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Hi, finally not just lurking anymore

So I bought a 1994 gsxr1100 last year and thought I would use it to learn a bit more wrenching to occupy me while studying. This is my second bike, after an RC390 (yes, I did want to buy a 600 to track since I took the 390 to the track a couple of times and absolutely loved it.) But after seeing some 1100 cafe racers I really wanted to make a badass 1100 that could be used on the track too.

It was supposedly in ok shape, cosmetically bad, but engine seemed to be running fine. Did not get to test it, and bought it cheap, so kind of a gamble.. But with my plans I didnt really want to "ruin" a nice example anyways.
Long story short: it has been a lot more work than I wanted..... To give you an idea of hos it had been used: the front sprocket nut was stripped completely and was hanging by the little "safetybolt" (and he said I could testdrive it.. right), the chain must have been greased with fuel because I used a week to degrease the whole bike (it had some shitty "automatic greaser" connected), and now I also think the rod-bearing on syl.2 is bad. Anyways.

Last year I removed fairings (they were ruined anyways), changed some bearings, new sprockets and chain, overhauled calipers, new tires. All the usual stuff. And rebuilt the subway "temporarily".
Time to drive. Realised the discs were warped badly, fork was shot completely it seemed, it seemingly ran cold (later found the gauge to be broken), and it completely drowned or cut above half full throttle. So no more driving that summer..

I will post some pictures of her below..

This winter I went over as much as I could on the car. And thought I had fixed the seemingly easy problems..

So, I have a couple of real headscratches for you that I cant figure out for the life of me:

1. "Drowning" under load.

Took the carburettors out, thought the diaphragms were all bad, they seemed nice. Changed them anyways. Cleaned the whole carb, but wasnt really dirty. And installed a jet kit as I am running open carbs (I have unifilter pods laying) since the airbox was broken from previous owner to remove it.. And yes, I am aware that it is not smart to run without airbox, but this is not an airbox issue I am certain, as it occurs when standing still also. And I am running a somewhat more open exhaust. Also checked boots for leaking, seemed fine.
Still exactly the same problem after all this.. only it seems to run a bit better low down. I havent gotten to synchronize them yet either. Checked all plugs, plugwires and both coils, also checked valveclearence which were all within spec.
I dont understand how it can be the carbs anymore, even sprayed wd40 everywhere, not finding any leaks. And they would have to be pretty big i guess. Also changed fuel-lines and overhauled petcock.
I am now thinking it could be timing related somehow? A bad igniter, although I can get it up to redline slowly.. could it be that the timing isnt advancing, or that something else just gives.
I will upload a youtubevideo that shows clearly what is happening.
And trying to check the timing brings me to the next question.

2. Checking timing

How do I check the timing on this bike, when trying to use the timing light on the signal generator it just spits out oil when running.. I hoped that it could give me a clue on my problem, but I dont want to run it when loosing so much oil.

3. The fork issue.

Problem was it seemed totally dead; soft and absolutely no rebound.
Opened it, changed both sliding metals with all bushings and new oil. Changed springs to some stiffer linear springs while I was in there. This was the first time I have opened a fork. Put all back together, and still no rebound? Even with rebound adjusted to the fastest.
I think it is the inner damper rod, it was really hard to pull both in and out when removing air, and there was always oil coming out in the middle of it? I didnt take out the damper rod, and I am guessing there isnt supposed to be oil entering the damper rod inside. Are there any seals around the damper rod assembly that can go bad and show these symptoms?

Bonus question?

Listening to the video (will be uploaded) do you think a rod-bearing has going bad? Or could it be a clutch-bearing or basket or something? The clutch is stuttering a bit when engaging, so there could be something there. Putting a screwdriver to the cranks does indicate something knocking inside under the second cylinder though..

Sorry for the long post, I like to write. Cheers :cheers
 

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A good first step would be to acquire a service manual. Good place to find proper procedures for setting timing, rebuilding forks, etc.
When you cleaned the carbs, did you remove and clear out the small pilot jets? They are quite small and clog quite easily. I had a 92 Katana that developed surface rust in the tank that would routinely clog the pilots and cause the same sort of bogging and flat spots in the throttle.
 

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Forgot to add that synchronizing the carbs will make a large difference in performance as well. Mine always ran 'well', but after synching, it ran like a totally different machine!
 

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Discussion Starter #5
Thanks for the reply!
I changed to a "custom" jetkit and went up on all jets if I remember correcly. Main jet is larger, but it seems I am stuck where the needle taper and raise comes in play. The needle is stock, but i changed the position of the clip to one richer (cant remember if it is on the richest position now). It seems to rune nicely for not having synched the carbs everywhere up to the where it dies. A couple of crackles when you let off the throttle as ususal. Exhaust is stock 4-2 headers and straight pipes after that, for now, so I doubt it gives much less backpressure than the stock to be honest. A video will maybe tell you more when I get to upload it.

That 390 looks really good! Hopefully I can buy one back sometime and prep it for track like yours, so much fun and great to learn on. Much more fun to overtake big bikes with a small bike.. up till the straights atleast. I dragged my footpegs first trackday, unfortunately I sold it before I got to track it with raised pegs. Suspension needed an upgrade badly, but it was predictable and easy to ride.

I am currently trying to find someone who really knows suspension to figure out the fork.
 

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Discussion Starter #6
A good first step would be to acquire a service manual. Good place to find proper procedures for setting timing, rebuilding forks, etc.
When you cleaned the carbs, did you remove and clear out the small pilot jets? They are quite small and clog quite easily. I had a 92 Katana that developed surface rust in the tank that would routinely clog the pilots and cause the same sort of bogging and flat spots in the throttle.
Hi,
Yes I have the service manual, and have used it a lot. Including youtube and forums ofcource. Pilot jets are new and everything is cleaned and all passages are blown with air. Running nicely up til the needle lifts. No rust from the tank at all.
Will be synching the carbs next, I tried with a homemade "meter" but the oil in the hoses just jumped around full of air it was impossible to adjust.. So I will just buy a proper synchroniser and do sync it, but it doesnt sound very out of sync.
 

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Common problem is that the needle jets wear oval and need replacing. Pull them out and have a look.
 

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This guy has some really good information on how the carbs work, and how to adjust, including custom jetting.
Changing the intake/filters and exhaust pipes can have a dramatic effect on carb tuning.

 

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Discussion Starter #9
Common problem is that the needle jets wear oval and need replacing. Pull them out and have a look.
They looked pretty good, and that would increase fuel flow meaning I am running so rich that it drowns completely I guess. Which could potentially be true, but I feel its unlikely. At this point I am open to anything though.
Will give it full throttle and cut the engine, then check plugs and probably look at the carbs again anyways. I will post a video where you can see through the carb when the problem arises.
Thanks.
 

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Discussion Starter #10
This guy has some really good information on how the carbs work, and how to adjust, including custom jetting.
Changing the intake/filters and exhaust pipes can have a dramatic effect on carb tuning.
Thanks man,
I have been through a lot of videos, but I think I have the basics down good enough. I have pretty much done the exact same jetting he explains in the video. The problem happens when the needle comes in play.
Happened when it was at stock height, and still happens when I raised it one. No vacuum leaks in diaphragms, even changed to new ones just in case. Basically went over the whole carb, jetted it, and still have the exact same issue. Yet it runs better up to the point of problem.

Will post a video which shows the problem in detail :thumbup
 

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Discussion Starter #11
Here is a video showing the problem :gaah

/watch?v=uaQqu_29LAw

(I cant post links directly yet.. just enter it after youtubedotcom
 

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So it seems to be worse when it is running off the main jets alone.
Have you checked the float levels? If they are too low, it could be leaning out under load.
I would also check the synchro port caps to be sure they are tight and not cracked or leaking. That is a common source of vacuum leaks.
Also, have you checked the synchronization at all? You can do a bench synchro without the gauges that will get you pretty close.
Adjust the idle screw until the butterflies just start to open.
I used a thin wire like a feeler gauge, and the manual for the proper order, and adjusted each until the butterflies all open the same amount. That should be close enough that only fine tuning would be needed.
In your video it looked like one carb that was jumping, are all four having the same issue?
 

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Discussion Starter #13
So it seems to be worse when it is running off the main jets alone.
Have you checked the float levels? If they are too low, it could be leaning out under load.
I would also check the synchro port caps to be sure they are tight and not cracked or leaking. That is a common source of vacuum leaks.
Also, have you checked the synchronization at all? You can do a bench synchro without the gauges that will get you pretty close.
Adjust the idle screw until the butterflies just start to open.
I used a thin wire like a feeler gauge, and the manual for the proper order, and adjusted each until the butterflies all open the same amount. That should be close enough that only fine tuning would be needed.
In your video it looked like one carb that was jumping, are all four having the same issue?
Definitely when the needle starts to raise from the main jet yes, otherwise it runs really fine for a non-synched carbed engine without original airbox.. It had the same issue before I touched the carbs. But when I opened and cleaned them I also changed float needles and set the float height (God damn is the manual bad at explaining this), so I dont think its the float height, but if all other fails I will check. They would have to be set very low though, or maybe very high so it drowns?..
Have ordered a synchronizer, tried to do it with some homemade hoses and oil, but the oil just jumped up and down and filled with air...
About the jumping I am not sure, will look closer, first carbs I have ever looked at, so I am not 100% sure how everything should look when working. As I mentioned it seems to run fine up to a certain load. One or two bangs on decel, but that is probably inevitable with changed AFR on carbs.
Will check closer for vacuum leaks, synchro caps had some cracks at the bottom, but I sprayed with wd40 and all seems tight. Only thing I see I havent tested for leak is by the throttle shaft. And I have only tested on idle, so as the vacuum increases with load there might be a crack that begins to leak.
"New" ignitor is underway also.. even though its really weird and rare if that is the fault, but it is the only odd one now.
Thanks for the pointers! :thumbup
 

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I just finished with sorting out my 1996 1100W yesterday. I bought this bike a little over two years ago. I had lots of electrical issues, leaking forks, and the engine cutting off at random times. The previous owner removed the stock carbs and air box and installed 41 mm Keihin FCR's. This bike would sometimes run great, but mostly not so much.

Make a long story short, I noticed yesterday that the last owner plugged the petcocks vacuum port, since the Keihin racing carbs don't have a vacuums port to hook into. I didn't know that the stock carbs fuel needs were regulated via a vacuum system. As a test trial, I removed an o-ring from the factory petcocks slide / regulator mechanism, which then bypass the need of a vacuum and allowed the fuel to run freely thru the petcock into the carbs. My bike has never run better since I modified the petcock. So it turns out that my engine dying or not being able to increase throttle fast was due to a disconnected vacuum line. I called Keihin to see on how I could address this issue, and they told me to run the vacuum line from the petcock to the manifold on either carb two or three. I would need to drill a hole into the manifold and install a vacuum port to which I could run the hose too. I decided to just buy me a $120.00 high flow racing petcock so I would not need to worry about the vacuum fueling issues anymore.

I'm not saying that this is the issue that you are having, but a vacuum leak, or in my case a removed vacuum line can really screw things up.

Andy
 

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Do yourself a favour and replace the needle jets and emulsion tubes these are known to wear out in under 10k miles from new this is a really common problem on these carbs fitted to GSXR's and Bandits. It just boggs down when you get onto the needle from around 3 - 4k revs onwards and then clears at the top end when you are only running on the main jet and not the needle.

I did it on my 1100WP and it now runs perfectly.
 
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