Just bought non-running GS850

[eil]

Although very eager to take the throttle right from an idle, I will have to do some synchronizing and very likely some idle trim, tuning. Maybe rejetting also to accomodate the 4 into 1 exhaust. For now, the carbs are staying mounted (sorry can't help myself). When fully warmed up the idle is solid at 1,000 RPM, when even hotter - after being in city traffic at stop lights etc, the idle is at about 2000. I get a small amount of "popping" from the exhaust but only sometimes and only during deceleration from above say around 4000 RPM.

The hanging idle is a symptom of running lean. Mine pops on deceleration as well, I attribute it either to a few small holes in the exhaust or just the fact that it's a carbureted engine.

The drivetrain seems quiet enough except when I go into 3rd gear I hear a distinct high-pitched whine.

If it's not very loud, then it's just the shaft drive doin' it's thang.

Once the engine became fully warmed up, oil heated up and thinned out, I could hear something else like a subdued knocking/clunking at idle that I did not notice before. Cannot hear it at all while moving. I'll be checking for loose nuts and bolts especially the exhaust flange mounts. I'm hoping for a slight exhaust leak but fearing a rod bearing has excessive play - or worse. Draining the engine oil will tell me a lot. Keeping my fingers crossed until then. Maybe I didn't get so lucky when I bought this bike

If it gets any worse, you may want to check the starter clutch or clutch hub nut. These engines are pretty darn solid, I'd be surprised if it's anything to worry about. They do make a few odd but perfectly normal noises. They do not sound anything like a sewing machine when idling.

 

[tirebiter]

100 miles so far and still hanging in there. Speedo cable nut backed off from the back of the speedo. Glad it was an easy fix. Wish I could figue out a sure-fire way to keep the rubber handlebar grips from sliding off. I have to continually push them back on, while riding. Non-stock I'm sure since they seem a little too long to begin with.

Did the high pressure self-serve car wash thing to clean the front of the engine ... and everywhere else. Heard an interesting crackling sound when I got back home and shut off the engine. The cylinder head was dry on top everywhere. I could not see anything but heard it for about a minute. Water boiling under or around the starter motor maybe ?

Retorqued the cylinder head nuts. One of the center front ones backed off with less than 15 ft/lbs torque !!! Another one took about 20. the rest seemed ok if not dry and had the bolt-in-aluminum "STICKtion" when they snapped loose. Everything felt like it torqued up ok. The 6mm upside down bolt at the center front turned with an estimated (by hand) less than 4 ft/lbs. One of the side ones was almost as loose.

Discovered the cam cover screws were hand tight as were the ignition pickup cover screws. Apparently I did not use my trusty JIS driver on them or forgot to tighten them properly when I had the covers off. Maybe that was some of the knocking sound I've heard.

I'll rack up some more miles tomorrow and see if the oil leak from the head gasket has stopped ... or got worse as a result of my tampering.

Backfiring when slowing down from highway speeds is excessive !!! Exhaust pipe is not grey near the outlet, by any means. VERY black and sooty. Calculated about 40 MPG combined highway and country backroads, driving conservatively. I'm thinking leaner mainjets are in order. Maybe as small as 135 from the stock 150 I saw in the one carb I took the float bowl off of.

I will be looking into everything I can find on these carbs next. I need to understand the theory behind them. I have experience with constant depression carbs, as they are called when used on British automobiles. Depression equals vacuum in Brit-speak for those who may not know that little tidbit. But I have no experience with carbs that use a vacuum operated piston/metering needle and individual idle circuits and main circuits. A visit to the carb tech forum on this website will be forthcoming and at least a question or two for those who have gone before me, in the next few days.

 

[cowboyup3371]

Which side grip is sliding off? Using hairspray or grip glue will help with that

 

[tirebiter]

Both sides cowboyup3371. I tired spray weatherstip adhesive and the handgrips still slip but not as badly. Never heard of grip glue. I will look for some and try that.

Meanwhile There does not seem to be any more oil leaking from the front of the engine ! I did not smell any hot oil either after getting of the highway and sitting at a stop light. Either I had not cleaned off all the oil previously and the high pressure spray from the self-serve car wash got the remaining oily residue or I was fortunate enough that by retorquing the cylinder head fasteners, I managed to stop the oil from leaking.

I had previously checked the pilot jet adjusting screw setting and they were backed out close to 3 1/2 turns except for #2 was at about 2 1/4 turns and # 1 was out about 3 turns from seated. Once the engine warmed up on my ride today, I pulled over, parked and tried setting each pilot screw to 2 turns out from seated. # 2 carb screw is a bugger to get to with a hot engine and the tank in place. The choke linkage and vent hose are both in the way. NOTE TO SELF : Get tiny thin handled screwdriver for adjusting carb pilot jet screws.

The engine responded well as far as taking the slightest amount of throttle opening. It was as if I had spent time synchronizing the carbs It seems the carbs had been synchronized and the screws had been adjusted unevenly after the fact.

Downside is the backfiring has become unbelievable upon closed throttle deceleration only. It is most severe when coming down from about 4,000 RPM or higher. Not too bad by the time the RPMS get down to 3,000 but still, unacceptably annoying as well as being very bad for the exhaust system.

I'm still looking for an explanation of the theory behind all the systems inside the Mikuni CV carbs. I found the pilot system explanation and adjustment procedure on this site. I thought I had run across something else out there on the Web that encompassed theory of the entire Mikuni CV carb and it's inner workings. I'll keep looking.

 

[850 Combat]

The best feeler gauges to use are metric ones:

Because they start at 0.02 mm and go in 0.01 mm increments up to 0.09 mm. The non-metric feelers that I have seen rarely have a useful range of sizes for doing GS valve clearance checks.

Unfortunately, these metric feelers are rarely available locally. The best place to get them is eBay. If memory serves, under $10 for ones that ship from the U.S. or under $5 for the same ones that ship from China but will take 2-3 weeks to arrive.

Those are nice. Where did you get them?

 

[cowboyup3371]

I can't post it here due to how it's saved but look at the 77-82 GS550 service manual on page 263 (page 269 for Adobe reader due to its pagination) for a good CV carb operations explanation

 

[tirebiter]

850Combat, I bought a set on eBay the other day. Have not taken the time to measure and see how accurate they are but if feel has anything to do with it, the black (plastic? unobtanium?) blade is mighty thin.

I am finding that I can start the engine and drive off immediately while on partial choke. I'm certain the valve clearances are not too tight at this time. If they were close to the trouble zone, I would expect a lot of misfiring, when the engine is cold.

Thanks Cowboyup3371, I'm beginning to see what I need to know about the Mikuni CV carbs. They seem to be a cross between Weber DGV downdraft carbs (the ones with no power valve) but without the accelerator pump or jet and Stromberg sidedraft Carbs which also have an air piston and a fuel enrichment circuit for cold starting. I almost feel right at home now. <right>. At least none of the concepts are new to me.

4 jets at a time though. Uggh ! I can see how rejetting this bike could get pretty time consuming. Another reason to switch to hex drive fasteners and maybe I can sneak the float bowls off without removing the airbox. Maybe this is why Snap-on Tools sells short hex bit drivers !!! Will take a couple of days at least, to digest this knowledge and figure out how I want to go about the rejetting procedure. Should be able to report back by Wednesday.

Where to get new jets in quadrature without buying stuff I probably won't use, is my next item of researching.

 

[tirebiter]

OK, I think I have a good idea of what to do about rejetting this bike.

I have driven several hundred miles on her so far, got the inspection sticker today and have tried two different adjustments of the pilot screws. Will be ordering jets next week.

Check my post in the carb forum if you want to help me with a couple of questions.

 

[tirebiter]

Put in a set of 120 mainjets today. Aso bench-synchronized the carb butterflies. Definitley headed in the right direction. Still some backfiring upon decel. Little Suzy just turned 30,000 miles. About the last thousand was with me riding.

 

[tirebiter]

Put in 42.5 pilot jets today and it's even better but still not 100% perfect. More rejetting to come ... when I can get back to it. It's nice to be able to at least count on having a consistant idle now, every time I come to a dead stop.

I also discovered I can get more fuel into the tank if I deliberately fill the expansion area while fueling. 2.8 gallons at 112 miles, just a hair into the red on the fuel gauge. Actually took the entire $10. To the penny ! All it takes is to wait a few seconds after the fuel has reached up to the base of the filler "neck". It slowly drops down as air escapes from somewhere and then I could add some more again, over and over. I was able to add an extra 10th of a gallon that way. Maybe MORE !!!


Getting used to how she rides, too. Very stiff !!! At some point I will endeavor to see what I can do to soften the jolt from bumps and potholes, which I keep finding in the road.

 

[tirebiter]

Finally got around to changing the engine oil and as some have mentioned, it comes as no surprise but the clutch has far less drag now. Almost non-existant when first started up to none when warm. Guess I'll just hang onto the used clutch setup I bought, instead of using it.

I'm learning that I need to keep the revs up a bit on my way home. If I don't, the battery does not want to crank the engine over much the next morning. This seems especially true if I have had the ignition/lights on for anymore than a few minutes. Not sure why/how I discovered this but she keeps starting up as long as I remember to "charge" the battery fully before parking her for the night, by using 2500 as a minimum RPM for a few miles just before coming home.

Maybe the 5-plus-some-more year old battery that was 100% dried out when I bought this bike, is beginning to tell me something.

 

[cowboyup3371]

Go through Posplayer's quick tests and start looking at why your charging isn't working well AFTER you have a known good battery

 

[wymple]

Finally got around to changing the engine oil and as some have mentioned, it comes as no surprise but the clutch has far less drag now. Almost non-existant when first started up to none when warm. Guess I'll just hang onto the used clutch setup I bought, instead of using it.

I'm learning that I need to keep the revs up a bit on my way home. If I don't, the battery does not want to crank the engine over much the next morning. This seems especially true if I have had the ignition/lights on for anymore than a few minutes. Not sure why/how I discovered this but she keeps starting up as long as I remember to "charge" the battery fully before parking her for the night, by using 2500 as a minimum RPM for a few miles just before coming home.

Maybe the 5-plus-some-more year old battery that was 100% dried out when I bought this bike, is beginning to tell me something.

Before You go running all sorts of tests on the charging system, clean up (really well) all the connectors. Run the 3 stator wires directly to the R/R, preferably with soldered connections, because you should anyway, and ground the R/R to the frame or battery. Then start checking the system. I picked up 1.5 volts on my 850 doing just that.

 

[tirebiter]

I put the battery on the charger and the Ammeter on the charger shows it's supplying 7 Amperes of charging current. Within 15 minutes the meter reads less than 2 amps. Bike starts ok but when I forget to fill the fuel bowls after changing jets, she won't crank for more than 10 seconds before the battery is kaputz again.

I don't believe this is a problem with the charging system. Time to shop for a battery that will fit underneath the tool tray.

 

[tirebiter]

Late summer in New England - I just drove Little Suzy home on the highway for 30 minutes, in 40 degree air ! Brrr.

Earlier today I found where the connections from the stator to the rectifier/regulator live. One of them was in real bad shape. Two others were not much better.

As well as some other work to clean up grounding points, I made a ground wire for the RR and soldered new connectors in after cutting out the bad ones. The needle deflects now on the el-cheapo multi-meter when I rev the engine whereas it did not budge, before doing this work. It does not deflect much and I may have burned up a diode in the rectifier. The stator tests fine though, which is good.

The battery has a bad cell according to the hygrometer. Not surprising. For now at least, it is getting recharged to some degree while the engine is running. The larger pilot jets arrived today also. I'll be doing some more jet-work tomorrow.

 

[Steve]

I'm thinking leaner mainjets are in order. Maybe as small as 135 from the stock 150 I saw in the one carb I took the float bowl off of.

Just in case you were not aware, ... 150 main jets are NOT stock in an 850. :-k

Stock jets are 115.

I don't remember from the first part of the thread, are you running stock airbox and exhaust?

Stock pilots were either 40 or 42.5, depending on the year.

.

 

[tirebiter]

Steve, That was a gross error on my part. A bad typo. I have 120 mains in there now with 45 pilot jets. Stock airbox with an air filter element support that I made. 4 into 1 -maybe Kerker - exhaust. Won't have tome to do much fiddling for a while. Little Suzy will be pressed into service over the next 4 days with a lot of highway use.

Had a few "issues" to deal with as things are starting the migration to getting loose and falling off. Notably I located a manometer port screw that dropped onto the top of the transmission tonight. I honestly thought that I had burnt a valve in the past few days of longer ranging at highway speeds, than I have done before. Lost a side cover as punishment.

NOTE TO SELF : Get new rubbers for the side cover plug-ins.

I was so concerned about the valves I performed a cylinder leakage test on Little Suzy. I am pleased to announce that all of her valves are good and leakage is less than 8 % across the board - on a COLD ENGINE !!!!!!

The lifter depress tool arrived the other day and after this week's workout, she will get the long ignored valve adjustment - that I keep hearing about - and promising to do. I was seriously concerned that I had done the bad thing.

Those pesky manometer port screws are now seated with 4 Nm of torque. Yes a little excessive, like me.

 

[Steve]

I was so concerned about the valves I performed a cylinder leakage test on Little Suzy. I am pleased to announce that all of her valves are good and leakage is less than 8 % across the board - on a COLD ENGINE !!!!!!

Good compression readings only show that the valves are not damaged.

There is still no guarantee of proper clearances.

Good to hear that you are planning an adjustment session.

.

 

[tirebiter]

I've been busy enjoying the ride. A couple of thousand miles so far even in the cold. Did the vlave adjustment. One major difference I noticed is a SOLID idle ! Will eventually post in the appropriate forum regarding that and some more electrical work - with photos. The battery finally gave up the ghost. I knew it was only a matter of time.

Latest irk is the clutch drag which basically disappears when everything is all warmed up. Trouble is, I had a chance to mount a friend's 1990 Kawaskai Ninja 750 which I replaced the alternator belt on. What a world of difference in the clutch on that motorcycle when compared to my 1980 Suzuki GS850LT ! I cannot imagine my bike is right.

Off to post in the proper forum about clutches on these machines.

 

[tirebiter]

Here is what everyone is talking about when they say you need to clean and secure all electrical connections. In particular the relatively high amperage carrying wires from the stator. I cut off these old connectors and soldered on new ones. I have read that some people solder the wires togetehr at this connection to ensure a good electrical load carrying capacity.

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