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GSX750ET Race Build


maxwin

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Hi all,

first post as I'm new to the forum, found it while digging up info on the old GSX.

I started racing a GSX750ET last year that I hastily threw together from the parts I had, for this season however I've decided to build a new more refined bike and thought it might be of interest to others to document my progress here :)

Cadwell%20Park_zpsf6au6bpq.jpg

Started with the frame I found on fleabay, only £60 and 5 miles from home :D.  Shot blast it chopped off the tail and welded in some bracing, there are some nice websites that give you printable profiles for the bracing tube cuts.  I'm hoping the bracing will get rid of the wobble I get tipping into fast corners like Coppice and Gerrards.

Frame01_zpszeelzkd1.jpg

I read that the cross brace gives more rigidity if its formed into a pyramid, not sure that the messing about with the cuts was worth it though...

Frame02_zpsbtbpczt1.jpg

Most of the engines I have have been crashed at some point so are missing fins here and there.

Block01_zpsrxpwf7zy.jpg

This was the most unpleasant casting I've welded so far, but after a bit of persistence I think it's passable

Block02_zpscpdmlcxl.jpg

To be continued...

  • Like 9
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Thanks a lot for the comments.

@Rene EFE - maybe next year, for now 1100 will have to stand for the number of helicoils I've used in these motors :P

@KATANAMANGLER - is that Pete Boyle?

@clivegto - http://cq.cx/tubejoin.pl - that's the one I use

@fatblokeonbandit - I race with Earlystocks and Formula Prostocks 

 

Decided to go all in and brace the head stock as well, just need to decide on the colour now.

Frame03_zpsk5nn7nwy.jpg

  • Like 3
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Pyramid bracing is less stiff if the diagonals of a flat x-brace are going to be in compression or tension, however if you're twisting the sides then it can be stiffer than a flat brace - *but* you'd need to complete the pyramid by adding a horizontal tube just behind the engine mounting points.

 

The latest version of bracing the headstock that I've seen (on one of the front runners in the historics down here) is a pair of tubes running from the headstock to the bend in the top tube - from side on they're completely parallel with the steerer "spine".

When I eventually pull mine apart and tweak the frame a bit more, I'm going to do that one as well - I believe the tank tunnel has plenty of room in that area.

  • Like 1
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Hi and welcome to oss, nice project and now you have done the frame bracing you will see better handling you can put a cross member in the front down tubes between 2/3 down pipes.

Are you going to tune the motor? 

One tweek is to put the ex cam in, out of a gsx750es.

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@Gammaboy thanks for the tips, I will put another brace between the rear engine mounts, not sure about the head stock though, wouldn't it obstruct the lugs that hold the front of the tank?

@wraith thanks for reminding me about that cross member, doesn't the 1100 have that as standard?  As for tuning my trusty cousin always says go with stock until you need to go faster, at the moment I'm going fast enough for my level of talent :D

What does the es cam do? advance or retard?

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ES cam has more lift and duration from memory.

Might obstruct the lugs on the gsx tank - Kat tank mounts slightly differently and should clear.

Didn't even realise it was minus the side to side tube above the front engine mounts - there's a bit more bracing you can do in there too (couple of diagonals into the centre of the horizontal tube, then diagonals back out to just above the bottom corner of the down tubes.

 

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  • 1 month later...

Update time, had a week off so progress has been slow but with race day 2 weeks off I'm spending every scrap of free time in the garage.

With the frame out of the way *I've been focusing on the Engine, started by striping it completely and giving it a bath. Swarfega Jizer is a pretty good degreaser never used it before but very happy with the results

Cleaning_zpsogsirgpx.jpg

The crank from this block was shot so I acquired a replacement from Grumpy1260, I went through my box of shell bearings and managed to scrap together a full set with 2 thou oil clearance on all journals which was a bonus.

Plasti01_zps2rl7q7ek.jpg

Plasti02_zpspakabysf.jpg

Honed the liners, still a bit pitted but they will do.

Honing_zpsldz8nyoc.jpg

Shot blast and a lick of paint...

Engine01_zpsvwuj1mdu.jpg

All laid out ready for reassembly.

Layout_zpshqgjbgog.jpg

When assembling these engines I find putting the cylinder block on last is a PITA, so I loaded the pistons in first...

Cylinder%20Head01_zpssw2ogzfx.jpg

Many hours of huffing and puffing...

Engine02_zpspkfpsubg.jpg

This set-up runs a constant loss so the alternator is removed and I cut off the fly wheel.

To help with clearance when leaning I also modified the fly wheel cover, it's my second attempt at aluminium welding so it's a bit naff...

Clearance01_zpsmq8qcl1l.jpg

Clearance02_zpsxvte8jh3.jpg

I'll shine it up at a later date as time is running short

Clearance03_zpsthkarxoc.jpg

Does anyone know if any more modern Suzuki's use the same spline pattern for front sprocket?

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1 hour ago, maxwin said:

Does anyone know if any more modern Suzuki's use the same spline pattern for front sprocket?

Sure do. Bandit sprockets are a cheap and easy 530 upgrade, I think modern GSXR 520 conversions are the same front sprocket spline.

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  • 3 weeks later...

Belated update time!

Did Brands last weekend and I have spent every waking hour in the garage for the last two weeks getting it ready, so I'm a bit light on photos buts here's what I've done so far.

To my horror I noticed the tank paint was bubbled, when I burst one of the bubbles it spelled of fuel :(

Turned out to be leaking from the thing they put in to hold the badge...

Tank01_zpsycq9owoh.jpg

so I tigged a piece of 1.5mm sheet over it after giving the tank the steaming of it's life... and a few brave blow lamp tests :D

Tank03_zpswhqzddqz.jpg

I was respraying the tank white anyway so apart from the welding and a bit of extra filling it wasn't too bad.

Next little snag was the front braces I had fitted, they were too far back and I couldn't get the engine in.  Fortunately I had not fully welded them up so was a quick grind off.

I'm still not finish with the frame as far as adding lugs and captive nuts so have held off of painting it, I found a great product called POR15 that gives bare metal a zinc phosphate coating.  I think its for priming metals really but works well as a stop gap, desipite some fine rain over the weekend there are no signs of any rust.

coating%20frame_zpsr740xuhg.jpg

Anyone who has humped one of these engines around will know they are effing heavy, I have taken a different approach to putting the engine in...

Engine%20in%2001_zpstibgk7sz.jpg

I madse the jig that picks up the cam tensioner holes and allows the frame to be fit around the suspended engine :D

Next up I fitted the front and rear wheels, suspension, brakes, etc. and fabbed up a box for the electrics and catch bottle out of trusty checker plate...

rear%20tray%202_zpsbx9nwk7w.jpg

Rear%20tray_zpsa6vahzk2.jpg

The little bottle on top is my temporary testing fuel tank.

I roughly tuned the carbs using my A/F sensor and got the bike running quite smoothly.

The following days were a frantic struggle to get finished, had help from my dad who came around most nights.  But it was all worth it in the end, got loaded up at about 4pm on Friday and made my way to Brands Hatch!

Loaded%20up_zpsl9kop6rg.jpg

Here are a few links to some action shots a don't want to post the actual pic's because of copyright infringement...

http://www.edpphoto.co.uk/ngroadracing/2016/NGRoadRacing200316/Adam%20Jeffery%20Flooring%20Pre-Injec%20700-1300/index.html#Pri_NGBH20_4981.JPG

http://www.edpphoto.co.uk/ngroadracing/2016/NGRoadRacing200316/Adam%20Jeffery%20Flooring%20Pre-Injec%20700-1300/index.html#Pri_NGBH20_5168.JPG

http://www.edpphoto.co.uk/ngroadracing/2016/NGRoadRacing200316/Adam%20Jeffery%20Flooring%20Pre-Injec%20700-1300/index.html#Pri_NGBH20_5029.JPG

http://www.edpphoto.co.uk/ngroadracing/2016/NGRoadRacing190316/Adam%20Jeffery%20Flooring%20Pre-Inj%20700-1300%20/index.html#Pri_NGBH_2243.JPG

http://www.edpphoto.co.uk/ngroadracing/2016/NGRoadRacing190316/Adam%20Jeffery%20Flooring%20Pre-Inj%20700-1300%20/index.html#Pri_NGBH_2155.JPG

All in all a great start to the year, lots of improvements to do so I'll be updating you as I go.

Thanks for reading :)

  • Like 12
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A 4.6 M6 bolt has a shear strength of about 500kg, times that by 2 bolts and your up to a tonne.  The engine doesn't weigh more than 150kg's, so theres loads of room for error lol.  Having said that though I always have the lift under it so it doesn't have far to fall and NEVER put my figures underneath.

Will try to take a pic tomorrow.

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