GSX750ES REVS SUPER HIGH AVTER INSTALLING CARBS

[SATANSAM]

Well, I've tried 3 sets of carbs, all the same and same problem... Floats correct, new float needles and seats with all new Orings, new Orings in 4 chokes, diaphragms perfect, slides shu down well, vacuum line correct and fuel pipe from tank/eternal “tank", new bowl gaskets, fuel screws with springs-washers and oring, new throttle shaft Viton new rings, butterflies installed correct (torch through and no light, maybe a tiiiiny bit but na).... Sync gauges correct, smaller pilot jet = no good, bigger pilot jet = no good, compressed aire everywhere after cleaned individually with 1L water, 200ml Amoniac, 20ml fairy and 10ml acetone, then carb cleaner in spray, then compressed air...Intake boots and o rings correct with no air leaks... Correct valve clearance, correct Cam timing when assembled the motor, no leaks through spark holes...I was going to check Ignition timing but it all depends on the CDI on this bike, Tested the cdi and it Sparx BUT I'm not sure it works correctly "dosifying" the sparks (Maybe too advanced?), so I found a "CHEAP" CDI... This is something personal as I disassembled these carbs before, mounted them and the bike run fine, but this time...Remember at the beginning of this post, 2 of the 3 cables coming from the alternator fried cause of hanging over the motor...Man...this thing is gonna work or I'll cut my balls off... But I'll use them before that I hope!!! WHISKY TIME¡ FIEW!! 

[TonyGee]

bloody hell, 3 sets of carbs can't all be wrong !!!!!!  what about a crack/hole in the inlet tract of the head ?  just grasping at straws now 

[SATANSAM]

29 minutes ago, TonyGee said:

bloody hell, 3 sets of carbs can't all be wrong !!!!!!  what about a crack/hole in the inlet tract of the head ?  just grasping at straws now 

Well I wasted 3 spray cans of brake and carb cleaner all around the head and whole motor with no difference, actually, that's how I found the leak at the head gasket that way, opened motor and changed it but hardly any difference 

[Pudzrx]

Start it up and when the revs are hanging , try removing individual ht leads one cyl at a time. See if the revs drop on any of them. I still think one cyl is overfuelling/ air leak , and hanging the revs up , which with cv carbs will pull them all up , which it shouldn't on slide carbs

[SATANSAM]

13 hours ago, Pudzrx said:

Start it up and when the revs are hanging , try removing individual ht leads one cyl at a time. See if the revs drop on any of them. I still think one cyl is overfuelling/ air leak , and hanging the revs up , which with cv carbs will pull them all up , which it shouldn't on slide carbs

Thanx Pud, sorry but What do you mean by ht leads? 

[Dezza]

The last time I had a similar 'carb' problem, by using a known good set of carbs I deduced it wasn't a carb problem at all: it was a faulty CDI unit.

[SATANSAM]

7 hours ago, Dezza said:

The last time I had a similar 'carb' problem, by using a known good set of carbs I deduced it wasn't a carb problem at all: it was a faulty CDI unit.

Man you've given me a bit of light there! Anyway, beer time!

[SATANSAM]

FINGERS CROSSED!

[Swiss Toni]

We’ve all  got fingers crossed!

[SATANSAM]

3 hours ago, Swiss Toni said:

We’ve all  got fingers crossed!

NO LUCK. Dammit no idea... And I've cleaned my other bikes carbs today, everything the same as with the 750 and no problem.. Its a 2 cilynder but still... I've had enough for some time... Thanx folx. 

[SATANSAM]

Hi amigos,

I was looking at photos I took when I disassembled the motor to change the head gasket, and Cylinder 2 had those marks...I suposed it didn't have to do with the problem BUT just in case...What would you think?

[SATANSAM]

By the way, I'm going out on the weekend in the van and there's a nice GSX750EF with 46000km's for 1000€...I'm thinking about bringing it back with me!

[Blubber]

4 hours ago, SATANSAM said:

By the way, I'm going out on the weekend in the van and there's a nice GSX750EF with 46000km's for 1000€...I'm thinking about bringing it back with me!

Check if it idles and rev's ok 

I read that these can have a problem with that and it is really time consuming to fix the problem 

[fab]

14 hours ago, SATANSAM said:

Hi amigos,

I was looking at photos I took when I disassembled the motor to change the head gasket, and Cylinder 2 had those marks...I suposed it didn't have to do with the problem BUT just in case...What would you think?

what did the piston top look like?

[SATANSAM]

12 minutes ago, fab said:

what did the piston top look like?

No marks on any of the pistons...Weird...

[SATANSAM]

Mornin' amigos!

Long time no speak...I've started with the suzi again, from the beginning, like a retarded (like always).

As I've got  3 sets of carbs, all clean 100%., with UC, carb cleaner and compressed air. All diaphragms perfect, gaskets too. Bech sync and mounted with air box and intake manifolds perfectly sealed...All jets correct size, choke working correctly...

Valve clearence correct, compression 160 each so correct.

I'm getting a set of carbs in with new throttle shaft viton rings and correct butterfly positions, now Vitons are the only part I can think about....Air lieak like most of you say. Bike synced, fuel screws 2,5 turns out (and more!), idle at about 2000rpm, I close the air filtet intake with my fingers and of course it loweres down...So excess of air...

Anyway, if anybody has a last tip...I might be near success or storing the bike...This bike uses a CDI so I don't think it can be anything to do with advanced timing (I've tried 3 CDIs already!).

Cheerz!

[Pudzrx]

So have you disconnected 1 x spark plug lead at a time when its revving to see which cylinder is hanging it up ? I still find it hard to believe you know what you are doing when it comes to balancing 4 x carbs as well , no offence.

Puddy 

[SATANSAM]

7 hours ago, Pudzrx said:

So have you disconnected 1 x spark plug lead at a time when its revving to see which cylinder is hanging it up ? I still find it hard to believe you know what you are doing when it comes to balancing 4 x carbs as well , no offence.

Puddy 

Thanx Pud. With 4 butterflies benchsynced with a soldering wire (for example)as measurement, all totally closed or open up to the 1st hole before butterfly.. there is not much space for bad balancing (nearly spot on) and to be honest, balancing,2, 3 or 4 carbs isn't that misterious...thanx anyway Pud. 

[Pudzrx]

17 hours ago, SATANSAM said:

Thanx Pud. With 4 butterflies benchsynced with a soldering wire (for example)as measurement, all totally closed or open up to the 1st hole before butterfly.. there is not much space for bad balancing (nearly spot on) and to be honest, balancing,2, 3 or 4 carbs isn't that misterious...thanx anyway Pud. 

Lol , first post was last November,  it obviously is !

[Dezza]

If it's running rough because of a reason unconnected with carb balancing (likely) then balancing the carbs with a set of meters is going to be nigh-on impossible.

BS carbs are a pain in the arse to get right anyway due to the screw and locknut adjusters, rather than the much more user friendly spring loaded adjusters on BSTs. I just bench sync my BS 36s and my engine runs fine. A bench sync will be fine until the fault(s) are finally found. If it's still running rough it's not due to poorly synced carbs.

If three sets of carbs have been tried this strongly suggests the poor running is not due to a carb problem. I would go through the ignition system wiring and then each component of the system. Try a set of Kawasaki 3ohm coils (ZXR, ZZR etc. cheap on eb@y) as you can easily renew the leads and caps, unlike Suzuki coils of the 80s in which the lead is moulded into the coil. Examine closely the connector blocks on the CDI. These corrode and work loose. New ones are a few quid each.

[SATANSAM]

3 hours ago, Dezza said:

If it's running rough because of a reason unconnected with carb balancing (likely) then balancing the carbs with a set of meters is going to be nigh-on impossible.

BS carbs are a pain in the arse to get right anyway due to the screw and locknut adjusters, rather than the much more user friendly spring loaded adjusters on BSTs. I just bench sync my BS 36s and my engine runs fine. A bench sync will be fine until the fault(s) are finally found. If it's still running rough it's not due to poorly synced carbs.

If three sets of carbs have been tried this strongly suggests the poor running is not due to a carb problem. I would go through the ignition system wiring and then each component of the system. Try a set of Kawasaki 3ohm coils (ZXR, ZZR etc. cheap on eb@y) as you can easily renew the leads and caps, unlike Suzuki coils of the 80s in which the lead is moulded into the coil. Examine closely the connector blocks on the CDI. These corrode and work loose. New ones are a few quid each.

Thanx Dezza, gonna try that tomorrow,ice got 2 new Toshiba coils at home 

[SATANSAM]

22 hours ago, Dezza said:

If it's running rough because of a reason unconnected with carb balancing (likely) then balancing the carbs with a set of meters is going to be nigh-on impossible.

BS carbs are a pain in the arse to get right anyway due to the screw and locknut adjusters, rather than the much more user friendly spring loaded adjusters on BSTs. I just bench sync my BS 36s and my engine runs fine. A bench sync will be fine until the fault(s) are finally found. If it's still running rough it's not due to poorly synced carbs.

If three sets of carbs have been tried this strongly suggests the poor running is not due to a carb problem. I would go through the ignition system wiring and then each component of the system. Try a set of Kawasaki 3ohm coils (ZXR, ZZR etc. cheap on eb@y) as you can easily renew the leads and caps, unlike Suzuki coils of the 80s in which the lead is moulded into the coil. Examine closely the connector blocks on the CDI. These corrode and work loose. New ones are a few quid each.

Hitachi not Toshiba hahaha...Gonna try them again...But as you say, going to test the signal cables, connectors...

[RickLee]

On 6/10/2021 at 1:03 AM, SATANSAM said:

Mornin' amigos!

Long time no speak...I've started with the suzi again, from the beginning, like a retarded (like always).

As I've got  3 sets of carbs, all clean 100%., with UC, carb cleaner and compressed air. All diaphragms perfect, gaskets too. Bech sync and mounted with air box and intake manifolds perfectly sealed...All jets correct size, choke working correctly...

Valve clearence correct, compression 160 each so correct.

I'm getting a set of carbs in with new throttle shaft viton rings and correct butterfly positions, now Vitons are the only part I can think about....Air lieak like most of you say. Bike synced, fuel screws 2,5 turns out (and more!), idle at about 2000rpm, I close the air filtet intake with my fingers and of course it loweres down...So excess of air...

Anyway, if anybody has a last tip...I might be near success or storing the bike...This bike uses a CDI so I don't think it can be anything to do with advanced timing (I've tried 3 CDIs already!).

Cheerz!

When fitting the air box to the carbs sometimes one of the intake tubes (usually an inner one) does not connect, or wrap its lips around the carb. And sucks a ton of unwanted air. 

[RickLee]

9 minutes ago, RickLee said:

When fitting the air box to the carbs sometimes one of the intake tubes (usually an inner one) does not connect, or wrap its lips around the carb. And sucks a ton of unwanted air. 

That said, my GS1000 is having miserable carb problems and certainly need rebuilding .... but judging from the nightmares many on this forum have gone through, I think I’m going to cash in some doges and spend the 750.00 on a new set of mikunis.   
 

 

[SATANSAM]

18 hours ago, RickLee said:

When fitting the air box to the carbs sometimes one of the intake tubes (usually an inner one) does not connect, or wrap its lips around the carb. And sucks a ton of unwanted air. 

Yep, I've sealed everything,sprayed with contact cleaner (the best response after starter spray) and nothing...Cylinder 3 runs leaner than the rest....Carbs spotless....What the heck!