1985 Tri-Z 250 - DG exhaust gasket question

[Baba Yaga]

Bought a Tri-Z with an old DG exhaust on it. Exhaust is in decent shape, so gonna refinish it and reuse.

When it came apart, there was a broken circular gasket where the pipe meets the exhaust port.

Anybody know if the gasket should be the OEM Yamaha part, or a different DG part? Looking to buy a replacement.

Thanks!!

[El Camexican]

There are two different sizes of DG exhaust flanges. Go to the three wheeler world store and under the tri-Z listings you will find a few collars. I suggest you contact the sellers and find out which collar it is that you need for your particular exhaust pipe.

You could just use a couple of automotive exhaust gaskets that are sold on eBay, but if you were to go that route you will damage your cylinder because the snout which is made of aluminum will get beat up by your steel exhaust pipe as it vibrates. You really don’t want to do this given the value of a cylinder, so please buy the proper collar for your pipe.

[Baba Yaga]

Here are pics of the pipe, with dimensions. Hopefully somebody knows the correct exhaust flange. I looked in the 3ww shop. There were 3 options, but no dimensions, etc.

Looks like the stock setup is a two piece setup. I've never seen that; bought the bike used with the DG pipe. The gasket that came out, was a low profile circular thing. (Likely the wrong type installed by previous owner)
One for OEM, one generic one, and one for DG pipes. None of them look anything like what came out of the trike. Maybe I should contact DG, or is it too old?

[El Camexican]

Both the ones I have are 2.25 inches in diameter. I will post photos later.

[NeverLift]

261028 you can get this at any auto parts store. Use it with some hi temp sealant and give it proper time to dry.

[NeverLift]

http://www.3wheelerworld.com/showthread.php/143309-feedback-for-muthey-bamuth?highlight=brandon+muth

this is the guy to ask.

[El Camexican]

261030

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261032

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Looking at the three that are for sale on the site, I realized I have one of each

The silver one is one my trike mated to a Jemco pipe, the gold one in the photo is the black one on the site that was stripped and plated and the one with the o-ring is probably the one I would recommend, but either of the three along with the gasket Neverlift posted and a little silicone is the way to go.

[Baba Yaga]

Thanks so much for the help all!

Question- what holds the steel exhaust flange (collar) in place, just the spring tension? Does it go into the cylinder exhaust port slightly? Also, what's the purpose of that O-ring?

[El Camexican]

So the metal collars you see for sale in the 3WW store slide (with the help of a rubber mallet) over the snout of the cylinder and protect it from wearing out fur to the vibrating steel pipe. The donut gasket fits against the step in the pipe and the steel collar you’re going to buy.

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If you had an old style DG pipe like the photo above you might need 2 or 3 donuts, but it seem you have a newer pipe, so one should be fine.

Notice how much deeper the collate is on the old pipe vs the new. I should mention that contrary to popular belief both styles are 2.375” ID.

261038

One of the reasons these pipes leak so badly is that Yamaha decided that they only needed two springs rather than three. A number of people including myself have added a third spring to utilize the third hoop
DG was so kind to include.

261039

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I had a bunch of these laser cut a few months back with the intent to sell a few, but so far they are just sitting in a box. I have them in silver and gold.

Use high-quality silicone wherever you can, but with out adding the third spring don’t expect it to last very long.

[Baba Yaga]

Lots of great info. I'll use the 3'rd spring if my pipe has it. And lots of high-temp RTV to seal it.

The bike is covered in oil, so was obviously not sealed for many hours.

If this is the trike's only mod, what should jetting be (compared to stock) with a DG pipe and stock muffler? I like reliable, conservative tunes. :) Nothing on the edge! LOL

[El Camexican]

Depends. Are you in the foot hills of Alberta, on the East coast, or somewhere in between? It’s all about air density, but as a general rule of thumb at 1,000’ (90 Meters) above sea level in the summer would be to start by lowering your needle one clip ring (that is to say raise the c-clip up on the needle so the needle sits lower). If there are 5 rings you should try the second from the top of the needle. If you’re already there leave it.

Drive it and check you plug colour, if it looks ok you can go down on size on your main jet and test again.

Being that’s it’s winter i wouldn’t do anything right now other than look at the plug to make sure you’re not too lean.i

[Baba Yaga]

I'm at 600', near Toronto. Summer jetting only, pretty much.

I'm at a bit of a loss for what I have here. I went outside and degreased the cylinder exhaust snout area. No steel collar, just the cylinder with the stepped diameter exhaust snout.

So, my pipe flange appears to have been all the way to the cylinder snout step, so I don't see how I could have had the steel exhaust flange (collar) there, as in your photos, as the collars appear to take up around .820" to .860".

Could I have some older DG pipe, that installed with a skinnier steel collar, etc.? Or had they just lost the collar, and installed the pipe on the cylinder snout as best they could? The previous owner owned the trike for over 30 years, and told me he replaced the pipe early on with a DG, due to the OEM pipe cracking. That's what he says, anyway.

I will fit the pipe on the trike and see if there is a gap there or not. When I disassembled it months ago, I wasn't looking at it in detail of course.

Question- if you buy a new pipe from DG, does it come with the steel exhaust flange (collar)?



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[El Camexican]

I can’t tell much from your photo, but I do know that when I bought my Tri Z it came with a DG pipe slipped over the aluminum snout and stuffed with a bunch of silicone and it was leaking horribly.

You’ve already measured the exhaust pipe collar, so all you need to do now is measure the aluminum portion of your cylinder to see if its anywhere near to a tight slip fit which I doubt it is.

As far as a new pipe coming with a collar, no it won’t.

Remember, the whole idea of having a collar was that it prevented the cylinder from being damaged by the steel pipe. I recall reading that the originals often ended up stuck inside the stock pipes when they were removed, hence their rarity.

[christph]

My solution to this problem was to buy copper pipe from the hardware store, 2 1/4 diameter I believe, and cut it a little longer than the exhaust spigot on the cylinder by about 1/8 inch. Then, cut a slit along the pipe's length so it will compress. Insert it in the DG exhaust and slide the pipe onto the cylinder. That way you get a tight fit diameter wise, and the wear happens on the extra 1/8 inch. Works great.

[Baba Yaga]

Thanks for the info guys. When I can, I'll put the pipe in place and see what it looks like.

Christph, is that your Tecate in your avatar?

[christph]

Thanks for the info guys. When I can, I'll put the pipe in place and see what it looks like.

Christph, is that your Tecate in your avatar?

Yeah, that's my 87.

[Baba Yaga]

Nice machine, not many around.