Parts required
1x standard Honda VFR 800 VTEC exhaust silencer unit ( good used and local £45 )
1x wire or graphite exhaust gasket (approx. £8 on ebay)
Tools required
1x High speed drill
1x core drill adapter (approx. £7 any DIY store)
3 or 4x 25mm Bi metal core cutter (Don't buy cheap ones) (approx. £6 each from DIY store)
1x dremel mini grinder or similar
4x mini grinder mandrels (approx. £6 on ebay)
4x 18mm diamond cutting discs (approx. £6 on ebay)
2x 24mm diamond cutting discs (approx. £6 on ebay)
1x ruler or tape measure
1x course round file
1x fine semi circle file
Modification and installation time
5 hours
Approximate total cost
£84.00
This can be done at half this cost if you choose not to purchase a donor part but who wants to put their bike off the road if the weather is sunny?
Introduction
I'm not going to mislead anyone and say this was an easy modification. It did present me with some difficulties along the way.
The following is just a guide as to how I did this modification and any attempt to follow this is done at your own risk.
Great care should be taken to protect yourself and avoid ruining the part being modified. Wear PPE, take your time and get it right 1st time.
I will apologise in advance as some of the pics in the guide are staged for the purposes of this guide and don't capture some of the steps as well as they could. This is mainly due to my reluctance to get my camera phone out and take pics every 2 minutes. The pics I have included give a good indication of what is required to complete the task though.
Standard exhaust off the bike
This modification of the standard exhaust is easiest and best done off the bike due to the metal fragments and filings that drop inside the silencers.
I then went about removing the outer covers to avoid damaging them. This will seem a little tricky but it is possible. The edges on these outer covers are very sharp and cut into my finger very easily so be careful.
Once the outer covers have been removed, clamp the exhaust onto a bench of some sort to stop it from moving around.
Views inside a standard and unmodified exhaust
Lets begin!!
Attach a 25mm bi metal hole cutter to a suitable adapter and attach to a high speed drill. I used a variable speed corded drill. Any drill including battery operated ones will do the job so long as they have good speed and torque when applying pressure to the drill.
I cannot stress the importance of buying good bi metal hole cutters though. The reason for this is they are not designed for cutting through tough Stainless Steel at all and go blunt quickly! Hence the reason you will need at least 3 or 4 of these hole cutters. Possible one for each exhaust exit. I managed it with 3. I used a metal cutting oil for 2 of the 4 exhaust exits to reduce the heat build up but it made little or no difference to the hole cutters.
Anyway,
Insert the drill into the 1st exhaust exit and go for it keeping a firm grip on the drill in case it bites and tries to rip your arms off. Check frequently to allow the hole cutter to cool down assess how the cut is going.
After a short period of time you should make it through into the chamber of the silencer. The actual exhaust exit holes are 26mm and because the hole cutters don't come in that size a 25mm is the nearest thing that will do the job. This can cause a little bit of an alignment issue and after drilling all 4 exhaust exits they can all vary. The purpose of this task is to separate the exhaust gas exit tubes from the end cap of the exhaust.
After drilling all 4 holes, some of these outlet tubes may still remain connected to the end cap. You will have to ensure these are separated from the end cap. The next step will then help you resolve this.
The next step
Now I believe a flexi attachment would definitely make this step easier and give better visibility when cutting but I was too impatient to wait on mines getting delivered. I did prove it can be done without one though.
once the inner tubes are fully detached th
Something to be prepared for is items that wear. You are better to be prepared to finish a job and have surplus items (that could be returned later) than be underprepared with insufficient items that will stop you finishing altogether.
The items below are mandrel collars from the dremel grinder, designed to grip the mandrel whilst it spins at 13000rpm. Occasionally you will get stuck and the torque from the dremel grinder (or equivalent) will cause the motor to continue to spin causing these to fail. Make sure you have a few!
File sharp edges
Results
Why do it?
Exhaust gases enter the 1st chamber of the silencer then move through to the 3rd chamber, then from the 3rd chamber to the 2nd chamber and finally, from the 2nd chamber out into the atmosphere.
This modification allows the exhaust gases to enter the silencer and come straight through the exit and the end result is a sound so good a video just doesn't do it any justice. Some restriction still remains but the result is loud enough for me and it looks completely standard. Its also stamped for road legal use too!
Cutting out these small pieces derestricts the exhaust gases alters the sound dramatically, but for the better! The singing V4 will not disappoint!
Over and out.
