F80 trlx timing belt help

[Gurkenrat]

I have determined I should change the belt on my 99 f80. Original owner has no recall of changing it so for piece of mind, I am going to have it done. I am considering doing it myself as it will be weeks before dealer can do it. Most of it looks straight forward. My service manual is not big on details. I was wondering if anyone has a picture or a specific puller i would need to pull the big flywheel? And the manual is not great with timing marks. Anyone have any pics or better manual pages?

I work on bikes a lot but this is first time on outboard. I just need a bit of clarification before I decide if I am going to wait or do it myself.

[Gurkenrat]

I have watched videos and read the service manual several times. One thing i cant see is how to tell if tension in belt is properly set. It basically says keep side opposite tensioner tight then install tensioner and adjust it till tight. What does that mean? How much slack/tension should there be?

and is piston #1 at TDC when the pickup sprocket mark is aligned with crankcase mark? Thats it? Just line it up and thats TDC?

[panasonic]

From your previous post ....changing that belt is a no brainer on 20 year old engine. I would recommend getting the proper YAMAHA manual to do it, it is not hard to do. Just make sure nothing moves when the belt is off. Wind it over by hand a few times after the replacement to insure timing Mark's line back up and nothing is out of wack.

[panasonic]

This should be very similar to yours...

https://youtu.be/i8NtHwAxaqU

[Gurkenrat]

Ive watched that several times. Similar but he also doesnt explain what proper belt tension is. F80 is funny. You lock down the tension pulley and THEN add a spring to it. If locked down, whats the spring doing?

[99yam40]

seems like you need to watch it again.
I just watched and there was no mention to add a spring

[panasonic]

You are getting that backwards...the spring puts the tension on the belt, then you lock the tensioner bolt so it cant move.

To take up the slack in the belt sometime in the future after belt starts to stretch you loosen tensioner bolt and the spring pulls the slack out of the belt and tighten the tensioner bolt again. Its not an automatic belt tensioner like you will find on a car or motorcycle engine.

I don't have the proper manual for your particular engine. I am looking at a 2004 F80 manual that is fuel injected.

Maybe you could post a picture of the page from your manual for all to see.

[panasonic]

seems like you need to watch it again.
I just watched and there was no mention to add a spring

Yam.. that's not his particular engine in the video I just posted it for general reference in changing a timing belt on a four stroke outboard. His has twin cams. I will look and see if i can find a more appropriate video.

[Gurkenrat]

Yeah. That video doesnt have the spring. There is a step by step instruction on “the hull truth” where buddy replaces belt on a 115. He tightens the tensioner then adds the spring. Thats the part that confused me

[Gurkenrat]

[Gurkenrat]

[panasonic]

Sometimes the manual is confusing. Here read this post the Rodbolt replied to on another forum about the spring and tensioner on yamaha engines.
https://forums.iboats.com/threads/ti...estion.238779/

[panasonic]

Also after reading your other post about vibration I would replace that tensioner as well. You know what you have then.

[Gurkenrat]

So if we trust Rodbolt’s info, I apply slight tension in a clockwise direction to ensure 1. Timing marks are lined up 2. slack is gone on port side of belt (non tensioner side). Then loosen the tensioner and allow the spring to set the correct belt tension and then tighten tensioner bolt to spec. Replace flywheel then hand turn the engine through twice and check timing marks. Run motor and inspect every 200 hours or annually (whichever comes first)?

When u say replace tensioner, u mean the spring or the tensioner itself?

So that means the fellow on thehulltruth did everything correct except he set belt tension himself then put the spring on after he tightened down the tensioner? It would be nice if there was a deflection spec in the manual so a person could tell if tension was correct. Most timing belts on bikes have a min-max deflection.

[panasonic]

You can absolutely trust Rodbolts instructions...people come here looking for him and his advice all the time...he is a master tech.

As far as I am concerned the guy on the hull truth followed the manual. He basically set the belt tension by hand...which is probably fine. The spring didn't do anything.

I have only done a couple of these belts on outboards..but many on cars. The belts are stiff when new and it seems to me that you have to help the spring out when you first install them by pushing on the tensioner to get them snug. After they have been run for awhile the spring is able to the job by itself when adjusting belt tension.

That's my take away from it. Manual does not always tell all.