Howdy all; I recently got the itch to purchase a spare motor for my 5 th gen . My plan is to take the engine apart and if need be get the .25 mm oversize Honda pistons, bore the cylinders and hone them and re-ring the engine. Here is what I dont know. Someone told me the fifth gen. engine block has a special plating on the cylinders and the proper way to bore them is to remove the plating ,cut the cylinder walls to match the piston size,then get the block re-plated and final size the block by plating then honing to match the pistons. For those of you that have experience with this ,what parts of my statement are true and what part of my statements are false. Also I was speaking to a shop that is supposed to be well versed in the Honda VFR motor and they told me that the Honda VFR block was sleeved and didnt have special plating on the cyl. walls and could be bored just as any standard motor. So now I dont know what or who to believe. Could one of you voices of experience steer me in the right direction! thanks eddie
�470.00 [image: ttsJE%20LOGO.jpg] H0839 [image: jelogo.gif] JE Pistons supply the highest quality forged pistons on the market. Most of our kits come complete with Pistons, Pins, Circlips and Rings. Standard bore piston kits do not come with piston rings. At TTS we can bore your cylinders, fit sleeves if required, bore and replate plated barrels. We also provide ride in, ride out services. Just bring your bike to us, we will remove the engine, do the work required, refit the engine and setup on the Dyno. Call us on the number at the bottom of this page for a competitive quote. Honda VFR800 837cc Big Bore Kit 74mm Bore, 12.5:1 Compression Ratio 4mm Overbore Size Barrels require bore and hone
Yeah, I know it says 837cc, but IIRC, that is for the VFR750 and is a typo. 870cc is the correct figure for the 800. That's what Dynamo Humm used to sell, but they are out of business.
IIRC, you need to bore the upper case and fit new cast iron sleeves.
Related thread: http://www.vfrdiscussion.com/forum/index.p...467162&st=0&
cant remember for sure about the 5th gen but if it does have FRM liners (fiber reinforced metal) then you can only hone them a little. maybe just enough for the OS pistons but say if you wanted to go with a big bore kit you would have to resleeve them. then you would be looking at big bucks. do some research on honing FRM liners, there is a specific hone and procedure you need to do.
the FRM liners are cool if you dont plan on doing anything with the motor. but if you wanna go big bore, their a pain in the a$$. my prelude has them and with 70,000 miles on them the bores are silky smooth with no signs of wear, i have it apart right now cause my timing belt tensioner failed ($77 part) and destroyed the valve train. sad.gif
i contacted JE last year and they said they didnt have them but could make them for something like a $1000 per set. sad.gif i think tts had a run of them made up.
ROUSE, Aug 14 2008, 04:19 PMcant remember for sure about the 5th gen but if it does have FRM liners (fiber reinforced metal) then you can only hone them a little. maybe just enough for the OS pistons but say if you wanted to go with a big bore kit you would have to resleeve them.
The bike's cylinder sleeves are now a composite created by impregnating ceramic and graphite into high-pressure-formed, sintered-aluminum powder. The composite sleeves are more wear-resistant than the antique steel ones. Also, the pistons have been redesigned and sport LUB-coat coatings on their skirts, which interrupts possible friction at the intense interface between them and the cylinder walls.
here is the bore honing procedure for FRM cylinder liners.
1. measure the cylinder bores, hone the cylinders and remeasure the bores.
2. to hone the cylinder bores, * Use only a rigid hone. * Honing Stone: GC-600-J or finer stone (for nonferrous metals) * Pressure: 200-300 kPa (2-3 kgf/cm2, 28-43psi) * Hone RPM: 45-50 rpm * Honing thickness Less than 0.02 mm (0.0008in) * Do NOT hone more then 20 cycles * Honing Lubricant: Oil Type * Honing Pattern: 60 Deg Cross hatch. * Clean the Honing Stone every 5 cycles.
3. When honing is complete, thoroughly clean the cylinder block of all metal particles. Wash the cylinder bores with hot soapy water, then dry and oil immediately to prevent rusting. Note: Never use solvent, it will only redistribute the grit on the cylinder walls.
4. If scoring or scratches are still present in the cylinder bores after honing to the service limit, rebore the cylinder block. Note: some light vertical scoring and scratching is acceptable if it is not deep enough to catch your fingernail and does not run the full length of the bore.
837cc is correct for VFR800 as well as VFR750, IIRC; Dynamo Humm actually sourced its 837cc piston kits from TTS (yes, made in the USA, exported to the UK and then imported into Canada--not terribly efficient!). Recognising this, and the limitations inherent in the TTS design, Brian Law (then proprietor of Dynamo Humm) took it one step further than TTS and had his own 870cc pistons made (I think also by JE). JE won't sell you any 837cc pistons unless you provide them with the specs--the specs provided to them by TTS belong to TTS.
I once had an infamously heated exchange about this whole piston sourcing thing with Brian on the VF/VFR List, after which we eventually became friends (well, friendly--I never did meet him in person). The interesting thing is, though, that if Dynamo Humm isn't in business any more (and if Picotte Performance doesn't sell big bore kits), it may be that the 870cc piston design could become available to other people? I have no idea who owns the 870cc piston spec now...
Of course, you'd still have to deal with the sleeve issue and the gasket issue, so maybe this is a non-starter--especially if a certain supercharger kit ever becomes available!
(VTEC , rapid bike, O2 eliminators, all valves working from 1 RPM till..., titanium exhaust, Repsol fairing, CBR1000RR front forks, check, check, check, check,check,check,check) .
JZH, Aug 15 2008, 04:22 PM837cc is correct for VFR800 as well as VFR750, IIRC; Dynamo Humm actually sourced its 837cc piston kits from TTS (yes, made in the USA, exported to the UK and then imported into Canada--not terribly efficient!). Recognising this, and the limitations inherent in the TTS design, Brian Law (then proprietor of Dynamo Humm) took it one step further than TTS and had his own 870cc pistons made (I think also by JE). JE won't sell you any 837cc pistons unless you provide them with the specs--the specs provided to them by TTS belong to TTS.
I once had an infamously heated exchange about this whole piston sourcing thing with Brian on the VF/VFR List, after which we eventually became friends (well, friendly--I never did meet him in person). The interesting thing is, though, that if Dynamo Humm isn't in business any more (and if Picotte Performance doesn't sell big bore kits), it may be that the 870cc piston design could become available to other people? I have no idea who owns the 870cc piston spec now...
Of course, you'd still have to deal with the sleeve issue and the gasket issue, so maybe this is a non-starter--especially if a certain supercharger kit ever becomes available!
Ciao,
End of thread · 10 posts recoveredWayback Machine snapshot 18 Aug 2008
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