[Tutorial] AIS Removal Guide – Hyosung GV125C (EGR Blank Kit Fitting Guide)
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Hi Everyone, just thought i’d do a quick guide on how to do the AIS delete kit on a GV125C and what AIS actually is :). In the future i’ll be doing a load of guide for bits and pieces if people like this. If i’ve posted in the wrong area feel free to move my post. The blanking kit really does make quite a big difference to the note of the bike, it does quite significantly stop the ‘burble pop pop’ in the exhaust and makes the bike sound much happier.
The reason for AIS to be fitted was to comply with EURO 3 emissions, however, the way it works is less prescise than any of the other methods, so it’s not checked in the UK MOT. it’s just a way of getting a bike compliant with Euro 3.
AIS, EGR, Catalyst and DPF(PPF) all reduce a certain kind of emission. EGR reduces NOX emmissions by feeding exhaust back into the engine and reducing engine combustion temperature, this also has a knock on effect of increasing efficiency. A catalyst (catalytic converter) is the second most important, as that will chemically break down shorter compounds in the exhaust into longer ones, such as Carbon monoxide and Hydrocarbons into CO2. The AIS system isn’t like either of those, it’s specifically for Hydrocarbons by feeding extra air into the exhaust to burn excess fuel not used by the engine.
DPF or PPFs are Particulate filters to remove soot, normally used in Diesels but some petrol cars have them now.Most engines, by design convert 80-90% of what they burn into C02, CO and a small amount of NOX. HCs and water are just a byproduct from the water in the air and maybe some incomplete combustion. For a fuel injected engine, HCs are minimal because under decelleration and idle, the engine self adjusts the mixture to ensure a clean burn, in a carb though you don’t have that luxury. at idle a carb is usually set a little richer, this is to counter a degree of leaning out under acceleration before the Main circuits take over and to help keep a stationary air cooled bike from overheating. Carbs also can’t stop fuel flow when you slam a throttle shut during decelleration, so all that extra fuel is thrown straight out the exhaust as unburnt hydrocarbons.
The AIS pumps more air into the exhaust system to help get that spare mixture to burn so that they can have similar emmissions to a fuel injected bike. It’s more a suggestion than an actually effective strategy but it’s a quite neat compromise.
the issue with AIS as a system is that it is a parasitic load on an engine for something that really doesn’t do much to influence burn quality in the engine, if an engine is tuned badly, then it will still massively pollute regardless of the AIS system. EGR and catalyst do a lot more to manage this, hence why I think they’re checked more thouroghly on the MOT.Now to the guide
My GV125 is a 2012 model with 2 AIS pipes, Anything newer I suspect will have the same setup.
What i needed was:
2 12mm vaccum blanks
1 6mm vaccum blank
2 AIS blanking plates
7 (for any hose clamps),8,10,12,14mm sockets
8mm and 10mm spanner
needle nose pliers
Phillips/JIS screwdriver
plastic oring tool (for persuading a stubborn vaccum hose)
rust penetrant
Strong and flexible fingers
Patience for daysthe basic principle is
1. Remove seat, tank, covers over coils and air box.2. Remove air filter bracket, lower the brackets for the coils.
3. losen the bolts (But don’t remove) for the AIS system on the side of the engine. THIS step is quite important, if any of these bolts put up a fight this is the time you have to make a descision whether to continue or not. I personally would leave them if they did but in my case they come straight out without any resistance BUT I would not risk my engine block removing something that really doesn’t affect running all that much and back out at this point.
4. Once the bolts are loose, remove the intake pipes for the AIS system from the airbox and seal them off with 12mm vaccum blanks. I used the clamps that came with the original system but really if you have new ones for the job here is the time to use them.
5. loosen the bolts to the AIS pumps by the horn and the coils, these were a pain to get loose for me so some rust penetrant would be a good idea for these bolts.
6. carefully disconnect the vacumm hoses from the pumps (the smallest ones), but leave the hoses connected to the engine intake boots, we’ll deal with that when we have more room.7. start to remove the bolts holding the hoses to the rear cylinder.
I made a mistake here by taking them out completely, my reccomendation is to loosen the bolts enough that you can fit the new blank behind it. Remove the bottom bolt and slide the blank under the old flange then put the bolt back through both. Then remove the top bolt, slide the old pipe to the side and use the nut in the kit to secure the blank loosely. then remove the guide bolt from the bottom hole, remove the AIS pipe from the engine and install the new bolt in the space the old one was. the reason for doing this is because the screws on the rear cylinder are a NIGHTMARE to refit. Being able to use the old flange as a guide would have saved me about an hour of faffing and dropping the blank over and over. The front was no bother.
Also tighten the both of them a smidge of a turn over finger tight and no more and make sure not to cross thread them.8. remove the left pump from the engine and set aside.
9. Repeat on the right side, this is the easier side though, the ais pump is mounted directly to the horn and the only thing risky is fishing the big air feed hose through the gap between the intake boots.
10. on the right side you will see a T piece from the rear cylinder that feeds vaccum to both pumps, you can disassemble it, like i did, or you can gently see if the entire thing will come off the vaccum nipple on the intake boots. BE SUPER GENLTE, think about kittens.
Seriously if you mess this bit up you can’t find replacement intake boots. In my case i used a pair of snips to cut the hose into two pieces leaving about 2 inches of hose on the intake boot. that meant i could remove that without worrying about having other hoses in my way.
10.5, in my case, the old vaccum hose had welded itself to the intake boot, what I ended up doing is running a really sharp knife gently over the old hose to weaken it (not to cut through), then it split off no bother.
11. put a 6mm vacumm blank on the intake boot with a clamp.
12. Reassembly!
on the right side, reinstall the Air filter, the chrome cover and move over to the left
on the left side, reinstall the coil bracket, tighten the nuts and reinstall the cover over them
to finish, reinstall the tank, seat and any covers you may have removed
You are now done. Give the bike a quick run to check for exhaust leaks (you hear a puff of exaust by the blanking plate) or vaccum leaks (the bike surges at idle, revving up and down randomly). both of those more than likely would be caused by things being loose.Also in the pictures if you notice i’ve disassembled more, i was also giving the fuel pump another look over, it’s not necessary to remove that or the coils.
If I was to make a suggestion for the AIS blanking kit, It would be to include some vaccum blanks. I had a hard time finding them.
Thanks everyone! -
Great article Darkvader, this is something I was considering doing on mine, I agre with you regarding the vacuum blanks that would be very handy if supplied in the kit as like you I was trying to source them but no joy. Does this conversion have any effect on the performance of the bike?
Alan.
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Thank you,
I managed to find a collection of them on ebay: Ebay Link Here
I’m not sure how long they will last so I will let you know if the heat will break them down in a few weeks. failing that you could get some vaccum hose, fold it over and use a cable tie or similar to tie the end off. It’s not as neat but it will work if you can crimp down on the hose tight.
I wouldn’t say it affects the performance that much, it just makes the bike sound nicer and removes all those hoses for doing other work. I’m going to be pulling the intake boots off next week or so and being able to work around them without a million hoses in the way is quite nice.
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I like the idea of “blanks” , will speak to a contact in supply chain to see if they can do a “blank kit” that supports both GV and the GT due to varying airbox sizes and will list them separate for shop if people need them
This is because i’ve leaned most people actually cut a short hose near the intake pipe and stick a bolt inside with a metal zip clamp tight. Job done! Cost = £0 and finding scrap bits in your shed lol.
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