blackhammer
Forum Mentor
Hey Chuck, i don't know if it's just me, but i can't load up your pics...
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1977 GS750B - my long awaited first bike!
- Thread starter Chuck78
- Start date
Hmmm didn't look like they were there until I signed in, and then I saw them. I wonder what was going on? Limited access to non-registered or non-logged in users?
I've since started using photobucket again to make sharing easier.
That's the latest incarnation since right before AMA Vintage Motorcycle Days weekend in early July. The rebuilt front end with straight triples and fork legs, more compression dampening on the emulators, and a slight bit more preload made a world of difference in the handling, coupled with those amazing Fox Factory Shox that I finally got rebuilt and installed a year later...
Bike is riding better than ever. The mud & dust from the camping area at the racetrack helped me discover that my bike was running slightly lean in some areas, and with a little restriction in those massive air filters, my bike all the sudden was pulling unintended acceleration wheelies without even hitting full throttle from about 10 or 15 mph throttle roll ons! even with the massively wide 280 degrees duration gs750 camshafts that bleed off a lot of compression at low rpms, a cold engine kickstart-only compression test was yielding almost 180 psi on all cylinders, those MTC 10:1 pistons are doing awesome!
I've since started using photobucket again to make sharing easier.
That's the latest incarnation since right before AMA Vintage Motorcycle Days weekend in early July. The rebuilt front end with straight triples and fork legs, more compression dampening on the emulators, and a slight bit more preload made a world of difference in the handling, coupled with those amazing Fox Factory Shox that I finally got rebuilt and installed a year later...
Bike is riding better than ever. The mud & dust from the camping area at the racetrack helped me discover that my bike was running slightly lean in some areas, and with a little restriction in those massive air filters, my bike all the sudden was pulling unintended acceleration wheelies without even hitting full throttle from about 10 or 15 mph throttle roll ons! even with the massively wide 280 degrees duration gs750 camshafts that bleed off a lot of compression at low rpms, a cold engine kickstart-only compression test was yielding almost 180 psi on all cylinders, those MTC 10:1 pistons are doing awesome!
meanwhile, a lot of my old parts and spares are now turning into this, a 78 gs750 for my good buddy Andy who has had nothing but headaches with DOHC cb750's charging system and electricals.
GS1000 37 mm forks, GS1100 aluminum lower triple, dual discs from GS750E parts bike he got for $80. My old MAC exhaust, maybe a set of 2.50&3.50 DID rims next spring. Custom seat coming also. Maybe a 798cc 10.5:1 or 894cc 11:1 engine build next year for it.
The bike was a base model that had Z1 carbs on it that were flooding and overflowing, valves out of adjustment and engine backfiring, which led to the uni pod filters catching on fire and melting all of the wiring on the bike while the bike was still running! Tank got a little messed up, so he still doesn't have a good tank out of the three that we have collectively. we were looking for a titled frame and a wiring harness, but picked up this burnt up bike for $250 and another rusted up stripped down parts bike for $80 to donate the wiring harness, front brakes, and carbs to the burnt bike. and eventually the gas tank that was on the $80 bike also. And then he dumped the rolling hulk of a gs750 engine holder into my backyard, so I now have 3 spare gs750 engines!
Once I get my house rehab done on the new 115 yr old brick fortress, I am hoping to come across a Rickman CR or Predator frame & repro aluminum stretched rsce tank to build up with all of my parts, and maybe upgrade to some late model Honda cartridge forks off a Superhawk that work with the same awesome 296mm CBR900RR floating rotors that I currently run, which are a direct bolt on to GS hubs after drilling the holes out larger. Dreaming... But it would ride light years better than even my current setup that rides awesome, and the Reynolds 531 tubing Rick frames are lighter and stiffer than even GS frames!
GS1000 37 mm forks, GS1100 aluminum lower triple, dual discs from GS750E parts bike he got for $80. My old MAC exhaust, maybe a set of 2.50&3.50 DID rims next spring. Custom seat coming also. Maybe a 798cc 10.5:1 or 894cc 11:1 engine build next year for it.
The bike was a base model that had Z1 carbs on it that were flooding and overflowing, valves out of adjustment and engine backfiring, which led to the uni pod filters catching on fire and melting all of the wiring on the bike while the bike was still running! Tank got a little messed up, so he still doesn't have a good tank out of the three that we have collectively. we were looking for a titled frame and a wiring harness, but picked up this burnt up bike for $250 and another rusted up stripped down parts bike for $80 to donate the wiring harness, front brakes, and carbs to the burnt bike. and eventually the gas tank that was on the $80 bike also. And then he dumped the rolling hulk of a gs750 engine holder into my backyard, so I now have 3 spare gs750 engines!
Once I get my house rehab done on the new 115 yr old brick fortress, I am hoping to come across a Rickman CR or Predator frame & repro aluminum stretched rsce tank to build up with all of my parts, and maybe upgrade to some late model Honda cartridge forks off a Superhawk that work with the same awesome 296mm CBR900RR floating rotors that I currently run, which are a direct bolt on to GS hubs after drilling the holes out larger. Dreaming... But it would ride light years better than even my current setup that rides awesome, and the Reynolds 531 tubing Rick frames are lighter and stiffer than even GS frames!
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blackhammer
Forum Mentor
Thanks for posting updates, you've done a great job on the bike, very well thought out mods.
I found some VTR-1000 (02 superhawk) forks and calipers I can get pretty cheap, no discs though..im thinking about picking them up now after reading your enthusiasm for them instead of using the GK 41s I've currently got..
I found some VTR-1000 (02 superhawk) forks and calipers I can get pretty cheap, no discs though..im thinking about picking them up now after reading your enthusiasm for them instead of using the GK 41s I've currently got..
the 97~06 VTR1000 Superhawk forks are great. A Dunstall-fared GS1000 vintage racer that a local guy modified and restored here in town used those forks by the time he got done with it, which turned me on to them, & I met another guy at AMA vintage motorcycle days from New Jersey that had the same forks on his bike I believe. The springs are typically a little bit soft and the rebound damping leaves a little bit to be desired according to some modern sport bike gurus, but those are easily fixed with Racetech add on parts. for something that runs the CBR rotor that practically bolts to our hubs with the addition of a spacer, having the correct steering stem height, & I believe the same axle diameter, not certain on that, these are a great modern forks for our bikes for a fully adjustable cartridge fork and rotors that will be able to be used fairly easily with the original GS spoked wheels.
also, with the popular Tokico twin pot mod for our bike using the Honda cbr/vfr/etc rotors, the pads only cover about 85% of the rotor surface, by using the Superhawk fork and its intended caliper, you get a pad that has full coverage of the rotor, increasing braking surface area even more. Bonus.
also, with the popular Tokico twin pot mod for our bike using the Honda cbr/vfr/etc rotors, the pads only cover about 85% of the rotor surface, by using the Superhawk fork and its intended caliper, you get a pad that has full coverage of the rotor, increasing braking surface area even more. Bonus.
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if you are running GS wheels, refer to my somewhat comprehensive listing of all rotor donor bikes to get the 296mm rotors needed in the 78 mm PCD bolt pattern for our bikes. I believe I posted it on page 7 or 9 of the "twinpot mod for 78 skunk" thread that is the go to page for information on the ninja caliper and CBR rotor swap.
The 599/Hornet rotors for 2 years or so were the best candidate, as they had nearly everything dead on, including the 22.5 mm offset, greater than most of them. You will definitely need that and then maybe some more spacing still with the Superhawk forks which I would imagine are slightly wider. Have not gotten my hands on a set yet to see what it would take to fit a GS wheel in them, but certainly doable.
blackhammer
Forum Mentor
So I grabbed the forks and calipers/mc before I saw your posts here Chuck, the deal was just too good and I figured I could move them on if I couldn't make them work.
I will read your posts on discs as I need to find a set to use. I suspect I may need disc spacers and new axle spacers to get my spoke hubs to work. But I won't be able to get an idea till I get the forks next week.
I thought I might just use the GK 41mm triples I already have. But I'll have a look and see how the VTR triples work in my gsx frame.
Thanks for your thoughts on these forks, I never would've thought to look for them if I hadn't read your posts.
I will read your posts on discs as I need to find a set to use. I suspect I may need disc spacers and new axle spacers to get my spoke hubs to work. But I won't be able to get an idea till I get the forks next week.
I thought I might just use the GK 41mm triples I already have. But I'll have a look and see how the VTR triples work in my gsx frame.
Thanks for your thoughts on these forks, I never would've thought to look for them if I hadn't read your posts.
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blackhammer
Forum Mentor
Chuck, in case you're interested the VTR triples are about 15mm narrower than the GK ones, even with the 23mm ofset discs i will still need some substantial spacers. Caliper clearance may be a concern also.
We can probably get by with spacing the calipers in slightly as well, but I'd rather take most of it up with spacers behind the rotors. More in the calipers and a fork brace would be a good idea to help stabilize the lowers from twisting forces on the axle.
Custom bullet triples could be made but then the vtr superhawk fork braces wouldn't fit, and we'd need a custom center fork brace piece made. Still, these are some very awesome advanced forks for our bikes, and are fully supported by racetech on cartridge upgrades. So at about 190 triple spacing I'm guessing we'll need 5-10mm on each rotor/hub? Easy spacer to machine up.
Custom bullet triples could be made but then the vtr superhawk fork braces wouldn't fit, and we'd need a custom center fork brace piece made. Still, these are some very awesome advanced forks for our bikes, and are fully supported by racetech on cartridge upgrades. So at about 190 triple spacing I'm guessing we'll need 5-10mm on each rotor/hub? Easy spacer to machine up.
blackhammer
Forum Mentor
Some pics in my build thread. Im using the GK bottom triple and having a custom billet top triple made currently. The fork brace dilemma is occupying some significant brain power currently.
Ive got CB 600 discs with the 23.5mm offset in the post. Going to use standard GK 15mm axel instead of the VTR 20mm (too short using GK triples). Disc spacers will be in the region of 20mm, leaving caliper mounts for maximum spoke clearance.
Ive got CB 600 discs with the 23.5mm offset in the post. Going to use standard GK 15mm axel instead of the VTR 20mm (too short using GK triples). Disc spacers will be in the region of 20mm, leaving caliper mounts for maximum spoke clearance.
Oh wow didn't realize you were using the GK triple on the vtr forks, you are going to have massive spacers.
Did you look into an SV650 triple, or gsxr??? Around 190mm or so, would solve some problems if you got one with the steering stem a good length that was useable. I compared some at the junkyard and thought they'd work, no precise measuring though.
Did you look into an SV650 triple, or gsxr??? Around 190mm or so, would solve some problems if you got one with the steering stem a good length that was useable. I compared some at the junkyard and thought they'd work, no precise measuring though.
blackhammer
Forum Mentor
Although i dont have bearings i still mocked it up with the VTR triples, the problem was the clearance of the calipers.
Spacing out the calipers is not an option as the discs in the standard mounting position is very close to the fork.
i think the VTR standard wheel must have very thin spokes
i could probably use the narrower VTR triples with a standard snowflake front wheel... but i worry about clearance using wire spoke wheels.
Spacing out the calipers is not an option as the discs in the standard mounting position is very close to the fork.
i think the VTR standard wheel must have very thin spokes
i could probably use the narrower VTR triples with a standard snowflake front wheel... but i worry about clearance using wire spoke wheels.
T
T8erbug
Guest
Although i dont have bearings i still mocked it up with the VTR triples, the problem was the clearance of the calipers.
Spacing out the calipers is not an option as the discs in the standard mounting position is very close to the fork.
i think the VTR standard wheel must have very thin spokes
i could probably use the narrower VTR triples with a standard snowflake front wheel... but i worry about clearance using wire spoke wheels.
I think you'll be ok with wire wheels. It will be close but I'm pretty sure you'll clear. I did a similar swap on my GS750 and made brake adapters with a 2001 GSXR600 fork and the spokes cleared the brakes. I ended up going a different route with the front end on it but I did complete the swap and everything cleared without modification. It looks very close to the VTR setup that you have pictured.
I can't get a picture from the same angle head on like you have (due to the rims and tires being installed), but I have nearly the same clearance to the plane of the hub flange from the backside of the caliper as your picture shows, & I have more than enough clearance to the spokes. The spokes angle inwards quite a bit toward the center of the rims even on these substantially wider aftermarket rims that I am running. this gives you more than adequate clearance. I would switch back to using the VTR triple for sure.
GS front hub flanges are about 2" (about 50mm) wide center to center, and I have 2-3/8" (60.3mm) clearance between the inner most points on the Ninja/Tokico brake calipers. I have 7/16" (11.2mm) clearance on each side at the closest point between the calipers and the spokes. I think you would be perfectly fine with the VTR setup.
My brakes' innermost point in the photo is a slight bit over 4mm more outboard than the CENTER of each hub flange. comparing that to your photo, it looks like you are nearly the same place.
I have read of other people using the Superhawk VTR1000C fork as an upgrade swap and using the Honda rc51 factory race bike calipers instead of the Super hawk calipers. Maybe they are a smaller casting and lighter weight, hence more clearance?
My brakes' innermost point in the photo is a slight bit over 4mm more outboard than the CENTER of each hub flange. comparing that to your photo, it looks like you are nearly the same place.
I have read of other people using the Superhawk VTR1000C fork as an upgrade swap and using the Honda rc51 factory race bike calipers instead of the Super hawk calipers. Maybe they are a smaller casting and lighter weight, hence more clearance?
maybe some of these aftermarket calipers would give you even more clearance?
"My VTR SP2 RC51 modified" from another forum said:Then bought some Discaciatti racing calipers (4 pot) from the factory to go with a Brembo RCS18 master cylinder.
These are much the same as Brembo's best racing calipers at less than half the price.
blackhammer
Forum Mentor
I really need to have the wheels built before making a final decision on what triples to use. Cant really think about spacers until then.
I'm leaning towards the GK triples though as i've had a top triple milled to integrate an electronic dash into it. But if the VTR triples allow the use of smaller spacers that would be preferable.
The standard VTR calipers are interesting, they've not got good feedback on the superhawk forums, lots of owners definitely do the RC51 upgrade and there are other options to fit the standard mounts. Those Discaciatti calipers are good looking things, but at almost 500 Euro each not something i think i need.
Although my GSX has an 1150efe with 33 smoothbores it will still be more a street cruiser/bruiser than a track bike, so i think the standard VTR calipers will be enough.
I'm leaning towards the GK triples though as i've had a top triple milled to integrate an electronic dash into it. But if the VTR triples allow the use of smaller spacers that would be preferable.
The standard VTR calipers are interesting, they've not got good feedback on the superhawk forums, lots of owners definitely do the RC51 upgrade and there are other options to fit the standard mounts. Those Discaciatti calipers are good looking things, but at almost 500 Euro each not something i think i need.
Although my GSX has an 1150efe with 33 smoothbores it will still be more a street cruiser/bruiser than a track bike, so i think the standard VTR calipers will be enough.
Well I just snatched up a set of VTR1000F forks lower triple and calipers for $130, too good of a deal to pass up. I'll probably be using these on the 894cc 11:1 GS750 powered '76 Rickman CR900 frame that I just acquired. the bike is going to be a nightmare of axle and brake spacing, converting from 11/16 inch rear axle required on the original Rickman CR900 swingarm to a 20 millimeter axle GS rear hub bearing setup with a custom machined sleeve, fork bearing conversion from standard to metric, front and rear axle spacing completely custom, and it looks like I will need some more custom hub rotor spacers to make the Superhawk brakes work. I will be getting some 04 cb600 rotors as well. I think I will be just fine with the Superhawk calipers even though I ride fairly aggressively, but I may look into other options before I put any money into these if they need pads or a rebuild kit.
