New to Valve shim clearances need explanation

[dnsmith]

I am working on a junk sale 78 GS550E and I have it running. I was having idle issues and mixture problems and got those fixed with carb rebuilds and new o rings on the boots. I was looking in the book and it suggests that before you sync the carbs and fine tune, the valve clearances need to be checked. Makes sense because I have no idea when they were last checked and serviced if ever. So I have the cover off and my first limitation is my feeler guage it only goes down to .051 mm (.002 inches). When I position the cam lobe up at 90 degrees that smallest feeler does not go in under the heel of the cam lobe. All of them are like that. Without a smaller guage I am not sure what they really are. If they are actually less than .001 how bad is that? Should they be brought up into the suggested range of .03 and .08 mm or does wear bring them to where they are now?

 

[KRISTI'SGS550]

dnsmith,
it sounds like you are doing everything right. If your .051 feeler gauge fit between all of your valves, then they would be perfectly in spec. But since they don't that means they all need to be smaller. you need to get a couple smaller feeler gauges and find out the actual gap, so you can figure out what shims you need to buy, swap or trade for. Since none of them .051, you can be sure they all will need to be replaced with a shim at least one size smaller. Example if it is 2.75, a 2.70 would more than likely put it into spec.

 

[hampshirehog]

I'm not going to be able to give you the spot on answer as I've been converted to metric since the 70s and thousandths of an inch means nothing to me.

Valve shim to cam clearances are a 'must check' on a GS. As the valves / valve seats wear the clearance will decrease - literally the valve will rise upwards. The minimum clearance is, as you say, .03mm with the engine cold. If the clearance is less than this you will start to lose compression as the valves may not fully close when they are warm and you run the risk of burning away the valves and seats.

You need to get a thinner set of feeler gauges (down to .03mm) and check those gaps. If you've got gaps closer than the minimum you'll need to swap shims (plenty of good threads on this site). Most people always err on the safe side and if you end up going slightly over .08mm as you juggle the shims that's fine.

 

[dnsmith]

so it is better to have them on the high end of suggested clearance rather then the low end?

 

[BassCliff]

Hey howdy hey!

Hey howdy hey!

Hi Mr. dnsmith,

Yes, get yourself a metric feeler gauge set (only about $5). Mine goes down only to .04mm but I figure if that doesn't fit then I'm going to put in a smaller shim anyway. Yes, you want to run the valve clearances toward the loose side of spec if you can. They tend to get tighter over time. But there's no need to be obsessive about it. I had to leave one of my clearances at .04mm the last time because swapping the shim made the clearance too big. I'll be looking at that one closely the next time I check. Feel free to check my little BikeCliff website for basic maintenance procedure guides.

Now, if I may, I don't think I've given you my mega-welcome! \\/

Let it be known that on this day you are cordially and formally welcomed to the GSR Forum as a Junior Member in good standing with all the rights and privileges thereof. Further let it be known that your good standing can be improved with pictures (not you, your bike)![FONT=Arial, sans-serif][/FONT]

Perhaps you've already seen these, but I like to remind all the new members. In addition to the carb rebuild series, I recommend visiting the In The Garage section via the GSR Homepage and check out the Stator Papers. There's also a lot of great information in the Old Q&A section. I have some documentation on my little BikeCliff website to help get you familiar with doing routine maintenance tasks (note that it is 850G-specific but many tasks are common to all GS bikes). Other "user contributed" informational sites include those of Mr. bwringer, Mr. tfb and Mr. robertbarr.

And here are some edited quotes from one of our dear beloved gurus, Mr. bwringer, with ideas on basic needs (depending on initial condition), parts, and accessories.
***********Quoted from Mr. bwringer************
Carburetor maintenance:

Replace the intake boot o-rings, and possibly the intake boots. Here's the procedure:
http://bwringer.com/gs/intakeorings.html
Here's an overview of what happens with this particular problem:
http://cycleorings.com/intake.html
You'll also want to examine the boots between the carbs and the airbox. There's a good chance these are OK, but check them over.
And finally, if things still aren't exactly right, you'll want to order a set of o-rings for BS carbs from the GS owner's best friend, Robert Barr:
http://cycleorings.com
Once you receive these rare rings of delight, then you'll want to thoroughly clean and rebuild your carburetors. Here are step-by-step instructions that make this simple:
http://thegsresources.com/gs_carbrebuild.htm
***********************************
Every GS850 has (or had) a set of well-known issues that MUST be addressed before you have a solid baseline for further troubleshooting. It's a vintage bike, and it's quite common (as in, every single GS850 I have had contact with) that there are multiple problems that have crept up and slowly gotten worse over the years. It's not like a newer vehicle, where there's generally one problem at a time.

These common issues are:

1. Intake O-rings (install NEW OEM or Viton only - common nitrile O-rings will quickly deteriorate from heat)
2. Intake Boots (install NEW -- these cannot be repaired)
3. Valve clearances (more important than most people think)
4. Carb/airbox boots
5. Airbox sealing
6. Air filter sealing
7. Petcock (install a NEW one)
8. On '79 models, install new points or Dyna electronic ignition (or at least verify that the old points are working correctly)
9. On all models, it's fairly common to have problems with the spark plug caps. These are $3 or $4 each, and often worth replacing if you're keeping the stock coils/wires.
10. Stock exhaust with NO leaks or holes -- good seals at the head and at the junctions underneath.
***************************************
OEM Parts/Online Fiches:

I would definitely double and triple the recommendations to use Cycle Recycle II and Z1 Enterprises as much as possible. These guys are priceless resources. Z1 tends to have slightly better prices, CRC2 has a wider range of goodies available. If you're near Indy and can bring in an old part to match, CRC2 has a vast inventory of used parts.
http://denniskirk.com - Put in your bike model and see what they have.
http://oldbikebarn.com - seems to be slowly regaining a decent reputation, but it's still caveat emptor. They don't have anything you can't get elsewhere at a better price anyway.
http://www.babbittsonline.com/ - Decent parts prices. Spendy shipping. Don't give you part numbers at all. Useful cross-reference if you obtain a part number elsewhere. Efficient service.
http://bikebandit.com - Fastest. Middlin' prices. Uses their own parts numbering system to obfuscate price comparisons -- can be very confusing for large orders. Cheapest shipping, so total cost usually isn't too bad.
http://flatoutmotorcycles.com - Slow. Cheapest parts prices, crazy shipping costs. Don't expect progress updates or much communication. Real Suzuki part numbers.
http://alpha-sports.com - Exorbitant parts prices. Different type of fiche interface that's quite useful at times, especially with superceded part numbers. Real parts numbers. Shipping cost and speed unknown due to insane, unholy pricing.

Stainless Bolts, Viton o-rings, metric taps, dies, assorted hard-to-find supplies and materials, etc:

http://mcmaster.com - Fast, cheap shipping, good prices. No order minimum, but many items like bolts come in packs of 25 or 50. Excellent resource.
http://motorcycleseatcovers.com - Great quality, perfect fit (on original seat foam), and available for pretty much every bike ever made. Avoid the textured vinyl -- it's perforated.
http://newenough.com - You DO have riding gear, don't you? Great clearances, always outstanding prices and impeccable service.
***************End Quote**********************
Here are some extra links:

GSR Forum member Mr. duaneage has great used upgraded Honda regulator/rectifiers for our bikes. Send him a PM.
New electrical parts:
http://stores.ebay.com/RMSTATOR or http://www.rmstator.com/
http://www.ricksmotorsportelectrics.com/index.php
http://www.electrosport.com/
The Rice Paddy (salvage/used)
http://www.ricepaddymotorcycles.com
Ron Ayers Motorsports
http://www.ronayers.com
MR Cycles
http://www.mrcycles.com
Moto Grid
http://www.motogrid.com
If all else fails, try this:
http://www.used-motorcycle-parts.org/
Used bike buying checklists:
http://www.amadirectlink.com/roadride/Riderresc/checklist.asp
http://www.clarity.net/~adam/buying-bike.html
Lots of good info/pictures here:
http://www.suzukicycles.org
http://www.cyclechaos.com/wiki/Motorcycle_Wiki

Thanks for joining us. Keep us informed of your progress. There's lots of good folk with good experience here.

Thank you for your indulgence,

BassCliff
(The unofficial GSR greeter)

 

[Steve]

dnsmith,

To help you keep track of your valve clearances and shim inventory, I have developed a little spreadsheet to make the chore a bit easier. It can be used with inch or metric measurements, and also includes a page to keep track of any service you do to the bike, so you have it all in one place.

To get your own copy, send me an e-mail (click on my name for my address), put something about valve adjust spreadsheet in the subject line to get it past the spam filters. If you don't mind, please also give me your name, bike info, and what little corner of the world you call "home". I will be home tomorrow night and will be able to reply to your e-mail then.

.