79 GS750 Top end rebuild Newbie

[4banger]

Hey everyone, just purchased a 79 GS750 and found you guys. Great and very specific site! Well here is the skinny:

I bought the bike for $350 with head yanked off and the previous owner attempting to removing the cylinder jug because he said the compression was low.

I'm going to get a full gasket set, rings, and whatever else y'all tell me is a must, but I'm trying to do it on a budget (if the original purchase price wasn't a big enough clue haha)

Questions are: where to get rings? I called the dealer and they said $42 a piston! That's like $170! I've found full gasket sets for around $100 on ebay but no sign of rings to be head anywhere but the stealership! I built hotrods all my life but this is my first dive into bikes and I have some cool plans for this one just need to see signs of life first.

Thanks!!

[DannyMotor]

Hahaha... welcome to the expensive stuff.

The money you 'saved' buying a bike that was torn apart with unknown history will come back to bite you starting NOW.

Head gasket (a good one) will be $60-70... if you find a gasket 'kit' for under 100 bucks, pass on it.

You will also need, base gasket.. (cheap), base gasket o-rings, a cam cover breather gasket, and a valve cover gasket..

Rings are that price... sorry. But wait on them... who knows if your cylinders need to be honed, do they still show factory cross hatching? If you need a hone, you need +1 size rings... so take a lot of measurements, and get yourself a Haynes or Clymer manual...

Go here: Read everything you can: http://members.dslextreme.com/users/bikecliff/

Do you know if the crank has been spun with the heads off? Something else to check into...


Why did you pay $350?

Rule #1: If a bike is over 25 years old, and you want it to be reliable... it will cost you $1500 dollars. Doesn't matter if you spend $1500 on the bike, or get the bike for free and put $1500 into it... your budget is now $1500 bucks -$350.

[tkent02]

Slap it back together and adjust the valves, ride it hard and check the compression... If it suddenly has decent compression you have saved a lot of money. Usually low compression means the valve clearances are too tight to close.

[Nessism]

Part Shark or Boulevard Suzuki have pretty good prices. I'd do the rings after bottle brushing the cylinders. ONLY use Suzuki brand gaskets; aftermarket gaskets are poor quality. Tom has a point about poor previous owner diagnoses, but gaskets are just too expensive to gamble with in my opinion.

Ebay sometimes has gaskets for cheap. This one is OEM Suzuki, but not sure the head gasket is there.

http://www.ebay.com/itm/SUZUKI-GS-750-GASKET-SET-PART-11400-45814-/320895401863?pt=Motorcycles_Parts_Accessories&hash=item4ab6db3f87&vxp=mtr#ht_500wt_1413

[MisterCinders]

You can read all about novice top end adventures in this thread

If you have the gaskets from the PO, I would take tkent's advice first. Button it back up and see what you've got, unless you don't have a new head gasket. Once you have to buy a head gasket (it needs to be new because they don't survive removal), best do everything you can while you are in there. Only use OEM head gaskets, even though they run about $100.

To rebuild the top end, you need to pick up at least the following parts:

Base gasket
Head gasket
Valve guide oil seals (these will not survive removal, are cheap, and always worth changing)
Piston rod circlips (cheap, but you should use new ones to put them back together)

While you are in there, check your pistons and rings. If they are within specs, you might be OK. When I did my top end, I replaced the rings, but the pistons were in good shape.

Pulling out the valves is a bitch, but worth doing. If you don't need to recut seats or replace them, you should still clean up the seats and lap the valves.

When you button it back up, you will need to adjust the valve clearances, because disturbing all that stuff can throw them off. Plus, you don't know what clearances you had before, so you have to set them new.

[4banger]

Thanks for all the replies, I have had a busy week at work but hopefully this holiday weekend I can really start tearing into it. I'm trying to get this done for under a grand and I really think it might be possible even resorting to stealership prices. (provided that it is basically straightforward and nothing is lurking in the crankcase)

I do have a clymer manual and this weekend should be a fun one!!

[7981GS]

The FAR SUPERIOR Factory manual should be on BassCliff's web site.

Eric

[4banger]

The FAR SUPERIOR Factory manual should be on BassCliff's web site.

Eric

You're not kidding there really is some great stuff on there!

[BassCliff]

Greetings and Salutations!!

Hi Mr. 4banger,

Sorry I'm late. Anyway, let me dump a TON of information on you and share some GS lovin'.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. This is what NOT to do: Top 10 Newbie Mistakes. Now let me roll out the welcome mat for you...



Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[MisterCinders]

Thanks for all the replies, I have had a busy week at work but hopefully this holiday weekend I can really start tearing into it. I'm trying to get this done for under a grand and I really think it might be possible even resorting to stealership prices. (provided that it is basically straightforward and nothing is lurking in the crankcase)

I do have a clymer manual and this weekend should be a fun one!!

Yeah, the Clymer Manual is pretty crappy. The parts covering the top end are not too terrible though. Definitely grab the Service Manual though, since it is more comprehensive. Note that the Service Manual will blithely tell you ram out the valve guides and replace them with every rebuild. That's NBD when you are in a Suzuki shop with a mountain of parts and machining gear. Mere mortals like us don't generally do that unless the valves have too much play within the guides.

You can absolutely rebuild that top end for less than $1,000. I spent a couple hundred bucks on parts (gaskets, new piston rings) to do mine. Had I needed new pistons, that might have added $150 more IIRC.

[4banger]

Basscliff and Mister Cinders you guys are great. And better than just answering the one or two questions I had, you sent me in the right direction to get the base I needed to build off of. It's the feed a man a fish, teach him how to fish scenario and now I feel like I understand a lot more about the bike. After some tear down and rebuild experience hopefully I be able to contribute more to the site rather than just asking a bunch of noob questions. Stay tuned for a good build here soon hopefully! (time and money permitting always right?)

[4banger]

Also, seems like there is a ton of problems with the airbox leaking and throwing everything off so why isn't everyone just updating their jets and running pods? If someone where to do this BTW what size would be best for pods with a kerker 4-1 exhaust? Probably posted elsewhere but while I was asking...

[cowboyup3371]

The problems of airboxes leaking really only comes from 30 yr old rubber pieces that are designed to fail. Replacing the boots (both intake and air box side) as well as the orings will fix the issues.

Throwing pods on creates a whole new set of problems as the rejetting doesn't always work the first time. There's a whole lot of time spent doing plug chops and fine tuning. However, using the stock airbox means a person can spend more time trying to ride (still good idea to do the plug chops but not as aggravating).

I considered going to pods only because it was looking like I couldn't find another airbox to first fix a problem of a piece being broken off (breather valve hose connection) and now this box not fitting correctly. Howevere, I have since found another airbox that should work and hopefully I can be done. If not, then I'll go to pods but I am also prepared for the work.

As far as your question on the pipes, you'll have to just play with the sizing until you find the right settings through all the ranges. That will take time so don't rush it. Follow the recommendations here by doing the plug chops and seeing what your bike does at different throttle positions.