Horizons Unlimited - The HUBB - Xt600 no top end power

Horizons Unlimited - The HUBB (https://www.horizonsunlimited.com/hubb/)

- Yamaha Tech (https://www.horizonsunlimited.com/hubb/yamaha-tech/)

- - Xt600 no top end power (https://www.horizonsunlimited.com/hubb/yamaha-tech/xt600-no-top-end-power-98807)

And ya it was worth a shot :cool4::thumbup1::thumbup1:

Quote:

Originally Posted by turboguzzi (Post 601522)

buy a timing gun, run the motor through revs and point at a degree wheel, only then youll see for real how your ign advance behaves.. :)

that drawing is quite "idealized" from my experience

CDI were developed for two strokes to solve plug fouling, then carried over to 4 stroke dirtbikes. 4 strokes dont really need CDI, 2 strokes do.
ALL 4 storkes are TCI nowadays

So I decided to e-mail the transmic guy and he replied me with this:

https://transmic.net/2016/07/14/yamaha/

Basically, all the answers are there, even with timing graphs.
And yes, the image from the manual is correct:

Code:

At starting of the engine, the pulses of the 1st pickup (White/Red at 36°) are blocked.

Only the pulses of the 2nd pickup (White/Green at 12°) are used to obtain 12° advance and not risk a kick back.



At idle and low revs, pulses from the 1st sensor at 36° are so delayed that they don’t have time to trigger the SCR.

Only the 12° is then used.



At mid revs, pulses from the 12° pickup loads a resistor + condensator cell to obtain a Frequency to Tension conversion. (the more the rpm, the more the tension.)

This resulting tension is used by a monoflop for delaying the pulses coming from the 1st pickup at 36°.

The more the revs raises, the less is the delay and the sooner is the spark until it comes before the spark triggered by the 12° pickup.



At high RPM then the SCR is triggerd 2 times (first by the 36° then after by the 12°).

edit: also, on this page you can also read that the 2nd pickup IS essential (on the FAQ he meant it differently and will change the text).

Code:

I meant : it's not essential for the working of the engine, it is "just" for startup and idle.

But you are right , this sentence can be misinterpreted. I'm going to modify that. Thanks

Hmm very interesting thanks for that info!

Just a little update on this setup:

Shortly after getting it all running the glue on the 12* pickup slowly cracked off and it got harder and harder to start until it just didn’t at all.

When I pulled off the pickup it turns out my glue job was really poor and it was only attached in a few places.

This time I welded the pickups on. There’s a steel mounting plate that I originally cut off of both, but was still enough that I just welded a small flat piece of metal to the edge of both pickups. Since then it has held just fine. Stupidly I don’t have any pictures, but if you’re doing this yourself you can figure out a way to do it.

Now I’m pretty sure the glue method would work, but I didn’t do it properly so who knows...

you are something, I got to say.... but better like this, i think i told you that having bits of epoxy fall off into the engine is a high risk. hope you didnt fried the wire's insulation while welding, worst comes to worst, no ignition :)

haha yeah I took off all the old epoxy before I welded the new setup together. And I was concerned about the heat, but I did short bursts and kept it cool. It's been about 2,500 miles and an oil change in its current configuration and its been working no prob!

Just an FYI for those who want to do this: the pickup coils I used were from a Chinese cb/cg 125/250 they were the cheapest I found and had the correct ohms

compliments on the persistence! thread is back from the dead....

post a pic of your running franken-bike when you can...

Quote:

Originally Posted by nickklugs (Post 619790)

Just an FYI for those who want to do this: the pickup coils I used were from a Chinese cb/cg 125/250 they were the cheapest I found and had the correct ohms

Hi Nickklugs

this tread is music to my ears as I have been searching for a pickup for months !! Do you have any images of the wiring or could you tell me what you did as Im assuming you have joined one of the wires from each pickups together and connected it to the the Green wire going to the CDI unit ?

cheers