Hello, I recently got a $300 1989 Xt600 from Craigslist. It is an absolute crackhead bike. Everything is spray painted black and it is somehow super grimy... but it is plated and came with an extra engine and parts, so I felt it was worth it.

Anyways, when I got it the carb boots were beyond destroyed, it had low compression and it all the cables were full of paint so they didn't move. After a bit of work, and a the good used piston/cylinder from the spare engine and a grizzly manifold (I actually had a grizzy 600 carb so this made the most sense as the original carbs were not in the best shape) I got it to run. No smoke and it has enough compression for me to use all my 160lbs to kick it over (the compression release isn't hooked up currently)

Now here's the issue, it runs very well at idle and up to probably around 3500rpm, nice and torquey. However after that it completely flattens out, I've ridden an srx600 and this feels about half the power that the srx did.

The carb isn't properly jetted and I am using the muffler from a yz250f, but those shouldn't cause it to have so little power. It feels as if the ignition timing is super retarded or as if the cdi isn't advancing the ignition. I tried swapping the cdi with the spare one in the box, but it made no difference... but they could both be not working.

When I threw in the other piston/cylinder I made sure all the ports weren't clogged/filled with carbon and I lapped the valves etc, freshened it all up. I am stumped, I think it may be the cdi, but if there is a way to test them I would love to know, or is there something I missed?

I may try buying and building those diy cdi's from France.


Thanks,
Nick

Okay we good news and bad news. Good news: I found the problem. After a little more digging I found out that there are two pickups for the cdi. The 12deg one works fine, but the other is kaput. I took the stator/ pickups out of the bike and it looks like the P.O. messed with them as the leads have been resoldered very terribly. Bad news: the 36deg pickup isn't showing any reading on the ohm meter even after a lot of probing, so I think it is fried. Now the question is if there is a replacement pickup or do I have to get an entire new stator setup? Could two single pickups be made to work if I made a custom bracket for them?

I want to do this as cheap as possible if possible...

Thanks again,
Nick

Can you take a picture of the pickups? Just curious

pickups are cheap, plenty of supply out there, used (ebay) or new


in europe id buy here, but there must be american suppliers too


Pick-ups - IgniTech Přelouč

Here is the wacky dual pickup. I've been looking around and there aren't any that I can find, and a whole new stator setup with the pickups are upwards of $300-$500 which is, um, a bit much. Also there are not really any models that share this pickup besides a few xt550's and the costs are similar.

So I ordered two pickups with the same resistance, and for only $12 I think it's a cheap experiment that's worth a shot.

Attached Thumbnails

 

 

 

And you can see the three wires going into the pickup are all mangled from the P.O. as well as some strange drill marks so I guess he was trying to fix it... oh well.

send an email to ignitech....they might have someting

Ill try that, thanks

Haha I fixed it.

So I couldn't find that dual pickup anywhere, so I made one. I just got two pickups and jb welded them to a bracket, wired them up and viola.

Hopefully it will hold up, I got the gas and oil resistant jb weld so I hope it will be fine. If not I know how to make a new one...


It isn't very pretty and the clamps shifted over night so it's a bit crooked, but it works. Full XT powa!!!!!

Attached Thumbnails

 

 

 

Well done!

Is there anywhere I can read up on the XT pickup etc?
Why does it have 2 offset pickups on the flywheel?

one PU is for starting low revs, second PU for normal higher rpm running spark advance, ign box simply switches to the second one when revs pickup.


Nice McGyvering it, but without wanting to scare you, would be wary of longish trips in hot weather or off-road.... failure in the gluing could mean serious damage in there.


Would try to build a small metal cage around the two


ignitech has some units that replace the two PU setup with a single one and advance is built-in into their ignition box. Have one in my DR350, works well.

Ah I will definitely check out that ignitech unit, and yeah I don't know how much I trust that epoxy but I will open it up at some point soonish and see how its doing.

Ah - that makes sense. However if it's using two mechanical magnets to change timing, can you explain this picture from the manual?



It clearly shows a smooth/linear advance from 2k-4k rpm, rather than a two-step?

EDIT: found this: "The XT600 uses the second pickup at 12° for a better starting, but it is not essential."
https://transmic.net/2016/07/02/faq/

From my understanding the first pickup still has electric advance. The second pickup is just used for better starting?



Ps.
Apparently from the 1990's / 3TB the electric start models got TCI instead of CDI. I wonder why. 3AJ electric still has CDI.
Is it because TCI is more reliable and produces stronger spark at low RPM?

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

Awesome stuff.

I know a lot of xt550 people have had the same trouble, but i'ver never seen who actually did the 2 seperate pickup-trick, only lots of talk about it.
Please keep the thread updated, as this could really help a lot of people.


Which pickups did you buy?