gorbys
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Posts posted by gorbys
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8 hours ago, Gixer1460 said:
In case you don't - a little blip of throttle whilst moving the gear lever, or moving the gear lever whilst still moving, will usually allow neutral selection. Basically either will 'unload' the clutch to allow easier movement - 101 big bike operation manual LOL!
Oh believe me I've been blipping it little and blipping it big without it helping. Going for neutral while it's in motion sometimes works
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7 hours ago, TonyGee said:
try and weeken the mixture screws off a quarter turn (in) and try it. and sounds like you have clutch drag !!!!!
I've tried some searching here, and it got me wondering, is the gs750 clutch lever and perch I'm using not supplying enough leverage or travel for the gsx1100 engine? Could that be the issue?
It was the same neutral problems with the cable adjusted to no slack at all, even with the clutch slipping if i where stopped I could not engange neutral easily.
4 hours ago, rodneya said:Popping through the pipe when you let off the throttle is lean. You need to go richer on the fuel screw and a bigger pilot if necessary.
You can get pops and bangs from an overly rich tune as well, granted it's more of a burbly sound but still. It's hard to convey sound through writing
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So after getting my cams and timing in order I synced my carbs, adjusted ignition timing and set off, and it was immediately awesome! Right until I hit 5k rpm and the clutch started to slip. Luckily it was just a matter of adjusting the clutch cable. So off I went again and I'm blown away, this thing moves! However there's a few kinks that needs ironing out, namely:
1. Mixture seems to be to rich, it idles nicely but if you rev it it will settle at a couple of hundred maybe 300 rpms lower and then slowly work it self up to idling speed over the course of maybe 10seconds. I'm at 2 turns out on the mix screws, at what point do I consider moving to a size smaller pilot jet?
2. Lots of pops and bangs if I do a slight pull and then quickly let off the throttle in the low to midrange. I have a Hindle 4-2-2-1 exhaust so it doesn't dampen much but still, seems excessive, scared a dog and it's owner.
Is this related to the rich idle mixture or more of a needle thing? Perhaps a combination?
3. Hard to get the thing into neutral, almost feels like the clutch is missing the last little bit to disengage enough. You have to force the shifter and because you force it it ends up usually jumping straight to second, or down to first depending on where you are. Any tips?-
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5 hours ago, AmericanDefender said:
I think I may have this issue as well. Where do I find the part # for the cam gear?
It's stamped right there on the cam wheel. 451.
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Short video of it idling and a little rev. Probably still a bit fat
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I couldn't get all this to add up with the low compression. Like why would it be so bad if the piston rings where new,valves lapped.... so I checked timing and... bingo!
Cams where off. I don't know, maybe the crank moved when they where installed
I redid them and boy did it make all the difference! After some fettling with the carbs and idle i had it sitting at 1200 for minutes! Damn steady! I'm delighted!
Will sync the carbs tomorrow, recheck ignition timing and compression. Take a test ride
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1 hour ago, Jonny said:
What are you using to balance them? Might be worth putting some gauges on when it's doing this and see if one carb is dropping when warm.
Just the standard set of four gauges with vacuum hose. Neat tip. Will try that.
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12 minutes ago, Jonny said:
This doesn't sound to me like an issue caused by compression.
If it were me, I'd try another set of carbs on it first. Sounds like you've already done all the things that would idenitfy the usual issues. If it works with different carbs, you know it's the carbs. You might have some sort of blockage in one of the fuel circuits responcible for idling. It take it you have completely striped and (ultrasonic) cleaned the carbs?
I do have another set of cv carbs on the shelf from the older gs850, but they are in no shape to be run as they sit now. They need a complete overhaul. Maybe I should just order some parts and get to work on them.
They weren't ultrasonic cleaned as my cleaner is dead (just ordered parts to repair it though). But all the jets are new, and I made sure to blow brake cleaner through all the circuits to check that they where open. Which they all where.
I also posted about this in a classic motorcycle group on facebook over here and one guy replied that he had a 82 1100 gsx that would behave exactly the same! And his problems disappeared after refitting the original airfilter box. I don't have the standard box, is there some other way to simulate this? Socks over the air filters? Sponges inside? Taping off a portion of the inlet?? -
Gonna do another compression test today and try to add some oil to the cylinders see what happens
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3 hours ago, PanzerWomble said:
It's a carb issue not a blocked oil filter ....
OK so got a high RPM using the pilots .... adjusted down with the throttle slide control and yet still hunting. ....and you reckon the diaphrams are ok ( how have you checked this ? )
POPs = Air leaks ....exhaust or manifold ....or switched ignition leads possibly .
I'm deja view on similar issues a few years ago n here ...which was a crappy throttle cable sticking .
Was checked when the carbs where disassembled and later when I adjusted the needle height.
Pops, true, but the exhaust is a straight through exhaust so pops and bangs aren't uncommon since there is no dampening
3 hours ago, TonyGee said:what where the compression readings out of interest ?
around 100-110 psi
EDIT: okay, so I see in the service manual now on gsarchive that standard is 128-171psi. Limit is 100psi. Out of the many indicators of malconditions the only one that sticks out to me is "poor sealing of valves" as the piston rings where replaced and cylinders honed when I bought the engine but not the valves, they where just lapped. But they didn't look good and should have been replaced but time and money wasn't available at the time.
Have we reached the consensus that low compression is to blame for this? Valves and poor sealing does pop up under "Engine idles poorly" and "Engine is hard to start"Perhaps cams are misaligned? I Think I should have another look at that too
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4 minutes ago, TonyGee said:
I think the next step is to check the engine, do a compression test just to rule out a mechanical issue.
I did that today as well. Looked alright. Checked valves probably a couple of times last year they're all within spec. Checked float level when they where apart last time so that's in spec. Also replaced all o rings on carbs.
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8 minutes ago, TonyGee said:
did you check the condition of the diaphragms ?
They where fine before winter and it had the same idling issues then so
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56 minutes ago, TonyGee said:
did you have the vacuum pipe plugged when you had the tank off ? and did you have some sort of fuel supply as its running ? got to keep the float bowls full at all times
Yes. And yes.
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3 hours ago, TonyGee said:
rev's that hang is a symptom of an air leak or a lean mixture when it comes to carbs.
3 hours ago, PanzerWomble said:As Tony says you will need to back the mixture/pilot screws out on all 4 carbs as they control idle circuit - the knob in the middle (57) just sets the throttles to idle.
Turn pilot screws in GENTLY until they bottom. Turn all out 1/4 turn at a time (wait 15 seconds between each 1/4 turn adjustment to give engine time to adjust) until highest RPM idle is obtained. Normally do not turn the pilot screw out more than 2.5 turns. If you must turn it out more than 2.5 turns go up to the next larger pilot jet. I've not an ET manual to hand so check that as it should give the the factory setting .
Once you get to high idle you should be able to turn the one control screw ( 57) in the middle of the bank to get the 800 revs.
Pilot screws are the ones in the turret at the front of the carb nearest the engine
Pilot jets sit below part 38
So I did that, I turned them all in, started it and set the idle adjustment screw so that it would idle without me holding the throttle. So now we're at 1500 or so rpm's. I turn them out 1/4 turn and wait for the rpm's to rise and they do and I continue to do so until its screaming at the neighbours at 3.3k rpms at which I then adjust the idle rpm down again. Perhaps this was wrong? should I just have continued upping the mixture until it doesn't go any higher? I have neighbours all around and 3k + rpms is frigging loud on a 4-1 with no db killer so I'm genuienly concerned about complaints at this point. Regardless, back to somewhat reasonable rpms and I try to adjust some more but it doesn't get much response.
And now begins the weirdness: I adjust the idle to a damn steady 1000rpms and it holds it for i dont know a minute or two and I'm all giggity then all of a sudden there's a little pop and it starts to race off up up until its now at 2200 at which point I back out the adjuster to bring it down again, then it almost dies and I turn it in and get it sitting at 1000 again but that only lasts for a short time before it dies.
And several times I got it sitting at a lower idle, 1000 one time, 1200 another time, but all of the times it only last a short while before it either races off the moon or just dies.I did all this with the tank removed and i watched the adjuster sometimes as i turned it and i turn it a little bit; nothing. A little bit more; still nothing, just a hair more: too much!
Would be pulling my hair out if only I had some left!2 hours ago, Gixer1460 said:Or sticky throttle cable
No that's not sticking, returns as it should and there's freeplay
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31 minutes ago, TonyGee said:
first off set the idle when the engine is at working temp. if the rev's are hanging and then dropping is sounds like its running lean (to much air), have you tried the mixture screws ?
If the idle is at 1500, and I rev it, it will rev and then settle at 1500. If I try to lower the idle to say 1000 and I give it a rev as it's about to die it will rev, hang at about 1500-2000 and then drop down and die again.
You suggesting I give it some more fuel and then see if I can manage to drop the idle a bit to? -
I have a 77 GS750 with a bandit swingarm. If you go wider than stock rear wheel the problem is you can't easily just offsett the front sprocket as the entire clutch release mechanism sits in the way. So it's either swapping to a gsx engine or a gs1000 as mentioned, or there are spacer kits as mentioned in another post here.
Chain and frame clearance also becomes a slight issue with a 180 rear wheel -
Last year was the first season properly running the gsx1100 engine in my gs750 and I spent so much time troubleshooting heaps of stuff without ever finding the root cause as to why I can't get a stable low idle on it. Yesterday I had it running again and I was reminded of this very annoying problem. It seems like every time I ride I have to adjust the idle rpm, sometimes even during a ride as it will be fine when I take off and then when I pull over it's too low, or to high.
Yesterday I got it running, warmed it up, bike idles high as it should on choke. After it's warmed up, choke off, it's idling at around 15-1600 rpm, and I want it to sit at 1000-1100. So i adjust it down with the idle screw until I get to around 1000, where it will sit for a few seconds before dropping to 6-800rpm struggle and eventually die. Now if I instead of letting it die I try to save it by giving it some throttle and revving it it will rev up and then it will usually settle at 1500 again for a short while before dropping down and eventually dying.
When adjusting it it seems like there's not enough "range" on the adjuster to get it to sit where I want. Like it's either 1500+ or 7-800 and subsequent death. Nothing in between no matter how minute of an adjustment I make on the screw. It's just so infuriating, I had a gsx750 for a couple of weeks last year and there was nothing like this, I adjusted the idle and thats where it sat. Granted that was a mostly stock bike. The 1100 has a full exhaust and K&N filters. But still, the 850 8v engine that was in it before also had exhaust/pods combo but idled like stock.
Any ideas or tips to try out?
-cable linkage is working smoothly
-carbs have been cleaned and synced
-rubber boots and clamps are new
-can't find any air leaks when spraying around carbs and bootsAlso to note: sometimes if I its idling at 1500 if I put it in gear and relase the clutch in to the friction zone and back in the idle will drop down to less than 1000.....
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On 2/1/2024 at 9:17 PM, ITSshaBOY said:
Can we get this alive again? Anyone fix it?
Yes i fixed it by replacing the 750 engine with a gsx1100 engine
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On 9/19/2023 at 1:41 AM, johnr said:
Did you clean out the fuel tank whilst you were at it? Don't assume a fuel filter will help, the fine dust from a rusty tank will go right through most petrol filters.
No I didn't, thanks for the info.
On 9/19/2023 at 8:27 AM, et1170 said:Have you done a compression test on the engine?
I was gonna but I didn't have the correct size adapter for the spark plug hole.
On 9/19/2023 at 9:27 AM, Safra said:Have you changed your plugs between all this carb fiddling sounds like your plugs are toast
No. You're right, they might be bad. I remember I experienced spark blow out on my Datsun due to bad plugs now that you mentioned it.
Anyways, I don't think I'll be fiddling anymore with it now. I don't have the time and space for it at the moment so I've put it up for sale. If it goes it goes, if it doesn't then maybe I'll come back to it next year when it's hot again and we get our three days of summer.
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17 hours ago, prutser said:
How is the float height of the carbs?
I ve had similar issues with my 1981 gsx750, having a weak spot around 3-4k. Found out one carb was having a low fuel level.
Running a 4-1 exhaust with stock airbox and stock jetting by the way. Once warmed up it pulls smoothly through all the rev range.
I've found one carb leaks, and the petcock leaks in the on position. So I'll bet the fuel level in that one is to the max!
Also noticed a bit of smoke today when I started it up.
So we have at least to high fuel level on one and possible some oil burning.
Weird thing is I watched a video yesterday I took from last week where I did a pull from standstill and it was freaking flawless. It's like it worked alright right after fixing the carbs and then it's gotten worse the more I drove it...
3 hours ago, johnr said:did you remove the emulsion tubes when you cleaned the carbs?
Yes. The where clogged as well. Had to poke out every single hole on every single tube...
I'm starting to think it needs another clean out. Like something has loosened and clogged up something.
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Drove pretty much the same route again with the new plug caps. Not sure I felt that much of an improvement. I mean the plugs are indicating a richer condition but it still doesn't feel like it pulls as hard as it should. And number two carb is leaking fuel through the fuel needle so maybe that's why it's not going as good, since it looks like it's drowning.
Edit: I did a couple of pulls 1-2 gear to redline and when I hit 8 or 9.5k rpm it kind of stopped, then came back again. Like a really lazy rev limiter. That's not right either I guess.
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So. I checked the ignition system. And found out that all the plug caps are wack except for one.
Primary resistance is good in both coils. Secondary was way higher than specified. One was at 70k ohm and the other one at over 800k ohm(this is the one that supplies plug 1-4)
The one plug cap that was good, was number two. Coincidentally the same plug that shows a little bit richer mixture than the three other. So weak spark=lean burn?
Secondary resistance with caps removed checked out at 11k ohms on both coils so they're good.
I'm gonna try with the caps off of my 1100 since they're pretty new and see if it goes any better but is there any thing detrimental to using 5kOhm caps instead of the oem 11kOhm? I haven't noticed anything on the 1100...
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1 hour ago, BigT said:
The first thing is that the Mikuni and Dynojet numbers are not the same
Second is the Dynojet kit should have adjustable needles
I know this. The numbers I mentioned are mikuni numbers.
And yes dj kits have adjustable needles with different tapers.
But none of that matters since I can't use the dj jets anyway. Cheaper as well to just buy four new mikuni jets instead of one more dj kit
56 minutes ago, ral said:My guess is the carbs are still not clean enough, I had similar issues to your description and it took three carb strips to get the internals squeaky clean, have you had the emulsion tubes out and cleaned all the holes out for example.
Once spotless get it on a dyno to set up optimum delivery and you won’t regret it, he’ll of a difference when done right.
Yes, every thing that could be taken apart was taken apart and cleaned, poked and blasted.
Dyno would be great but this is Norway. I know of one, and that's a cross country trip for me...
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17 minutes ago, Gixer1460 said:
It was 30+ years ago - maybe they put their sensible head on and changed the threads?
One would assume so, I haven't heard anything about this when browsing the Web.
Anyways, browsing the dynojet pages I have found a kit for the 750 and I have checked the installation manual but unfortunately the jets recommended doesn't match the extra jets I have. So I have to buy new ones.
According to this guide I need to go up two sizes. https://www.caferacerwebshop.com/en/blogs/blog/how-to-rejet-your-cafe-racer-carburetor/
If my stock ones are 112.5 that would mean a 115 jet right? But should I buy a set of 117.5 just incase? I need to order from the UK so shipping takes a while.
GS1000st cam timing.
in Air Cooled
Posted
Chain stretch perhaps? Mine wasnt 100% flush either. Somewhere in between yours and completely straight.
Compression is good and the bike runs like it should so not to fussed about it