Topic: Component weight- 1100 gsxr vs stock K6

[EnginebyAdam]

I'm not sure if this is the right section but I started weighting the 1100 gsxr parts I picked up. I will have the stock K6 pretty much striped over the next week and will grab some of those weights as well.

-1100 gsxr rear wheel, 17" wheel, 180/55/17 tire, stock sprocket, sprocket carrier and rotor- 31 lbs

-1100 swing arm, shock mount and hard ware, with adjusters- 14 lbs

-complete 1100 front end, 17" wheel, 120/70/17 tire, 2 x rotors, 2 x brake callipers, fork brace, stem bearings, stem, top and bottom tree, stock bars, retaining washer and bolt- 45 lbs

I had the stock swing arm off to test fit the gsxr arm so I weighted this as well. The 1100 gsxr swing arm will fit up nicely once I remove the rear loop for the passenger pegs, with very little shimming needed in the stock pivot area.

-Stock K6 swing arm with out adjusters- 9 lbs


From the numbers I have posted am I on the right track weight wise for the drag bike? The swing arm will have the mono shock mounts removed and is also 22” in stock form from center of the pivot point to the axle position. I should be closer to 10 lbs when the mount is removed, and providing I leave the swing arm at current length. 

[EnginebyAdam]

Weighted some more of the stock parts as I striped them off.

The K6 front end complete, front tire and rim, rotor, brake caliper, upper and lower trees, neck stem- 56 lbs

K6 rear wheel with brake drum- 40 lbs

BPellerine mentioned that I might look at a smaller, lighter, front end instead of the gsxr front end and this sounds right to me. I'm thinking the gsxr rear wheel and swing arm is still a good option for now.

I saw joe p used a KZ305 Kawasaki front and he said it saw 125 mph in the 1/4 with a fork brace. Any other suggestions for a small single disc front end?

[TurboD]

I have used 80-81 GS250 front wheels on a couple bikes, pretty easy way to save some weight.

[754]

Ceriani and Betor.. The 32 mm Ceriani is sometimes reasonable, came on Harley 250 and other singles..

[EnginebyAdam]

754 this was a post I came across by you in the "What is everyone stripping off to save weight?" that makes me think I'm on track weight wise with the gsxr rear wheel.

The tire weight of the Dunlop 180/55/17 on the gsxr rear wheel comes in at 12 lbs. So that leaves the wheel with sprocket, carrier, rotor, brake caliper and axle at 19lbs - 20 lbs. The whole package with swing arm is 45 lbs. Swing arm is 14 lbs the tire is 12 lbs.

"754:
Got some weight that are amazing;
05 R-6 rear wheel alloy 17 x 5.5"rim(less tire), includes disc mounted, 48T 520 sprkt mounted with cush drive, axle and swingarm internal spacers, nut & washer...19ish lbs

gets even better, all that PLUS;
rear brake caliper and mounting, brake line, M/C, res, linkage footped bracket and bootguard, missing only 1/2 the footpeg..

All that & the wheel stuff..23 lbs...
 
That is at least 23lbs or more less than the stock parts it replaces! So change pips, lose c-stand, go kick-only, and change rear wheel.. 10% lighter bike!!"


[scottly]

Hey Adam, welcome to the CB 750 Diet Club!
http://forums.sohc4.net/index.php?topic=88214.0

[dragracer]

I took off the stock Comstar front wheel with dual discs, both calipers, removed the rear spoked disc wheel and stock rotor, caliper, replaced the 630 chain with 530. Then put on a set of race weight PM Chicane wheels. Dropped over 45 lbs from the bike. It still feels heavy as heck but thats about all the weight i intend to remove- ummm, maybe the rider can drop a few pounds.

[EnginebyAdam]

Hey Adam, welcome to the CB 750 Diet Club!
http://forums.sohc4.net/index.php?topic=88214.0

That's a good read and impressive too I have to have the bike at 600 lbs with me on it to get the times I am looking for. The gsxr front end is going in favor of a small light weight unit, not sure what yet. I like the rear wheel and swing arm set up from the gsxr but that is up in the air as well.

[EnginebyAdam]

I took off the stock Comstar front wheel with dual discs, both calipers, removed the rear spoked disc wheel and stock rotor, caliper, replaced the 630 chain with 530. Then put on a set of race weight PM Chicane wheels. Dropped over 45 lbs from the bike. It still feels heavy as heck but thats about all the weight i intend to remove- ummm, maybe the rider can drop a few pounds.

dragracer I have been following your "Time to freshen up the F Model bracket bike " thread. I know your rear wheel is a 17" and you run a 190/50 Z rated Mickey Thompson shootout tire. Is that mounted on a 5.5" or 6.0" rim? The gsxr wheel I have is a 17" 5.5" rim. 

I have been looking at your setup very closely because it is pretty close to what I have in mind for this build. I don't plan to run a fairing, any body work, or a full size gas tank as I will be running alcohol or methanol with the fuel injection. That part of the plan may change, but either way a small tank will be built into the frame in the triple backbone area.

I need to figure out what I need for oil capacity but the tank should sit low in the frame under where the original battery box sat. Will fabricate a aluminum tank to suit that need. The battery will sit on the swing arm in a aluminum box as well, and will hold the limited wiring harness. This should lose some weight and give better balance to the bike... I think

[dragracer]

The PM wheel is 5.5" in width. I intend to replace the 190 M/T tire with a 180/17  Shinko Hookup. I left my oil tank in the stock location but moved my battery down inside the swingarm to free up space and lower the center of gravity. I did make an inner fender onto which i attached my air shifter tank.

I contemplated completely gutting out a stock tank for a basic shell and adding a back bone fuel cell. I swayed away from that idea to save some money and reducing weight at that time was not as important. I did want the bike to look as close to stock as possible while making it a fully functional dragike using up to date ideas. The use of dual shocks helped to make the bike look original but I really would like to eventually convert this chassis into a mono shock set up so i can tune the suspension better. Dual shocks simply don't allow for changes in dampening and rebound necessary to properly launch an extended wheel base bike. I built the bike with a street tire to begin with but i couldn't find a 18" tire sticky enough to hook. I ended up putting a 5.5" rear slick on the bike and it worked great but it also exlcuded me from running street ET in most sanctioned races. Now that i have the 17" sticky tire on the bike, i'm once again faced with the limitation of tuning the suspension to make a street tire hook.  The use of struts  on a no bar bike is an antiquated concept- it doesn't allow the suspension to assist the bike in moving off the line in a smooth linear fashion.

[EnginebyAdam]

The PM wheel is 5.5" in width. I intend to replace the 190 M/T tire with a 180/17  Shinko Hookup. I left my oil tank in the stock location but moved my battery down inside the swingarm to free up space and lower the center of gravity. I did make an inner fender onto which i attached my air shifter tank.

I contemplated completely gutting out a stock tank for a basic shell and adding a back bone fuel cell. I swayed away from that idea to save some money and reducing weight at that time was not as important. I did want the bike to look as close to stock as possible while making it a fully functional dragike using up to date ideas. The use of dual shocks helped to make the bike look original but I really would like to eventually convert this chassis into a mono shock set up so i can tune the suspension better. Dual shocks simply don't allow for changes in dampening and rebound necessary to properly launch an extended wheel base bike. I built the bike with a street tire to begin with but i couldn't find a 18" tire sticky enough to hook. I ended up putting a 5.5" rear slick on the bike and it worked great but it also exlcuded me from running street ET in most sanctioned races. Now that i have the 17" sticky tire on the bike, i'm once again faced with the limitation of tuning the suspension to make a street tire hook.  The use of struts  on a no bar bike is an antiquated concept- it doesn't allow the suspension to assist the bike in moving off the line in a smooth linear fashion.

Struts was the plan as was a bar but I do still have the mono shock off the donor gsxr. I am open to all suggestions here as I have absolutely no experience drag racing. We don't have any rules to follow so I am just looking for the best set up overall. I have no problem running a 5.5" slick, Jon Weeks suggested this as well. Which 5.5" slick did you run dragracer and was it on your 18" or 17" rim?

Thank you for the responses I have lots to learn.

[dragracer]

The PM wheel is 5.5" in width. I intend to replace the 190 M/T tire with a 180/17  Shinko Hookup. I left my oil tank in the stock location but moved my battery down inside the swingarm to free up space and lower the center of gravity. I did make an inner fender onto which i attached my air shifter tank.

I contemplated completely gutting out a stock tank for a basic shell and adding a back bone fuel cell. I swayed away from that idea to save some money and reducing weight at that time was not as important. I did want the bike to look as close to stock as possible while making it a fully functional dragike using up to date ideas. The use of dual shocks helped to make the bike look original but I really would like to eventually convert this chassis into a mono shock set up so i can tune the suspension better. Dual shocks simply don't allow for changes in dampening and rebound necessary to properly launch an extended wheel base bike. I built the bike with a street tire to begin with but i couldn't find a 18" tire sticky enough to hook. I ended up putting a 5.5" rear slick on the bike and it worked great but it also exlcuded me from running street ET in most sanctioned races. Now that i have the 17" sticky tire on the bike, i'm once again faced with the limitation of tuning the suspension to make a street tire hook.  The use of struts  on a no bar bike is an antiquated concept- it doesn't allow the suspension to assist the bike in moving off the line in a smooth linear fashion.

Struts was the plan as was a bar but I do still have the mono shock off the donor gsxr. I am open to all suggestions here as I have absolutely no experience drag racing. We don't have any rules to follow so I am just looking for the best set up overall. I have no problem running a 5.5" slick, Jon Weeks suggested this as well. Which 5.5" slick did you run dragracer and was it on your 18" or 17" rim?

Thank you for the responses I have lots to learn.

If you plan to use a wheelie bar then  of course a strut suspension is necessary. As to the 5.5" slick, it was a Mickey Thompson and it only comes in 18". I had it on a Sunstar rim that i laced up to an earlier model stock F model disc brake hub. I think that rim was 4.50 or 4.75" wide. If you go without a wheelie bar you want to consider using shocks of some kind. Again, the mono shcok set up allows you to tune the rer suspension better in order to plant the rear tire without causing the bike to wheelie or pogo. Rebound and proper dampening are highly adjustable with a mono shock( they can be revalved to your specs) - not so versatile  with dual shocks.

With no rules and a goal of running your best times, i would lean towards building a wheelie bar bike so you can leave full throttle off the 2 step. The lower the 60', the lower the ET, especially in a normally aspirated package. I would use the wider GSXR back wheel with a 17" slick. Shinko now makes an affordable 7X17" rear slick or you can go with the tried and true M/T 7x17" slick. I like the 17" slick versus 18" in the 7" width because the sidewall is taller alllowing the tire to roll up more on the initial hit assisting in a harder launch. I prefer the MT.

[EnginebyAdam]

I was liking the gsxr parts for the swing arm and the rear wheel after reading this I'm defiantly going this route. My main concern was slick availability. The length of the gsxr swing arm is 22" pivot center to rear axle center. This should be a good setup length wise, for a wheelie bar bike.

I can shave some weight off the swing arm by removing the shock mount and get it down from 14 lbs to 10-10 1/2 lbs. The gsxr rear end compete weights 4-5lbs lighter than the stock K6 stuff as it sits now. The Mickey Thompson 26 x 7 x 17 tire weights 13 lbs which is 1 lb heavier than the Dunlop on the 17" gsxr wheel I have now, not a big deal.

I know the stock K6 shocks are 3 lbs a piece so I'm looking to replace them with struts that are 1-1.5 lbs each. 

I have also started a list of the small throw away parts weights and will post this as well when complete. I have to grab the stock tank and some other parts back from my buddy I gave them to so I can weight them as well.

[dragracer]

Not sure i would cut off the shock linkage mounts from the arm- i would leave them in place in case you decide in the future to go without a wheelie bar and needed a place to mount the mono shock again. Of course if  this bike will always be a dedicated bar bike or acquiring another one of these arms is not a problem where you live or  you can free up space without it, then by all means, shed the weight. Just my opinion.

[EnginebyAdam]

Not sure i would cut off the shock linkage mounts from the arm- i would leave them in place in case you decide in the future to go without a wheelie bar and needed a place to mount the mono shock again. Of course if  this bike will always be a dedicated bar bike or acquiring another one of these arms is not a problem where you live or  you can free up space without it, then by all means, shed the weight. Just my opinion.

First off happy New Year

That's good advice. As I get deeper into this the weight I can lose by removing the mount might not be needed. It will have to be decided as I get towards final weight in.

[dragracer]

And don't forget, you will need an offset front sprocket sprocket to maintain proper chain alignment and to clear the tire. Cycle Ex makes offset sprockets. My drag F model has one. I used one on an F model we built for the street also. It had GSXR wheels on it too. I do recommend you come up with a means to build a bearing support plate for the offset sprocket. You don't want that small output shaft stressed beyond its limits trying to turn that 7" slick off the line at 8,000 rpm with no support on the end. I did see a post by a fellow forum member who bought up a lot of cheap hi po parts no long ago. One of the pics he posted had a homemade bearing support. I will try to search the posts and see if i can paste the picture or link in your thread for illustration purposes. We use outboard bearing supports on our old school KZ's with 5/8" and up offset sprockets. 

[dragracer]

Scroll to the end of the linked thread for pics on the bearing support plate.

http://forums.sohc4.net/index.php?topic=132232.msg1480369#msg1480369

[EnginebyAdam]

Scroll to the end of the linked thread for pics on the bearing support plate.

http://forums.sohc4.net/index.php?topic=132232.msg1480369#msg1480369

Thanks, bookmarked

I am trying to see if I can swap a complete F2 transmission as well as the output shaft into my K6 case to help with alignment. The F2 transmission should have a better gear ratio for drag racing. Here is my thread on that. Not much info yet but I am digging into it: http://forums.sohc4.net/index.php?topic=132597.0

Support plate sounds like a good idea to me. Just a matter of working out the details from the looks of it. Another thing added to the list for the build.

I'm thinking 7" slick is a lot of tire and maybe that's why Jon recommended a 5.5" slick for the engine I'm building. That being said I'm good with the 7" slick and the gsxr wheel. The alignment issue with be sorted as I go along.

[jweeks]

     A little history note - Most slicks used to come in 7" and 8" sizes. That was the measurement of the width of the tire "tread". The tire manufacturers found that when a slick was worn out, the outer edges never were. They decided to remove the rubber from the outer edges that never got worn out. That lead to the 7" slick actually measuring 5.5" wide, weighing less than the old 7" version, with the same traction as before. Going to a wider slick will help with traction (if you need it), but will weigh more. It will also be more complicated to get the chains and sprockets aligned and fitting with your swingarm. Wider slicks also take more energy to move. Traction shouldn't be an issue at a good track for your CB750 based bike running the 5.5" wide version. If they don't use traction compound and don't prep the track for traction, you may need wider rubber. The quick way to tell about this is seeing what bikes use on your local track. If you see the quicker bikes that run slicks using the 5.5" versions, you'll do fine with one.
     There's more to be learned about bike setup for maximum traction- Shocks verses struts; tire air pressure; nitrogen in the tire; length of swingarm; length of wheelie bars; launch rpm; air shifter; clutch setup, etc. For a new rider, getting an educated butt can't be easily taught. You have to make your passes and keep everything under control. No form of racing is simple if done well.

Just my opinion as usual. 

[EnginebyAdam]

     A little history note - Most slicks used to come in 7" and 8" sizes. That was the measurement of the width of the tire "tread". The tire manufacturers found that when a slick was worn out, the outer edges never were. They decided to remove the rubber from the outer edges that never got worn out. That lead to the 7" slick actually measuring 5.5" wide, weighing less than the old 7" version, with the same traction as before. Going to a wider slick will help with traction (if you need it), but will weigh more. It will also be more complicated to get the chains and sprockets aligned and fitting with your swingarm. Wider slicks also take more energy to move. Traction shouldn't be an issue at a good track for your CB750 based bike running the 5.5" wide version. If they don't use traction compound and don't prep the track for traction, you may need wider rubber. The quick way to tell about this is seeing what bikes use on your local track. If you see the quicker bikes that run slicks using the 5.5" versions, you'll do fine with one.
     There's more to be learned about bike setup for maximum traction- Shocks verses struts; tire air pressure; nitrogen in the tire; length of swingarm; length of wheelie bars; launch rpm; air shifter; clutch setup, etc. For a new rider, getting an educated butt can't be easily taught. You have to make your passes and keep everything under control. No form of racing is simple if done well.

Just my opinion as usual. 

Jon, your opinion is always appreciated

As I have mentioned before there are not a lot of bikes drag racing around here. All the factory superbikes with 160-190 size tires seem to hook up well. None of these bikes launch hard as they all drive them there and they all wish to drive them home, so it's hard to say what a proper launch will result in. I know the rail cars and some of the high HP drag cars can get squirrely off the line at times, but this is usually towards the end of the day.

Just found this on dragbike.com.

" The early GSXR wheels (1986, 87 and 88) were 18" diameter and the 1989 model was 17" diameter, but only 4.5" wide. The 1990 - 1998 should be the same size axle (20mm) but the brake-rotor and caliper-hanger varies (I forget which years are which type) based on whether there is a torque-arm or a tab on the swingarm."

If I could find the early '86-'88 rear wheel, providing it is indeed 18" x 4.5", I could run the 5.5" MT slick and still use my swing arm. The MT 5.5" slick is 11 lbs vs 13 lbs of the 7" slick. The 5.5" would be a lot better to line up.

Retro Rocket talks about using a 160 tire, a 4.5" rim and a 1100 swing arm. His arm is a older 1988 gsxr1100 arm so slight difference than mine, but this would imply the 5.5" slick would line up nicely. About quarter the way down the page.
http://forums.sohc4.net/index.php?topic=106733.0

Edit: everything I am coming up with says the '86-'88 rear wheel on the gsxr is 18" x 3.5". I'm still good with the 7" slick or a Shinko hook up, just good to have options with something like this.

[EnginebyAdam]

I have been over thinking this a little when it comes to the weight of the bike, I do believe. I spent last night doing some math using dragracer's F model bracket bike as my main example.

Dragracer posted in the "1055 drag bike" thread that he saw "high 6.60's in the 1/8th mile and 10.6?'s@120mph or so in the 1/4 mile." At the time the bike weighted 465 lbs. By crunching the numbers that should put the bike with dragracer on it at 665 lbs, and 110 RWHP. Do this numbers come close dragracer?

Some engine horsepower examples for comparison:

Mec's stroker, cb900 crank and 71.25mm pistons, makes 109 RWHP. His 1000cc makes 113 RWHP. Dyno sheet here for both: http://forums.sohc4.net/index.php?topic=54803.100

A well built 836cc can see 84-85 RWHP. Voxonda, and Doctor_D's dyno sheets, among others here: http://forums.sohc4.net/index.php?topic=54803.100

Weight wise if my bike ends up being 650 lbs with me on it and I only make 90 RWHP I should run 11.25 @121. Realistically that translates to mid 11's and I'd be happy with mid 11's for this set up for it's first season. I also expect more than 90 RWHP
 
I am 210 lbs without gear on I'll be hitting the treadmill before the drag season starts

[TurboD]

Adam The GSXR 89-92 750/1100 rear 17 inch wheels here in the states that I have found are 17 x 5.5 and yes they use a 20mm axle. Some 600's thru those years also shared the same wheel. There are a couple variations of brake rotors and also sprocket hubs.

Too bad you are not closer to me, as I also have a set (front and rear) of the 86-88 wheels.

Another option would be to use a Katana GSX 1100 wheel from the early 90's, it looks like the GSXR wheel but is 17 x 4.5.

I personally have a couple 17 x 5.5's, they allow you to use a 180 55 17 Shinko Hookup, they are inexpensive and you will not have a traction problem. Guys around here are putting down 300 RWHP on the street. 

[EnginebyAdam]

Adam The GSXR 89-92 750/1100 rear 17 inch wheels here in the states that I have found are 17 x 5.5 and yes they use a 20mm axle. Some 600's thru those years also shared the same wheel. There are a couple variations of brake rotors and also sprocket hubs.

Too bad you are not closer to me, as I also have a set (front and rear) of the 86-88 wheels.

Another option would be to use a Katana GSX 1100 wheel from the early 90's, it looks like the GSXR wheel but is 17 x 4.5.

I personally have a couple 17 x 5.5's, they allow you to use a 180 55 17 Shinko Hookup, they are inexpensive and you will not have a traction problem. Guys around here are putting down 300 RWHP on the street.

Thanks for the info TurboD. I am feeling pretty good about using the 17 x 5.5 and like both the Shinko Hookup and the 7" slick. I don't think alignment will be a huge deal, will have to see how much I can take down the carrier. The support that dragracer mentioned will be incorporated as well to help it all out.

The other aspect I like about using the gsxr parts that I have not mentioned, is the appeal to potential customers. Using newer sport bike parts on a cb750 sohc Honda will get people interested pretty quick around here, as it's not done, or if it is I have not witnessed it. Should look pretty trick.