Vfr848Rr Anyone ?

[Veefer800Canuck]

That is brilliant! Love the idea of a custom copper head gasket!

[JES_VFR]

I agree the R/S ratio has nothing to do with the bore. My points are that the larger the piston diameter the more it will exaggerate the rock by moving a greater distance at the edge of the piston for the same degree of piston rock when compared to a smaller diameter piston; second, when the Honda engineers designed these pistons they know way more than I do about piston rock and they specifically design the skirts, rings & landings, and piston geometry for specific applications and using them for alternative applications may have unforeseen complications.

Okay, Now that makes sense. So what you really want then a piston with larger bore, nearly the same deck height, perhaps less dome, the same ring and pin, but a shorter skirt, reduce the travel when the piston rocks.

If anyone knows the con-rod length of the 5th gen VFR a quick calculation will tell if these pistons will be more or less stable in the cylinder bore than their originally designed application. I'm hoping more stable... that will open up more opportunities!

Well, all the strokes of the other honda engine that I was considering pistons from have longer strokes, but again we would need the conrod lengths. Surely somebody, like Carrillo would have them their rod catalog..

Where are you finding all the dimensions for the honda pistons, I keep just finding bore, rings and pin measurements.

I believe the whole 8mm cylinder thick sleeve is made of aluminum Powder/Metal composite so boring it out won't remove any coating. It is a mixture of argil, aluminum oxide and graphite. The manual states that as long as heat is controlled they can be "re-bored in the same manner as conventional sleeves".

Your right, I was mistaken thinking they were NikaSil.. Still, How much of that 8mm thick sleeve can you safely remove in boring, before the sleeve itself is too weak?? So the question I have is at what point, do you have to bore out the case, removing the original sleeve and adding clearance for another larger sleeve. That's a question for a company like Millennium..

PS: A quick calculation based on our 48mm stroke shows that as long as the 5th gen VFR con-rods are longer than 93.4mm C-C than these 929/954 pistons will be more stable in the new cylinder bore than in their engineered application... does anyone have a 5th gen con-rod measurement? Seb... Veefer... Bueller?

Can you show us your calculation please, because in my mind that would be a very long rod. Now maybe I'm missing some large piston height or something.

[JZH]

FYI: VFR400R NC30 redlines at 12,500rpm. CBR400RR redlines at 13,000rpm. Both are listed as having 55x42 bore/stroke (or stroke/bore?), and make the same horesepower. Interestingly, they use the same piston part number.

Ciao,

[Switchblade]

If you watch this clip from 1:20 onwards, you can tell that the HRC RC45 was NOT a 750. They were reportedly 870 or thereabouts and it obviously has some power , because it is pulling past a race prepared R1. (note the dual exhaust on the RC45)

Poor Joey but he had a great life yeah R's1 paid the price that day for sure , Timmy right it obvious what you can do with the 870cc

[Rush2112]

Where are you finding all the dimensions for the honda pistons, I keep just finding bore, rings and pin measurements.

Can you show us your calculation please, because in my mind that would be a very long rod...

I found the service manuals online somewhere along the way. I have the VFR manuals and the CBR929 manual I downloaded. The parts numbers are from RonAyers.com,

http://www.ronayers.com/

The bike model info I get from BikeZ.com. It has specs for most bikes from 1970 on

http://www.bikez.com/brands/index.php

CBR 929/954 have a 105 mm connecting rod (I measured center to center (C-C) the one in my garage) and a 54 mm stroke. This gives a Rod length to Stroke ratio (R/S) of 1.94.

The 5th gen VFR has a 48mm stroke and it needs a R/S > 1.94 for the pistons to be more stable in the new bore. Therefore,

R/48 mm > 1.94

= R>(48mm*1.94)

= R>93.12 mm, (or 93.4 mm if all the decimal points are left in the calculator and my actual CBR929 con rod measurement was 105.025 mm).

That's a little longer than 3.6" con rod length measured C-C. I don't consider that to be a very long rod...

...YRMV

[JES_VFR]

The bike model info I get from BikeZ.com. It has specs for most bikes from 1970 on

CBR 929/954 have a 105 mm connecting rod (I measured center to center (C-C) the one in my garage) and a 54 mm stroke. This gives a Rod length to Stroke ratio (R/S) of 1.94.

The 5th gen VFR has a 48mm stroke and it needs a R/S > 1.94 for the pistons to be more stable in the new bore. Therefore,

R/48 mm > 1.94

= R>(48mm*1.94)

= R>93.12 mm, (or 93.4 mm if all the decimal points are left in the calculator and my actual CBR929 con rod measurement was 105.025 mm).

That's a little longer than 3.6" con rod length measured C-C. I don't consider that to be a very long rod...

...YRMV

The rod length you talking about s what you hope, but that is based on your using the 1.94 R/s ratio from the 929

I was thinking that was a long rod based on the compactness of the VFR block and the deck height limit. My last couple of bore and stroke engine upgrade were car engines where a R/s ratio of better than 1.6:1 was considered good.

I remember having to choose a very short piston with the pin bore literally up into the oil ring groove, just to be able to run a long enough rod to hold a 1.67:1 ratio.

FWIW, I can't find a C-to-C length for the VFR800 rod.

IIRC the 870cc Big bores done by TTS and Dynamohumm all worked fine on the stock VFR800 rods. Now going beyond that might increase the chances of piston rocking, but your not going there.

I look forward to finding out the vfr800 rod length, but unless it is really close to 1.6:1 I'm not going to panic.

Heck I still don't have the info on how big a sleeve I can put in the VFR800 cases.

[number9]

That video wasn't the IOM TT, it was the Ulster GP.

[CornerCarver]

OK, so to summarize:

1. what is the displacement of the 5th gen engine when fitted with 954 pistons?

2. what is the displacement of the 5th gen engine when fitted with CBR 1000 pistons?

3. Do the 1000 and the VFR share wrist pin heights as the VFR and 954 do?

4. What was the displacement of the Dynammo Humm kit, 870cc? If so what bore diameter did they employ and did they bore the MMC liners or replace them?

5. Anyone known to have played with the stroke of the 5th gen engine?

[Rush2112]

OK, so to summarize:

1. what is the displacement of the 5th gen engine when fitted with 954 pistons?

848 cc

2. what is the displacement of the 5th gen engine when fitted with CBR 1000 pistons?

pre-2008 = 848cc

2008 - 2012 = 871cc

3. Do the 1000 and the VFR share wrist pin heights as the VFR and 954 do?

Don't know

4. What was the displacement of the Dynammo Humm kit, 870cc? If so what bore diameter did they employ and did they bore the MMC liners or replace them?

I think it was 870cc, IDK but boring out the 8mm MMC liner by 4mm would be seriously reducing it's strength.

5. Anyone known to have played with the stroke of the 5th gen engine?

I contacted A.P.E. and they could stroke the crank but their equipment was only set-up to balance I-4 cranks and wouldn't work on a V configuration. Balancing would have to be done elsewhere, I tried to see if someone doing Ducati cranks could do it with no luck. That was last year and they may have updated equipment since then.

[spinalator]

Not sure if any of the people here are involved in the thread over at bikers oracle in the UK:

http://www.bikersoracle.com/vfr/forum/showthread.php?t=123379

Also here is the internet snapshot of Dynamo Humm from 10 years ago, look at the shop rates!!! They are 310% higher now locally!

[spinalator]

Here is a 94-97 750 big bore on the dyno, he had a staintune high mount, Ducati rear wheel, and likely a jet kit:

Different bike, 1995 750 torque curves:

Sorry for the distractions, I find these things fun to dig up.

[CornerCarver]

Thanks for the link but not much more info there, unless you are looking for Kawasaki dyno chart...

Here is a 94-97 750 big bore on the dyno, he had a staintune high mount, Ducati rear wheel, and likely a jet kit:

Screen Shot 2013-08-01 at 12.48.23 PM.png

Different bike, 1995 750 torque curves:

Screen Shot 2013-08-01 at 12.51.04 PM.png

Sorry for the distractions, I find these things fun to dig up.

Screen Shot 2013-08-01 at 12.54.13 PM.png

Now these are interesting...if I could get 120hp at the wheel by dropping CBR1000 pistons into my spare 5th gen engine I would be very pleased with my track bike...

[Mohawk]

Cylinder Sleeve Info

http://www.vfrdiscussion.com/forum/index.php/gallery/image/64997-vfr800-cylinder-sleeve-info/

Hey Rush thanks very much for that it's the one bit of info I had not managed to find ! So the 929 74mm bore looks like the max without serious work.

Cheers

Vfr800 5th gen conrod length is 102mm or 4" as near as damn it ! Measured by yours truly ! So R/S ratio of 2.125.

[Mohawk]

Thanks for the 750 dyno info. Running those torque numbers shows that that is a Factory Pro dyno, so a DJ figure would be 133hp.

So assuming the same dyno for VFR870 that showed 120hp, then a DJ figure would be 138hp, due to the lower rev max torque figure & the fact that the engine probably had no other tuning.

From what I gather that 870 used 76mm pistons & had the MMC completely bored out & 2mm SS liners inserted. So the physical maths is as follows. STD bore = 72mm, cylinder wall thickness = 8mm, so 72+16mm=88mm. So an 870 would be 88- (76+4=80)=8mm or 4mm cylinder wall left !

Now I've seen those MMC cutaways, I can workout the thickness on my spare engine, I'll report back after the weekend.

Don't use copper gaskets, when Cometic in the US can make MLS like the originals, just supply an old one as a template & ask for a larger bore !

[Mohawk]

Options ?

4. Have made or modify standard head gasket to fit pistons.

Remember that the gear-driven cams don't leave a lot of room to move with different thickness head gaskets.

The Gaskets Need a Bigger hole in the middle for the pistons, nothing else, same thickness as stock ! :) A cold 929 piston just fits in the stock gasket, but those forged slipper pistons expand a lot so it won't fit when hot. If you have to bore through the MMC liner, then it will become a Nikasil coated bore, the other concern is if the MMC is not thick enough, then you would have to go to a bigger bore to remove all the MMC, then the question is does that leave enough meat in the unsupported liner ?

[CornerCarver]

In a week or so we will tear down the spare 5th gen engine. If anyone wants any pics or measurements please let us know...

[Grayv3]

I know I'm late to this but has the st xx00 or vfr1200 piston or crank specs been checked? It would seem natural to stick with the v engine family.

[VFR4Lee]

Couldn't say where she's coming from,

but I just met a lady named Dynamo Humm.

She strolled on over, said look here bum,

I gotta $40 bill says you can't make this thing run.

Ya just can't do it.

Suggest you whip off its bloomers and stiffen your thumb and apply rotation as needed.

With apologies to FZ.

[Guest]

What? Does it work?

We need more HP from the best engine and not a hand grenade.

Can this be done????.

[JES_VFR]

In a week or so we will tear down the spare 5th gen engine. If anyone wants any pics or measurements please let us know...

Yeah I want to know the cylinder to cylinder measurement,

as well as the total depth to the cylinder liner.

Hey Rush thanks very much for that it's the one bit of info I had not managed to find ! So the 929 74mm bore looks like the max without serious work.

Cheers

Vfr800 5th gen conrod length is 102mm or 4" as near as damn it ! Measured by yours truly ! So R/S ratio of 2.125.

870cc big bores have been done, I just don't know how to get in touch with the true source Brian Law..

I would think that either Brian worked out that 6mm MMC sleeve walls were still thick enough or He replaced them with them with tougher steel sleeves 6mm thick.

What I'm thinking is what if someone was willing to bore the cases for sleeve larger than 88mm in diameter, say 92 mm?

Even if you stay with 7mm walls (the allowed overbore thickness of the mmc liners) your talking about being able to fit 78mm pistons.

That puts you over 917cc's.

That's getting into a very over square engine. In fact it is so far oversquare, that I'm starting to think about the rods and a stroke increase again.

Now with the information about length of the rods, and total length of the cylinders, a stroker kit could be put together with a crank and alternate length rods.

[Mohawk]

JES, the cylinder wall thickness is 8mm, so a 72mm bore + 16mm walls, means 88mm to remove the cylinder. The spacing between cylinder walls is 5mm, or 93mm piston centre to piston centre. The problem with the VFR cylinders are mainly that the cylinders are NOT full depth, the bearing supports intrude in to the bottom of the bore, so unlike a straight 4 you can't just bore straight through & fit a steel liner. I'm sure a step fit could be made to allow a steel liner to work, but the CBR pistons are NOT designed to work in a steel liner, plus the engine & cooling systems are NOT designed to work with a steel sleeve !

[belovian]

In a week or so we will tear down the spare 5th gen engine. If anyone wants any pics or measurements please let us know...

Yeah I want to know the cylinder to cylinder measurement,

as well as the total depth to the cylinder liner.

Hey Rush thanks very much for that it's the one bit of info I had not managed to find ! So the 929 74mm bore looks like the max without serious work.

Cheers

Vfr800 5th gen conrod length is 102mm or 4" as near as damn it ! Measured by yours truly ! So R/S ratio of 2.125.

870cc big bores have been done, I just don't know how to get in touch with the true source Brian Law..

I would think that either Brian worked out that 6mm MMC sleeve walls were still thick enough or He replaced them with them with tougher steel sleeves 6mm thick.

What I'm thinking is what if someone was willing to bore the cases for sleeve larger than 88mm in diameter, say 92 mm?

Even if you stay with 7mm walls (the allowed overbore thickness of the mmc liners) your talking about being able to fit 78mm pistons.

That puts you over 917cc's.

That's getting into a very over square engine. In fact it is so far oversquare, that I'm starting to think about the rods and a stroke increase again.

Now with the information about length of the rods, and total length of the cylinders, a stroker kit could be put together with a crank and alternate length rods.

well John your in luck. I know Brian, grew up with his boys. he lives about ten minutes from my house. I also know Bruce Allnut the mechanic that worked with Brian when he had dynamohumm. I've brought up a few of these threads to him in the past, explaining there is still interest in the projects they we were working on. But that whole endeavor ended kind of bad. there seemed to be little interest on his part. But I will give it another shot and see what he says. I'll try and get him to read some of the threads. Who knows I might be able to convince him to join for some Q&A (don't hold your breath) .

Jess

[daword2011]

sub'd :)

[Mohawk]

well John your in luck. I know Brian, grew up with his boys. he lives about ten minutes from my house. I also know Bruce Allnut the mechanic that worked with Brian when he had dynamohumm. I've brought up a few of these threads to him in the past, explaining there is still interest in the projects they we were working on. But that whole endeavor ended kind of bad. there seemed to be little interest on his part. But I will give it another shot and see what he says. I'll try and get him to read some of the threads. Who knows I might be able to convince him to join for some Q&A (don't hold your breath) .

Jess

Hi Jess, even if you can extract from him how they got the 76mm bore & what was the max possible staying within the MMC liner, that would save me destroying a crankcase to find out !

Thanks

[CornerCarver]

thanks Jess, hope you are successful. beer's in it for you.