GasGas TXT Flywheel ID & Ignition timing

[2smoke]

Morning,

 

As per my other thread, I'm trying to fix a running problem with my 2003 TXT300.

I ditched the Ducati ignition system, and replaced it with a Kokusan complete system (Flywheel, stator, cdi, regulator, rectifier and coil).

It'll run fine, then restart and it runs like crap (like the timing is out). I'm trying to ID the flywheel.

Going through the wiring diagrams, it seems I have fitted a 1996-2000 Kokusan ignition system, my flywheel is stamped 'FP8102'. Anyone with a similar year bike able to confirm they have the same flywheel fitted?

Most I see on ebay from around that year are stamped 'FP5367'.

Also does anyone know what the static timing should be? Just for checking with a strobe as there are no timing marks on the flywheel so I'll have to do my own.

 

Thanks in advance!

Paul

[huski]

Your bike looks to be an 05,going by it's plastics.The timing is non adjustable on these,the stator mountings aren't slots.Seems the ignition system you've fitted is for the earlier model which has a different engine

[2smoke]

29 minutes ago, huski said:

Your bike looks to be an 05,going by it's plastics.The timing is non adjustable on these,the stator mountings aren't slots.Seems the ignition system you've fitted is for the earlier model which has a different engine

Did they run the ducati ignition system by 05 though? 

I know the timing isn't adjustable, but am trying to see what the timing is doing while it's running, as it seems its not working as it should be. Hence needing the btdc firing info. 

AFAIK it's a 2003, the shop I was dealing with confirmed this. 

[huski]

Google 2005 gas gas pro ignition,I just did,quite informative 

[2smoke]

38 minutes ago, huski said:

Google 2005 gas gas pro ignition,I just did,quite informative 

Ok,but it doesn't really answer my original question though.

Whether or not its an 03 or an 05, the Ducati ignition has been replaced with a Kokusan system. Hence me asking about the flywheel ID number differences.

It's a fairly common mod to ditch the Ducati stuff and replace it with the Kokusan setup.

[mcman56]

Not the same bike but a 2008 Rev 3 was 8 degrees BTDC at idle and 12 BTDC at high rpm  From my understanding, a system designed without any kind of advance will give you around 5 degrees just due to increased voltage making things happen quicker.  By contrast, a 1997 Techno had 21 degrees of advance.  I can't find the numbers but it went from something like 5 degrees at idle to 26 at full scream.  I suspect that porting is different to take advantage of the additional advance.

One failure mode is that an ignition with advance can get stuck in full retard or full advance.  You may have that failure mode.  If you can catch it running good and bad with a timing light, it should tell you something.

 

 

 

[2smoke]

45 minutes ago, mcman56 said:

Not the same bike but a 2008 Rev 3 was 8 degrees BTDC at idle and 12 BTDC at high rpm  From my understanding, a system designed without any kind of advance will give you around 5 degrees just due to increased voltage making things happen quicker.  By contrast, a 1997 Techno had 21 degrees of advance.  I can't find the numbers but it went from something like 5 degrees at idle to 26 at full scream.  I suspect that porting is different to take advantage of the additional advance.

One failure mode is that an ignition with advance can get stuck in full retard or full advance.  You may have that failure mode.  If you can catch it running good and bad with a timing light, it should tell you something.

 

 

 

Thanks mate, that's what I was aiming to try and find with the timing light. See if I can get it running good and bad to check, but without knowing the ignition timing it was going to be hard to mark the flywheel. 

I was going to mark 20 degrees btdc for a starting point. See how that goes! 

It's had another 3 cdi's (including one off a bike that was running fine) and still the same. Real puzzler! 

 

Thanks! 

[mcman56]

Does the stator have multiple trigger sensors?  I understand some have a low speed trigger and a high speed trigger.  When it runs poorly, is it everywhere or just idle or just higher speeds?

Edited April 17, 2020 by mcman56
add question

[2smoke]

20 minutes ago, mcman56 said:

Does the stator have multiple trigger sensors?  I understand some have a low speed trigger and a high speed trigger.  When it runs poorly, is it everywhere or just idle or just higher speeds?

Just the one lobe (or inverted lobe). 

I got it running this eve, got the strobe on and at idle normally the marks are so (it's marked around 20 degrees, couldn't find my dial gauge or degree wheel) 

Increase the rpm and it goes near tdc

This is when it's running right mind.. 

 

So turned it off, started again and its running crap. Marks are fixed here no matter the rpm

So it's definitely an ignition problem. But what?! 

[mcman56]

Are you saying that when running well, idle is 20 degrees BTDC and reved up is near TDC?  That seems backwards.  

The last picture suggests it is stuck in retard mode and does not advance with rpm.  The CDI should handle advance but you have tried a few so that is odd.  Are the CDIs from the same year?  The ignition mapping switches are supposed to affect advance but supposedly at higher rpms.  Does yours have a map switch?  They supposedly work by seeing if the switch is to ground or not when started.  Have you checked all grounds and connections?  That is a frustrating problem.  

 

[feetupfun]

Some racing ignitions for two strokes retard the ignition as the revs rise

[2smoke]

5 hours ago, mcman56 said:

Are you saying that when running well, idle is 20 degrees BTDC and reved up is near TDC?  That seems backwards.  

The last picture suggests it is stuck in retard mode and does not advance with rpm.  The CDI should handle advance but you have tried a few so that is odd.  Are the CDIs from the same year?  The ignition mapping switches are supposed to affect advance but supposedly at higher rpms.  Does yours have a map switch?  They supposedly work by seeing if the switch is to ground or not when started.  Have you checked all grounds and connections?  That is a frustrating problem.  

 

Odd eh! 

It goes near tdc just above idle, then advances when running well. 

Does seem to be stuck fully retarded when running badly. 

There's no map switch & I've been through every connection & earth. All good. 

The only theory I've got is maybe there's an issue with the flywheel & the pickup is triggering twice for some unknown reason when it's running badly. So the cdi thinks it's running at double rpm, retarding the ignition. But it will not rev any higher due to lack of enough voltage from the stator at a low rpm. 

I'm going to check with the strobe again later, I couldn't remember how much it was flashing at idle when running badly. 

I've got a dyno with an rpm pickup, may hook that up later. 

Mystery! 

[mcman56]

6 hours ago, 2smoke said:

t goes near tdc just above idle, then advances when running well. 

That sounds correct.   The few trials bikes I looked at did not retard at high rpm and I took them to full scream. It could be that the porting is so different they become inefficient at high rpms anyway or maybe they just never reach the kind of rpms where it is useful.  I even hooked one up on an oscilloscope looking at all of the outputs of the stator.  It was hard to view on a running bike but was clear when running the whole ignition on a milling machine.   

[2smoke]

Well I borrowed a complete 2005 ignition setup off a friend's bike, and lo and behold it runs fine. 

No idea why the 2002 stuff isn't working with it, unless there was some mismatch somewhere. 

 

Anyhow, few more test rides then rebuild my mates bike. 

And the hunt for a stator, flywheel and cdi begins.. 

[2smoke]

Update. Refitted the old ignition, found the pickup wires were reversed in the loom! 

Corrected that and it runs properly every time now ?

Timing advances rather than retards. Just the owner to sort now!!