GS850 carbs had some good progress

[Guest]

Still getting to know the bike, looking at the paper work I have the bike has only done 4k miles in the last 10yrs, the PO has looked after the bike and I have lots of receipts for work carried out, including valve cleareance checks just over 2k miles ago, the plugs when I got the bike looked as though the bike had been previously started on the choke and left to run for a while, time and time again. been doing a lot of searching/reading on here with some good results so far, taking information from one of the links http://www.factorypro.com/tech_tunin...m_engines.html
It gave a word for word example of how my bike was running, under the section : idle and low speed running, I adjusted the mixture screws as per the info idle was greatly improved, stopped it running up after small throttle blips, now revs and drops to idle with no issues, it also helped a lot with low speed in 1st 2nd 3rd though this still felt a little hesitant.
I have balanced the carbs though this was done before I had ridden it and discovered it was on the lean side.
Bikes starts no problem at all from cold with some choke on until it warms up, then choke off, restats no problem when warm/hot. Prior to making any adjustments the mixture screws were just under 2 1/4 turns out.

Plugs 1 2 and 3 have good coloration, on inspection after a good ride today (just trying to get some miles on its back after) no4 though is still on the lean side did a few plug chops today, mixture screws on 1,2,3 from memory after adjustment are just over 2 1/2 full turns, No4 now out a good 3 1/2 turns some improvement regarding colouration, but not as good a the others. it will pull in top gear from 30mph right through and feels nice and smooth.

Long winded I know, what I was trying to find out, would a worn o ring on No4 mixture screw be enough to cause what I'm seeing, also can the small spring, washer and o ring be easly removed ones the mixture screw is out.

Also been on with replacing a blown fork seal, man old fork oil has a smell all of its own.
Thanks for any info.

[tom203]

".....also can the small spring, washer and o ring be easly removed ones the mixture screw is out."

Sure but you might have to make a small hook to grab them. Inspect tip in case it got mangled. Sounds like some/all of your carbs are slightly gunked up and not passing enough mixture at low speeds. If it was me, I'd try some cleaner like Seafoam and run it a bit, especially if you haven't run it much. Sometimes you get lucky.

[Paul]

for good measure it might also be worth spraying some easystart ( or propane etc..) around No 4 in case there's a slight air leak

[Chris G]

for good measure it might also be worth spraying some easystart ( or propane etc..) around No 4 in case there's a slight air leak

Hi Paul, did try this earlier, I'll give it ago with easy start instead, that was my gut feeling at first, but my initial try made no difference to idle speed ramping up, also running some good quality fuel cleaner through the system, will try this for a few tank fulls, thanks for the reply

[Chris G]

".....also can the small spring, washer and o ring be easly removed ones the mixture screw is out."

Sure but you might have to make a small hook to grab them. Inspect tip in case it got mangled. Sounds like some/all of your carbs are slightly gunked up and not passing enough mixture at low speeds. If it was me, I'd try some cleaner like Seafoam and run it a bit, especially if you haven't run it much. Sometimes you get lucky.

Thanks for the reply, I have a small hooked tool that should do the job, I removed the mixture screw on no3 for comparison it looked the same as no4 they both go to a taper with the very tip being more flat, than pointed from a recent picture I saw of a mixture that seems normal, is this the case. Thanks

[Chris G]

Update
I removed all the mixture screws, and fished out the o rings did No4 first as this was the leanest of them all, on inspection the o ring looked ok, but with a closer look it was like a pancake very flat making the centre hole appear to large to seal properly, No2 was the same the others looked better.
Bought new OEM seals these part numbers have been superseded when compared to the old ones it was quite evident the old ones were past it

Once replaced I started her up, running was not the best, let her warm up and checked the plugs for coloration, good news as before even at idle and doing numerous plug chops with the screw 4 turns out on No4 this plugs was running very lean.
What I also found while trying to set things up was the header on No4 was no where near the same temperature as the others, checking the spark it was weak and intermittent, I had put new plug caps on last week and cut back the lead by 1/4" but what I found was the lead was very hard/stiff so I cut another 1/2" off and tried again, instant improvement went from running on 3 1/2 to 4 cylinders, would have been a waste of time trying to set the mixtures unless it was running properly, also found the rubber boot on the air box side for No4 just didn't look to be sat properly, removed the original clamp, as I couldn't get it to sit how I wanted it, used a jubilee clip for now and got it to seal fully, all the boots are still pliable, but there replacement may be on my next shopping list.

Spent quite a bit of time setting the mixture screws to all 4, for better idle and throttle response, now have all four plugs with much better coloration, now have a bench mark, not road tested yet due to poor weather, but making progress