Bought a project bike and am new to motorcycles, could use some help with diagnosis

[Guest]

Hello,

I'm new to the forum, and motorcycles in general. I picked up a 1983 GS 450L really cheaply on Friday and is running on only one cylinder. I currently have the carbs pulled off, but I didn't see any obvious issues (I'm new to carbs). My roommate is thinking it's a possible compression or valve gap issue. How much compression should I see when I test, and what are the specs for valve adjustments?

Also, anything else I should check that may keep it from running properly. I have a friend helping me check the carbs over and probably rebuild them, but I'd really like to just get things running right before I start spending money making it nice.

Thanks in advance for any help I do appreciate it.

[chuck hahn]

The carbs can look like new and still be clogged up inside the passages. Look on the right side margin here and look for the CV carb rebuild tutorial.

http://members.dslextreme.com/users/bikecliff/

Get the oring kit here from our member Robert Barr and check the valve adjustments per the manual. When doing a compression check hold the throttle grip wide open and roll the engine over a good 3 or 4 revs to get a good reading. You should see around 140ish on near perfect cylinders. Maybe a bit higher.

http://cycleorings.com/

Rebuild the carbs and DIP THEM in Berrymans carb and parts cleaner for 24 hrs after FULLY disassembly. Get the valves checked out for proper clearance and once its running get the carbs synced with the vacuum gauges. Do all the maintenance as if it has never been touched before and youll avoid TONS of bullcrap down the road. You cant tell what wrong till your sure its all been checked..otherwise your just a dog chasing its own tail.

[mtbspm]

Any recommendations on where should I go for the gaskets and new jets?

What should the valve clearance be when I check and adjust them?

Thanks for the help so far. I've worked on cars all my life, but bikes are completely new to me.

[steveb922]

You may well not need new jets - do what Chuck advised in post 2. As long as they haven't been mangled by a PO, they should clean up fine.

I'll let the US guys advise you on where to get gaskets.

[Wallowgreen]

Go to the sites Chuck listed for you. At the first, also download the manual for your machine from the middle of the top section and refer to page 28 where it details the valve clearance adjustment. All the clearance and tolerance values are shown there along with the correct method for performing the check.

When you get the o rings from Robert at cycleorings get the intake o rings at the same time and replace those while the carbs are off. Save yourself a lot of potential frustration by doing that now.

As mentioned, do not be tempted to buy a refurb kit of jets etc. in fact avoid that at all cost. Assuming the jets you have are original OEM they are of far superior quality, will clean up and be perfectly usable. As you go through the two carbs, don't assume everything is as it should be, check each jet is correct against the parts list. If not, post up here in the parts wanted section for what you need.

I typically use OEM gaskets for pretty much everything, others have had good luck with different sellers and can chime in with the info on where to go and who to buy from.

Use the tutorial Chuck pointed you to and it's easy enough to follow the process. There are no short cuts though. Good luck!

[mtbspm]

The rebuild seems pretty straight forward. Where do you source things like the OEM gaskets? I'm also debating on doing pod filters while I rebuild the carbs and rejetting for them at the same time. I like the look better and the stock filter is missing anyhow.

[Nessism]

Please check the Newbie Mistakes thread linked in my signature. And do NOT get pod filters unless you are willing to spend the money on real K&N type, not generic knockoffs, and spend a ton of time experimenting with jets.

[Wallowgreen]

OEM gaskets are typically available from the parts list at your favourite online retailer, think one of the most frequently used by form members is partsoutlaw. I have "an arrangement" with a local dealer that gives me dealer prices on the parts I need so don't tend to order much online any more.

Going the pod route can be tricky getting the fueling correct. Personally I've never tried because I like my machines to be stock so will defer to others that can help you figure that out. From what I've read though, setting the expectation your carbs will be on and off like the proverbial "whore's drawers" will be a good mind set to start with.

[mtbspm]

I found a source for the OEM stuff now. I will go with the stock filters for the time being, but like how the Pods look enough for me to play with that down the road. I would be willing to buy the real ones once I get the bike running and driving correctly.

[sam000lee]

I get jets from jetsrus. They sell genuine Mikuni jets so they match up to whatever the OEM settings were. They also sell gaskets you can see what you need here:

http://www.jetsrus.com/needle_valve_float_bowl_gasket/needle_valve_and_float_bowl_gasket_suzuki_street.html

[jdvorchak]

I'm surprised no one said this yet. First step in diagnosis is to make sure you have spark on all plugs and that spark is good and strong. Your problem can be as simple as a $5 spark plug cap (they just screw off and back on) or a $3 spark plug.

Now since you're new to motorcycles the cylinders are numbered, from left to right as you sit on the bike, #1 #2 etc.

You probably do need to clean the carbs but without spark it still won't run. On cleaning the carbs, there is no such thing as too clean. Be prepared to remove and replace those carbs numerous times until you really get them clean. The idle jets are tiny and clog easily if the bike sat for a few months.

Most important advice I can give you is to take your time and have FUN while you're learning!