Exhaust and other parts.


New Member

I bought a used Ace 125 almost half a year ago, and it's a blast to ride!

However, the former owner changed some stuff that I want to undo. 2 problems: I know nothing about engines or electronics (well, a bit about that) or mechanics, and the Skyteam dealers in the area don't seem to picky to work in my bike. So I'm considering to do it myself, but I'll need some help...

First off, the exhaust... The bike is FAR too loud! The sound itself is awesome, but the volume is not safe for me and irresponsible towards my neighbourhood.

Now, the bike has this exhaust: https://www.ooracing.com/store/silencer-end-can-cafe-racer-straight-end-steel-chrome-construction.html

I used to think the former owner actually put on the entire exhaust system (pipe + end can), but now I'm thinking he just sawed off a bit of the pipe and only installed the end can. Which would explain the noise :s

Either way, I'm looking to install an entirely new exhaust (pipe + end can), and I think it's an easy job. However, where do I order the parts...? From Skyteam themselves or a site like OORacing? I'm in Belgium by the way.

Also, I'd need cables for the choque. When I had my 500km maintenance, the mechanic said there's no cable running from the toggle at the left handlebar to the engine. Is that something I could order as well?
Finally, I'd need a new fuel tap and "tube". The old fuel tap is always open (bike stood still for over a year), so the former owner put a new tap in the middle of the tube. I'd like to restore that to the original situation.

I'll try and get pictures in, that might be helpful to get a grasp of the situation.

But basically, my questions sofar are:
What stuff do I need and where should I get it? :)


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Hello spiffmeister, welcome.

First of all, cable for the choke:


And a new petcock and tubing:



Second, your bike, lacking a general shot of it, seems like the PO kept the original header, cut it at the point where the CAT is, and clamped the silencer on top. This, although it works as a makeshift mod, hampers the potential of the bike. The original header the bike comes with, is double walled and the inside diameter of the pipe is actually smaller than you'd think seeing it from the outside; this leads to hotter operating temps and hinders the performance.

And yes, universal silencers that are a straight through design are loud as hell. Specially in your case, as that muffler has:
1. An end diameter hole that is way too big.
2. Being one piece, it seems it doesn't have a removeable core. Removeable cores are essential in a straight through design, as it has multiple holes around which you can wrap fiberglass that will soften the exhaust note, although still being loud. This kind of muffler design is known as absorption tipe. Check this out

You are in Belgium, therefore shipping costs from OOracing in UK will be around 25 euros or less which is acceptable. therefore, you should go for the header they sell here:


The people you see in this forum running the modified (sawed) header are doing it in part because they are from australia, and shipping costs for them are way over the top, as I understand.

Also, unless you love the shape of the silencer you currently have, I'd reccommend you order a reverse cone megaphone style silencer. OOracing sells this type:


This is the one i have. Comes with a removeable core and is already packed with soundproofing material. key thing is that down the line you'll be able to replace it with better fiberglass sheets, as this designs slowly burns the material and you have to replace it eventually (chances are, your silencer has already burnt all the material, therefore why its so loud, and you can't repack it). However, this silencer, even with fiberglass packing, is still loud. Not obnoxiously so, but after a couple months you might get tired of it if you don't use earplugs.

For this, I have used the following:


This mute attaches on the outside of the header, then you slip on top of it the silencer. This, in combination with repacking the silencer with fiberglass, gives me the correct amount of noise so that I'm eager to twist the throttle, but does not tire me on longer trips.

Finally, you may consider from this shop also (same as above, the classic bike shop) a megaphone exhaust that has a smaller end opening than the OOracing one and should be quieter( plus looks beautiful IMO):


As a final note, I have ordered multiple times and trust both of them. OOracing is a well respected site that offers a lot of real world tested, dyno proven mods for our ACE (the owner had one for himself on which he tested the mods) and ClassicBikeShop were quick and answered my emails.
Even if british pound/ Euro exchange rate is quite disfavorable for us europeans at the moment, They're still reasonable prices.

Hope it helps.

Hey man,
I've got the same exhaust from OORacing and it's very loud indeed. It comes with a baffle that doesn't do much at all. I've replaced it with this one: http://www.customparts4less.com/epages/268147.sf/en_GB/?ObjectPath=/Shops/268147/Products/H65-8171 and stuffed some extra dampening wool into the exhaust. Now it's still noisy but acceptablly loud.

My fuel tap has a similar issue too. It leaks even if it's closed. Very irritating when working on the carb. So I ordered a new one from skyteam for about 15 euros. I still need to install it though.

I ordered my parts at Vanroosbroeck in Merksem. They are an official skyteam dealer and very helpfull.

By the way, I removed my choke cable. It kept the butterly valve thing from being wide open. So now I use my left hand to operate the choke on the carb and my right foot to kickstart. Works perfectly
Over on Facebook I think Nick Tadman modded the same muffler you have to quieten it down
See May 4th and 2nd

After trying the Skyteam sports chrome exhaust I went for the OO Racing header and Emgo Reverse Cone muffler and rejetted, which seems quite popular for Aces. I repacked as shown in this video. Still quite loud at full throttle but idling and around town it is fine. Accelerates much better.

See vid at bottom of this page

I haven't bothered with the crumb cup mod, might do later

Wow, thanks for all the info, especially Waketrip, you've given me a lot of stuff I can work with! I'm pretty hopeful about the future with my bike now :)

For the exhaust, I'll go with the OORacing header and the Classicbike exhaust, because it does look great and I hope it'll be quiter. I can always get a mute later on if it's still too much.
But from what I understand, changing the exhaust should already help with noise and even performance, which I didn't expect.

The fuel tap shouldn't be a problem to change, however, I have another question on the choque cable.

Racing Ruben, you said you had problems with the butterfly valve staying open when using the choque with the cable? What does that mean exactly?
Also, when starting, do you operate the choque at the carburator whilst kickstarting, or operate the choque at the carborator, let it go and thén kickstart?
When the choke is off, the butterfly valve inside the carb should sit horizontal so that it does not 'choke' off any airflow. If the cable is not adjusted right the butterfly valve sits at a slight angle. So removing the cable allows the spring mechanism on the carb to switch the choke truly off.

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The problem I had with the choke lever was small but irritating. The lever didn't stay open whilst riding. Because of the vibrations it closed up a little. Because of that the engine didn't perform well at high rpm. So I removed the cable and the butterfly valve is now completely open.
To start with choke I use the choke lever on the carb and kickstart at the same time. I hold it for a few seconds and then I'm good to go.
Good luck with the Ace,


I fixed my exhaust and noise problems :D

I received the parts on friday, and only had 2 hours before leaving for a weekend. I did run into some little problems though.

First I noticed that the "thingy" that should fix the header on the engine was too wide, the holes at least. So it took me like an hour to use my Dremel to make the holes bigger/wider, so that they'd fit on the screws.
Then, I noticed that the header from OORacing is actually far too long, so that was a bummer.

However, I managed to install the silencer on the original header for now (will get the header cut tomorrow, I don't really have the stuff to do that job). I didn't really know how to use the copper rings to make the silencer fit on the header correctly, but it seems like it worked.

The performance improved véry noticeably! The Ace pulls up faster, and I can get a higher top speed out of it.
But, the noise... The level has been reduced to a very good level, and the sound is just crazy! Still rather low and "baritone"-ish, and the engine just screams when getting into higher revs. Brilliant :)

All in all, I'm quite proud of myself for doing this on my own, and the result is much better than I dared to anticipate.

Next up: the fuel gauge and my battery! I have a thingy that slowly loads the battery, don't know the English word, here it's a "druppellader" in Dutch. Gonna see if that can fix my dead battery :)
Pics coming up soon!
That's the one :)

Speaking of the battery... i've never done this before. The negative and positive wires from the bike are screwed onto the battery, from what I can see. But that means that you can get a shock when trying to screw those connections loose... or am I missing something?
You can not get a shock from 12 volt. Skin resistance is too high. Do you mean short something out?

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Spiffmeister, Glad we could help you out.

About the header connection to he exhaust flange, yes it is common, quite a few of us has had to enlarge slightly the bolt holes for it to fit. But not that much of a problem as you can see. I suppose ooracing had a bad batch of those.

On the other hand the header being too long is not a design fault. It was meant to be that long. This is so you can tune yourself the length you want to have so it matches with your silencer. Once you have the desired length, you cut it up. At this point I reccommend that you keep your total exhaust length so it goes at least up to the rear axle of the wheel.

If you cut it shorter you will lose power and torque, and the exhaust note will be louder. Small displacement single cylinder bikes like long exhausts. this basically means that the exhaust has to be long enough so that the first pressure wave doesnt leave the exhaust before the next one is already going through the exhaust, so it doesn't create a vacuum at the end of the silencer and blocks exhaust flow.

Please look in this thread http://www.dotheton.com/forum/index.php?topic=39814.60 to reply #67 from sonreir to fully understand my crude explanation.

Tempted you may be, don't cut it as short as you have your other header, or you'll largely lose the benefits of this modification.

I got the chrome header cut and installed the exhaust like it should, but I did ran into some problems. Obviously :)

The biggest/main problem is the fitting of the silencer on the header. There's ample room there, so I needed to use the copper-coloured tubes to put in there so it fits more.

However, 2 of them isn't enough, there's too much room. And 3 barely fit in the silencer. So I went all-out and got the 3 of them inside of the silencer, but i had to use some force... they're not coming out again.

Either way, it's still not enough to make the silencer fit tightly on the header, it always keeps moving no matter what I do or how tight I try to make it.
Now, here's the tricky part. The end of the silencer is attached to the frame, but that has suspension. I just noticed that when I push down on the bike, the exhaust moves. And basically, since the silencer doesn't fit well on the header, the header just moves in and out of the silencer...
There's a tiny bit of fumes coming out of there, but it's negligible. I did lose some power compared to putting the silencer on the old short exhaust. But, that one moves as well.

Got some pictures now.

Is this the best I'll get? Or did I do something horribly wrong? Also, is there a way to make the silencer fit evne more tightly, perhaps with some non-metal material?


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I used the large adaptor and a graphite ring to get a nearly air tight joint between header and muffler.

The graphite ring was something like this OO racing one. Not sure that is the right size, you would need to measure it up. And this seems to be two gaskets a steel and a graphite one. I bought mine at a local bike spares shop in New Zealand.


To secure the muffler, uUnscrew the footpeg, put the end of the bracket on the bolt, then screw back in.


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Hi 2b!

I'm going to try and make it fit with the copper rings some more first, see what happens...

I tried securing the silencer on the footpeg, but the footpeg bolt is too wide, but only like a millimeter or so.

I could widen the hole of the metal plate with my dremel. You think that's a good idea?

I'm starting to notice some stuff the former owner didn't tell me about, like attaching the exhaust to the frame that's subject to suspension. He should've told me about that. Hopefully that's all I'll find :p
Just a thought i have had after reading this and other threads on replacement exhausts...... I have had a pattern Honda CG125 exhaust fitted on my Ace for quite a while now, total cost £45 plus VAT from David Silver. The bike runs superbly with it on, sounds good but is not too loud and it was reasonably easy to fit. Has any other owner fitted a CG125 exhaust and if so what do they reckon to it?
Oh yes it did need a bit of filing, not much, to make it fit. If you look at other pics of ace exhausts you will see that most of us use the footpeg

I managed to install the chrome header and the silencer, and attached it to the frame at the footpeg.

It was all a bit of work getting it all right and making it all fit, and in the end I went with the best I could get out of it. The silencer is a little far from the wheel, but not weirdly so. It may be just slightly weirdly angled compared to the header, but... it fits! And it's not moving anymore.
Also, sound and performance are great!

So that's brilliant :) Thanks for all the help on this!

I also managed to trickel charge my apparently not broken battery, and now the lights go on when I switch the contact, and the electrostarter works as well! Brilliant!

Next step is replacing the fuel gauge, and then it's up to the next steps of fixing/upgrading my ace: fixing the bent rear fender, covering up the scratches on the fuel tank, and fixing the front light which points too much to the left :)
I'm having a blast :)

Have just been looking at the CG exhaust from David Silver-Did you need any other bits and bobs from him to make it fit-gasket, split collar or the cylinder head/exhaust clamp? Or are there enough things transferable from the monstrosity that is the Skyteam exhaust?



You will also need a gasket, split collars and clamp and also fabricate a bracket for the silencer. I posted pictures of my bike with the exhaust on 24th September 2014 if you wish to take a look.

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