YZF 600 R (Thindercat) front end

[Millietant]

Good evening guys and gals,

A friend has asked me to help with putting a YZF 600R front end on his FJ (3CV).

I'm aware some members have already done this and wondered if anyone could please point me to a guide, or instructions (I could work out all out for myself, but I'd rather work smart than work hard) on the swap?

I've had a look through the Files section but haven't turned anything up, but in the back of my mind I thought I recalled hearing/seeing that Jon Cain might have done this swap as well as the rear wheel swap.

Many thanks

[fj1289]

The write up was on Barry Edward's FJMods site - but it looks like we've lost that resource

I tried waybacking the site - but can't find the page linked to (it's two levels down from the main page - wayback machine only seems to go one level down)

The "trick" I recall is using the correct year FZR1000 triple clamps to make it a bolt-in.  The FZR triples have the same 35mm offset as the FJ (and most all Yamaha street bikes from that era it seems) and the correct spacing for the YZF600R forks.  Pretty sure it is the first gen 87/88 FZR1000 triples that are needed for this swap.  I don't remember details why the YZF600R triples aren't suitable?

Maybe we can find all the details again and capture it in the files section ...

[Millietant]

Thanks Chris, I've got the archive link to Barry' site and also got some information on the swap by a guy called Joe Soto - he fitted the YZF 600R forks into the FJ triple trees (the stanchions are the same diameter and made some spacers for the wheel and brake calipers. I'll look into that.

I've also contacted Jon Cain to see if he can assist as I think he did the swap also and provided the info that was in Barry's site.

If we go ahead, I'll document the process and put it in the Files section.

[fj1289]

The only drawback I can think of with using the FJ triple trees - if the spacing is different - then the YZF600R fender might not mount up?  Maybe find a way to mount the FJ fender?

Only one way to find out - give it a go!

[gdfj12]

I've done the YZF600R front end swap on my 89 FJ. The 87-88 YZF 750/1000 teiple clamps make it an almost bolt on swap. The only modding you need to do is to remove some aluminum from where the ignition switch/steering lock mounts to get the steering lock to work. I think it is 5-10 mm to remove. I've got an 87 that I'm going to do the conversion on and another 89 to do if I can find 1 more good fork as the set I got had one slightly bent tube. I also have at least 3 FZR triple clamp sets.

As I recall the YZF 600 has the same fork tube diameter and offset from the stem but is 10mm wider on the spacing and the FZR750/1000 matches this. I have also found on eBay, top triple clamps for converting to standard 7/8" tubular handlebars for about $250-300.

George D

[Millietant]

The only drawback I can think of with using the FJ triple trees - if the spacing is different - then the YZF600R fender might not mount up?  Maybe find a way to mount the FJ fender?

Only one way to find out - give it a go!

Good point and I think we'll just go ahead as you say,  if we can find a front end at the right price. George mentions the spacing is 10mm wider, so if I'm making spacers for the spindle & calipers already, I can easily knock out a few 5mm spacers for the fender mounts.

George - I joined the UK FZR owners forum when I was converting my FJ to the FZR USD front end and I keep tabs on what comes up for sale there - I got my triple clamp set for £35 in total and have often seen them go for £20-£30 for each one, especially the pre-USD ones, where no one here wants them  So it's great to know that's an option too 

Thanks guys - you came through, as always !!

[fj1289]

I think it is the opposite problem - I think the YZF600R fork spacing is 10mm wider than the FJ.   

[Urx]

If the yzf600 spacing is 10mm wider than an fj1200 then the genesys triple tree should do the trick width wise to allow the use of the yzf spacers and front mudguard.
I cant recall if the stem is the right length to fit the fj or needs swapped though?

[Millietant]

I think it is the opposite problem - I think the YZF600R fork spacing is 10mm wider than the FJ.   

Yeah, I picked that up a bit later Chris, but I've had info from another guy, who says he's done the swap and used the YZF forks in the FJ yokes. I'll have to delve into the detail of what he says to understand completely the solution he's talking about, but at the very least it looks like we have plenty of options. I had to modify the ignition mount on my current FZR top yoke to get the steering lock to work properly on my FJ, so I think I've got everything covered - but if I get stuck, you can bet I'll be back here asking questions again 

[fj1289]

For folks that are following along - the "simple solution would be to swap the FJ stem into the YZF600R triples - BUT most of the later Yamahas used a stem with a slightly larger base diameter.  I don't know if this is the case with the YZF600R triple clamps, but assume it is a problem since I've never seen that solution mentioned.  

Don't remember if it was Jon Cain or Mark Rittner had the lower end of the FJ stem welded up and machined to the correct diameter for (I think) an R1 fork swap.  I've also had a new stem machined with the R1 lower diameter and FJ length. 

Looking forward to this one getting documented. 

[Millietant]

For folks that are following along - the "simple solution would be to swap the FJ stem into the YZF600R triples - BUT most of the later Yamahas used a stem with a slightly larger base diameter.  I don't know if this is the case with the YZF600R triple clamps, but assume it is a problem since I've never seen that solution mentioned.  

Don't remember if it was Jon Cain or Mark Rittner had the lower end of the FJ stem welded up and machined to the correct diameter for (I think) an R1 fork swap.  I've also had a new stem machined with the R1 lower diameter and FJ length. 

Looking forward to this one getting documented. 

Jon has sent me a note with the swap details. I'll copy them here shortly to save in the Files.

Thank you Jon.