at a total loss as to how to tune up my new 1980 gs450

[Anonymous]

i bought this piece of junk for $250 based on the fact that the engine could run for at least 20 seconds. I cleaned the carbs and took off the air filter. After a long time of simply starting it and throttling it the baby could idle fine non-stop. The obvious problem now is that with the choke off throttling it kills the engine. The only way i can safely get the thing to show me some of its true power is by throttling it with the choke on or by putting my hand over the intakes-but then this isnt good for it either and it starts to backfire. Although i am pleased to see my engine problems are most likely with the mixture or valves, I dont know how to adjust either. I cant find a mixture screw, or a valve adjustment window. This project has turned out a lot more complicated than my first bike which was a kz400. Another concern is that i dont know if the engine has oil because i cant find a window for that either. If you can help me simply find these simple adjustment spots on my engine i'm pretty sure i can do the rest on my own. THANKS

[Anonymous]

First: the engine will NOT run properly without the airbox and filter!
Before you try to adjust anything, put the airbox back on and clean the filter.

Your bike has CV carbs. I don't know much about adjusting CV's, but I'm sure other GSR members are more qualified and they will to help you.

According to the microfiche ( http://www.alpha-sports.com/suzuki_parts.htm ) the oil level can be measured through the oil filling cap on top of the clutch cover on the right side of the engine.

[focus frenzy]

yep, it won't run right without the air cleaner installed, in fact with out the air cleaner, it will do exactly what you have described.
the 450, for some odd reason used a dip stick attached to the oil filler cap, unlike the bigger GS's that used a sight glass.

[Anonymous]

wow guys thanks a lot you sure are quick

man this website's a real lifesaver. Anyway i have the box but i dont have the filter. When it came to filters i started thinking... Ever since i got this bike i've been concidering chopping the frame, and this might require me to get rid of that huge box. What would you say about me getting custom single air filters for each carborator (dont know thw word for them). Do you think this would work? or are gs400's really that weird and need exactly the original air filter setup? I mean so far the whole air filter thing is a big change from how i got my kz to work by taking the filters off, which has run great since. THANKS again, you guys are awesome.

[Joe Nardy]

Like most bikes, your GS was engineered to run properly with a certain amount of intake air flow, a certain amount of fuel to be added to the intake air flow, and certain amount of exhaust system flow. Altering any of these will require changes to others. I would suggest getting an air filter and getting the bike running well with the stock setup. You may then change to pods (individual air filters) but this will probably require changing the jetting of your carbs.

Also, the carbs may need a good cleaning. You don't mention the history of the bike but if it has been sitting for a while there's a good chance a carb cleaning is in order.

Good Luck,
Joe

[argonsagas]

I cannot understand why you are doing anything with tuning if you do not KNOW how much oil is in the engine!

I don't know the requirement for the GS450, but I suspect it may be stamped on the engine or the cover. Whether or not this is the case, someone on the Forum wll certainly be able to tell you the correct amount, both with a filter and without.

It seems you are running it with whatever oil came with it.

Surely oil is the FIRST requirement to look after.


If you want to keep the engine for a while, drain the old oil and refill it with the correct quantity of fresh oil. The engine will thank you.

[snark]

The GS450 takes 3 quarts of 10W40. Get a Haynes or Clymer manual and it will help you out. As for the Carb adjustments, alot of them are factory set and sealed in honor of the EPA. Again, the clymer manual will help you out. You'll need to airbox and a CORRECT filter to get it running right to start with. When I really started checking my new used bike out, I found a peice of A/C filter foam where the real filter should be. The right part makes a big difference. The Airbox and filter help to control and direct the airflow coming into the carbs. Withoput a controled intake, the right volume of air won't get into the mix.
I have a Suzuki Factory manual for this bike and it helped me out a lot with mine.

[Anonymous]

yeah i figured out the oil thing

right after i wrote that i found the dipstick. Luckily it read full. I guess the reason i felt confident that i wasnt running it without oil is because i bought it from a guy who had been working on it for a while and i assumed he'd do that. I'm gonna buy the factory filter and two pods. If they both work the same then i'll use the pods and continue my project. If the factory filter works conciderably better i guess i chose the wrong bike to get creative on. Thanks for your help i think i'm also gonna get a manual with that filter so some of the simpler questions i wont be asking. On the other hand if you have any suggestions or if you know of any similar gs chopper projects feel free to continue posting.

[nabrams]

I've "restored" two GS450 bikes that had been sitting for long periods (mine and a friend's) so I've encountered almost all the typical issues.
It will not produce smooth, full power till you get those carbs absolutely spotless. Your air filter element, air box and all boots that connect to the carbs will have to be checked (any air leaks and all bets are off - see my other posts about this).
The GS450 will not have any chance of running properly if these two issues are not properly dealt with.
Deviating from the stock set-up will require much painful trail-and-error carb adjustment and/or re-jetting - not worth the effort, in my opinion.
Your regulator/rectifier and stator should be checked (as described in the garage section of this site). It is also likely that you'll have some loose and/or dirty electrical connections.
Some of the cables may need lubrication and adjustment. Of course, you will need a new battery.
The second time I did a "restore" (on my friend's GS450) it went much, much faster. A Clymer's manual is a must.
Once you get that bike running properly, you'll find that it's extremely reliable.

[Anonymous]

what exactly is rejetting and is it possible without a kit?

i havent bought the original filter yet cause im on a real tight budget. However i did buy the foam pods which were cheap and seemed reliable. So ive decided that laboring over the consequinces of having a custom air filter would be worth the effort before possibly returning to the stock setup. So I've gathered that the first two things im gonna have to slave over is carb rejeting and carb timing. I checked out kits and unfortunately they also fell just beyond my budget. Therefore i was wondering what is entailed in regetting a carburator, and though probably ill-advised, i was wondering if i could alter the jets myself. I figured this couldnt hurt in the end assuming i would buy a kit eventually anyway. While im on the topic of unorthodox repairs, it is there a way to test the carb timing with some tricks rather than kits?

Thanks for your help, i dont think homemade carb rejetting will be covered in my new manual.