5th Gen Engine in an 8th Gen?

[Ziffer]

I have a 5th gen VFR.

 

I think Honda did a pretty good job when styling all the VFRs, but I think the 8th gen looks the best...but I hate V-tech. So I've started wondering if a 5th gen engine would bolt up to an 8th gen frame. Has anyone done it?

 

I've also heard that the 6th gen and 8th gen share the same frame. So, will the 8th gen seat, tank, and plastics fit on the 6th gen frame?

[Duc2V4]

I and another VFRD member have put 5 Gen engines into our 6 Gen frames. I put a 98 engine into an 09 frame. The key mounting locations were all in the right places. If the 8 Gen frames are the same as the 6 Gen, then I don’t see why it wouldn’t work.

[mello dude]

That's an interesting project 🤔

[Lorne]

19 hours ago, Duc2V4 said:

I and another VFRD member have put 5 Gen engines into our 6 Gen frames.

 

I'm sure you've already detailed this project before, but would you mind refreshing my memory of which combination of 5th & 6th gen parts you used? Exhaust, intake, cpu, etc.

[Duc2V4]

1 hour ago, Lorne said:

 

I'm sure you've already detailed this project before, but would you mind refreshing my memory of which combination of 5th & 6th gen parts you used? Exhaust, intake, cpu, etc.

Ironically I don't believe I did a post about it, I was in "solitude" mode at the time, just dealing with pandemic lock down and all the rubbish that went with that mess. Essentially, I left ALL the 6 Gen stuff intact, wiring harness, cooling system, even the CPU. Although I took the opportunity to put the performance headers sfdownhill and I had produced when I did the swap. These fit either generation, with the exception of exit tube length. Here my memory is a little fuzzy as to which Gen header has the longer exit tube, but that was the header I had and no header exit tube to exhaust can tube issues, other than I had to expand the exhaust can link pipe where it met the header exit tube, as the headers exit tube has a bigger diameter than the 6 Gen OEM headers.

 

Also note that I have a Rapid Bike tuning module installed in auto-tune mode, so that may have helped the switch out go smoothly. The engine was essentially a one for one swap. All of the mounting points on the frame line up right where they are supposed to be. One word of caution here though, there is a sensor or some sort of electronic solenoid that is in the "V" of the 6 Gen engine, make sure that stays connected to the wiring harness, otherwise you'll get a fault code when you run the motor. You will have to detach oit from the 6 Gen engine to keep it with the swap out. You don't want to try and get this connected afterward with all of the other stuff installed, trust me on that! I was able to fish the wire/connector where I could connect the unit back on and bolt it to the outer part the frame. I'll see if can grab a photo of what I'm talking about so it will make sense.

 

The only other minor concern is for the "coil on plug" connections that the 6 Gen uses, as these are usually attached to the 6 Gen motor with bolts. The 5 Gen engine does not use these and also does not have the mounting bolts or attachment points on the engine valve cover. Unfortunately too, you cannot just swap valve covers as, the 5 Gen engine uses gear driven cams, the 6 Gen uses chain driven cams, so the heads are totally different widths. My recollection is that fellow member 'SEBSPEED' had made some adapters so you can bolt the coil on plugs to the 5 Gen engine. Back when I did the swap however, I asked Seb about these but he was really busy at that time to have them made for me. He and I were going to follow up afterward, which reminds me, I still have to do that.

 

If my memory serves me correctly here, I believe the other VFRD member who also did the 5/6 Gen engine swap was 'MiniCarver'. I hope this was helpful.

[bmart]

But it it "better?" (Like the '89 vs '90 neverending discussion about CB-1s!)

 

Are there any pics of the work or end product?

[Lorne]

On 2/15/2023 at 7:01 PM, Duc2V4 said:

Ironically I don't believe I did a post about it

 

Thanks for the insight into your swap. Probably just wishful thinking on my part, but I can at least fantasize about excising the two shortcomings of the 6th gen.

[Lorne]

13 hours ago, bmart said:

But it it "better?

 

While I have zero 1st hand experience, I had two 5th gens on which I'd totalled ~120K km and now a 6th gen with ~93K km.

My 6th gen has three annoying flaws absent from my 5th gens: a lot vibration in the handlebars, snatchy throttle response, and VTEC.  The vibration is my main complaint, but all three would be solved by swapping in a (good) 5th gen engine.

[Duc2V4]

14 hours ago, bmart said:

But it it "better?" (Like the '89 vs '90 neverending discussion about CB-1s!)

 

Are there any pics of the work or end product?

If that question is for me, I like the 5 Gen engine better, particularly the lack of the chain driven cams. The 2 reasons I did the swap were, the original motor had more than 100k miles on the odo and the engine was starting to burn coolant, not leak externally but actually leak into the combustion chamber, so the engine needed to be serviced/repaired. The other was the cam chain was technically over due for replacement as well, so I took care of both issues with the 5 Gen engine swap. In all honesty, with a Power Commander or Rapid Bike module, the 6 Gens short comings are not as noticeable or really an issue at all IMO, but I still prefer the 5 Gen engine over the 6 Gen. As for pics, I’d have to dig through my photos on my phone because I did take pics while doing the swap.

[Ziffer]

On 2/15/2023 at 7:01 PM, Duc2V4 said:

Essentially, I left ALL the 6 Gen stuff intact, wiring harness, cooling system, even the CPU.

 

You didn't have to change the CPU?!

 

I was just assuming this would be required, along with checking/swapping/re-pinning the connector!

 

Sounds like a relatively easy swap.

[Duc2V4]

8 hours ago, Ziffer said:

 

You didn't have to change the CPU?!

 

I was just assuming this would be required, along with checking/swapping/re-pinning the connector!

 

Sounds like a relatively easy swap.

No CPU change. Here’s where I looked to MiniCarver to what he had done and essentially that’s how he did it too, motor swap only. Happy so far but because of my “little” (haha) medical issue, I can’t strap on a helmet, or let alone drive a car for at least 3 months, I’m might take this opportunity to do some cleaning and polishing of my black beauty while I wait.

[ShipFixer]

I think in @Duc2V4's explanation you see the real answer, which is this is a whole lot of work for two engines that aren't really that far apart, unless you have a real reason to do it.  If my engine was leaking coolant then I also might try a 2000-2001 engine, but I would not shy away from a 6th gen engine.  There's some things that can make the VTEC transition noticeable (my bike was rich for a little bit, etc.) and the ECU has some bad habits for emissions control and mpg.  The RBR covers up both of those where a PC has no way to do it AFAIK.  

 

My 2002 has always been very well behaved except the lean/surge behavior, which was the #1 thing that separated it from the just-expired carbureted generation, especially in long sweeping corners with constant throttle or long straight stretches on the highway.  Riding it back to back with some 2001's in excellent condition even way back in the day before I put 02 eliminators in, the difference in linked brakes and even the tiny bit of fork difference (no joke) was more noticeable to me than any difference in throttle manageability - except for lean/surge.  When I was playing around with all the theories we explored on VFRD on starter sync and runner length back in the day, I "could" make it all slightly bad, but mine has always been good when in baseline.

 

Also worth mentioning when talking about motorcycles with less sophisticated engine sensors and controls than cars of the same vintage, and highly variable material condition status over two decades, putting one 6th gen next to any other 5th gen in 2023 is going to have a wild number of results when it comes to injecting half the amount of gas in cylinders half as big, at twice the Hz compared to cars.  And...notice how many people who are probably very, very good riders here who also do or do not notice the things the ECU is built to do in closed loop mode, which goes to the proprioception part of "does this all work how I think it should work?"  That's wild too, but I have friends who surf waaaay better than me who can't tell the difference between wildly different fin sets.  Anyway, I would go after the other stuff in the two decade old sixth gen motor I have like injector cleaning (observable difference, both in riding and what my RBR thinks in auto tune), starter valve sync, the RBR unit I wish I had two decades ago, etc.  

[voodoo]

I wouldn't mind getting an 8th gen engine in my 5th gen..... 

[Ziffer]

On 2/18/2023 at 1:45 PM, ShipFixer said:

I think in @Duc2V4's explanation you see the real answer, which is this is a whole lot of work for two engines that aren't really that far apart, unless you have a real reason to do it.  If my engine was leaking coolant then I also might try a 2000-2001 engine, but I would not shy away from a 6th gen engine.  There's some things that can make the VTEC transition noticeable (my bike was rich for a little bit, etc.) and the ECU has some bad habits for emissions control and mpg.  The RBR covers up both of those where a PC has no way to do it AFAIK.  

 

My 2002 has always been very well behaved except the lean/surge behavior, which was the #1 thing that separated it from the just-expired carbureted generation, especially in long sweeping corners with constant throttle or long straight stretches on the highway.  Riding it back to back with some 2001's in excellent condition even way back in the day before I put 02 eliminators in, the difference in linked brakes and even the tiny bit of fork difference (no joke) was more noticeable to me than any difference in throttle manageability - except for lean/surge.  When I was playing around with all the theories we explored on VFRD on starter sync and runner length back in the day, I "could" make it all slightly bad, but mine has always been good when in baseline.

 

Also worth mentioning when talking about motorcycles with less sophisticated engine sensors and controls than cars of the same vintage, and highly variable material condition status over two decades, putting one 6th gen next to any other 5th gen in 2023 is going to have a wild number of results when it comes to injecting half the amount of gas in cylinders half as big, at twice the Hz compared to cars.  And...notice how many people who are probably very, very good riders here who also do or do not notice the things the ECU is built to do in closed loop mode, which goes to the proprioception part of "does this all work how I think it should work?"  That's wild too, but I have friends who surf waaaay better than me who can't tell the difference between wildly different fin sets.  Anyway, I would go after the other stuff in the two decade old sixth gen motor I have like injector cleaning (observable difference, both in riding and what my RBR thinks in auto tune), starter valve sync, the RBR unit I wish I had two decades ago, etc.  

 

"proprioception"... Lol, I had to look that word up!

 

Part of why I don't like VTEC is philosophical/emotional. I used to work for Honda R&D of America in OH, so I feel a bit of connection with the company. They had VTEC in cars (yes, I know it functions a little differently) in the mid 90s. I have always considered it to be a good INTERIM technology, until they could develop something better. We're talking about Honda, who at one time was THE provider of engines to the F1 race series. They know how to build an engine. I would have thought by now they'd be on to electric/hydraulic/pneumatic actuation of valves of some sort. Such a system could give you infinitely variable valve timing, duration, and lift.

 

The other thing I don't like about it is the trade off of reliability for MPG. I've heard about chain tensioner issues on the 6th gens. I don't know, but I would guess the VTEC engines pull harder through the low and mid RPM ranges. Still not worth the trade off for me. Plus, I like the biddy, biddy, biddy sound, like I'm in the Jetson's car. 

 

I have a friend I ride with sometimes that rides a 6th gen. He loves it. To each his own.

[Ziffer]

On 2/18/2023 at 1:57 PM, voodoo said:

I wouldn't mind getting an 8th gen engine in my 5th gen..... 

 

Well, opinions vary... 

 

I know where I can get a 5th gen engine (actually, the entire crashed bike) pretty cheap. I started wondering if I could find a nice-ish 8th gen with a blown motor (cuz I like the way they look), and put the 5th gen engine in it. I also figure the 8th gen probably has an upgraded frame and suspension. Obviously, it has more modern electronics, but that doesn't matter to me much.