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it won't be.....ignition timing is controlled by the ecu (black box).

however, if the timing pickups aren't working right or are connected wrong somehow, that could cause problems....not to mention a whole shitload of other things that can go wrong...
 

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Discussion Starter #3
OK Jeff

But if black box work fine and coils pickups wrking fine, why do not start?. I check the carb maybe need adjust but I think that do not deliver fuel to spark Plug.

Do you know trick?
 

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Discussion Starter #5
Yes, I pull the choke but nothing happened.

The carb it's clean, think that the float level is rigth and lines is clear, now maybe the pilot screw haven't the turns correct.

My bike is Suzuki GSXR 750N 1992

Thanks Jeff
 

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assuming the choke is working, the mixture screws could be turned all the way in and the bike should still start.

i think you may have been on the right track about this being either a fuel delivery or an ignition issue.

are the carbs getting gas? one quick way to tell is to open the drain screw on the float bowls and see if anything comes out (hold a cup underneath the bowl to catch any gas).....at the very least, that would indicate that fuel is flowing from the tank and through the petcock.

if your fuel petcock has a 'pri' position, try switching it to that instead.....in case the vacuum operated part of the petcock isn't working properly.
 

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Discussion Starter #7
Yes the carb getting gas i open the screw and adjust the level of the float bowl

I check the choke and look clear.

Check Jet needle, needle jet, pilot scre, jet main and change the o-rings

I'm little confuse, what is the mixture screw and how many turns will have?
 

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mixture screw is the pilot screw....at this point i'd suspect an issue with the ignition.

have you checked the spark plugs recently?
 

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what color were the spark plugs?

how did you make sure the spark plugs were working? keep in mind, a weak ignition system could cause the plugs to appear to work with the spark plug outside of the engine, but not spark properly when the spark plug is in the combustion chamber...
 

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Discussion Starter #11
Thanks Jeff for oyur help

The color spark plug is black

Tomorrow will buy new spark plug and try again star engine.

Tell you what hapen
 

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spark plugs shouldn't be black, they should come out a tan color.

if they're black, that indicates the fuel mixture is too rich, you have a clogged air filter, or the ignition is weak.

replace the plugs and see how it goes.

[ 10-26-2001: Message edited by: jeff ]</p>
 

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Discussion Starter #13
hey Jeff

I change the spark plug

But the problem is that the engine don`t make explosion to start

I hear only the the starter motor moving the engine but don`t listen the fire explosion in spark plug

I check the spark and is blue but i don`t know if is weak?

I have to tell that the bike turn on but engine no idle. A mechanic open engine and seat valves, after this the bike don't start again

My father tell me that check valve clearence, maybe need adjust?

What you do thing about this?

[ 10-27-2001: Message edited by: Cocho-cho ]</p>
 

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yes, that's another possibility - if this 'mechanic' has messed up the cam timing or valve clearances, that can cause problems with the bike not running.

if the valve clearances are so tight that the valves don't completely close, that will cause a loss in compression and the bike will be very difficult if not impossible to start.

a motor needs three things to run:

fuel and air in the proper ratio,
spark,
compression


do you have the service manual for your bike?

if so, you can open the valve cover and check cam timing as well valve clearances.


why was this 'mechanic' working on the bike?
 

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Discussion Starter #15
Well

The engine don't stay in low rpm but in high rpm work fine, the mechanic said maybe problems with carbs, black box and valve clearence. Now I believe that he make bad work. I prefer repair myself the bike.

And yes i have the manual, i'm guide by that, but need something help.

Thanks a lot Jeff
 

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okay....so before he worked on the bike, it wouldn't run well at low rpm's? but after he got through with it, it doesn't run at all now?

i think you should try pulling the valve cover off, and then make sure cam timing is correct (when the crankshaft is turned to the timing mark, the arrows on the camshaft sprockets need to be pointing a certain way, also, double check the number of cam chain link pins between the two camshafts.....instructions are in the service manual), and check the valve clearances.
 

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Discussion Starter #17
Hi

I check the clearence valve and require adjustment

The camshaft don`t have especified torque.

i can`t insert nor one size of the flat feeler gauge beetwen the shim and the rocket arm. (Intake)

Truely the mechanic made very bad work.


Now i ask myself if this mistake may damaged another thing in the bike and had to review another parts


[ 10-30-2001: Message edited by: Cocho-cho ]</p>
 

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did you check the timing of the cams? if they were installed wrong, that would cause problems with measuring valve clearances.

once you've verified that the cams are installed correctly, then measure the clearances.....if you can't even get the feeler gauge in to measure the valve clearance, then that's a big problem right there.....essentially, that valve wouldn't close completely, and thus the combustion chamber would lose compression.
 

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Discussion Starter #19
The timing cam is OK together with sensor mark.
and yet can't insert the fleet gauge.

Now I need re-adjust the valve clearence.

I have to do change the shim or have to wear away
the shim?

[ 10-30-2001: Message edited by: Cocho-cho ]</p>
 

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it'll be a little tricky since you have no clearance at all, so you'll need to go through a bit of trial and error before you end up with the correct shim....

how many valves have incorrect clearance? remove the shims from the valves that have the wrong clearance....keep track of which shims go where.

then go from one 'incorrect' valve to the next, and try thinner shims than the one that was on that valve originally, until you can actually fit the feeler gauge in it.....then calculate the correct shim size for that valve, and make note of it. then move on to the next 'incorrect' valve.

once you've finished going through all the valves, you'll have a list of the correct shims you need. compare this list to the list of incorrect shims you had removed.....you might have some which match, in which case you can just use those in the appropriate valves. the ones that you need but don't have, you'd need to buy.

just take your time, go slow, and you'll be okay......double check all of the valve clearances when you've replaced the shims.

[ 10-30-2001: Message edited by: jeff ]</p>
 
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