Oil leak problem.
 

I wonder if anyone else have problems with the sealent of the valve cover, i have done the sealent now 3 times and its a small leak on the right side in the front. Its hard to tell exactly where it comes from due to the small amount and it only comes when riding. I have taken the head off the last 2 times and cleaned it well before applying the Loctite, maybe making a normal paper gasket is the only way getting it sealed?

Can you post a good picture???
Be careful where you use a paper gasket as usually in heads where isn’t one is for a reason.

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Seems like its somewhere here in the front right side.

Stick some masking tape over/along the head joint - the "paper based " type used for decorating etc. Clean the surfaces thoroughly first so that the tape sticks well and it is not stained by existing oil.
Then take the bike for a ride and see where the tape is stained by new leakage; this should give you a good clue about where the leak originates.

Using any gasket at all under the rockerbox will alter the clearance for the cam shaft bearings. I would NOT do that under any circumstances. Perhaps some high temp silicon, let it cure before starting.

Yamabond 4, I believe. It could be 7 though. One of them is low viscosity so it won't build up. There must be one little low spot in one of the surfaces that need a good liquid gasket to fill and seal.

I use Yamabond #4 as well. Just sealed a rocker box but waiting on CDI to start bike.

I will be getting the first production unit that is fully programmable, shipping next week. I'll report on it after running it a bit.

The antikickback feature will be a good addition. Kicking minimum RPM is adjustable and if rpm is slower than programmed value, no spark, no kickback.

More later

I was checking the data sheet for the product and it says 3. The bond should be allowed to cure (e.g. seven days),
before subjecting to heavy service loads.

Is that normal? Nothing about this on the package, it ony says 15min for parts to come togheter.

Talked to Loctite and they recomended Loctite 5188 or 574 instead of the silicon, how much clearence do you think its between the cover and head around?

7days was if you have a thick line.

Wurth super RTV is also used, Yamaha dealer didnt have the Yamabond 4.

Iam going to do some reaserch to find out exactly where its coming from, the suggestion with maskin tape was good and ill try it next trip. Thanks.

Since this is a machined surface, the sealer will only be filling the very small voids, the rest is squeezed out. It is engineered for this so the cam bearing clearances will be fine.

I've noticed on eBay that the head and rocker box is sometimes sold separately, which is a mistake. There are markings on both that is some type of matchings system. I just don't know what it it. I have see this type of marking on primary drive gear and clutch driven gear. The total of the numbers etched in must fall within a certain range to be a match. Most likely the same way here or they MUST be a matched pair. I seen case halfs that have numbers on the top and bottom half on horizontally split cases that must match to be sure it seals.

Yes, I would think you'd want to let dry once assembled. The assembly time is just that, let it get tacky before assembling. Yamabond #4 is like that. My rocker box will have been sitting a month before I get to start it....

Steve

Ya it stinks to put it all together and then sit, and wait. But to get best seal and not have those annoying oil spots that collect dust, a few days isn't so bad. If I did some motor work, I'll assemble and start to make sure all is well then shutdown and take the covers back off, cleanup, then do the sealing and wait a few days to ride.

Toyoto dealerships have a really nice sealant, don't know the name right now but it comes highly recommended.

Ye maybe thats the problem, i waited for 3 hours before riding. But then again why would i get the oil out on the same side every time and its not like a big pressure and oil flowing all over the inside wall. As you all know its not a very fun job doing time after time stripping all down to get the cover off..

Have been out riding and not much to see under the tape, iam starting to think the problem comes from the O ring part 16 on this Yamaha Xt600ea (non-cal./cal) 1990 Valve - schematic partsfiche

I was looking at this last time i had the cover off, but couldnt remove the shaft, i removed the bolt 17 but the shaft just turned around. Is this a shaft you have to tap out?

My Honda XL has shafts similar to that and one really leaked.The shaft should just slip out , maybe the o-ring has a slight groove it rides in or the rocker has worn a burr on it. Did you pry on it rom the inside?

No i was i bit careful last time, i will try to seal it from outside just to make shure its the correct place the oil is coming from. I cant see any good reason why they made this open in the end, the other side is not open and they are not connected.

The leak came from the rocker shaft O-ring seal..Tried to do a seal from outside but ot wont last so then i have to take the cover off again..