Cam tension guide question

[Gibson]

Hey folks, I know there are some threads already on this topic, but I have a couple of questions maybe someone may be able to answer. I had a small amount of black plastic and aluminum particles in the side filter. (nothing like some of the photos in the threads) I was wondering at what point should the cam chain guide be serviced? Also If I do a tear down and replace this part, how many miles do they last? I gather it is not a bad design, but just an age thing.

 

[XSLeo]

Were the black bits you found very hard as in plastic or not so hard like hard rubber?
If very hard they came from the front cam chain guide, if softer it came from the rubber cushion ring on the starter gears. As the starter works it draws together the gears to engage the crank. Where these gears come together they put a hard rubber ring on one gear, this stops the gears from hitting steel to steel. Quiets them and prevents damage.
Most don't replace the front guide unless they are in there for something else or things get very noisy and there is a lot of aluminum debris in the oil. After the plastic part fails by either breaking up or falling off, the chain can run against the aluminum part of the guide. This makes a lot of noise as the chain grinds into the aluminum. The aluminum that gets ground off gets trapped by the filters.
If your engine is fairly quiet and you aren't getting any aluminum in the filters and oil then your ok for now. Just keep close track of the oil and filters, Once it gets noisy and aluminum starts showing up it's time for a replacement.
If you pull down the engine for something else like rings or valves, then replace the front guide.
The stock ones lasted 30-40 years so I doubt you will need to do it again.
Leo

 

[Gibson]

Thanks Leo. They looked like very tiny bits of hard plastic. The metal was tiny bits of aluminum. There was not a lot, but anything in the side filter got there by going through that poor old oil pump. I don't use the electric start. The first time I tried it I discovered it does nothing but grind horribly, so I kick start it only.

 

[XSLeo]

The fix for the grinding is easy. There is a wish bone shaped spring on the gears. It gets weak over the years. Next oil change pull the right side engine cover, pull off clutch, pull the starter gears, remove the spring, squeeze in a vice, replace, put the gears back in. You can test if they work without replacing the clutch or side cover. Just don't let it run long without oil. Doing the cranking test without oil won't hurt anything.
The spring holds the gears from turning so it slides into engagement with the crank.
It should take at least 5 lbs. to turn the spring on the gear. Most any hand scale will work. I use the fish weighing scale I have. If you don't have a scale you can use a gallon jug. Tie a string to the loop on the spring, tie other end to jug. Fill jug with 5 lbs. of water. Easy to do, one pint of water weighs one pound. Thus the old saying a pints a pound the world around.
So 5 pints of water in the jug. Now try to lift the jug of water by holding the gear with the spring loop out to the side. If you can lift the jug with out the spring slipping it's strong enough, If not squeeze the spring more.
I'll post a pic of the spring that shows where to squeeze.
There are threads about this, search starter fix.
Leo

 

[Gibson]

Thanks again. I saw that thread. These machines are so needy! Its a good thing I like working on bikes or I'd hate this thing. Can you start these bikes in gear with the clutch pulled?

 

[5twins]

With the electric starter, yes, kicker, no. The kicker works through the clutch so if you pull it in, you lose the connection between kicker and crank.

I think the grinding starter generates lots of the junk you find in the filters. I also think this is a rather crude motor and produces lots of particulates during it's break-in process. The crude oil filtration set-up makes frequent oil changes and filter cleanings a must. Most of these bikes didn't get that in the past. I think a lot of what we find now is just an accumulation of junk from the bike's neglected past. It took me probably 6 to 8 oil changes and filter cleaning before my filters started coming out relatively clean.

It's pretty much a given that you will need a new front cam chain guide. I think it's the age of the part. I've never found one worn through, most have the rubber strip coming loose and partially unglued, or fallen right off. Best to replace the cam chain as well while in there.

 

[gggGary]

Normally if you have a non-breached sump screen you will see little if any debris in the side screen. Just sayin' or a hint.

 

[Gibson]

That is a nice looking scoot! Great work!
I agree, there should not be much if anything in there if lower screen is good. I replaced both a few months ago, and was very careful to do it right. Perhaps it is residual junk that was in the galley ways (hope). There really isn't a very good seal between that crude sump filter and the plate. I am looking into the spin on filter mods. Why not filter oil correctly before the pump? That kinda makes sense to me. I guess Yamaha engineers decided they can solve all problems by fitting 1 lb drain plugs everywhere with giant magnets.
Maybe some day my lump of iron can look good too...If I could just solve the multitude of issues first.

 

[5twins]

One step at a time, but it usually does take a couple seasons to fully sort through one of these. You can usually "ride and wrench" your way through it though. Fix this, improve that, eventually it gets done, then you need another, lol.

 

[Gibson]

Yea, good thing its not my only bike. I really wanted to take a road trip this spring on the XS though. I want to make sure I don't get stranded somewhere 250 miles from home.