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Keeping the Doo doing (hehe, clever, right?)

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jisgett

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OK, so I have been furiously reading as many posts as I possibly can, all with the intent of keeping my precious new yellow and black baby running and purring and having a ball.

My question is for DR HONDA! or anyone else, of course, but in response to a post he made regarding exhaust valves.

Question is this: Other than checking valve clearances every 20 hours or so, do you have any other suggestions that can help prevent severe engine/pwc damages that can result in keltonks-like angst and hefty repair bills?

I have read posts re: possibly weak timing chain bolts, etc. I am never happier than when I am elbows deep in grease and figuring something out, so maybe we can turn this into a crazy-person's (like me) preventative maintenance/inspection thread.

Pitch in if you want, folks, I have read from some seriously experienced riders/maintainers.

Thanks!

Jeff
 
I'm afraid you might have been a little mislead. What we were talking about were RAVE valves. This is a system developed by ROTAX in about 1995 for their two stroke engines. This system was developed to get extra HP by varying the exhaust port timing. It really doesn't apply to 4-tek engines.

One of the problems with this system, the problem was new to me, is when you rebuild an engine and if the RAVE valve is not shaved (shaped to the new piston size), it can catch a piston ring and lock the engine.

Here's a link explaining the care and maintenance of RAVE valves.

http://saldman.tripod.com/Rave_valve/Rave.html

Lou
 
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Ahh, ok. I apologize if I'm spamming a bit then. I was reading up on one of the forums posts regarding how long should/could a four stroke motor last, and I was reading this from Dr. Honda:

[In the new world of 4-strokes… the dirt bike industry has gone though the same changes. The new 4-stroke MX bikes (not the old, low RPM air cooled engine) we have all the same problems. The number one thing to do is to check your valve clearance. I have said this many times on this board… but I kind of get brushed off. To make a 4-stroke rev… you have to loose weight in the reciprocating parts. One place is in the valve stems. On our Rotax engines, they are about 5 mm. (that’s thin) and to get them to open and close fast… the springs have to be strong. Eventually, the stem will start to stretch. If you are lucky… you will experience hard starting when this happens. But, unfortunately, with fuel injection, and a good starter, this may never happen. (when you kick start a bike, it’s easy to feel) OK… so, once you have a stem stretch… the next thing that will happen is the valve head will pop off. This happens when the engine is spinning at very high RPM’s, and one of the jugs will eat itself, resulting in a $3k to $5k engine replacement.

If you check your valve clearance every 20 hours or so… you will intercept this problem. When the clearance starts to close up… pop the head off, and replace the valve. That will cost you a head gasket, and a set of valves… and the engine will continue to run for a long time.]

I'm a bit confused, so any comments are welcome at this point.

-Jeff
 
Seadoolou is wrong in telling you that you have read the wrong thread you are correct the 4 tec 4 stroke engines have had been know to brake exhaust valves after a number of hours a far as checking them every 20hrs I wouldn't do it my ski is brand new with 22hrs I'm not goin to pull the valve cover and check valves that's just crazy maybe every beginning of the season I will just my opinion tho
 
Kozerxp said:
Seadoolou is wrong in telling you that you have read the wrong thread you are correct the 4 tec 4 stroke engines have had been know to brake exhaust valves after a number of hours a far as checking them every 20hrs I wouldn't do it my ski is brand new with 22hrs I'm not goin to pull the valve cover and check valves that's just crazy maybe every beginning of the season I will just my opinion tho
Click to expand...

I'm not sure what thread you are referring to, we had a recent, in fact it's still going about problems with RAVE valves. Perhaps you should be more specific in the thread you are referring. Dr Honda and I are both 2 stroke guys, and I assumed these were the threads he was referring to.

http://www.seadooforum.com/showthre...-Valve-need-advice-help-PLZ!!-yet-another-one

http://www.seadooforum.com/showthread.php?46116-99-spx-won-t-start-turn-over

If I am wrong I apologize for the confusion.

Lou
 
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Hey fellas, this is just a little misunderstanding, and I understand where you both are coming from. Being a noob here, I have been reading up on a lot of different posts. There is a thread in the 4 stroke PWC forum regarding a question about how long should a 4 stroke motor last. Dr. Honda had posted a reply in that thread (it is the one I quoted in my last reply), but I apologize for not being more specific about the thread. I can certainly see where I may have generated some confusion. Either way, this forum is great thanks to folks like both of you who will take out of your own time to help fix my many levels of ignorance ;).:stupid: (<---that one is for me, btw)

Thanks again to you both,

Jeff
 
He has a 4 stroke engine (this is the 4 stoke section)so rave valves do not apply to his ski the thread he was referring to dr Honda spoke about exhaust valves in the head of a 4 stroke engine Breaking but I am also pretty sure the valve have been updated in the newer Seadoo engine from the previous ones that were prone to breaking Im not touching my engine till the 100 mark then I will do the super charger rebuild and maybe pull the head and replace the exhaust valves to ensure a long life (if I keep the ski that long) no need for to apologize I was just informing him he is correct in his thoughts
 
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coastiejoe those links to the rave valves do not apply to the skis in your profile your engines are 4 strove and dont have rave valves just reg intake and exhaust valves like your car engine does
 
Jeff, up thru 2006 the 4TEC engines had sodium filled valves which were prone to breaking... sometime in 2006 the exhaust valves were changed to stronger material (mine has the updated exhaust valves I recently checked their numbers and was pleasantly suprised!). There is a rather large long thread regarding reliability of 4TEC engines and what to look for and/or change to increase their longevity.

1st most critical item was to get the ceramic washers replaced on the Supercharged models up thru 2008 year model, as the washers were prone to breaking apart and falling down into the engine before the 100 hr SC rebuild interval. 2nd most critical item was the sodium filled exhaust valves which were prone to snapping in two... not a good thing that! Sodium filled exhaust valves were phased out in 2006 year model production run at some point (as I recall I was told exhaust valves with 72 stamped on the ends are sodium filled, while 75 is the updated non-sodium exhaust valve).

So Jeff unless you're modding the engine to build more horsepower to go faster for racing purposes, there's really not much you should be worried about. Your 2009 RXT should be good to go for hundreds of hours of good clean fun!

Regards!

- Michael
 
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jisgett said:
[If you check your valve clearance every 20 hours or so… you will intercept this problem. When the clearance starts to close up… pop the head off, and replace the valve. That will cost you a head gasket, and a set of valves… and the engine will continue to run for a long time.]

-Jeff
Click to expand...

Actually, it'll cost you a head gasket, the valves (only sold in sets of 3 I'm told), and a new set of head stretch bolts (they should NOT be re-used as they stretch a little each time they're torqued down and will break when the engine heats up, expands and stretches them again).

I just wanted to make sure this point is clear: Anytime you pull the head off you must replace the head gasket AND head stretch bolts, neither are re-usable items. I've read that you can measure the length of the stretch bolts and if they haven't been stretched out beyond a certain length you can re-use them, but it's just not worth the risk IMHO.

Regards!

p.s. Jeff why are you trying to siphon the gas out of the tank? Did you get bad fuel or something?

- Michael
 
Yep, I am trying to eliminate all possible causes for lack of performance. Suspicious of the gas just based off of some comments from the PO.
 
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