98 VFR800 motor upgrade question

Haha you right

 

I hear ya TW, and that was a benefit of the older PC, the newer ones don't have that function as they don't integrate to the ECU they found it easier to tap into the EFI cabling, as then one unit with a different harness per bike is Plug & play & many from the same manufacturer use the same EFI supplier so use the same connectors, so one size nearly fits all by brand !

That said I'm sure in my research that some old thread showed a PC equipped bike that was really bad & when the operator looked at the PC settings the advance was set to maximum, they took all PC advance off & the bike ran sweet as a nut. So there may be some gains from ignition advance, but that would have to be dyno tested !

 

I read that same article. He was running 87 octane. And 4 degrees advance at idle on 87 octane is a big no no. Of course it ran horrible. I would like run 93 octane and bump up the timing from say 8000 rpms wide open and up.

(ninja edit: 2500-8000 rpms is where the timing needs to be advanced)

 

I'm wondering with you guys running the cbr1000 coils, could you use a power commander ignition module designed to run on the cbr1000 too?

 

This details that 4 degrees of advance caused issues Piston Powered Passion - Present Bikes - Power Commander II

 

i would leave the head bone stock. maybe freshen it up if it was high miles though.

stock rods, they are over built anyways.

stop looking at pistons on ebay, grossly overpriced

the throttle bodies are large enough to handle that power stock.

the machine work would add to the cost but it still would not be a significant increase.

all im saying is the VFR has potential, stop selling the motor short. timing and ECU mods alone with a 93 octane curve would make a significant boost in HP. let alone adding compression. heck not doing a stroker, just doing high comp pistons, ECU tune, ignition and run 93 oct i bet 130 (similar to the bioblade) could be possible.

 

i think you guys are missing the point that 130 hp isnt going to happen while breathing out a simple slip on and 98 header combo. I've got a motad on mine, and ill be the first to say its a bull shit mod (purely weight savings). a custom header with 35-38mm steped primaries, where the front bank merges together after stepping up and the rear does the same. and they are kept separate the whole way, or at least to the very end. or a 2bros full system to say the least.

 

yup, exhaust would need work. their is an exhaust shop here in town that will build an exhaust for ANYTHING as long as you bring him the flanges. crazy thing is the entire custom system, (you would have to bring in a can to cuz its a bike) might run 200$. exhaust sytems are cheap for HIGH quality work if you avaoid having a name stuck on it.

head work is kind of opinionated also, say 'do it right' is dependent on what you are doing. if you are JUST going high compression and not changing anything else, then you are not changing the amount of air entering or leaving the engine, thus, head work may do more harm then good. if you were to go high comp, add a big bore and stroke, then you might be outside of the design of the stock head and some shaping could help. otherwise if you bench flow a head and dont change the amo00unt of air going through it then you kill air speed. on my cbr600F2 we were actually experimenting with making the port sizes smaller to help add air speed at low RPM (low rpm in a small I-4 is like around 8000)

bench racing the vfr800 looks like a major under rated engine. the bike in general has racing lineage and it shows, but its been muted and tamed. i would love to do a build of a 5th or even 6th gen. unfortunatley ive got a DSM getting a 16g stroker build to do, a 3rd gen eclipse getting a stroker high comp 6g74, and an ascot 500 air cooled high comp build, all in front of this. so the vfr is probably just gunna be 'on paper".

 

It's interesting to see some statements, that whilst apparent common procedure really should be preceded by research.

The 1998 & Motad headers are the same diameter as the RC45's & good for 130hp flow.
Race exhausts are known to kill the power on the 45, unless it has race cams & pistons.
So no need for a bigger bore exhaust.

The heads & valves are good for 160hp in WSBK trim, so that is not a restrictive area.
So no need for head work unless you are after a race engine.

I've spent 3 years researching this & made my cams for a road bike. My power target is 120rwhp. Combined with my weight savings this is a 50% power to weight increase !!!

 

ARE YOU 100% THE RC45 AND THE 1998 VFR800 HEADERS HAVE THE SAME DIAMETER PRIMARIES??
i think it also has a lot to do with the way they merge together too. like how on the rc45 the front two come together and the rear two come together. then those two come together at the very end right before the silencer.



(ninja edit: 1998/1999/motad/delkevic/etc headers are 31mm in dia, +2000 headers are 28mm in dia, rc45 headers are 35mm in dia but with dents, Two Brotthers/Erion Racing are 35mm in Dia with no dents. Two brothers headers have now proven to make power)

 

you are correct in that the hrc exhaust at 38mm start to finish is too large unless the engine is race kitted, but the factory rc45 system at 35mm and full of dents leaves a lot of room for improvement. the idea is to combine the best of both worlds. start the primaries at 35mm and slowly step up to 38mm. this results in about the same bottom end as the factory system and almost as much top end as the hrc and termi systems.

 

Oh my what have we here. Hmmm I'll comment later...

 

out with it

 

Have a look here, Force-V4 :: Index , most of the research has been done for the RC45, including power gains with various changes. I paid to join the forum to read the HRC stuff & more indepth info. The 45 does NOT gain much if anything more than the same changes to a VFR800. The 800 is short on valve duration for high rpm power. My cams addressed some of that.

The 45 has a 360 degree crank & that dictates its firing order. the 800 has a 180 degree crank which means an odd firing order. And this determines which headers can be merged for a 4-2-1 system.
Various people have tried various exhausts on the 45, including a hand build multi taper system much like what is being suggested here, but the increase in power after all the work is very limited, compared to a slipon giving 6-8+hp & the full systems give another 2-4 not really worth the effort of replacing all the headers unles syou are racing where every HP counts !

So improving the intake is the best area to concentrate on IMO. I expect shorter velocity stacks to move the peak torque above 9500rpm, that will boost the HP figure & allow the engine to breath a bit better at higher rpm.

Keep the ideas coming, but it would be nice if some others actually did some WORK, as oppsoed to spouting tuning talk with no evidence to back it up. My dyno figures speak for themselves from work that has actually been done ! That plus the Dyno house I use is a proper racing outfit & do all of Fast Bikes magazine dyno testing too !

 

i was going to mention the odd firing order determines the order of merging the exhaust.

will also mention my experience is more tuned to other vehicles.

along that note, when building a STREET vehicle most of the time the sheer peak HP number is of less importance, so like on a rev happy engine more often we actually lengthen the velocity stacks. this smooths the response out and adds to the mid-range.

another thing that helps acceleration and has not been touched on, cut some mass off of the flywheel. that dead slug of weight can be shed and make NOTICEABLE gains in acceleration.

also a cbr600f2 (utx9 compatible) battery can be used, direct drop in, and sheds a few pounds off the bike, if the lithium packs are out of your price range.

 

"so like on a rev happy engine more often we actually lengthen the velocity stacks. this smooths the response out and adds to the mid-range."
Yep & I think Mr Honda leaned a bit to far to the touring side on this, hence my planned shorter ones !

"another thing that helps acceleration and has not been touched on, cut some mass off of the flywheel."
The generator will be puled off my spare engine over christmas break to see if any of the newer lighter rare-earth magnet ones will fit instead, that will save a kilo or possibly more of the cranks rotaional weight !

"also a cbr600f2 (utx9 compatible) battery can be used, direct drop in, and sheds a few pounds off the bike, if the lithium packs are out of your price range."
Made my own from commercial cells, standard Lead battery is 4.35Kg, my LiFe one is 1.4Kg, so nearly 3Kg lighter.

All good stuff, keep it coming.

 

You guys have really taken this thread off course with the lack of personal insults and chest beating.
But, it's nice to see all the info being submitted and discussed. :wink:

 

Some of that may be due to the latest legislation in effect in Colorado and Washington.