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93 gsxr600 (shitbox of the week)

10K views 164 replies 13 participants last post by  HipsterSquid 
#1 ·
Picked this up for 500 yesterday with a legitimate title but no key
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After bypassing all the safety switches (clutch, neutral, etc.) She turns over, but no spark. Have voltage at the coils, pickup coil reads 170 ohms (withing spec) ignition coils read 3ohms (good) I have read that a 100ohm resistor is needed with an aftermarket ignition switch, or the ecu will not fire the coils. This may be for a later model (not sure the 93 has an ecu) what should I test next? Cdi?
 
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#37 ·
As CaTaC1sm pointed out, cut a slot.
I've used a hacksaw before now.
Isn't that motor the same as the RF600/900?
It isn't an oilboiler with the header tank at left rear of frame.
Suzuki use a very coarse spline on gearchange of many models, can't remember if that one has it though (I had a few years off from working in dealerships)
 
#39 ·
I got them out by slotting them with a cutoff wheel and turning them out with a flathead screwdriver. Guys I'm having a problem. Cylinder 4 is not firing. I have spark, fuel, compression, and the carbs are spotless. (Slides work flawlessly too) what is left? Could a grossly misadjusted valve be the cause?
 
#40 · (Edited)
Try a different spark plug. You can have a plug that sparks in open air fail under compression. the lead and cap could also be suspect. If the second lead on that coil is long enough swap it to see if you move the problem. With poor valve adjustment you would not have compression. One more thing to look at is that if your carb is fueling and you ran it without that cylinder firing you should get a wet plug when you pull it to verify the fuel charge is there.
 
#47 ·
Well I got the new ignition switch installed:
Wheel Vehicle Car Automotive lighting Motor vehicle

The label is upside down:
Automotive tire Motor vehicle Rim Automotive wheel system Gas

I attempted to pop of the shroud so I could rotate it 180degrees, but it would not go easily and I didn't want to break the plastic so who cares. ...

While I was waiting for the switch to come in I was using this:
Circuit component Composite material Electrical wiring Wire Cable

It's wireless:
Car alarm Communication Device Everyday carry Gesture Thumb

It has two channels (two spst relays):
Passive circuit component Circuit component Hardware programmer Electronic engineering Electronic component

You can program them for latching, toggle, or momentary. I wired it so "A" controlled ignition and "B" for parking lights. Another setup i tried was channel "B" set for momentary to control starter switch. It was pretty cool setup for wireless start. I don't know what I'll do with it now. I could wire it parallel and use it in conjuction with the keyed switch but I will probably forget and leave the ignition on one day... maybe I'll use it for some LED'S on a future flip..

Anyways, none of this matters when the bike is only running on 3/4's cylinders. I'm going to take a nap
 
#49 ·
Alright! She's running on all four cylinders now! I think my gas was contaminated with water. Maybe I didn't get it all out after soldering the pinholes in the tank. Anyways I drained the tank and the bowls and the problem is solved. The next thing I need to adress is a rev hang at idle. With the idle set to 1k I blip the throttle and she hangs up at 3k and takes a very long time to return to idle. I'm gonna try turning the pilot screws out. Unfortunately this requires pulling the rack because it's next to impossible to get to the screws for 2 and 3 when the carbs are mounted.
 
#50 ·
You need a hanging fuel supply or low pressure pump to tune the carbs. I had a used Honda cvcc pump for the gsxr's. Syncing the things is key to getting any real idle or acceleration. Hanging idle to me with these things sounds like you may have muffed up the carb reassembly after cleaning them. I found this was quite a common mistake with many people in the past. Take the caps off and make sure the bellows and the o ring are in the proper location. I liked to sync the carbs closest for a strong takeoff rpm not at a flat idle. Probably best to go with flat idle if you just want to be done. I miss the rumble of these beasts.
 
#51 ·
All 4 cylinders sounds good, so many guys with 4-cylinder carb problems here lately it's difficult to remember what they look like. Water in fuel; didn't we talk about isopropyl alcohol aka gas line anti-freeze before? If you don't collect the water out of the lowest part of the float bowls the next best is to carry the water through the engine and that takes alcohol. It's not a fix but it is a fuel treatment.
 
#53 ·
Yes. They are cv carbs. All of my bikes will probably be cv carbs because I buy bikes that people are practically giving away due to "carb problems"

I inspected the diaphragms when I replaced the needles last Friday. They are in good condition. No tears or pinholes. Soft and pliable. The slides are working correctly after reassembly, Verified by blowing in the port and observing them rise and fall consistently.

I have the pilot screws 5 turns out and the rev hang is improved but not completely eliminated. I would no longer call it a "hang" more like a "mildly sluggish return to idle" Its time to move up to a larger pilot jet. I supposed the aftermarket can that was crudely installed has changed the jetting requirements. She is only a brake job and turn signals away from being rideable now. Finally sat on her and rocked through all six gears in the driveway tonight. I'm getting excited now. So glad someone else gave up on this bike!
 
#58 · (Edited)
See the extra plunger pump assembly on a typical #2 carb in a bank of CV carburetors:
Fuel tank Motor vehicle Vehicle Automotive lighting Automotive tire

My understanding is they put that diaphragm pump on there so the engine returns to idle better, it does it by enriching the fuel mix just slightly on deceleration.
... note the only carb that is different is #2, the rest are virtual parts interchangeable.

Point of this post is, look for something that looks like a fuel pump, study the linkage to determine if that pump is actuated on acceleration or deceleration at the linkage and then look for problems relating to that fuel circuit.
 
#59 ·
See the extra plunger pump assembly on a typical #2 carb in a bank of CV carburetors:
View attachment 106993
My understanding is they put that diaphragm pump on there so the engine returns to idle better, it does it by enriching the fuel mix just slightly on deceleration.
... note the only carb that is different is #2, the rest are virtual parts interchangeable.

Point of this post is, look for something that looks like a fuel pump, study the linkage to determine if that pump is actuated on acceleration or deceleration at the linkage and then look for problems relating to that fuel circuit.
These are the mikuni bst36ss and there is no such provision. At idle the fuel is metered by the pilot jet and the pilot air jet. The mixture is partially discharged into the main bore out of the bypass ports and the remainder is metered by the pilot screw and sprayed into the main bore through the pilot output.

I flushed and bled the brakes then took the bike around the block today and I am satisfied with the motor, the transmission and the clutch. I think i did very well for the initial investment of $500

Tomorrow I will pull the wheels and inspect the bearings and drivetrain and replace a dry-rotted valve stem on the front tire. She's at least safe an reliable enough to ride to the bmv for a vin inspection during lunch. I can hardly wait to get her on the freeway and really knock the dust off!
 
#61 ·
I made a cradle from some 2x4's and plywood so I can jack up the frame without putting stress on the exhaust:
Automotive tire Motor vehicle Hood Wood Bumper

Front wheel bearings are fine. The front brake pads have life left in them but I scored a full set of 4x EBC pads (new) on ebay for $15.00!

Whats the best way to freshen up the rotors (I don't currently have access to a lathe, there is no gouging, just a little rust
 
#62 ·
I put a cheap streetfighter fairing on it to satisfy the turnsignal/headlight requirements in my state:
Tire Wheel Automotive lighting Automotive tire Plant

I find it amusing that I was already running a gsxr clutch perch on my old kaw750 and now I'm running the perch I took off the kaw on this one because I needed a mirror mount:
Tire Automotive lighting Automotive tire Automotive design Bicycle part

Now that she's road legal I've had a chance to put some miles on her. I've discovered it runs great and pulls hard for the first 15 minutes but once it's completely warmed up the idle creeps down and it wants to stall at redlights..... what do you guys think? Valves too tight? I'd like to have the shims on hand before I pull the covers. How do you guys usually go about this? Should I buy an assortment? Or do you measure first and only buy the ones you need? Most of the kits I see online only have 3 of each size. What if I need four? Please advise...
 
#63 ·
Fuel problem would be my first guess. Start from checking to make sure the gas tank is ventilating, petcock isn't clogging, no kink in the line or gunk buildup in filter (if you have filters) and finally making sure that the idle mixture is correct (perhaps too rich). May be electrical too, have you tested the battery while it's running? Probe while it's off, should be around 12.6-12.8v, start bike at idle check and see if it's a little more than that, and finally rev the engine and see if it goes above that number but no more than 15v
 
#64 ·
Its funny you mention fuel because I have been having some issues that seemed like a vapor lock and I think the brass tee may be the culprit. The problem started after I filled my tank full for the first time. Early on I replaced the original dual port petcock with a single and then used a tee to split it into the two separate fuel lines to the carbs. I have another petcock (dual port like the original) that is being delivered today, we'll see if there is any improvement.
 
#70 ·
This is the original petcock:
Automotive tire Tire Rim Gas Bicycle part


Replaced with this:
Hood Automotive tire Automotive lighting Motor vehicle Vehicle


Single fuel line goes to a tee:
Automotive tire Automotive design Motor vehicle Auto part Gas
Motor vehicle Automotive design Vehicle Automotive tire Automotive exhaust


Then down to the carbs. There was a clear fuel filter on each line (now removed) and the first time the bike died i pulled over and noticed at least on of the filters had mostly air in it. As soon as I lifted the tank the filter filled back up with fuel. The bike started right up and I drove it home.
I thought maybe the routing of the fuel line was the problem so I re-did everything taking care to make sure all the lines we sloping downhill and as short as possible. It cannot be avoided that a short portion of the line between the petcock and the tee must run almost horizontal for a few inches. I wonder if this is part of the problem.... I guess I should go mow the lawn while I wait for my package to arrive
 

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