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People have/can/will achive higher numbers than your 78/48 with just cams, timming, carb mods. Considering the HP/$ ratio. You have some expensive horses in there, buddy.

I mean, you can make a SV750 run reletively safely @ below, say, 75HPs. But why go through all the trouble/$ on boring out the cylinders, when keeping the stock slugs will achieve the same goal. Unless you just want to have a bored out engine for the sake of having a bored out engine. :dontknow:

EDIT: If you are looking for a fatter TQ curve,then this might work using a set of big bore pisons with cams that are profiled accordingly. This is all theoretic still, since it has not been done yet. On top of that, larger pistons will increase the load on the crank. You got to be real conservative with HP expectations if you deside to go with the big bore on the 650 block.
 

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I'm also aware of the extreme variances from dyno to dyno, so the claims / comparisons between bikes on different dynos/ different days /different operators, are not very reliable. But regardless of that, I do know that the driveability with the increased torque is real. I had a strong running stock motor to begin with and this one is definitely stronger. If you look at my post again, you'll see that I commented that the bike is still running rich, so there's still horsepower to be gained. I'm NOT DONE WITH IT YET!
I started racing bikes 27 years ago, and I've learned a few things along the way, I'm glad to learn from others, and I like to share what I've learned but you don't know what I paid to do the work and you don't know me, so don't insult me by calling me buddy like I'm some sort of clown.
 

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tgold said:
I'm also aware of the extreme variances from dyno to dyno, so the claims / comparisons between bikes on different dynos/ different days /different operators, are not very reliable. But regardless of that, I do know that the driveability with the increased torque is real. I had a strong running stock motor to begin with and this one is definitely stronger. If you look at my post again, you'll see that I commented that the bike is still running rich, so there's still horsepower to be gained. I'm NOT DONE WITH IT YET!
I started racing bikes 27 years ago, and I've learned a few things along the way, I'm glad to learn from others, and I like to share what I've learned but you don't know what I paid to do the work and you don't know me, so don't insult me by calling me buddy like I'm some sort of clown.
Simmer down, now. He's just trying to get a better understanding of this whole issue, just as we all are. As Ruefus said, Zoran has forgotten more about SVs than you and I will ever know. I'm willing to believe him when he says that the bottom end will grenade as it passes 85hp.

The verdict on boring out the SV engine seems to be that it makes very little sense from a HP/$$$ perspective. It's your bike, though, so do what makes you happy.
 

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Guiswa said:
Simmer down, now. He's just trying to get a better understanding of this whole issue, just as we all are. As Ruefus said, Zoran has forgotten more about SVs than you and I will ever know. I'm willing to believe him when he says that the bottom end will grenade as it passes 85hp.

The verdict on boring out the SV engine seems to be that it makes very little sense from a HP/$$$ perspective. It's your bike, though, so do what makes you happy.
I am quite happy with the low 80's for hp from my SV which was my target, but I also know that the torque is going to be better simply because of the increased surface area of the piston.
The cost per hp isn't necessarily a good comparison either. Percent gain would be a better one. If I had a ZX10 and and gained 15 hp it would be a lot more expensive and less significant when you look at the hp the bike had to begin with when compared to the gain with an SV.
My bike may blow up. I hope it doesn't. I'l let everybody know whether it blows up or I get good results at the racetrack. ;)
 

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tgold said:
so don't insult me by calling me buddy like I'm some sort of clown.
:eek: When did calling someone 'buddy' become an insult? How much did you pay to get the pistons installed? Labor and parts?
 

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solidONE said:
:eek: When did calling someone 'buddy' become an insult? How much did you pay to get the pistons installed? Labor and parts?
Grasshopper ... the answer to your question lies in your eagerness to
jump into a discussion in which you have some knowledge but no experience.

Time and time again, it happens when you tell people how to do something
when they have been doing it for longer than you have been alive.

I have pointed this out to you several times. You only get respect when
you give it. You don't get it by patronizing people that know more than
you do.

You are obviously intelligent. Learn to temper that intelligence with wisdom
and experience. That takes time. TIME is This I Must Earn.

Again, step back from the keyboard and count to a hundred.
 

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Currently said:
Grasshopper ...
:rollingeyes:

You guys misunderstand me.

tgold said:
I am quite happy with the low 80's for hp from my SV which was my target, but I also know that the torque is going to be better simply because of the increased surface area of the piston.
Do you have the dyno graphs for those pulls on the dyno? I'm sure the 'big bore' and 'low-end power' SVRiders will greatly appreciate if you post it up.
 

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solidONE said:
:rollingeyes:

You guys misunderstand me.

Do you have the dyno graphs for those pulls on the dyno? I'm sure the 'big bore' and 'low-end power' SVRiders will greatly appreciate if you post it up.
I'll have to scan them in so it may be a day or two before I get it done.
 

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tgold said:
I'll have to scan them in so it may be a day or two before I get it done.
Sweet! :thumbsup: Did you ever make pulls on that dyno before all the engine work? That would be cool if there was a before and after big bore comparison.
 

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Well, I'd have to call the the first race weekend with the 677cc kit a success. I did a dyno run Friday morning to confirm that the jetting was ok and it was ok but I dropped about half a horsepower from the previous run, so I was at 77.5. I have the original stock (dirty) air filter, so I plan to replace it with a BMC or pod filters and recheck the jetting and expect it to breathe easier and gain back an hp or two.

On Saturday, the only scare was when I downshifted 1 gear too many during practice and I thought I might have floated/bent a valve. It turned out to be ok. I definitely had the strongest SV at the track and pulled off a monster holeshot from the fourth row into 4th place for the half hour mini-endurance. By the second turn, I was thinking podium when a guy ran up the inside of me and took me off the track with him and I must say thankful that I was able to keep the bike up while going through the grass at about 60mph. I got back on the track and procedeed to put my head down and get back a bunch of spots that I lost, then I pitted and sent my race partner went out for some practice laps, then he gained some spots too. I don't remember where we finished but it didn't matter because we were using the 1/2 hr race to confirm that the bike was ok. It turned that we had overfilled the tranny and the bike was probably inhaling a little oil through the filter which made it hiccup. The bike was fine and we then got ready to start the 3 hour endurance. We ran in first and second place for over half of the endurance and the motor worked awesome. It's nice to be able to use the motor to hang with or pass somebody and be able to conserve your energy by not having to push so hard in the in the corners. I even got a couple of little power wheelies when I would get a good drive out of some of the corners. And we didn't baby the motor either. My buddy did crash about 1hr 45 min into the race while we were in second place, but he's ok and we can fix the crash damage, so no big deal except i'll have to save my podium speech for another day! So far, with the 1st trackday and the 1st race weekend, I have approx 6-7 hard hours on the motor and it has run great and I hope that it stays that way.
I'll try to get the Current dyno charts up soon.
 

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Did you do the cams at all? Are you running stock cams?
 

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Oh yeah, I got a used set off ebay for $50.00 and put them in. Forgot that, Doh! BTW Zoran's pics of the cam markings made it super easy to do. Thanks to TWF for that and Greg Spears for the motor building advice.
 

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My old roommate built a '01 SV with modified stock crank, big bore kit, ported heads, Megacycle cams, and stock carbs properly jetted with an airbox mod to increase volume and the bike put 88HP to the rear wheel. He raced in three different sprint classes in the CMRA in '04-05. He won all three classes both years without blowing the motor. These motors can be built to be reliable but the devil is in the details -tgold is spot on.
The older carbureted motors are stronger than the fuel injected ones. From what I have read in Roadracing World, Suzuki made a production change to the motor when it was updated for fuel injection. They eliminated the trust washer to set crankshaft end play. This is not to say the carbureted models won’t break but the will definitely last longer on average than the fuel injected motors if endurance raced.
One trick to extend the life of the motor my old roommate did was to remove every other magnet from the flywheel. This helped the motor spool up faster but also reduced the harmonic stress on the end of the crank where they usually break. Of course he had no charging system and during a sprint race the bike was running of the relocated battery only. Sprint races are short enough to do this. This guy was not a trust-fund baby. He did the research, spent the money where it counted and built his own motors in the garage we shared on a non-union aircraft mechanic’s modest paycheck. (no sponsors). He went through the whole motor once a year and freshened up the top at the half-way point during the racing season. During the whole-motor rebuild he usually just replaced rod bearings, and the cam chains.
Obviously, a street bike is not going to endure constant red-line shifting, hard downshifting and launches like a race bike but the same care in building the motor is required. If money is no object then Falicon has 1mm & 2mm billet stroker cranks with matching connecting rods, JE, Wiseco, BRC, Arias, Ross and others make or can make the big bore kits and Carrillo makes some really nice connecting rods. But where does the insanity end:)
 

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My old roommate built a '01 SV with modified stock crank, big bore kit, ported heads, Megacycle cams, and stock carbs properly jetted with an airbox mod to increase volume and the bike put 88HP to the rear wheel.
What did he modify on the crank? Compression ratio? Stock or slipper clutch?

I'm about to do a rebuild myself this winter. I've have been told that "85" is a magic number for reliability. I still have a couple of more parts to piece to togther before starting the rebuild. I had hoped to yeild around a 85hps with the second gen cam swap, raised compression, port polish and blueprint. It will still have about stock displacement.

You wouldn't happen to know some more detailed specs on your friend's engine, would you? Namely the compression ratio and cam specs. I'm also interested infinding out what did he modify on the crankshaft.
 

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It has been a few years but I believe he sent the stock crank to APE or Falicon for lightening via knife edging and to have it balanced. The knife edging also helps with windage so the weights can slice through oil easier. Magnaflux and micro polish the journals. The stock connecting rods were shot peened & magnafluxed. I am not sure which cam specs he used but they had more lift and more duration. I know he had to experiment with inner valve springs for the new cams. I think the inner springs were stock ones from a GSXR but I am not sure about the details.
Many of these decisions were made to keep the motor legal for the three classes he raced in. If you are not worried about being teched and having to tear down the engine at the track then there are a lot more options. Falicon makes a nice billet crank and their own rods for $2300.
 

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Here are 2 of the 3 Dyno Charts for the 2mm over (677cc) 13:1 pistons & intake cam swap. Sorry I left the chart from the first run at work. It had a similar shape for the hp & torque curves, but eak hp was 74 and peak torque was 44 with dynojet 138 mainjets running Cam2 110 fuel. The second run was 77.89/48 with 136 mains also running Cam2 fuel. The third run was 77.68/47 on a different day with 134 mains, needle lowered one notch and the fuel was VP Hydrocarbons C-12. I think that the change in fuel could easily have been a factor in the slight horsepower loss, especially if there was a change in viscosity between the Cam2 and the VP C-12. The air filter is old & dirty so I plan to remove the airbox & install pod air filters to try and get a little better airflow and bring it up to 80 hp. I also plan to try and stick with Cam2 since it should make jetting more consistent and its easier for me to get.

Funny thing: I did the dyno runs at a Harley shop and a guy brought his 1600cc Ultra Double Wide Glide in to do a dyno run while I was there. We had the same peak hp!


 

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Wow... what is your elevation? I wonder if if you can run premium pump gas with 13:1 cr. I'm sure you still got some power hiding in the engine somewhere. :thumbsup:

The chart on the bottom has a much nicer looking curve than the top. I'm guessing that dip @ around 5.5K~6.5K is going to be there nomatter what... I've seen that "dip" on pretty much every SV650 dyno graph I've ever seen to date. :dontknow:

Awesome info guys! :eek:ccasion14:
 

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Wow... what is your elevation? I wonder if if you can run premium pump gas with 13:1 cr. I'm sure you still got some power hiding in the engine somewhere. :thumbsup:

The chart on the bottom has a much nicer looking curve than the top. I'm guessing that dip @ around 5.5K~6.5K is going to be there nomatter what... I've seen that "dip" on pretty much every SV650 dyno graph I've ever seen to date. :dontknow:

Awesome info guys! :eek:ccasion14:
Only about 520 ft above sea level. Actually the graph is a little deceiving, I think the dip is about the same. I'm not sure why, but they shrank the scale on the 1st graph.

I think that there's a few more ponies in there too, but I'm probably going to wait till winter to do the fine tuning. I'm looking to stay right around 80-82 hp to keep it reliable since I'm mostly endurance racing.
 
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