Thread: Troubleshooting Gas valves
10-09-2007, 06:42 AM #1
Troubleshooting Gas valves
I recently installed a set of gas valves. Before installation I looked over all the bellows etc.. everything was nice and soft/no cracks tears (black bellows).
I do have one where there are traces of oil in the housing and I saw the many threads on leak fixes (braided wire) so I will fix that.
The same one that was leaking doesnt pop down like the rest when I give it a little gas it seems to get stuck in the open position (looking with black caps removed).
Is this what happens when it leaks ?
Could a leak like this cause a 100-125 RPM loss ? (checking RPMS with all caps off)
Should I switch over to the Green Bellows ? I already have the "red" springs.
10-09-2007, 10:28 AM #2
Does the valve move freely by hand no binding? also check that the piston caps are tight on the stem of the valve. I use a little blue loctite when I install them. if you used the spring that comes with them on the upper part of the bellows it might be rubbing the insied of the adapter plate there is not much clearance those. if the leak is the bellow do upgrade to the green ones I got some from Parker Yamaha for $15 ea. The only thing that would affect RPM is if the valve is not opening all the way.
10-09-2007, 10:43 AM #3
I double checked the bellow and the movement it isnt binding at all....
All three should open and close at the same time right ? There is no question the one I am having a problem with doesnt go back down when I let off of the throttle.
10-09-2007, 11:07 AM #4
10-09-2007, 12:36 PM #5
Lately I havent been cranking the top caps all the way tight. I usually tighten it then back off 1/8-1/4 turn. Seems they are prone to bind if tightened all the way.
Loosten the top cap a little and see.
10-09-2007, 12:47 PM #6
When the valve screw cap is at its lowest setting the spring is callapsed to600 thousandths,with the screw all the way up its at .850 or so depending on what you consider safe thread engagement. Coil bind occurs at .300. Cutting .050 or so off the front cap to make room for the pipe is not going to have much effect on the reaction of the valves and has nothing to do with letting it open all the way. For example, you can screw #3 adjuster all the way down and it will still open fully but at a slightly different time. When the other valves open the exaust pressure goes high instantly sending the valve with more spring pressure to its limit. I seriously doubt you could even feel it. If all three were set all the way down it would be more noticable but still would open all the way not effecting top rpms. At least this is the case with the Riva valves on my boat.
A large leak could prevent the valve from opening all the way. A small one no. There is a good deal amount of exhaust pressure that builds in the bellows. I use the green bellows and the OEM Seadoo spings on the top and bottom and haven't had a leak in 30+ hours of hard run time. The safety wire is OK but have seen it cut the bellows or cause a pinch at the twist letting some pressure out.
Just my .02
Last edited by Duke; 10-09-2007 at 12:51 PM.
10-09-2007, 12:51 PM #7
10-09-2007, 01:19 PM #8
You guys are AWESOME !!!!
Since the bellow that was leaking was the one that was not closing (dropping back down) and there was a substansial amount of oil inside I am going to go ahead and swap them all over to the Green bellows and try to use new SeaDoo clamp springs to get them to seal.
If I were to use wire I may try and cut some zip ties to wrap around the bellow and then get it tight with the wire ? It could stop it from cutting through.
10-09-2007, 01:34 PM #9
I also use the green O-ring on the valve stem too. The black ones fail due to heat and allow to much gas in the bellows.
10-09-2007, 02:04 PM #10
I use the thin zip ties to secure the bellows on my caps. Have had the same zip ties on there for 2 years and never had any leaks or issues. They're hard to find, though, because of the size. I believe they are 12" or 14" long and 2mm wide. Fercho got 'em for me.
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
By GP1500SC in forum Yamaha PWC Performance (2-stroke)Replies: 7Last Post: 11-01-2007, 05:32 PM
By John in forum Yamaha How To & FAQsReplies: 18Last Post: 05-04-2006, 04:48 PM
By IrishGpr05 in forum Yamaha PWC Performance (2-stroke)Replies: 5Last Post: 04-02-2006, 09:21 PM
By shooter98xpl in forum Yamaha PWC Performance (2-stroke)Replies: 1Last Post: 02-26-2006, 10:30 PM
By ramnj in forum Yamaha How To & FAQsReplies: 0Last Post: 12-28-2005, 09:11 PM