Modern Vespa

Since even Jess is having problems with a stocker, which pipe would you have. LV? PM (if you can still get it in the states)? Prima/Scorpion?

I'm thinking I'll beat the blown gasket by just going after market again. I used to have a PM62 on the GT and loved it but I don't think I can find a PM65 for the GTS.

Check the SIP catalog, they have them. Check on line for their web site.

I would find a better gasket and see how long you can last with the stock exhaust. unless you are riding WOT for a long time you may be better off stock. when you change you exhaust you should also change air, and fuel too.

Even Jess? Is he immune?

You could go aftermarket with the culprit: the gasket. Bronze sleeve

I think the sentiment was something along the lines of "everyone has this problem". Meh. Then you'll break the header pipe.

A rock and a hard place.

Maybe we should experiment and come up with our own solution. Plenty of lateral thinking engineers on here...

I think we need one of those flexible exhaust tubes so that the header pipe can move and the exhaust can flex independently of each other.

It'd be more reasonable if the collars were GBP5 (USD 8 say) a time - every 4,000 miles (two months for some) wouldn't be so bad. They are fairly cheap here, but hugely more expensive relatively in the US apparently - just like belts. Bummer on both counts.

Plain stainless steel woven mesh works for other bikes - vastly more powerful ones - with no problems bleated about AFAICS. Perhaps we need a fine s/s tape similar to plumbers PTFE tape. Wind on, cut off, clamp down. Perhaps only good until the next exhaust removal, but cheap and easy.

It's only 4000 miles (which is too short) the first time. After that, it's every 100 miles.

Interesting idea...

Auto mufflers always hang on rubber.

I've got a plan myself to have some flexibility in the system, but outside of the exhaust system--I want to let the whole thing float on the mounts.

Next spring I think I'm going to do this:

slots on hanger instead of holes. shouldered bolts. Rubber grommets.

P.

I put my old LV on WM's 300 on Saturday. I was VERY careful not to put any tension on it as I was fitting it. Hopefully it will be fine!

These hi-temp fluoroelastomer grommets might be useful, they are good to 450 deg: http://www.mcmaster.com/#5273t14/=3qc0ji

They do, but there are some important differences there, too. Car engines are universally mounted on motor mounts such that the engine can twist under load. Car exhausts are (almost) universally mounted to the body. These two things do not move in sync, and so something has to make up the difference.

With the GTS engine, the motor and the exhaust are effectively bolted together, and move in unison. There's some heat-related distortion going on, but we're not talking anywhere near the kind of movement that you'd encounter in a car. The movement we're talking about is slow, and accumulates over time. I've been considering something along the lines of the shoulder bolts you've drawn. I'm not convinced that the rubber mounts are necessary, since that will allow the exhaust can to move while the header pipe is still fixed to the position of the engine. Actually, I think this will probably make the problem worse.

Elongated holes in the muffler tabs, though, are probably a great solution to the movement of the muffler. Periodically loosening up the bolts, letting the muffler move, and then torquing it back down again would probably take care of most of the potential stress in the system.

I hope so too!

That's why it took so long. Apart from the "wimen an' the lord" giving muted yabber-yabber instructions in the background.

heh...

Which of course, if Mr Wonder(ful) and I had listened to, would have shortened the process considerably...

So heh is indeed correct.

it's not really about the exhaust moving due to use ie bouncing about, it's more about the subtle expansion that takes place when the exhaust comes up to and cools down from (it's very high) operating temperature, making the joint any more solid than it is (such as welding the joint) will result in the metal breaking.

an interference sleeve joint held with springs would solve the problem, the same system as used on the PM68 etc.

having the same system on the stock exhaust thus dispensing with the need for a gasket would see the problem disappear i'm sure.

Everything you say makes perfect sense.
I'd like to think that you're correct in saying that the pm has a better system, but there have been at least two pm header pipes reported broken: suit scoot's pm68 and alfamoi's.

https://modernvespa.com/forum/topic27059?highlight=pipe#364072

https://modernvespa.com/forum/topic27059?highlight=pipe#364072

It doesn't seem like it's possible to prove that one has found a better system until lots of people have tried it and there are no failures.
I use the motoamore bushing with molylube and under-torque the clamp to allow some room for expansion. The problem seems to be that lack of failure doesn't really prove anything.

My system works for me (at least so far), Turkman's welded pipe works for him, and so on. I'd sure like to know what system is foolproof, though.

cheers

whatever happened to the prima pipe ???(i'm still sure it was just a re-badged scorpion, or at the very least a scorpion copy) are they still about?? any problems with them? folk were RAVING about how good they were going to be....

Prima ?

Enough failures reported here to make it seem like a poor choice. The problem is that the people who haven't had a failure consider them a bargain.

cheers

A two-piece design based on the PM but with the can acting as a shroud to hide a looped-back length of tubing, to quiet the exhaust note, would make a mint. The market is so ready for a pimp-ass pipe.

I'm still happy with my LV pipe after almost 2 or so years.

Questions from a newbie. What is wrong with the original exhaust pipe on a gs 250ie? I notice that there are several discussions about changing them out. Is this just the need for speed going on or is there a true advantage to making a change. My scooter only has about 1800 miles but seems to be just as fast as I need at this point. Goes the speed limit with every one else.

There is nothing inherently wrong with the OEM pipe, however, it does have a propensity to rust rather quickly, however, regular washings can help prevent that along with a fresh coat of paint.

The problems with the pipe are related to Vespa's design of the pipe and how it connects to your bike. There is a collar (we often call it the exhaust gasket) that if not installed properly can fail and allow hot exhaust gases to leak. Vespa views this piece and one time use only and intends that a new one be installed each time the exhaust is removed which is every time the rear wheel needs to be removed. If the gasket isn't replaced carefully or a new one not installed properly, you can have failure of this piece.

The stock exhaust isn't bad, depending on what you're after. It's very quiet, which some people (even myself) actually like. It is very heavy, though -- very heavy -- and the joint that Benny mentioned has a tendency to break.

If it didn't break so often, I would be perfectly content to continue using it.

Thanks for the info. I think I will wait until something breaks fbe4ofre I fix it

Well, I just ordered a PM68 from PMtuning in the UK. Hope I made the right choice. I sure liked my old one. The LV pipe looks great but I just love the way the PM pipe looks.

Does anybody have any long time experience with the Giannelli exhaust. I got the impression from the GTS Owners Club Forum that they think it is the solution to the leaky exhaust. I understand that it connects directly to the manifold, not to the little piece of pipe that hangs out from the manifold. This makes the initial installation a little tougher but if it holds up as expected should solve the clamping problem as it eliminates it.

Or am I missing something?

mgg

Doug, I love how the PM pipe looks too. When I was in the market for a new pipe the PM wasn't available with the noise reducer and I found it was too loud. Thus I chose the LV partly because of the volume of sound.

The Gianelli is a two piece exhaust also, but doesn't have a graphite gasket. the header pipe runs back from the manifold to just past the water pump, and the muffler slides over it and it has a clamp to fasten the two together.

I have only had it on for 1500 miles, so no long term results yet.

Thanks Benny. I hope I actually get it. I ordered it on the PMtuning website in the UK and paid with a credit card but I've never ordered anything like this from over seas before so I'm not really sure how it works. We'll see.

you can buy DB killer for most exhust on the after market

PM does come with a db killer fitted as standard now.

However, it makes near as no difference. PM is friendly neighbour destroying loud, with or without it.

i've ordered from pm on several occasions and have never had any complaints about the service. if your order is held up it'll more likely be HM Customs and Excise making the fuss.

the PM pipe is crazy loud.

Scorpion is working on one for the 300 here in the U.K.

http://www.gtsownersclub.co.uk/forum/viewtopic.php?f=14&t=1737

Sweet. Thanks for the input. I remember my old GT PM62 not really being all that loud. I kind of hope it is loud though....I like loud 8) .

I didin't know that at the time, otherwise I would probably have gone the route of the PM pipe.

It looks as though the Scorpion muffler is mounted using cushioned straps. This could allow the exhaust system to move slightly forward and back as it gets hotter and cooler, thereby eliminating the broken exhaust studs. Does anyone have experience with this type of exhaust? Perhaps there is a way to modify other exhaust systems using this type of mount.

Just a thought,
Bob