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GSX750ES REVS SUPER HIGH AVTER INSTALLING CARBS


SATANSAM

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Na, mixture screw o'rings in it's place...Measured all of them and they all measure the same....I'm totally lost...Can't be anything electric, CDI tested OK, Alternator OK, regulator OK, couls OK, caps OK, sparx OK, Valve clearance OK, no air leaks, damn thing is asking to be sold.

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Hi folx,

Do you think a low float height could cause this? Excesive petrol in the pilot circuit...the the float vallve and oring are new (aftermarket but new).

The circuit is clean as I stuffed it with intake cleaner, compressed air....

I'm using an external plastic tank ait a transparent fuel filter between (you can see fuel getting in perfectly) for this and blocked the vacuum pipe from carbs with a screw ok.

As you can see on. the carb balancer, cylinder 3 does not vacuum as much as the rest, and if I get all the same bike goes up to 4000rpm or so...Does this suggest anything to anybody? 

Man....This is really driving me nuts.

BALANCER.jpg

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I have -recently- not gone through your previous attempts to fix this but here are a few pointers:

Compression ok?

Valve clearance ok?

Valve lift / caml obe  ok?

Have you checked the carb top for cracks or leaks? / is the o-ring installed ( if applicable )?

Is the carb diaphragm pinched, ruptures or even a pinhole->easiliy overlooked

If you connect vacuumgage 3 on 4.. do you get the same results?

Have you bench sync the carbs prior to this result?

 

HTH to keep you sane

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Hi B,

The only thing that is "weird" is the compression (all 90PSI except the 3rd cylinder that reads bout 110PSI)...But loox like it's the compression tester as the other bike reads very underneath too.

Compression ok? NO

Valve clearance ok? YES

Valve lift / caml obe  ok? Sorry but What does this mean? The valve lift ok...

Have you checked the carb top for cracks or leaks? / is the o-ring installed ( if applicable )? NO LIEAKS OR CRACKS

Is the carb diaphragm pinched, ruptures or even a pinhole->easiliy overlooked - OK, BUT I'LL PUT A TORCH BEHIND IN THE DARK.

If you connect vacuumgage 3 on 4.. do you get the same results? - SAME READINGS ON 3 AND 4 (3 POOR VACUUM)

Have you bench sync the carbs prior to this result? YES

So, I'm stripping them out AGAIN, see float height, spray the needle valve, see the diaphragm, bench sync...

It's all so weird, the bike started failing when I changed the tank, it rusted and carbs got full of rust (1 cylinder off sometimes). Hamered the carb and cylinder in again...Took them out, cleaned them, on again, all cylinders ok BUT REVED. Now other carbs restored on the spot and  still over reved...

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2 hours ago, SATANSAM said:

Hi B,

The only thing that is "weird" is the compression (all 90PSI except the 3rd cylinder that reads bout 110PSI)...But loox like it's the compression tester as the other bike reads very underneath too.

Compression ok? NO

Valve clearance ok? YES

Valve lift / caml obe  ok? Sorry but What does this mean? The valve lift ok...

Have you checked the carb top for cracks or leaks? / is the o-ring installed ( if applicable )? NO LIEAKS OR CRACKS

Is the carb diaphragm pinched, ruptures or even a pinhole->easiliy overlooked - OK, BUT I'LL PUT A TORCH BEHIND IN THE DARK.

If you connect vacuumgage 3 on 4.. do you get the same results? - SAME READINGS ON 3 AND 4 (3 POOR VACUUM)

Have you bench sync the carbs prior to this result? YES

It should have read "Valve lift / cam lobes ok" .  

A worn camshaft lobe or camshaft profile will result in a weird running bike because the valve will open less. 

 

Happy hunting ;)

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I'll do a propper compression test tomorrow...But this afternoon I put my hand on the air filter intake, only fingers (didn't cover it completely) the bike lowered revs of course but without stalling, then revs up again then down, up, down, up, down, up, down, mathematically....What the heck? I directly thought abuut electric...More or less at the same time of the super dirty carbs making the cylinder fail, 2 of the 3 alternator cables were melted by hanging on the motor...I re-soldered them OK, but I'm thinking that maybe that issue maybe fried the rectifier...Things are coming out and now I'm sure it's not the carbs, followed the manual strictly, like a monkey in a circus. Thanx guys, U R the best help.

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18 hours ago, TonyGee said:

i wouldn't be happy with the compression test figures !!!!  anything below 100psi is not good !!!  they sould be done with a warm engine so it might be worth letting it rev for a while and re'doing the test and with full open throttle. 

You R gonna kill me but yep, motor warm and here are the resoults:

4 = 140Psi
3 = 127psi
2 = 120Psi
1 =140Psi

Well at least I know it hasn't got to do with the motor, well, I think hahaha 

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2 hours ago, Swiss Toni said:

Just a small point, as you seem to be getting there ... when you’re balancing your carbs with the gauges, the #3 carb is usually the ‘datum’, ie, non-adjustable. Set the other 3’s vacuum to this one. Might be a different set-up on yours, but worth checking. 

Thanx Swiss, yes I'm actually doing that, all butterflies closed, use the idle screw to open or close the number 3, then sync.carb 2 to 3 (reference) , then 1 to 2 and then the 4....the thing is that to be balanced the bike has to be at bout 3000 or more rpm...

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17 hours ago, TonyGee said:

not sure about your bike Sam but generally you do 1 to 2 then 3 to 4 and then 1and2 to 3and4 

Thats what I  said. 

Can't  be arsed to go back over the thread again , but have either set of carbs been PROPERLY ultrasonically cleaned ?

Puddy  :)

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I took all air filter boots that go to the carbs out and found this crack in the boot that goes to cylinder 3...Stuffet it with gasket silicone to try tomorrow... I don't think that crack would hang the idle this much, but I've already been wrong in most of the thingsxD

Beer time. 

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