Procedure for VFR (NC30) engine into RVF (NC35) Frame

[punchsponge]

First off, let me preface this note by saying that I'm in South Korea where RVFs are fairly rare and there hasn't been a salvage engine to be found in the country for the last eight months. $1,200 US to have a no-guarantee salvage engine shipped from Japan. My engine runs strong, but it's got one heck of a bottom end noise, a clunk that is most pronounced when I let off the throttle. Noise gets far worse - almost tragic - with the clutch removed; the mechanic and I are pretty much in agreement that it's a crank / main bearing problem (more wobble without the clutch). Does this sound reasonable? Rod bearing maybe? New crank / main bearings is a terrible idea in terms of cost. I know that RVF and VFR engines are not interchangable becasue of the mounting points, etc., but what about just the bottom ends? Becasue what I do have access to is a trashed old VFR salvage bike. When I look at the parts catalogus I see that the part numbers generally agree in terms of bearings between the VFR and RVF, and though the last four digits are different in the crank parts numbers, the bore and stroke of the two bikes are the same. Also, the bottem end cases appear to be identical between the two bikes, but the same problem arises in terms of part numbers: 0000 to end the VFR, 9000 to end the RVF. All total here in Korea we are talking about a $2,800 US bike with maybe a $1,500 salvage value, so what I'm looking for is a quick and easy fix. They look like they will swap, but will they actually swap? Obviously, I'm clueless and out of options. Thanks for your help. ****I should probably mention that a head gasket was replaced by the previous owner, so there's a chance he could have lubricated it with coolant at some point. Compression was great, bike pulled strong and there was no valve noise, etc. but still... I probably put 8,000 km on the bike before this happened...

[skinnydog0_0]

Hi,
You can swap VFR and RVF engines. You will need to swap the pick ups in the engine if you intend to use the same loom and CDI. So if you use a vfr engine you will need to remove the VFR pickups and replace with the RVF pickups. It may be far simpler to swap engines than spending money on new bearings, gaskets and a host of other parts.

[punchsponge]

Skinnydog, thanks.
So no problem with the engine mounts? No problem with clearance around the different carbs / velocity stacks? Just pickups? It's funny, becasue the guys at the shop took one glance at the mounts and gave up, and since I'm a bit of a mechanical moron and I can only communicate with these guys via an awkward combination of Korean, English, hand signals and laughter, this might turn out to be a challenge. A Clymer-type step-by-step would be really helpful for this - simply as far as convincing them to give it a shot - but thus far I've been unable to find anything in the archives or on the net as a whole. Any ideas? And just to clarify in an awkward way, since I don't have the bike in front of me right now to look, but by "pickups" you mean the plug coming out of the alternator, and / or the ones coming out of the starter, pulse generator and neutral switch?

[Cammo]

I put an rvf engine in my vfr, no problems.

You're right, the mounts are different but the unused mount holes in each engine can be tapped and it will fit up to the frame fine (tap size is M10 x 1.25).

As said above, you need to use the ignition pick ups specific to your loom (rvf pick up from your old engine to suit your rvf loom). The ignition pick ups are bolted to the engine block inside the flywheel cover. The vfr has 2, the rvf has only 1.

You also need to use your old starter clutch I think (can't remember sorry!). Your existing carbs will fit fine. The gearbox gearing is different between the 2 engines, you'll get used to it. Swapping an engine is much easier than changing a bottom end!

There's a thread on putting a vfr engine in an rvf here: viewtopic.php?f=24&t=24374&hilit=starter+clutch

[Drunkn Munky]

Yes you also need the starter clutch. You also need to space the front sprocket over 5mm so the chain lines up.

[punchsponge]

Alright, I went to the shop with my proposal, (Thanks for the help!), and it prompted a lot of excited discussion in Korean. So I've gotten that far - but the new direction is to keep the VFR engine in the VFR frame and just swap my swingarm, wheels, etc, since my RVF frame has been rewelded at the head tube at some point, (don't worry about the numbers). So now, since I've already asked plenty of stupid questions, how about that... I think the RVF swingarm is a little shorter, but will it fit? I read somewhere that the spindles are different diameters, and I know RVF and VFR rear wheels are different. And I heard that the triple trees won't switch out, which makes me wonder about the fork tubes fitting without the switch - as I know they are inverted on the RVF - since my VFR doner bike has a tweaked front end. Actually, just to clarify, becasue looking back this reads like I'm rambling, what we want to do is go with as much as the RVF as possible, (or is practical), save the using the VFR frame and engine (including carb setup). Engine pick up switchouts is the only mod thus far confirmed in this process, with a probable on the front sprocket spacing with the RVF swing arm. Advice? Like I said, my primary concerns are the front end and swing arm. Thanks!

[skinnydog0_0]

From the sounds of it, i would use the VFR as your base bike and use the RVF as the doner. The swing arms are not interchangable as one is wider across the mounting pivot than teh other (cant remember which way round) The VFR later type forks are as good if not better than the RVF ones. I would swap the Wheels and use the 17inch RVF ones and use the rear suspension linkage from the RVF too.