Author Topic: Adding a GS750EC to the stable!  (Read 1282 times)

Offline Bryanj

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Re: Adding a GS750EC to the stable!
« Reply #30 on: February 16, 2018, 07:11:52 PM »
looks like a piper on there, leave it on and wake the neighbours-----in the next county!

Offline Jamesh_sussex

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Re: Adding a GS750EC to the stable!
« Reply #31 on: February 16, 2018, 07:26:29 PM »
looks like a piper on there, leave it on and wake the neighbours-----in the next county!

Offline Laverda120

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Re: Adding a GS750EC to the stable!
« Reply #32 on: February 17, 2018, 03:05:11 PM »
John Naish of Classic Bike was in the process of undertaking a rolling restoration of one of these big Suzuki's in the same colour. Unfortunately CB appears to have undergone a bit of a clearout in the past couple of months with John Naish, Mike Nicks, Mark Gardiner and Mick Duckworth all appearing to have left and with them the progress of the Suzuki rebuild.

Offline royhall

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Re: Adding a GS750EC to the stable!
« Reply #33 on: February 18, 2018, 10:21:03 AM »
James. Your going to have fun getting the airbox and carbs off and on. If you find an easy way to do it you will let me know. Also, there's a really good clutch basket fix that stops the rattling completely using Falicon springs and welded rivets.

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Current bikes:
TriBsa CCM 350 Twin
CB350F in Candy Bacchus Olive (still smoking on pot 4 Ggrrrrrr)
CB750F2 in Candy Apple Red
CB1300SA in Black
Triumph T100C
Suzuki GS1000HC (DHL morons ruined my tank)
CB450K0 Black Bomber (current project)

Offline Jamesh_sussex

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Re: Adding a GS750EC to the stable!
« Reply #34 on: February 18, 2018, 02:42:30 PM »
James. Your going to have fun getting the airbox and carbs off and on. If you find an easy way to do it you will let me know. Also, there's a really good clutch basket fix that stops the rattling completely using Falicon springs and welded rivets.

Sent from my Nexus 6 using Tapatalk
Hi Roy. I’m sure I’ll share your pain when I get to it

So have had the Grumpy1260 clutch mod done then?

Offline royhall

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Re: Adding a GS750EC to the stable!
« Reply #35 on: February 18, 2018, 06:51:43 PM »
Ah you've heard about the Falicon mod then James, all I can say is it really does work. The clutch on mine now makes zero noise, shame there's not a similar fix for the CB750 mine drives me mad.
Current bikes:
TriBsa CCM 350 Twin
CB350F in Candy Bacchus Olive (still smoking on pot 4 Ggrrrrrr)
CB750F2 in Candy Apple Red
CB1300SA in Black
Triumph T100C
Suzuki GS1000HC (DHL morons ruined my tank)
CB450K0 Black Bomber (current project)

Offline Woodside

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Re: Adding a GS750EC to the stable!
« Reply #36 on: March 28, 2018, 06:43:13 PM »
just seen these and it reminded me of  this thread

m.carandclassic.co.uk/car/C976025

Offline K2-K6

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Re: Adding a GS750EC to the stable!
« Reply #37 on: April 26, 2018, 10:25:37 AM »
Ah you've heard about the Falicon mod then James, all I can say is it really does work. The clutch on mine now makes zero noise, shame there's not a similar fix for the CB750 mine drives me mad.

Royhall, have you been through the Honda routine for setting the carb idle jets to stabilise the tickover? When you hear some of them which are well set up they do sound much smoother as you've effectively taken out that hunting from running too rich at tickover. Even if it's one cylinder they just keep "chuntering" which makes the primary drive flap around.

This is what current fuel injection on cars does,  both diesel and petrol,  they optimise the fuel amount on tickover while monitoring individual cylinder speed via flywheel sensor,  so they have effectively mimicked Honda practice albeit with on the fly monitoring. That's why when you start modern stuff you get that flat very stable idle immediately.

The idle screws are set as a baseline by turns out figure given as start point and should be set properly when warmed up and running.

It may get you closer to what you're after on the Honda.

Offline royhall

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Re: Adding a GS750EC to the stable!
« Reply #38 on: April 27, 2018, 10:45:48 AM »
Ah you've heard about the Falicon mod then James, all I can say is it really does work. The clutch on mine now makes zero noise, shame there's not a similar fix for the CB750 mine drives me mad.

Royhall, have you been through the Honda routine for setting the carb idle jets to stabilise the tickover? When you hear some of them which are well set up they do sound much smoother as you've effectively taken out that hunting from running too rich at tickover. Even if it's one cylinder they just keep "chuntering" which makes the primary drive flap around.

This is what current fuel injection on cars does,  both diesel and petrol,  they optimise the fuel amount on tickover while monitoring individual cylinder speed via flywheel sensor,  so they have effectively mimicked Honda practice albeit with on the fly monitoring. That's why when you start modern stuff you get that flat very stable idle immediately.

The idle screws are set as a baseline by turns out figure given as start point and should be set properly when warmed up and running.

It may get you closer to what you're after on the Honda.
Thanks for that. The carbs are synced quite well. They are spot on at tickover and very very slightly out at 5000rpm. Have had a play with the idle screws but it does not appear to make any difference to the clutch noise and the engine runs best at standard basepoint settings. Plugs are the correct colour as well. The clutch is rebuilt with all new plates/springs/bearings etc. I think this problem appears to be slightly worse on the F2 than the K's, I had another F2 and that was the same so think it may be PD carb related. Would be interested to know if the K7 does the same. The noise completely disappears when the clutch is pulled in so will just live with it.
Current bikes:
TriBsa CCM 350 Twin
CB350F in Candy Bacchus Olive (still smoking on pot 4 Ggrrrrrr)
CB750F2 in Candy Apple Red
CB1300SA in Black
Triumph T100C
Suzuki GS1000HC (DHL morons ruined my tank)
CB450K0 Black Bomber (current project)

Offline K2-K6

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Re: Adding a GS750EC to the stable!
« Reply #39 on: April 27, 2018, 08:46:05 PM »
I understand where you've got regarding syncing the carb slides but believe Honda go further onto the pilot setting to finish the setup.

It's not the clutch that rattles on these and generally all the 750s are the same I feel. When you pull and hold the clutch lever it isolates the gearbox which becomes stationery if the clutch is held open. With the clutch left alone,  the gearbox is left to oscillate in response to changes in crankshaft speed.

The Honda routine is such a benign piece of text that it's easily missed as to its true purpose. But I feel it's worth expanding to give a better assessment of what they are doing. I've come back to it and realised only after working on other things what they are achieving.
It's not an absolute setting of pilot jets (they give a start point for the F2 of 1 3/4 turns out) but accepting through their process the individual calibration of each idle circuit. This would take into account any physical difference in each jet and also how each cylinder is burning the mixture it's tgiven. And hence an equilibrium of piston speed when fired at tickover.

The crank speed,  if for example one cylinder requires a slightly different set point,  would speed up or slow down on that cylinder's power pulse. It's this effect that makes the crank speed oscillate,  and so makes the transmission clatter. Remember, you're altering the mixture via fuel quantity as you've already set the air via syncing.

They start by warning not to change the idle screws,  but if you've stripped the carbs and rebuilt,  then advise to follow this routine to set them again to factory spec.
So it's quite likely you'll end up with an aggregated level the same as you feel is correct now,  but with each cylinder calibrated to work with the true flow achieved through individual circuits, giving even combustion for all cylinders. And not an even turn of the screwdriver.

It's a bit like we set tappets. You could touch them all down to no clearance,  then back them out a pre-determined amount. But we don't do that,  we measure them with,  in effect a calibrated shim. Their routine is just doing that but with engine rpm as the calibrator.

Offline yozzer74

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Re: Adding a GS750EC to the stable!
« Reply #40 on: May 12, 2018, 05:47:44 PM »
Nice looking bike .I can agree with royhall the parts are eye watering bout ,two inlet rubbers for my gs550 yesterday 80 quid ooch

Offline Jamesh_sussex

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Re: Adding a GS750EC to the stable!
« Reply #41 on: May 13, 2018, 01:14:29 PM »
I understand where you've got regarding syncing the carb slides but believe Honda go further onto the pilot setting to finish the setup.

It's not the clutch that rattles on these and generally all the 750s are the same I feel. When you pull and hold the clutch lever it isolates the gearbox which becomes stationery if the clutch is held open. With the clutch left alone,  the gearbox is left to oscillate in response to changes in crankshaft speed.

The Honda routine is such a benign piece of text that it's easily missed as to its true purpose. But I feel it's worth expanding to give a better assessment of what they are doing. I've come back to it and realised only after working on other things what they are achieving.
It's not an absolute setting of pilot jets (they give a start point for the F2 of 1 3/4 turns out) but accepting through their process the individual calibration of each idle circuit. This would take into account any physical difference in each jet and also how each cylinder is burning the mixture it's tgiven. And hence an equilibrium of piston speed when fired at tickover.

The crank speed,  if for example one cylinder requires a slightly different set point,  would speed up or slow down on that cylinder's power pulse. It's this effect that makes the crank speed oscillate,  and so makes the transmission clatter. Remember, you're altering the mixture via fuel quantity as you've already set the air via syncing.

They start by warning not to change the idle screws,  but if you've stripped the carbs and rebuilt,  then advise to follow this routine to set them again to factory spec.
So it's quite likely you'll end up with an aggregated level the same as you feel is correct now,  but with each cylinder calibrated to work with the true flow achieved through individual circuits, giving even combustion for all cylinders. And not an even turn of the screwdriver.

It's a bit like we set tappets. You could touch them all down to no clearance,  then back them out a pre-determined amount. But we don't do that,  we measure them with,  in effect a calibrated shim. Their routine is just doing that but with engine rpm as the calibrator.
Think you’ve hit the nail on the head with this one. Really enjoy your posts where you take time to clearly assess and explain your views. Keep them coming - they're certainly not wasted on me...

Offline AndyH

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Re: Adding a GS750EC to the stable!
« Reply #42 on: June 20, 2018, 11:49:35 AM »
OK some interesting reading folks.....but back to the Suzi  :P....I've been on a few rides over the late Summer/Autumn here in West Aus and the bike has certainly lived up to expectations!  It has this lovely howl as you open the throttle at highway speeds but it's a cold bitch first thing in the morning!  ::)
I get positive comments wherever I take it so pretty chuffed!  8)
It does need the odd few things updated/repaired but as a basically unrestored/original example it's pretty good!  Winter is here now so rides will be less frequent so once I finalise some oil seal replacements on my Honda CB500K1, it will soon to be up for sale, and funds from this will go to updating the Suzi.
Andy

1972 CB500 Four K1 (AUS version) 8)
Previously owned..
1967 Honda Sports 90
1971 Yamaha CT2 175
1973 Yamaha RD250
1975 Kawasaki KX125
1979 Yamaha XT250T
BMW R65
BMW R80
BMW R100LT