GS450S, won't take over 3500rpm

[VT86]

What to do I finally get new signal generator to my bike and it started very well with it. But when I went to test ride it I notice that it takes quite slowly RPMs and it won't take over 3500rpm. When I try to engine brakeing (drop 4th gear to 2nd) It "back fires" inside of silenser.

Any Ideas ?

[onchiman]

Did the bike run before you replaced the part? Are you getting a good spark to both plugs? Also, did you check the ignition timing when you replaced the signal generator?

[VT86]

Nope coz signal generator was broken. (but before brakeing it worked well)
I was wondering that can new NGKs spark plug caps do that (with 5komh resistanse). I have changes new spark plugs, wires and caps, just before i notice real reason why it won't start is that signal generator.

How I can check that timing ?

[doctorgonzo]

What kind of wires? If you combine suppression wires (should use old style copper core wires with NGK caps) with resistance caps, you get zero spark.

[VT86]

What kind of wires? If you combine suppression wires (should use old style copper core wires with NGK caps) with resistance caps, you get zero spark.

Some copper wire.

I forget to say that that signal generator in my bike is samekind than in GSX400. (was bit difficult to find right part... first I get some signal generator from GS450 '85 and it was wrong and that GSX400 singal generator is precis samekind than than my broken one)

[onchiman]

How about the ignition advance (or governor as it's sometimes called). Is that operating as it should? Somewhere around 2500-3000 rpm it should advance the timing. It's a mechanical device that sits on the end of the crankshaft behind the signal generator and has small springs and weights. If that is binding or stuck, it could cause the symptoms you're describing because as the engine speed increases the timing is supposed to advance to maintain power.

[VT86]

How about the ignition advance (or governor as it's sometimes called). Is that operating as it should? Somewhere around 2500-3000 rpm it should advance the timing. It's a mechanical device that sits on the end of the crankshaft behind the signal generator and has small springs and weights. If that is binding or stuck, it could cause the symptoms you're describing because as the engine speed increases the timing is supposed to advance to maintain power.

I don't have that kind thing at all.

here's few pic of signal generator and all parts of it

That's whole signal generator and all parts of it






This last part is connected to crankshaft


ps. Don't mind finish texts. Those was for firm where I order used part. And they told that it was from GSX400 (coz first i get GS450 part but it was different)

[doctorgonzo]

I didn't see it in any of the posts, but what year is the bike? In 82 the mechanical advance went away, but if it's an 81 or earlier there should be something behind the signal generator.

[doctorgonzo]

#5 in the picture below (which is an 81 GS450S)

[VT86]

#5 in the picture below (which is an 81 GS450S)

oops my bad, My bike is 1985 and First I get that kind of signal generator but it was wrong. I don't have that mechanical device at all.

So any ideas where to start look fault ?

[tkent02]

So it sounds like you have no spark advance at all.
No mechanical advance as your bike came with an electronic one.
No electronic advance as you have the early unit designed to work with the mechanical advance?

Need to do something else.

[doctorgonzo]

Check the voltage drop at the coils. Connect one probe of a multimeter to positive coil wire, and one to negative. Should be 11 volts or better (search the forum for the coil relay mod if the voltage is low). Check the igniter (which on yours handles the timing advance) per the test in the manual. Check the resistance in the plug wire from the cap back to the end that connects to coils. Should only be 5ohms from the cap. Some places to start.

[VT86]

I just cleaned carbs and so one. Still won't run well. Then I notice that Stator gives only voltage between A-B and A-C but not between B-C

Is it possible that that is reason why engine won't take over 3500rpm and engine response is damn slow.

(This is my idea cos engine takes almost 4500rpm when some reason battery voltage rise higher)


And most important Is Suzuki RG125 Gamma '85 startor same as that GS450 stator. I have my old RG still so I think that first I will try that stator (if it's same)

[earlfor]

1985 did not have the mechanical advance. It was eliminated and that function was performed by the electronic ignition system. You have a built in electronic advance. The ignition timing is not adjustable and the breaker plate can only be installed one way, so it is not possible that you have the timing set incorrectly or that it can be incorrect.

I had you same voltage problem with my 450. (one pair of stator leads not having sufficient output) With only two legs of the stator working correctly, the charging system is running at a loss relative to what the bike consumes to operate, so yes, that will cause the engine response you describe (it did on my 450). Also, low voltage supply to the coils will cause that problem too. With the charging system only partially working, you will still have 12 volts, but you will have insufficient amperage.

Its somewhat like putting one ounce of gas in your car's empty tank. Yeah, its real gas, but that amount isnt going to work. :-)

Earl

I just cleaned carbs and so one. Still won't run well. Then I notice that Stator gives only voltage between A-B and A-C but not between B-C

Is it possible that that is reason why engine won't take over 3500rpm and engine response is damn slow.

(This is my idea cos engine takes almost 4500rpm when some reason battery voltage rise higher)


And most important Is Suzuki RG125 Gamma '85 startor same as that GS450 stator. I have my old RG still so I think that first I will try that stator (if it's same)

[VT86]

Does anyone have a clue can I use my old RG125 Gamma's stator ?