'88 max pick up coil wires question

Kalchev · May 22, 2016

Hey all, first post here, be gentle :biglaugh: Great place you got, been finding lots of usefull info.
Got me a 1988 max to restore - while buying it noticed right exhaust way too colder than the left, and the v4 was working quite irregularly. Right exhaust seemed to spew petrol and you could smell it close to the bike.

Previous owner did change the spark plugs, I checked the ignition coils today (all within 3.1 to 3.3), so decided to check out the pick up coils connector too. The entire front end is dissassembled at the moment, so I'm stuck doing tests without the max working.

Here's my problem: the p/u coil connector has been removed and I have 7 wires comming out under the gear cover, going back around the battery. 5 of them are braided, cut and directly connected onwards, the other two have rubber insulation and seem to have original cable boots, so I reckon the ones I need to check are the former. After the improvised connections, one of these five continues black, another seems to be gray, and the rest are white-ish - thicker than the first two and going to the regulator me thinks.

At around 20C degrees, resiatance black-gray is around 101-102ohm, but there's none between either black or gray and the other three white wires.

Can anyone shed some light whether I'm looking at the proper wires and what my readings (and lack there of) mean?

Cheers

PS
Made some photos of the mess aswell, attaching a couple.

blaxmax · May 22, 2016

Looks like someone spliced in a R/R. I have to run right now maybe this will help.

http://vmaxoutlaw.com/tech/VMX12-Service-Manual.pdf

DMAN999 · May 22, 2016

This Charging System guide will help you also:
http://www.vmaxforum.net/showthread.php?t=19108

Kalchev · Jun 7, 2016

Right, thanks for the manual, it's quite a resource to have at hand.

First thing I did was check both harnesses at the TCI. From the ignition diagram I cross checked all wires by color and if they aren't cut somewhere along the way:
- ignition coils are ok;
- pressure sensor wires are ok;
- the side stand relay wire is there, but has been cut off from the sensor (bike starts no problem);

Regarding the p/u coils wires though the diagram it seems might not be for my model exactly. I don't have 5 wires coming to the TCI from the pick-ups, just two - one black and another grey. As it turns out these are the same two wires I found coming from under the flywheel cover and going back under the seat (where as per the manual I should be having a 5 wire harness). The other three thicker white wires were for the r/r and yeah, it's been moded as per the advice in the link for the charging system guide. The r/r itself hasn't been changed, so that's something I'll do myself this season. Again, thanks for the charging guide, very useful stuff!

So resistance between the two wires, supposedly coming from the p/u coils was around 103-104 ohm at close to 20°C. I'm not sure why I'd have only two, perhaps it's a different model? I think it's a VMX12U but could be wrong.

Anyways, primary resistance on the ignition coils was according to spec (although the rear right one has been tampered with), I'd still have to test the secondary resistance and spark plugs themselves. P/u coil resistance seems to be in order, there's no damage to both harnesses coming to the TCI (no wire issue). Harness and TCI plugs look clean, I sprayed them a bit just to be sure. Is there anything else I could test on the ignition system in regards to the supposedly one or two cylinders not firing problem I have? The bike's gonna be assembled this week me thinks, so I'll make sure to fire it up and see how it idles.

Cheers

wildweasel_pt · Jun 7, 2016

The model you have is a post 89 which is single pickup. 85-89 is 4 pickups. You have the wrong model manual. Wires coming from below should be (need to confirm colors) 3 thick braided white ones from stator and a pair gray/orange with a black double connector for the pickup. A green wire with bullet connector and a yellow with a bullet connector for the oil level sensor and neutral sensor. And a other pair for the side stand switch with a double connector.

Miles Long · Jun 7, 2016

On European models, beginning in 1990, changes were made to the ignition system.
Instead of two alternator pickups, only one is used. The Ignition Control Unit was also changed.
Consequently, pre-90 alternator wiring consisted of 8 wires - three white for the R/R, and 5 for the pick-up coils.
Post-90 wiring consists of 5 wires total - three white for the R/R, and only two for the P/U coil - originally black and orange in color.
It appears the previous owner may have installed a post-90 flywheel/alternator (with only one magnetic pickup), trying to mate it with a pre-90 ICU (which requires two pickup signals) This would certainly explain why your bike is only running on two legs!
Easiest way to check - how many inputs does your ICU have? Should be 13 for the old style, while an upgraded (one pickup signal) model will have 11 inputs.
Cheers, and welcome to the forum!