Rodbolt, I could use your advice on a C40TLRX timing problem

[rodbolt]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

does this C40 have the link from the carb to the wiper on the CDI unit?
I am to lazy to look it up tonight. or tired.

 

[99yam40]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

the throttle cable is tied to an arm that has a link to the wiper on the CDI.
The arm has the retard and avance stop screws on it

 

[rodbolt]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

CDI has a set of marks, idle mark meets the idle pointer and WOT meets the marks at WOT.
if it overshoots it runs nasty.
so adjust the stops so dynamically the idle timing is correct and the WOT is correct and forget about the static timing.

 

[99yam40]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

does dynamically mean to set it at the marks or with the timing light?

 

[rodbolt]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

dynamic is with the engine runnig and a normal loat or with a test wheel.

 

[99yam40]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

I do not believe I can adjust the retard stop screw far enough to get it to 7 ATDC without it opening the butterflies some.
This is why I was asking what could cause the timing to be so far off from factory spec. when the linkage is set to spec in manual.

 

[JustJason]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

uhmmm... do you have a screw that's just to short?.... for whatever reason..

 

[99yam40]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

The wiper pointer is at the 7 degree ATDC mark when the idle stop screw is adjusted to 20 mm, but the timing is at 14 ATDC when checked with a timing light.
If I adjust the link long enough to get the 7 ATDC with timing light then the threaded rod on the link to the wiper is only screwing into the plastic end connector 3 mm and the manual said to make sure is is threaded at least 8 mm into plastic. Maybe I can get away with that since it is only moving the wiper, not much resistance or strain on it. But I will have to adjust the advance stop adjustment screw quite a ways to keep the wiper pointer at the 25 BTDC mark at WOT and the pointer is not even close to the 7 ATDC mark on the CDI unit at idle. I will see if I can get some pictures and post them.

 

[99yam40]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

I will try to post some pics.

The 1st one 001 is of the wiper at idle 7 ATDC mark with linkage at 20 mm but timing with light at 14 ATDC

OO7 is with the linkage adjusted to where the timing light shows to be at 7 ATDC

011 shows the actual time with timing light

014 shows the 3 mm of threaded rod that is left for screwing into plastic connector attached to wiper

 

[99yam40]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

As I have said before this motor has run fine for the last year untill about 2 weeks ago when it started having some surrging and then it got where it did not whant to idle properly. That's when I looked at the timing.

I will ask again what could cause the timing not to be where the wiper pointer is saying it is suppose to be?
And has this been seen before on other motors?

 

[rodbolt]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

that wiper is actually connected to a TPS, the timing is controled by the CDI based on the wiper position.
could be yours is failing, has incorrect voltage or your link and sync is off.

 

[99yam40]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

OK we may be getting somewhere now!
How do I check the voltage you are talking about?

I have adjusted the retard stop screw to 20 mm like the manual said to and then adjusted the timing to 7 degrees ATDC dynamic( timing light, motor running and idling) like you said to with the threaded linkage between the wiper and throttle lever and then set the WOT timing to 25 BTDC by adjusting the advance stop screw.
I have not seen anything about checking voltage in the manual.
Or do I need to find a replacement for the CDI

 

[99yam40]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

that wiper is actually connected to a TPS, the timing is controled by the CDI based on the wiper position.
could be yours is failing, has incorrect voltage or your link and sync is off.

Rodbolt, could you elaborate on the incorrect voltage and how to check?
I have gone through the link and sync several times while playing with the linkage.

Just some information. The timing always goes to 4 degrees BTDC at start and warm up, whether the idle timing is at 7ATDC or 14ATDC, and the WOT timing is at the 25 BTDC when the wiper pointer is at the mark.

 

[99yam40]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

Just checking to see if Rodbolt has seem my last post and question?


Rodbolt, could you elaborate on the incorrect voltage and how to check?
I have gone through the link and sync several times while playing with the linkage.

Just some information. The timing always goes to 4 degrees BTDC at start and warm up, whether the idle timing is at 7ATDC or 14ATDC, and the WOT timing is at the 25 BTDC when the wiper pointer is at the mark.

 

[rodbolt]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

ok, when you do the carb shutters and the carb linkage and oil linkage then you ajust the linkage for the wiper so that at idle with the idle stopper hitting the block the wiper on the CDI unit is pointed at the idle marks, may be off a bit on either side, at wot adjust the wot stopper so the wiper mark lines up with the wot marks on the CDI.
dynamically check that the idle timing is about right within 4 degrees or so and the WOT with a normal load is 25*BTDC or less within 4degrees.
that engines normal warmup cycle automatically advances the ign timing based on thermosensor inputs.
which is why you see the timing change as the engine warms up.

 

[99yam40]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

Thanks for the reply Rodbolt, and I understand the process of setting the link and sync.
But I was asking where the timing is suppose to go to during certain periods of time like start up or over tempature, low oil level, etc. and what else would effect the timing besides linkage.

I have heard that the idle timing is never or hardly ever at what the manual says when checked with a timing light and just to worry about the WOT timing.

Is this something you would agree with?

 

[Grew2maxum]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

The wiper pointer is at the 7 degree ATDC mark when the idle stop screw is adjusted to 20 mm, but the timing is at 14 ATDC when checked with a timing light.
If I adjust the link long enough to get the 7 ATDC with timing light then the threaded rod on the link to the wiper is only screwing into the plastic end connector 3 mm and the manual said to make sure is is threaded at least 8 mm into plastic. Maybe I can get away with that since it is only moving the wiper, not much resistance or strain on it. But I will have to adjust the advance stop adjustment screw quite a ways to keep the wiper pointer at the 25 BTDC mark at WOT and the pointer is not even close to the 7 ATDC mark on the CDI unit at idle. I will see if I can get some pictures and post them.

I am having the exact same problem with my 89 Pro50 and have done the same troubleshooting with the same results as 99yam40. It is like a piece of the puzzle is suddenly missing!
Has anyone found what was causing this and found a solution?
I can re-engineer the linkage and settings to get the dynamic timing correct but something has gone funny with the original setup. Any solution found?

 

[rodbolt]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

while the timing specs are in the book you go by the marks on the wiper and the CDI, only thing I really look for is timing at WOT.
as long as the idle is stable.
this system is funny and not normally problematic but when it does its crazy to test.

 

[Grew2maxum]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

Thanks Rodbolt,
I have adjusted the dynamic WOT and idle timing to book spec using a timing light as the marks on the CDI box are now useless for some reason (my full retard screw is fully extended and the pointer/throttle link is near it's max length). I have it running good at WOT and throughout the range. It has a bit of an issue just after it comes down off its initial startup advance when it warms up after 15-60 seconds (depending if engine is hot or cold). The idle drops quite a bit at this point and it misses a bit till it is thoroughly warmed up then it's ok. I could advance the idle timing a bit to get rid of this but I can live with it now if it stays like this. Something has definitely changed as the adjustments are way off from where they were when it was running fine up to a couple of weeks ago. I suspect that the throttle position sensor (pointer dial) on the CDI box has become defective or changed a bit. While I can tell when something is wrong, my fear is that it will suddenly go back to it's original state at some point and throw the timing off when the kids are using it and it will blow up. Too bad they did not mount the TPS separate like in a FI car so you do not have to replace the entire CDI. I will probably replace the CDI box before next season just for peace of mind.
Thanks again and I will keep you posted if I find anything else.

 

[Grew2maxum]

Re: Rodbolt, I could use your advice on a C40TLRX timing problem

I will try to post some pics.

The 1st one 001 is of the wiper at idle 7 ATDC mark with linkage at 20 mm but timing with light at 14 ATDC

OO7 is with the linkage adjusted to where the timing light shows to be at 7 ATDC

011 shows the actual time with timing light

014 shows the 3 mm of threaded rod that is left for screwing into plastic connector attached to wiper

I noticed that in 99yam40's pictures in his 19 June post at 11:47 something does not look right. In picture #1 the pointer looks like it has been removed and spun 180 degrees. Maybe his is different but I think it should be installed with the pointer towards the raised curved arch with the timing marks on it. There appears to be timing marks on the box where the pointer is pointing now but i'm not sure if they were added? The throttle/pointer rod looks like it is on an angle and should be straight up and down? Maybe it's right on his model but it looks funny to me. That may explain why it's too short and he has issues with setting his timing??? Someone with more experience can have a look at his pics.