I got me a Half-Breed!

[jimboreeno]

I have recently found that my sweet XJ11 is actually an XJ with an XS engine!! Now I need to know what year the engine is. The serial # on the engine is 8J6-009022. Any one have any ideas on this??

I discoverd this while having my carb boots replaced and the carbs synced (yes HAVING it done, I do alot, but not all!)
The guy doing it said that since the XS engine is hooked to an XJ cam that is why it doggs at around 5000rpm. I have not rejetted but the carbs are "supposedly" synced and clean.

I also lost power at the top of the gear since he worked on it. Ie. I have to downshift for power where I didn't use to.

Thoughts on any or all of this???

[TopCatGr58]

"Half breed, I learned to hate the word!"

Hey Jim,

You've got me and at least 27 others stumped!

The XJ's of course used the 10M designation. The XS's used from 2H7 thru 4RO. I looked up the cross reference web site one of the members put up in the UK, and it doesn't list any bike with the 8J6- prefix, even like the 850's, 650's, etc.!

Where are you getting this number from? There should be a plate on the engine case, just below where the carbs are, just above the clutch chamber with the # etched on it! Do you have 4 cylinders? Does it say YICS on the side covers of the engine?

A photo or 3 would really help here! IF it is in fact an XJ, then the "guy" synching them may NOT have know or used the special YICS tool?? What other mods if any have you done to the bike, pipes, intakes, air filter, etc.? XJ cams are not much different than later year XS cams, so it should NOT fall on it's face because of that!! Vacuum hose may have been left OFF of sensor box, may need rejetting, etc.!?
T.C.

[xj11john]

Hey T.C.

Jimbo is prob sleeping now, but I can attest to him having a motor that doesnt have YICS on the engine anywhere, and from the pics I have seen of and XS motor on this site I'd say it is one.

We have ridden together on several occations and I had commented on his engine not saying YICS on it and looking different, we figured it had to be off and XS.

Anyway I'll let him fill you in further, Sorry Jimbo for jumping in but I was curious about you engine as well, good luck on it.

[Hired_Goon]

A quick google on Yamaha 8J6 brings up nothing but snowmobiles.

Very strange indeed. But if it is 3J6 then that would make it an 80 XS1100SG

[GNEPIG]

.. yeah thats what i'm thinkin, someone misread the numbers. 3J6 is more like it.
these bikes dont dog out at around 5 grand because of the cams, you have a different problem.

[trbig]

I am in agreement with that. You hear about it time and time again.... "I took it in to get the carbs synch'd and it isn't running right". My guess is that you will need to spend a lot less than you did for someone else to synch them for you... and buy the carb sticks and do this simple thing yourself. Mine would do the same thing as this one, only mine would also rev up at idle after warm... but pulling any kind of grade, I would have to downshift and rev the @#$% out of it to try to maintain even 70mph. After I synched mine, when I leave my road, I have to go up a hill.... I described to TC what happened when I twisted that throttle... it was nothing at all like I expected and almost lost my grip on the bars. It went from feeling like a big, heavy, lead pig, to almost feeling like a 2 stroke dirt bike.... best description I can come up with. As quickly as the RPMs were coming up... so were the corners of my mouth into a Sh#%- eating grin!

Tod

[jimboreeno]

The number is 3J6 NOT 8J6. I was trying to decide between 3 and 8 when reading it so the 3 is it. So it is an '80 XS1100SG..good to know!

Mine would do the same thing as this one, only mine would also rev up at idle after warm... but pulling any kind of grade, I would have to downshift and rev the @#$% out of it to try to maintain even 70mph.

This is my EXACT issue. right down to the rev when idle.
I spoke to the guy (talking about Paul, Jon)and he said bring it in and he will do what it takes to get it right. Is it just a sync problem then??

[trbig]

I say that's all it was, but I gave the carbs a good cleaning and adjusted all the floats, THEN did the synch. It cured what ailed me!
I am curious to what you are running for an alternator now. I have an XS motor also, but whoever did it, put on all the electrical stuff for the XJ. If they went with the XS alternator on yours, they would have had to change the plugs going to the Reg/Rect unit.... or splice the wires. They say the XJ has a better charging system... wonder if the XS's is still enough to run it correctly??


Tod

[jimboreeno]

Hey Todd,
Not a clue! I do know the bike's wiring had burned and it looked like a rat's nest. A guy rewired it and got the signals and lights working. the main computer stuff does not work though. The electrical is weak and I am about to replace the fuseblock with the stab style fuses.

[trbig]

If you unscrew the 5 allen bolts on the right sideplate of your motor, you can see which alternator you have. An XJ will have the stator in the sidecover along with a set of 2 brushes that ride on the face of the rotor.
From what I have read on here, if your sideplate doesn't say "Yamaha"... then YICS under that, it is probably an XS alternator and sideplate, since a regular XS sideplate isn't big enough for the XJ's rotor and stator.... someone please correct me if I am wrong.
I don't know if you need the XJ alternator if you aren't running the computerized dash,(Again... read on here that that was the reason for the hotter alternator) but if at some time you decide you want to get that back working, you might watch EBAY. This would have gotten you everything you needed. This went cheaper than I have ever seen, so don't expect to get to pay that price! lol.

EBAY

Just keep your eyes open and watch out for those bid Snipers (Like me! ) : )

Tod

[trbig]

I am still curious as to how they connected yours to the bike if indeed it is an XS. If you follow the 2 lines coming out of the alternator, there's a green and black wire that will go to a 2 pronged plug. I believe this is the same on both bikes, but the other wire on an XJ has 3 white wires going into a 4 pronged plug. (One of the slots is empty). If it is a 3 pronged plug on both sides, they either changed plug ends, or they just used the regulator/rectifier from the XS as well?? Doesn't really mean anything either way, but would be good to know if you ever need to change that Reg/Rect unit. if it is an XJ R/R unit, it will have a part number starting with "10M".

Tod

[TopCatGr58]

What's under the hood?

Hey Jim,

You'll definitely want to know what kind of ignition system is being used!! Look at the TCI under the seat, if it starts with 10M, it's the XJ, if it starts with 2H7, then it's the 80SG!

You'll also want to pull the timing cover off and inspect in it, looking for either the XJ plate and pickups, there won't be a vacuum advance module! IF there is a vacuum module and centrifical weights and springs, then it's the 80SG.

The thing you DON'T want to find is the 80SG timing cover parts AND the 10M TCI, or vice versa!

Like Todd said, the PO swapped the XJ ignition parts onto his XS engine, and it works just fine! But they don't mix and match well at all, needs to be all XS or all XJ, not some of each!
T.C.

[jimboreeno]

Now you guys are scaring me! I will take a look and let you know what I find!

HAPPY 4TH EVERYBODY!

[trbig]

Naw... no reason to be scared. It's kind of nice knowing I don't have the only Frankenstein's Bride out there! Just remember... Half-Breeds need lovin' too!

Tod