!?!?!

Anyway, sounds like at least a partial disassemble needs to be done, it may need to have the case split to inspect for any objects still in there, such as broken gear teeth or a screw. pieces of gear in there will need to be removed and the lower RV shaft bearing replaced or inspected.

Why was the engine squealing, something stuck in rotary valve? This seems to be what happened.

If not just normal wear then the root cause for what caused the timing to jump needs to be examined, a screw or something may have fallen into the crankcase?

 

[VaDeerHunter]

I accidently ran it dry because I failed to bleed the oil pump. At first I thought it was lost screw but all were accounted for. So my guess is the plate got stuck and that probably trashed the brass gear enough to have it turn but not in time. So I assume when they reset the timing all they did was change the set of the valve plate versus the shaft after rotating the crank to the proper position. In the end though, its screwed one way or the other. So here are my questions: Can I pull the intake off with out taking the engine out? Can I suck out or get the pieces out from that point? I know you can change the shaft and upper bearing without pulling the engine out as an assembly. How much is involved with pulling the engine out and splitting the block? Would be easier to work on and reassemble if its pulled?

I assume until I get the old shaft pulled I really do not know what I need to do. Too bad they don't use a woodruff key at the Valve plate rather than sacrificing the internal gear. This so badly reminds me of my first oil pump failure on an Oil Injected Merc outboard. Appreciate everyone's help.

Pat

 

[Sportster-2001-951C-Stock]

I accidently ran it dry because I failed to bleed the oil pump.

I assume until I get the old shaft pulled I really do not know what I need to do.

This so badly reminds me of my first oil pump failure on an Oil Injected Merc outboard. Appreciate everyone's help.

Pat

I'm surprised the RV gears ran dry considering the tubing should be set up such that air bubbles naturally float to tank return? Maybe you were pre-mixing, not using oil injection pump, and the oil tank went dry. But it doesn't sound that way.

I guess you won't know what action to take till the gear inspection. Squeaking could've been dry RV shaft bearings, the lower RV shaft bearing access is only by splitting the crank case.

Merc vs Rotax: The difference in this case of failure is the Merc outboard(aka in some circles as Welfare Motor) kept running after the gear sheared and cylinder damage occurred, Rotax motor will stop immediately when the driven gear fails with no cylinder damage? No 2 stroke on earth is capable of running without lubricant though, don't try it. Also, a plugged carburetor on a 2 stroke also means lack of lube as well, b/c the lube is carried throughout the crank case and into the cylinders by the fuel.

 

[VaDeerHunter]

Thanks for the advice, I spoke with the mech and he didn't pull the shaft so no visual inspection. He commented that everything turned with no slippage and then reset the timing by moving the plate I guess. So sometime over the next couple weeks when I am not on the road I will pull the carbs off (at least I know they are good and rebuilt) pull the rotary valve cover off and get a puller and get the shaft assembly out. I am hoping it is just worn down and no teeth are missing. I am a bit hesitant about pulling the engine out and taking it apart completely. I assume that if I go that far I should replace all the seals, bearings, rings and clean the RAVE valves before putting it back in. The guy did say it ran great for the 5-8 minutes he had it running. Seems it idled fine, then revved once with no problem, second time the timing slipped and it stopped. Is a rebuilt long block a better idea? Any comments appreciated! By chance is there a step by step for this on the site?

 

[VaDeerHunter]

Okay after 8 out of 9 weeks on travel I finally got the engine out, and the rotary shaft pulled. It is damaged. the teeth are worn but the real problem is there are 4 teeth that appear to be broken on the carb side. The spring is good and the bearing seems okay but I am no expert, when I compare the old and the new they are both straight and the only thing that is slightly different is there is some play, very little in the old units bearing. Other than that the teeth being chipped is the only thing. The crank gear looks good and the crank shaft turns freely with no binding at all and zero play. So I must assume there are some pieces of the old gear in the crank case. I assume there is no way to clean them out other than splitting the block.

That brings me to that process. Is it possible to split it without removing the fly wheel etc? Also I am considering changing it to premix to avoid this happening again. Is there a sticky for that?

Help appreciated!

Pat

 

[El Toro 33809]

You will need to pull the flywheel to split the cases. When you inspect the crank, be sure that the gear that engages with the RV gear has not moved from the center of the two crank halves.

I am not sure how removing the oil injection would prevent something like this from happening again. If it was a bolt that well in the carb, be sure that the bolts that are under the spark arrestor are the proper length. If they come loose they should hit the arrestor before they could fall in the carb.

 

[AdamXP800]

Is this the same as the other thread?

 

[VaDeerHunter]

Yeah I posted in on the other one since I had started a new one.