What's the best handling slingshot gsxr frame?

[SlingshotSteve]

I've had a few gsfs and gsxrs and I want to build one more, but I want the best handling possible, I want to avoid the b12 frame obviously and I don't like the slabside frame as much as the slingshot so which oil cooled slingshot 750/1110 frame is best for this?

It's going to be either an 1127 or 1157 oil cooled motor, probably the 1157 as I've got a nice low mileage engine. Which is going to be best for handling? And which year/model?

 

Edited July 16, 2016 by SlingshotSteve

[Oilyspanner]

Probably stuff you already know Steve, but just from my experience and info gathered.

The suspension set-up and quality of suspension will have a much greater bearing on the handling than just which Slingshot frame is used. That said, if the same suspension was used on each frame the slightly smaller and lighter 750 frames would turn quicker - shorter wheel base mostly, using lighter wheels with better suspension is very noticeable too.  Exactly which 750 frame to use will vary according to who you ask, many like the  lightest framed 1988/89 frames, which were made for the short stroke 750s - this also means that adjusting the valve clearances can only be done by lowering the engine to get the cam cover out of the way.

I was going to make a 7/11, so spent loads of time gathering info, but in the end  I was so happy with my  lightened 1100 with up- rated suspension I didn't bother ! - still might make one though, whilst parts are still plentiful enough.

[Rene EFE]

88/89 750, the others simply don't come close. Went on track with a '90 750 which seems a bit more civilised although the earlier frontend did speed up turn in. For handling; stay away from the 1100 frames.

[colinworth79]

me and a mate were building a couple gsxr's and I had a 750 m frame and he had a 1100 l frame . Both frames were put side by side on a bench and neither of us could see any physical difference once the sub frames were removed . As mentioned 750 j/k physically smaller . If you want good handling modern forks,shock and good tyres set up by a suspension specialist . Things have moved on since the last slingshots were built .

[Oilyspanner]

With you on this CW79, only a small difference between 1100 and 750 L/M frames (which were very decent handling), the 750s had Showa suspension though, not Kayaba, which helps, plus lower bars which alters the riding position and weight distribution - a modern twin spar frame that drops the fuel load etc etc would be better - but !!!  hell it's not as good looking, working around problems has always been a part of the fun.

[dupersunc]

1100L frame is taller than a 750m frame by about 12mm. 

I run a 7/11m with 180/60 rear tyre, 10mm shorter rear dog bones, and stiffer springs. Other wise the suspension is stock but refreshed and carefully set-up.

It handles ok.

I'm starting another build around a 750k frame, as I've heard they're lighter better handling. I won't know for sure until I finish the bike which is better.

 I know I will definitely be fitting lighter wheels, and better brakes, as well as the other mods. The current bike takes a lot of effort to stop and change direction.

 

[SlingshotSteve]

One things for sure, it's got to handle better than my bandit. I'm almost finished my 1100k Gsxr so I want to compare that to the bandit. I actually thought that bandit handled ok until my Mrs bought an exup 1000 and that thing handles tons better than my bandit. So this got me thinking about building another slingshot and getting some decent suspension on it.

 

[MeanBean49]

My old race bike was an 88 frame, when I totalled it ended up with a later 90 frame, didn't quite handle as well as the older one, wasn't as sharp, however what I did notice was with modern running gear (k-series front and rear end) the frame really quickly becomes the weak link, they do like to twist a bit.

[jonny1bump]

Its what you attach to the frame that counts and how you set geometry.

 

[alfiestorm]

1100L frame with 750L swingarm and the best bouncy bits you can afford at each end

[Sandman]

In my opinion, the GSXR750RK is the best handling frame. I have one GSXR 750RK-89 and one GSXR 750J-88, both of them are race bikes, as shown in the Picture.

 

Specification for GSXR 750RK-89:

Frame: GSXR 750RK

 Rear swing: GSXR 750RK

 Engine: GSXR 1100 (1052 ccm)

 Sylinder head: GSXR 1100, shimmed and race ported, heavy duty valve springs

 Camshafts: Webcam grind 236/223

 Carburetors: Mikuni RS 38mm

 Bodywork: Sebimoto race fairing GSXR 750-91 and custom made race tail (molded by me).

 Exhaust system: Akrapovic Race, stainless steel headers/Titanium muffler

 Front fork: YZF R6 -03/04 (43mm) with K-Tech 25 SSK (RDS) race cartridges

 Wheels: Marchisini magnesium, 3.5-17 front and 5.5-17 rear.

 Tyres: Pirelli

 Rear suspension: GSXR 1000 K5/K6 Ohlins SU 503 with spring 1093-29/90

 Ignition: Dyna 2000/mini coils

 Brakes: Brembo P4 30/34 calipers and 320mm SUNSTAR Neo Classic Front Disc Rotors

 

Specification for GSXR 750J-88:

Frame: GSXR 750 -88

 Rear swing: GSXR 750 -95

 Engine: GSXR 1100 (1052 ccm)

 Sylinder head: GSXR 1100, shimmed and race ported, heavy duty valve springs

 Camshafts: Webcam grind 236/223

 Carburetors: Keihin CR Special 37mm

 Bodywork: Sebimoto race fairing GSXR 750-91 and custom made race tail (molded by me).

 Exhaust system: Yoshimura steel headers/alu muffler

 Front fork: YZF R6 -03/04 (43mm) with K-Tech 25 SSK (RDS) race cartridges

 Wheels: CBR1000RR -08, 3.5-17 front and GSXR-600 01 5.5-17 rear.

 Rear suspension: GSXR 1000 K5/K6 Ohlins SU 503 with spring 1093-29/90

 Ignition: Dyna 2000/mini coils

 Brakes: Brembo P4 30/34 calipers and CBR1000RR -08 320mm brake discs.

[gsxr884]

you can make any frame handle , its down to how much you brace it and set up  the angles, rake, trail ,swingarm angle ,are the most important ones but then you get into swingarm spindle height, rocker arm ratio, yoke offset , the wheels suspension , the difference made to my RK when I fitted ZX10R forks , yokes,wheel ,brakes and  amatching 5.5" ZX6R rear wheel was like night and day compared to the SRAD stuff I had in before, turns in super late and holds a line with ease.

[Sandman]

If we are talking about standard frames without extensive bracing, then the GSXR750RK frame is the best frame. It is possible to modify a slabside frame to handle very well, but this frame needs a lot of bracing.

 

Whatever is done with respect to suspension setup of slabsides and slingshots, these bikes are quite heavy handling bikes compared to modern superbikes.

Quote

 

 

[dupersunc]

What Differences are there on the RK frame compared to the 750 j/K frames? Other then the seat subframe.

[Oilyspanner]

The  750RK had the long stroke motor, but the frame was very similar to the J/K frame (same head angle), but with some strengthening around the headstock.  From the time I seem to remember that the RK had a braced swing-arm 10mm longer than a 750L and ally tank 19L not 21L - the engine had a few differences, close ratio box, long stroke engine, 40mm carbs and it had higher spec suspension - I don't think the frame was very different though, don't think it even had swing-arm pivot height adjustment.

There's not night and day between any of the Slingshot frames, but there can be with careful set-up and good components on any. The earlier frames (Slabbies) were lighter, especially the 750, but they are different to ride.

 

[Sandman]

Spec for GSXR 750RK

Rake: 24.5°

Trail: 102 mm

Wheelbase: 1405 mm (55.3 in)

 

Spec for GSXR 750J

Rake: 24.8°

Trail: 99 mm

Wheelbase: 14010 mm (55.5 in)

 

The RK frame is slightly higher than the J frame. It is possible to get valve cover off the engine while it is in the RK frame. The engine has to be removed from the J frame to take off the valve cover.

Compared to my latest superbike (CBR1000RR 2010)

Rake: 23.3°

Trail: 96 mm

Wheelbase: 1407 mm (55.4 in)

Weigth: 168 kg with oil and two litre of fuel.

 

One of the problems with the GSXR750RK and GSXR750J is the lack of ground clearance. This can be modified by altering the height of the bike, both front and rear. The original front fork is to short. By using a longer front fork, the height of the front can be increased. The rear height can be increased by using a longer rear shock. The Ohlins rear shock for the GSXR 1000 K5/K6 is approximately 10mm longer than the standard shock. The length of the Ohlins shock can also be adjusted and lengthened additional 5mm. The adjustable shock mount (Optional kit part for the RK) also gives additional adjustments of the rear height. In this manner, the total height of my bikes is increased by approximately 50 mm front and rear.

Another problem with these bikes is that they are quite top heavy, which is the reason for the heavy handling, especially in chicanes.

[MeanBean49]

Never had ground clearence issues with mine with shorter forks in. Just had rear jacked up about 25mm and front about 10mm shorter iirc.

Putting the whole lot up by 50mm is going to make the handling feel even more heavy and cumbersome as well as reducing grip.

Get as much weight on the front as you can (60/40 think i was at) seemed only way to get em to turn in decent and hold a tight line, 

Still perfectly setup on modern running gear, you find the frame is the limiting factor.

[Del]

There is no real difference between the the 750l/m and 1100k-n frames.The 11k frame is slightly lighter than the 750l/m and 11l-n frames,as it doesn't have the castlatted adjuster at the arm pivot,the 11k also has the added bonus of a removeable top shock mount like the 750's(it also uses the same linkages as the 750's with a 10mm longer arm).I have had 750j/k/l/m and 11k frames now.The 750j/k were the smallest and the 11k/l/m frames were all about the same size.
On my 11k,I am using 750 running gear(just got a 750k arm for it)and bodywork.It is setup with a hagon shock from an 1100ws(slightly longer than the k shock)and 750l front end dropped through the yokes by 30mm(no clearance problems).I set it up for me and handles really well(stayed with my other brothers old 1000k4) 

You can also tell there isn't alot of difference between the slingshot frames,as I am using the 750k full bodywork on mine.The mid panels just need pulling into place(no bracket is needed like the slabby 750/11 mid panel swaps)because of the top end height difference between the 748 and 1127cc(I am even using a full 4-1 micron system from a 750L,just needed a bandit sump fitting,as the collector sits on the sump plug)  

In this pic,you can see there is no real difference between the 2 frames.Sonny's old resident evil 7/12 and my 11k

Edited July 27, 2016 by Del

[Sandman]

If you don’t have problems with ground clearance on a GSXR slingshot, than you’re not riding fast enough…and the corner speed is too low :-)

[MeanBean49]

No problems running near the front of the grid in national level racing. :-)

Paddock hill bend at Brands hatch, if anywhere will show clearence issues its here

[Sandman]

It is evident from the pictures above that you do not use a standard front fork, but an upside down fork of a newer brand. It may be that this fork is longer than a standard GSXR slingshot fork , and therefore you don’t have any ground clearance issues? ( I know that  ground clearance is also dependent of suspension setup, but assuming correct setup for static and race sag, rebound and compression damping).

The standard fork length for GSXR 750J is only 555mm, which is the shortest of all GSXR forks. The upside down forks for GSXR-750/1000/1100 is in the range of 715mm-740mm.

[MeanBean49]

Yeah i think those figures for the fork length are pretty wrong.

Youce got say 30cm between the yokes. And about 30cm from wheel spindle to top of the mudguard. That 60cm if the mudguard was touching the top yoke and that already longer than the 55cm your quoting. Physical imposibility. And then if it did fit you still have no travel 

The gsxr 1000 forks in my bike were setup shorter than the 750 slingshot ones they replaced. I set it that way myself

[Del]

(IIrc,it's been a few years)My 11k rwu's(720-30mm) were slightly shorter  than my 750 usd's(740mm).That is fork top to centre of the spindle . The 11k forks were 20mm longer than my old 750k forks because the 11 used top mount clip-ons.
The 555mm measurement is for the fork stanchions alone  

Edited July 28, 2016 by Del

[Del]

Just double checked,555mm comes just above the bottom yoke,so it is definitely the stanchions alone measurement. As Rob said,it is physically impossible for the overall length to be 555mm,as the wheel would be rubbing on the oil-cooler

[MeanBean49]

Yep. Like i said in my earlier post. Im fairly sure the gsxr 1000 forks came up about 10mm shorter than standard.

Think i had 10mm drop at front 25-30 lift on the rear and about 20mm shorter wheelbase with k-series swingarm.

Was the best handling setup i found without making it unstable or top heavy. Probably bit too much for road use. Never once had a ground clearence issue.