well im bleeding gutted this morning gsxr 400 gk76a

[djheard91]

Ye when I set the timing up before it was set up like the picture with the gap of 20. I haven't had the bike running properly yet though, still waiting on parts.

[minkathecat]

hi variablevalve
Now this is making sence
1990 is dj bike with the larger ex 1.311 and ex 1.291 which i have fitted seeing as other heads i have with cams r different
let hope this is the case and swap them back.
but i have gas flowed stage one/d the head the larger cams came out off that HOPE THE JAPS DIDNT HAVE A DO AT THAT TO. (o shit)

lOOKED AT THE VALVES R CLOSED AT TDC but like u say dosnt mean the timing will be right this will depend on the dwell angle etc Let hope we havent crashed a valve OR valves

The prof off the pudding will be when i put piston at tdc and pressurise the bores reverse enginering this will sort out if possibly rings or a bent valve when checking every cylinder but yep variablevalves u got as major point their watch this space on monday for The continuing storey of a former nuclear engineer who has gone to the dogs LOL

I LIVE IN HOPE OF 150 PSI ON THE TEST BUT SOME HOW IM SCEPTIC

[Variablevalves suck]

Haha,
I can't say this is the answer but I'm scratching my head and trying to piece it together, not having a 76a I had a dig in the bandit book I have that covers all the model range from 'K' through to the 'VR' model and they changed the cams at 'P',
This will be the same with the 76a due to the 53hp rule and they have different height cam lobes giving less lift and different duration.

I'm thinking the no run problems that pre/ post cdi's give could follow across to the cams, might be wrong but the timing mark is on the starter clutch and these being different might time everything up wrongly.

I know 76a and bandit are different , bandit doesn't use shims for a start but the way they go about dropping the power will surely be similar.

Out of interest 'L' model bandit has valve lift of 7.5mm inlet and 7mm ex.
P model has 6.2mm both.

[minkathecat]

lifes a bitch when just to drop bhp they do all this sort of shit.
drop power on a norton or triump u buy the thicker head gasket lol

these buggers alter cdi ,cam, exhaust,my be head and the cuddley toy lol
be back when the things come from ebay for me snap on air purge system


alls well that ends well vairiable valves r us
ps i would have said if u use the barrels head larger cams correct cdi for this u would be cooking on gas but then again its suzuki.

[Variablevalves suck]

quite clever stuff as they didn't just drop the top power they moved it down the rev range so 53 hp motors have more bottom end and make around 10 hp more at 7000 rpm.

[minkathecat]

HI VARIABLEVALVE
BARRELS R SAME HIGHT JUST CHECKING YESTERDAY AND GOT SOME MORE RINGS KNOW THE GUY AT IMD

GOT HIM INTERESTED IN MAKING PISTONS I THINK COS HE HAS ASKED ME IF I HAVE AN OLD SCRAP PISTON U GOT OUT GK76A ALL MINE AINT THAT BAD
STRIPPED THE BARREL OF THE 1991 59BHP (IM LEARNING ) lol AND THOUGHT SHIT LOOK AT THOSE PISTONS THEY R LIKE NEW THOUGHT DONT TELL ME THEY R PLUS AND SOMEONE HAS HAD A REBORE (NOPE SAME SIZE AS MINE )
I WILL ALSO HAVE THE CDI BOX OF THIS FOR SPARES ON MONDAY . JUST IN CASE I DO THAT OTHER ENGINE UP NEXT YEAR

MEAN WHILE IM WAITING FOR A SNAP CONNECTOR FOR THE AIRLINE FOR PRESSURE TEST ON BORES IF ALL OK I WILL TRY THE ORGINAL CAMS BACK IN
ALLS WELL THAT END WELL

[djheard91]

I was in contact with a guy at IMD pistons recently, over ebay, about their piston ring set but the oil ring is 2mm thick unlike those fitted to the GK76 which are 1.5mm thick. Has he sourced a thinner oil ring or are you planning on machining your pistons?

[Variablevalves suck]

If you speak to him again tell him they are not off the bandit, RF or later GSXR like he says
Early GSXR had 53mm piston and a 2mm oil ring, think the compression rings were .9 mm at least they were not both .8

There's very little data regarding the 'F' model so id put money on them being from that bike, would have had the .8 mm ring change but still had the 2 mm oil ring, this then changed to the 1.5mm as the bike was developed.

[minkathecat]

no not machining pistons took the other engine to bits and scrappers r like new even the pistons r like new dont know whats gone on their so will only use the top 2 rings out of the set
could machine them up in the lathe though
the pic on the cam chain settings
wonder why the hell they didnt put these on the near side of the bike then when u have the timing marks set u dont have to walk round to the other side of the bike to see if your settings have changed tightening up the cams
seems stupid to me
still waiting of bits off ebay to compression purge the bores then it will tell me whats wrong at tdc or give idea.
if thats ok will put other cams back but i haven been able to see or find out what valve lobe messurments r for the 1994 year of manufacture bike

[stripes1976]

Best cams to use are 90sp with pre 93sp cdi and timing rotor if your after power. I modified a set of cam gear and made adjustable a and dialled them in. Also modified the ignition pick up for more advance.
Have your cam gears been removed from the cams?