New guy from Ohio - '82 GS750T

[sailor_bob]

Hey there my name is Bob, not completely new to searching around the forum but new to actually making an account, figured I should post something finally instead of just lurking. I'm only 22 and fairly new to working on bikes but eager to learn. This isn't my first bike but I used to be more so the type to pay someone else to do my mechanical work being too nervous to do it myself and make an issue worse. Picked up my 1982 GS750T last summer in Cleveland and brought it back to Youngstown. Rode it all summer long even though she was ugly as could be (paint very faded and clear coat destroyed by years of spilling gas and sun beating on it) and had a bit of a valve cover leak. Nothing major, so I figured I'd enjoy it for the few short months of really good riding weather we get here and put off the tearing it all down until winter. When I finally got to working on it discovered my head gasket was leaking too, so I broke out the Clymer's manual and started learning my way around with the help of a friend. so I got everything all changed and dialed in as far as the timing goes but I eliminated the factory air box and put pods on each carb and now need to re-jet the carbs because of too much airflow. If anyone has any info regarding that type of issue I'd love to hear your opinion! anyways, here's a few before and after pictures. Still haven't got my side covers or emblems back on and have a few more cosmetic things to do. I'll post the before picture in another comment. Can anyone explain to me as well how to post multiple photos at once?

 

[sailor_bob]

This was the day I picked it up.

 

[loud et]

Well if you are going to run the pods you are going to want to get the dynojet stage 1 kit. Stage 3 is for if you are running pods AND an aftermarket 4-1 exhaust.
If will save you lots of time trying to order jets and tuning all summer long instead of riding.
Also get the kit asap or you are going to burn your headers.
They will turn yellow/ dark colored, if they haven't already because the bike will run lean (not getting enough fuel) with the stock jets.
No, you cannot just adjust the 4 mixture screws and get it rich enough to run properly.
Get on Bass cliffs site, there are Suzuki manuals there for free download. Forget clymers.
In the carb, fuel , exhaust section the top 4 threads that are marked sticky have all the info you need to tune a bike with pods.
Do some good reading and get it running good.

 

[sailor_bob]

Thanks man, I appreciate it. I'll have to find those threads and check it out

 

[storm 64]

Well, I told Sailor Bob to not go the Dyno jet route and to just up the Mikuni main jet two sizes and he'll be in the ball park. He's a bright young man and I'm sure he'll do the research. Also if he has any questions or needs anything he's only three houses down from me! It's been awhile since I tuned a motorcycle for individual type air cleaners, but it's not rocket science...

 

[loud et]

Well, I told Sailor Bob to not go the Dyno jet route and to just up the Mikuni main jet two sizes and he'll be in the ball park. He's a bright young man and I'm sure he'll do the research. Also if he has any questions or needs anything he's only three houses down from me! It's been awhile since I tuned a motorcycle for individual type air cleaners, but it's not rocket science...

I was wondering if this was the guy you mentioned that you met. Cool. My 850 is soo close to being done. I still have my other 2 running. If you guys wanna meet up sometime, let me know.

 

[steve murdoch]

Welcome to the site, Bob.
Having a knowledgeable GSer like Storm nearby is a bonus.

 

[sailor_bob]

I appreciate your help! I'll hopefully be stopping at Golan's after work Monday to see if they have the jets I need. I'll throw them in real quick and see where I'm at with it. Might even just buy a couple sizes at once and play around with it. I'll let you know how it comes out.

 

[sailor_bob]

Will do man!

 

[sailor_bob]

Yep definitely. I was not really surprised completely that it ran different with the pods but in a way I was because this is my second GS. The first one was also and '82 but a GS650g, shaft driven model. I sold it to a buddy a few blocks over and he still has it to this day. He also eliminated the airbox and went with some pods, and he never had to change anything. He threw them on and the bike didn't change a single bit. Still purred like a kitten and ran just as good if not better than with the factory box. Any thoughts on that? Just pure luck maybe lol.

 

[tkent02]

No, if the pods were any good they flow more air, if it flows more air through the engine it needs bigger jets to flow more fuel. Could be it had too big jets in it already, but stock jetting cannot run right with pods, especially on a bike with CV carburetors.

 

[storm 64]

Also Bob your filters will need oiled. Stop on over, I have a big can of K&N filter oil.

 

[Chuck78]

Might want to get some ebay rebuild kits than contain jet needles that have adjustable clip notches. Or get the radio shack washer pack assortment that is very popular for shimming slide needles on motorcycle carbs that do not have adjustable needles. Shim it up slightly, a little less than 1mm. Try that.

adjust the mixture screws for idle, needle will adjust 1/4 to 3/4 throttle, 2 or 3 sizes large main jets will affect 1/2 to full throttle. Norm's been doing this for a while, you're in good hands!

Come down to the Cambridge/Zanesville area or south of there sometime with Norm and Adam and ride some really fun twisty roads in the hills down this way with us. I've got tons of really great routes plotted out all over southeast Ohio and around zanesville/coshocton/etc.

Ask Norm about how the roads compare that I took him and David Drey6 on this past September on Labor Day. We rode 8 hours or so all on super fun very twisty roads in the hills...
-Chuck in Columbus

 

[sailor_bob]

Okay thanks! And I actually did shim them up 20 thousandths. Helped a little but I went back down to one size above factory on the main jet. Need to go up one more I think and think might need to go up a size on my pilot jet as well. My dead spot is right 1/4 and 1/2 throttle somewhere. Pulled a couple plugs and it was still running super lean. Need to go back to a bigger jet for sure.

 

[Chuck78]

1/4 to 1/2 throttle is all in the needle jet i.d. and jet needle taper/height-clip position

Needle jets are not readily available so the best you can easily do is adjust the needle height a little higher (more shims) and richen the pilot circuit slightly.

Needle jet i.d. and jet needle diameter at the thick part and the start of the taper are what you use to adjust that. A set of slides with a lower cutaway would also work, but slides and needle jets are not common tuning parts these days for these vintage carbs, so go at it with the needle height. Then adjust your mains to WOT pulls at high rpm, waiting enough time to ensure the diaphragm has risen up all the way (a very steep straight long uphill desolate stretch is really needed especially on CV's - you need to set the main size for good plug chop coloration and great power at near max rpm under load. Best to be slightly rich than to melt a piston.

 

[Chuck78]

Really by 1/4 throttle, the pilot circuit has less and less to do with the mixture. Almost out of the picture be then.

 

[Guest]

Have fun with explorations, hang onto that air box. I say that after seeing years of T owners struggling with pods.

 

[GSXR7ED]

Welcome Sailor Bob,

Love your "T". Wanted to see full-size pic:



So...you're going with Pods, huh? I've never had the inclination to pursue this but like yasser suggests, keep the original Airbox.

Also, post your "T" here:

http://www.thegsresources.com/_foru...-2nd-Thread)-3rd-Overall-(I-think)&highlight=

Ed

 

[sailor_bob]

Hey guys, thanks for the advice! Over the past few weeks that I've been in active I have been trying different jetting combos, tried raising the needle jet around .040 so far, bigger and bigger main jets up to as much as 4 sizes above factory (112.5 is factory, 122.5 is highest I tried), one size larger pilot, and of course playing with my mixture screws til it's running at it's best. All this and still somehow running lean... I feel as if it should practically be drowing in fuel by this point but I can't get it to richen up. But the fuel mixture isn't even the biggest problem, my worst problem is still the dead spot in the throttle between 1/4 and 1/2 throttle. Closer to the 1/2 margin. I hate to say it but I think i've finally given up. Probably going to put the airbox back in and go back to factory jetting this weekend. It ran great there and I'm somewhat regretting ever messing with it. At least I tried but I'm missing to many riding days.

 

[Chuck78]

This is the biggest reason why a Dynojet kit is sometimes the easiest route for owners who are just starting to wrench, & are going pods & pipe with stock bore pistons & stock cams.
Having CV carbs complicates this even more, because in terms of carb tuning, "1/4 to 1/2 throttle" is when the slides are 1/4 to 1/2 raised. On direct linkage carbs, your throttle wrist only opens the butterflies at the outlet of the carbs, the slides still do their own thing based on airflow velocity through the carbs. There is often a lag in the slide raising to the same position as your throttle grip is twisted. So there is still a slight possibility that richening your pilot jets is needed.

Now if you go from running good at 3/4 throttle and back off the throttle down to say 3/8 throttle in the middle of the problem area, and it still acts up, your engine is definitely telling you that the upper area of the needle (largest diameter that the needle jet sees) and the beginning of the taper of the needle are too thick, or also that the needle jet opening on the top end of the emulsion tube is too small of diameter.
The needle jet emulsion tube/bleed pipe assembly (all 1 piece on those carbs, earlier vm carbs the bleed pipe /emulsion tube and Jet are 2 seperate pieces stacked onto each other) is what the main jet screws into. You can get smaller or larger needle jets readily from jetsrus.com or Z1 enterprises, and you probably need to go up one size to alleviate this problem. Problem is the needle jets are generally around $16.99 each! There are a million different types of them, but if you pull one of yours, you will see stampings on them. One will be the mikuni logo (little square inside of a big square, like a right triangle notation, but 4 sided square) then the type/style of needle jet (a number like 186), then the size, letter then a number - like O-6, or P-4. The jets r us site will tell you which is richer and which is leaner. So it really sounds like you probably need a needle jet that is one size larger. Putting in a needle with a skinnier base and sooner or more drastic taper would do the exact same thing however. Needles are much more complicated to look up with all different lengths, clip locations, tapers and dual tapers, taper beginning location, etc... needle jets are just #1 - one type only that fits your carb, & #2 - a single large orifice with only 1 measurement

Dynojet gets fancy with their needles and reconfigures the tapers and the beginning diameter as well, but Dynojet. kits tend to run you on the rich side just to keep them safe from ruining anyone's engine by running it too lean. Often, every one of the 3 sets of mains they give will be too rich, but better for them than melting a hole in someone's pistons.
Their jet sizes are also rated differently, a 120 Mikuni hex head main does not equal a 120 Dynojet. That is always confusing for people all across the board.

If I were you, I would experiment by shimming the needle up substantially, as in .080" or .120", and see if the problem was partially solved at at a small range closer to half throttle. This will probably make you way too rich above half throttle, but if you pay attention to exactly where the problem ended previously, and then do the exact same observation after shimming the needle up substantially, then that will tell you that your needle jets need to be larger but 1+ size. There is also the mod that some people do by cutting the diaphragm spring shorter. I will not recomended this as I don't work on CV carbs much to have any advanced knowledge on this. Shortening a spring makes it stiffer (slower opening side) as long as it doesn't get cut too short to have freeplay. Don't do this unless someone extremely well versed in tuning gives you very clear explanations on every aspect of it.

People always complain that you will never get your bike tuned right with pods, but the thing they never considered is they are only raising the needle and changing the pilot jet and main jets. That jet that dictates quarter throttle to half throttle is not something that people think about changing, and that is generally always why people say that you will never get your bike to ride with pods.

You CAN tune your bike properly with pods, the only thing that you will have trouble with his heavy cross winds making your bike go extremely clean, or heavy rains making your bike go extremely rich. Your air filters on 2 carbs are now completely exposed to the elements on the outside. After an unfortunate carburetor theft, I am now running individual pods as opposed to dual oval air filters that I much preferred (Google k&n RC-2222), and in doing so, I have grown even more accustomed to the fact that I really need to clench my legs around the outside of the air filters when I ride in the rain or when it gets very windy. For the rain aspect, I almost put my factory air box back on, but the 1977 air box was just too heavy and bulky when I had it in my hands about ready to swap it in place, so I threw on a pair of 30 year old K&N pods after heating the old rubber up on my halogen work lamp to get them flexible enough!

Best of luck

Chuck in Columbus