Rally 210 - which exhaust?

Hey everyone.

Ive built a tuned late Rally 200 with a 210 Malossi kit, 3 ported crankcase, 26/26 carb & lightnened flywheel. Timing put back to 125 mark. It currently runs with a SITO exhaust but I want to upgrade.

Im looking for probably the ‚EVO‘ style so the black disapates the heat from the ehaust manifold. Does anyone have any experience of SIP pipes or RZ? I also want to keep the spare wheel and will not drill my frame to move the stand.

Scorpion is also an option though I have heard of some bad stories??

Any ideas ladies & Gentleman??

Looking at the list again it appears the way froward is to buy a stainless exhaust & spray with heat resistive clear laquer - has a emissivity value of 0.9 - way to go!!

Original von jimmer: Yep though cooling the exhaust gases as quickly as possible must help it can't make much of a difference.

I am sorry I don’t understand it.
The thing I said about gas temperature is related to time advance.
In few words: The less advanced time the more the developped heat created from combustion will be transfered to the gases, the cylinder + head will run cooler, the gas beeing higher in temperature will travell faster and will profit better of the expansion effect.

The less advance time as possible without loosing performance will give you the best performance.

hello jimmer,

ok, I have sent some picture of this mod.
Remember to put a washer and a circlip under each nut that hold the alu cylinder and use loctite on the nut. If not clear yet ask again.
To see them go on my: http://vesparacingteam.blogspot.com

Top advice thanks Curacure.

Yes if you dont mind a pic of the mounting system would be much appreciated- May I ask your email & I’ll send you mine.

In your opinion do coated mild steel exhausts last longer than stainless due to the brittleness ie cracking?

If there is not much in it I may buy the stainless exhaust & to be on the safe side spray the manifold part with heat proof black exhaust paint top dissapate the heat from the immediate exhaust gases.

Does anyone also know where you can get a Vespa Dynoed in the Surrey area. I would like my timing & jetting checked to give best results. It may be cheaper just to buy a strobe. The jetting is not so much of a problem. Is there a protocol for setting up the timing with a 210 Malossi? The bike does have a tendancy to ‚kick back‘ on the kickstart quite a bit. Ive gone through 3 kickstarts in the last year! The timing is currently set on the ‚125‘ mark.

Glad you enjoyed the beer Curacure!

Hey Curare

I was talking about the exit gases in the exhaust manifold after combustion ie the exhaust ambient temperature not the timing.

Obviously timing & barrel cooling effect running temperature & is fundermental to the efficency but a red hot exhaust is not good form & heat transfer back to the barrel can only be detremental.

Think we were on cross wires old chap!

hello,

it is a PX. The exhaust doesn’t interf. with either stand or spare wheel.
If when you get it something it is not clear you could always write again!
Just don’t be afraid with the standard muffler support. It looks ok but he won’t last, sometimes not even for a first time.
I forgot…

you need to change the screw that connect the rear shock absorb. with the enginecase. It is needed a longer one since the RZ muffler support. It easy to find. Of course with coupple of washer and circlips.

Thanks Curacure again.

Always better to have the better looking girl for a shorter period agreed!

With regards to the spraying black manifold… Ive just been chatting to our satellite thermal anaylisis engineers. They confirm that just spraying the manifold would make a large difference & probably double the heat dissipation of the whole exhaust. The polished/rolled st.st emisivity value is around 0.11. The value for a black paint/ coating is around 0.88 (See attached). Therefore if the black is around 12% of the total surface area (ie the manifold) it will give you as much emissivity as the rest of the exhaust. Considering the temp drop along the exhaust is constant the most important and the area where most heat is disappated is the manifold therfore the total heat loss/emissivity in this area will be probably far exceed the rest of the unit.

Sorry to be boring!

The link for anyone as sad as me:-

http://www.electro-optical.com/bb_rad/emissivity/matlemisivty.htm

Curacure do you know what the tining for a Malossi should be? If I buy a strobe is there a mark on a HP4 flywheel/crankcase to set TDC?

Cyber jug of ale on its way!

Yep though cooling the exhaust gases as quickly as possible must help it can’t make much of a difference.

Totally agree - I didnt know before seeing that list that the laquer would help in heat dissapation - Always thought it was to act as a protective finish - well you live and learn heh!

Cool - thankyou Curare - Im off out to buy a strobe

Thanks very much Curacure.

Looks like I will go for the RZ/SIP RH. I can still keep my spare wheel & keep the Rally’s original looks somewhat too. ( I hope the muffler fits under a rally panel!).

In the SIP scootershop here there is a note specifying that the muffler may ‚rip‘ on the RH version. In which case do you think its better to go for stainless? (I know it depends on matl. grade & properties). The bike isnt used that often & only 1 or 2 runs a year.

Do you think its a must to go for heat radiating black? In hindsight the St.St would look better on a classic bike.

Thaks again in advance - I would buy you a cyber beer if I could!

…you can click on the picture to make them larger and then if you wait you can enlarge them more when the multi arrows appear… you know how it works.

Brilliant thankyou Curare,

I think I get the general idea - I’m sure it will become clear when I get the exhaust.

Is that a Rally or a PX in your phots? I presume the RH Exhaust does not inpeed on the stand or the spare wheel?

Thanks again

hello,

thanks for the beer!

The RZ right hand is a very good choice. Buy the version that you prefer. A really heating issue is with cromed exhausts. Stainless is ok. It is just more fragile since more rigid.

The problem, about the muffler is its rubber mount.
It won’t last, sometimes you can even fit once properly. But you can do easy mod that would cost few euros.

You can replace the mounting muffler with:

take a cilinder alu of about 2cm diam. cut of the equivalent rubber mount size.
Take two washer of correct size, a stud of correct leght in which at both ends you can screw a bolt.
Change the rubber mount with this and : finished problems.
I hope it is clear. In case ask and maybe I could take if possible a picture.

hello,

mild steel exhausts last longer than stainless steel version, not in my opinion, but by matter of fact.
But stainless look good. It is more like it is better to have a better looking girl for shorter time than …

Spray black the manifold = nothing. The area it is too small for the black paint to improve heat dissipation. But if it makes you feel better…

Timing it is better set by strobo. After you set with strobo you fine tune by feeling. Secret is setting as less advance as possible without compromising the performance. With lower advance (as possible with no performance loss) the gasses will be higher in temperature so they carry away the heat and dissipate temperature, and also higher temperature will make them go faster and the effect of the expansion will be more evident.

My e-mail is visible on my profile, but since I have to make this simple mod for somebody I will post either this evening or tomorrow (it depend when he leave me its scooter ) a photo at my:
http://vesparacingteam.blogspot.com

hello,

thank you for the additional info, I already knew something like that, the thing is that I have tried few times with the paint manifold and with no black paint and… if it is cooler this level of being cooler doesn’t help an engine that overheats. It is not liquid cooling. I think it is more a numbers battle.
At the end I am pragmatic. If it works by number and I can feel the changes in reality OK, if I can’t feel the differences I don’t care or I could advice it just for peace of mind.

The HP4 has a mark in one of its fins for the cases allin.

stainless exhaust sprayed with heat clear laquer: yes it is what I always do. I should have said it at the beggin! The thing is that already most of the people that by stainless paint it with clear heat laquer just for protection.

hello,

you can hear bad stories about almost anything, but this bad stories generally come from a bad marriage of components, exhaust , cylinder kit, gear.
The Scorpion exhaust is a very good exhaust and the RZ and SIP are very good exhausts too.
The bad stories heard about the scorpion comes from its power range response. The Malossi 210 kit it is at the base not that strong at low, mid-low and mid, then from mid high grows fast.
Scorpion it is the same thing. If you have a Malossi with 26 then you won’t have the same high rpm power then a modified reed and 30 carb. So when with a Scorpion you will hit its peak this peak will be lower and when you go from 3 to 4 you will find your engine in a rpm zone that the engine will find difficult to climb.
With a Malossi 210 reed and 30 in dyno test I generally find in the range from 5000 to 6500 a difference of more or less 2 hp in favour of SIP and RZ in comparison with scorpion. What scorpion looses in this range it gains after 6500.

The differences from RZ and SIP are in few words:

RZ right hand more low mid to mid-high, less high then SIP,
RZ 2000 left hand very similar to SIP just slitly better poower curve.

The SIP performance is avalable only in stainless version.
The RZ also in black.

This means that with your engine set up I will forget the Scorpion even though excellent for other kind of engine.

Hope this would help.

Top man - thanks- I’ll size up the bolt & order a longer one.