850 top end rebuild

[fredbail]

First time in for me. God bless all in this house! My question is about an '80 850 gs g. I rebouilt the carbs(I think) to get this heap to run, and finds that it blows a good deal of smoke, and no. 2 looks nasty from removing the plug. I have not done compression test yet. The filter was let go for years,and God knows what wandered in. I am wondering about $, and time and trouble to pull heads and such. I am a good shade tree, but have no specific knowledge about this bike. I tind to be anal, and get hung up by not knowing which way this washere went, and such as that. I am looking for advice, opinions, and best of all, a local guru. I live in Frederick, Md. Everything has been done backwards on this clunker, but I have limped it around the block. I enjoy getting old stuff going again, but I don't want to hurt myself, either. Thanks for reading, and pre thanks to all respondents. Dan B.

[bwringer]

Richness in #2 is the textbook sign of a failed petcock diaphragm. You'll need to replace the petcock with a new OEM one from your favorite source for Suzuki parts.

A few good sources:
http://flatoutmotorcycles.com <== cheapest, real part numbers
http://bikebandit.com <== fastest, confusing fake part numbers
http://babbittsonline.com <== no part numbers, good cross-reference tool if you find part numbers elsewhere
http://alpha-sports.com <== real part numbers, nosebleed prices, useful interface


You'll also want to get a shop manual:

http://repairmanuals.com

I have both the Clymer and Haynes -- they are both frustratingly opaque at times, but it's often valuable to have both perspectives. I think you can also get the Suzuki manual, but it's full of baffling references to obscure and no longer available special dealer tools.

As far as parts for the rebuild (if you decide one is truly needed after checking compression and such), don't fart around with aftermarket gasket kits. They're incomplete and very poor quality. (Guess how I know... ) Everything you need is still available from Suzuki.

[BassCliff]

Greetings and Salutations!

Hi Mr. fredbail,

Please click here to receive your mega-welcome, chock full of suggestions and tips, links to vendors and other resources. Then feel free to visit my little BikeCliff website for lots of GS lovin'. Thanks for joining us. Please keep us informed.


Thank you for your indulgence,

BassCliff

[fredbail]

Thanks for response. I cleaned and inspected petcock ...looked o.k. but I don't understand, If diaphram is open when it has intake preasure doesn't gas just flow to carbs as float jets allow? I am not getting something here, and I fear it is from ignorance. I assume the tank with a properly working petcock is like a tank with no petcock at all ...no wait do you mean a failed petcock would allow gas or air to travel throgh the line that gives negative pressure...which is from #2? and "whose behind is the giant rat of sumatra? "firesign theater thanks again, D. B.

[bwringer]

Thanks for response. I cleaned and inspected petcock ...looked o.k. but I don't understand, If diaphram is open when it has intake preasure doesn't gas just flow to carbs as float jets allow? I am not getting something here, and I fear it is from ignorance. I assume the tank with a properly working petcock is like a tank with no petcock at all ...no wait do you mean a failed petcock would allow gas or air to travel throgh the line that gives negative pressure...which is from #2? and "whose behind is the giant rat of sumatra? "firesign theater thanks again, D. B.

Correct -- when the petcock diaphragm goes bad, gas will travel down the vacuum line into #2 when the engine is running. Buy a new petcock -- they last about 20-25 years.

The float valves in the carbs aren't designed or able to hold back gasoline while the bike is sitting. If you leave the petcock on prime (open all the time) for a couple of days, gas will seep in, make its way into the engine, contaminate the oil, and could even hydro-lock the engine.

When it's working right, the petcock in the "on" position is actually off, unless the engine is running. Engine vacuum yanks the diaphragm and opens the valve. You shut off the engine, there's no more vacuum, and the petcock shuts off. Very tidy, and perfectly safe and reliable for 20-25 years.

"Reserve" works just like "on", except that it draws fuel from lower in the tank.

In the "prime" position, fuel can flow through the petcock no matter what. Therefore, it is only used for a minute or so at a time to fill the carbs after they've been drained for whatever reason.

[fredbail]

Thanks again for response. I checked compression...800 dry... 1100wet... all 4...There is a lot good in this bike, but if I sell, I will tell what I know, maby it will c atch on.....yours, D. B.

[Thomas Kenny]

Thanks again for response. I checked compression...800 dry... 1100wet... all 4...There is a lot good in this bike, but if I sell, I will tell what I know, maby it will c atch on.....yours, D. B.

Did you perform your check on a warmed up engine with the throttle held wide open?? :-)

[fredbail]

Yes, burnt knuckles to prove it. Went by the book....throttle wide open..

[chef1366]

Holy high compression Batman. Are we talking pounds?

[psyguy]

so, is that like 80-110psi ?

(that'd be a bit on the low side then)

[SqDancerLynn1]

I don't know what the conversion is, 850 should be around 130 psi. Was not designed as a high compression motor. It needs to run for an hour or two before you decide on condition

[49er]

The figures quoted will be in kilopascals (kpa). 800 dry converts to around 113 psi, 1100 wet is around 155 psi. It neeeds to be checked again after a decent run.

[chef1366]

The figures quoted will be in kilopascals (kpa). 800 dry converts to around 113 psi, 1100 wet is around 155 psi. It neeeds to be checked again after a decent run.

Thanks Ian.
Whew!