givemea5 Posted March 10, 2016 Report Share Posted March 10, 2016 Hi all, As the title, i have a 315 but was thinking of modernising it and freshening it up with a 4rt rear mudguard. I have seen pics of bikes with them on so i know its do-able, but how?? Obviously it will need to be cut down at the front, and a hole drilled for the top bolt to go through but does the rear subframe need modifying to accept the rear fastening points? Thanks for any advice! Quote Link to comment Share on other sites More sharing options...
gazza7965 Posted March 11, 2016 Report Share Posted March 11, 2016 (edited) Hi givemea5 I did this conversion for my 315 and it does make it look much more modern.It is not too difficult to do but there are some mods needed to make it fit correctly. I will try and detail everything I did: 1. Obviously cut down the mudguard, I did this carefully with a large hacksaw blade. You need to line it up by fitting the mudguard to the bike with the 2 mounting holes fitted to the brackets on the airbox and mark where it meets the tank on each side of the new mudguard. Make a template from 2 inch masking tape of the profile of the edge of the fuel tank where the mudguard will meet or the original 315 mudguard front edge. use this as a template to cut across the the 4rt mudguard, this also helps not to scratch the new mudguard when cutting. Once cut you will find you will have to chamfer the edge of the mudguard where it meets the tank as the edge of the fuel tank is angled. (The cut should go through the middle of the two front square vent holes on the mudguard) see picture 2. Drilling the hole to mount the mudguard at the front.- I drilled a 6 mm clearance hole in the centre of the mudguard, 35mm from the front edge once it had been cut. This may need to slightly elongated but not by much to fit perfectly. 3. Mudguard mounting brackets on the airbox..I found that the original airbox mounting brackets not to be correctly located to make the mudguard sit right. I found that only one of these brackets can be used. To get the mudguard to sit correctly, i swapped the right hand bracket to the left hand side which in effect moves the mounting position up a little. I made a new bracket for the other side, it is not too difficult they are only sheet metal. This bracket is best made once you have the mudguard sitting correctly on the front mounting and the left hand side mounting. This then shows you exactly what shape the right hand side bracket has to be. 4. Modifications under the mudguard. The 4RT mudguard has a plastic plate moulded into the guard towards the front that when fitted, sits on top of the airbox, I think its stops the mudguard flexing downwards when sitting on it. The airbox is obviously different on the 315 so this has to be modified. I pop rivetted an aluminium plate to the original plastic tab that when fitted gave a measurement of 55mm from the bottom of the plate (where it would touch the 315 airbox) to the underneath of the mudguard. There is also a gap where the underneath of the mudguard meets the back of airbox which if not covered in some way would allow all the mud/water thrown off the tyres to go through the gap and run down on top of the air filter area. I made another metal plate and sandwiched a rubber flap (made from an old inner tube) and pop riveted this to the flange that runs across the middle of the mudguard underneath. This flange must also be trimmed to fit before fitting the plate as it fouls the airbox mounting brackets. Finally glue some expanded foam rubber to the underneath the mudguard with contact adhesive to close the gap completely and allow no mud/debris thrown off the rear wheel to enter the top of the airbox. see picture. 5. The front mounting bolt. On the 315 mudguard, the front mounting bolt sits in a recess and the underneath of the recess sits on top of the fuel tank mounting grommet. This is not the case on the cut down 4RT mudguard, which means a much longer bolt is required. I found this gives a problem, when sitting on the bike, the mudguard still wants to flex and put this bolt under a lot of pressure. I got round this by making a new fixing that fixes the fuel tank in position first and then allows the new mudguard to sit on top of this fixing and allows a much shorter bolt to be used to secure the mudguard. This is made from a 10 mm bolt with the unthreaded shaft part cut to a length of 15mm. (This replaces the spacer used to originally fix the fuel tank) Drill through the centre of the entire 10 mm bolt and tap all the way through the 10 mm bolt to a 6mm thread.Thread lock a 20 mm stud of 6mm studding into the bottom leaving around 12 mm of the thread exposed. You then have plenty of female thread on top of the bolt to use to fix the mudguard using a 12 mm long, 6mm button head allen screw. see picture. 6. Finishing touches. Where the 4RT mudguard now meets the fuel tank, the front vent square holes are no longer the same shape. I made some decals that give the appearance that the mudguard shape and appearance has been maintained - see picture. I hope I have covered everything and this makes sense but if you have any questions then please let me know. Edited March 11, 2016 by gazza7965 8 Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted March 12, 2016 Report Share Posted March 12, 2016 very helpful. Quote Link to comment Share on other sites More sharing options...
mike64 Posted March 12, 2016 Report Share Posted March 12, 2016 That looks a great 315, is the bike a lot lighter than the 4rt ?? Quote Link to comment Share on other sites More sharing options...
gazza7965 Posted March 12, 2016 Report Share Posted March 12, 2016 I am not sure about the weight difference but I don't think there is much in it. I would say that the 315 feels much lighter than the 4RT and for me is a much nicer bike to ride. 1 Quote Link to comment Share on other sites More sharing options...
madmostin Posted March 12, 2016 Report Share Posted March 12, 2016 Really informative post. The bike looks really smart. What other mods did you do? Quote Link to comment Share on other sites More sharing options...
gazza7965 Posted March 13, 2016 Report Share Posted March 13, 2016 Renthal Fat bar conversion Raptor pegs Keihin Carb 1mm head spacer to cure pinking issues 4rt Showa fork stanchions Boyeson reeds Mitani carbon fibre fuel tank H & D racing rear suspension linkage plates 1 Quote Link to comment Share on other sites More sharing options...
barnesy Posted March 13, 2016 Report Share Posted March 13, 2016 Hi Gazza, That's a great looking bike it looks like production model ... One question did you paint the mitani tank or does it have 4rt decals applied to it. Cheers B Quote Link to comment Share on other sites More sharing options...
gazza7965 Posted March 13, 2016 Report Share Posted March 13, 2016 Hi barnesy The white and orange are painted, the only decal is the black 4RT style one. I did deliberate not painting the tank cover as it seemed a shame to paint over the carbon fibre but it would not have gone with the colour scheme Regards Quote Link to comment Share on other sites More sharing options...
barnesy Posted March 14, 2016 Report Share Posted March 14, 2016 I've got a carbon tank as well and I'm in the same position cant decide whether to paint it or not ... Cheers Quote Link to comment Share on other sites More sharing options...
givemea5 Posted March 14, 2016 Author Report Share Posted March 14, 2016 Gazza, Brilliant post! I have everything I need from that and will be giving that a go as soon as I get the 4rt mudguard. I really appreciate the time you have taken responding. By the way the 315 looks absolutely mint, you have done an excellent job with it! Cheers 1 Quote Link to comment Share on other sites More sharing options...
ridgrunr Posted August 21, 2016 Report Share Posted August 21, 2016 Terrific write up! I'll be looking forward to a winter project to spruce up my 2002 315R! Quote Link to comment Share on other sites More sharing options...
lampshade Posted March 4, 2018 Report Share Posted March 4, 2018 On 3/11/2016 at 7:09 PM, gazza7965 said: Hi givemea5 I did this conversion for my 315 and it does make it look much more modern.It is not too difficult to do but there are some mods needed to make it fit correctly. I will try and detail everything I did: 1. Obviously cut down the mudguard, I did this carefully with a large hacksaw blade. You need to line it up by fitting the mudguard to the bike with the 2 mounting holes fitted to the brackets on the airbox and mark where it meets the tank on each side of the new mudguard. Make a template from 2 inch masking tape of the profile of the edge of the fuel tank where the mudguard will meet or the original 315 mudguard front edge. use this as a template to cut across the the 4rt mudguard, this also helps not to scratch the new mudguard when cutting. Once cut you will find you will have to chamfer the edge of the mudguard where it meets the tank as the edge of the fuel tank is angled. (The cut should go through the middle of the two front square vent holes on the mudguard) see picture 2. Drilling the hole to mount the mudguard at the front.- I drilled a 6 mm clearance hole in the centre of the mudguard, 35mm from the front edge once it had been cut. This may need to slightly elongated but not by much to fit perfectly. 3. Mudguard mounting brackets on the airbox..I found that the original airbox mounting brackets not to be correctly located to make the mudguard sit right. I found that only one of these brackets can be used. To get the mudguard to sit correctly, i swapped the right hand bracket to the left hand side which in effect moves the mounting position up a little. I made a new bracket for the other side, it is not too difficult they are only sheet metal. This bracket is best made once you have the mudguard sitting correctly on the front mounting and the left hand side mounting. This then shows you exactly what shape the right hand side bracket has to be. 4. Modifications under the mudguard. The 4RT mudguard has a plastic plate moulded into the guard towards the front that when fitted, sits on top of the airbox, I think its stops the mudguard flexing downwards when sitting on it. The airbox is obviously different on the 315 so this has to be modified. I pop rivetted an aluminium plate to the original plastic tab that when fitted gave a measurement of 55mm from the bottom of the plate (where it would touch the 315 airbox) to the underneath of the mudguard. There is also a gap where the underneath of the mudguard meets the back of airbox which if not covered in some way would allow all the mud/water thrown off the tyres to go through the gap and run down on top of the air filter area. I made another metal plate and sandwiched a rubber flap (made from an old inner tube) and pop riveted this to the flange that runs across the middle of the mudguard underneath. This flange must also be trimmed to fit before fitting the plate as it fouls the airbox mounting brackets. Finally glue some expanded foam rubber to the underneath the mudguard with contact adhesive to close the gap completely and allow no mud/debris thrown off the rear wheel to enter the top of the airbox. see picture. 5. The front mounting bolt. On the 315 mudguard, the front mounting bolt sits in a recess and the underneath of the recess sits on top of the fuel tank mounting grommet. This is not the case on the cut down 4RT mudguard, which means a much longer bolt is required. I found this gives a problem, when sitting on the bike, the mudguard still wants to flex and put this bolt under a lot of pressure. I got round this by making a new fixing that fixes the fuel tank in position first and then allows the new mudguard to sit on top of this fixing and allows a much shorter bolt to be used to secure the mudguard. This is made from a 10 mm bolt with the unthreaded shaft part cut to a length of 15mm. (This replaces the spacer used to originally fix the fuel tank) Drill through the centre of the entire 10 mm bolt and tap all the way through the 10 mm bolt to a 6mm thread.Thread lock a 20 mm stud of 6mm studding into the bottom leaving around 12 mm of the thread exposed. You then have plenty of female thread on top of the bolt to use to fix the mudguard using a 12 mm long, 6mm button head allen screw. see picture. 6. Finishing touches. Where the 4RT mudguard now meets the fuel tank, the front vent square holes are no longer the same shape. I made some decals that give the appearance that the mudguard shape and appearance has been maintained - see picture. I hope I have covered everything and this makes sense but if you have any questions then please let me know. Hi, im currently doing this to my 315, just wondering though, what decal kit did you buy? I will obviously have the front and rear mudguard from the 4rt, but the other stickers ie the frame etc will be for the 315. Did you just adapt a 4rt kit or did you buy 315 specific decals? Regards Quote Link to comment Share on other sites More sharing options...
Andyb1987 Posted March 19, 2018 Report Share Posted March 19, 2018 On 13/03/2016 at 7:12 AM, gazza7965 said: Renthal Fat bar conversion Raptor pegs Keihin Carb 1mm head spacer to cure pinking issues 4rt Showa fork stanchions Boyeson reeds Mitani carbon fibre fuel tank H & D racing rear suspension linkage plates What's the 1mm head spacer to cure pinking issues Quote Link to comment Share on other sites More sharing options...
Andyb1987 Posted March 26, 2018 Report Share Posted March 26, 2018 Thanks a lot currently having issues also what year 4rt mudguard did you use? Quote Link to comment Share on other sites More sharing options...
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