Had a thought

[audijunky]

I am no motorcycle mechanic so don't laugh....
Is there a top end off a different bike (newer) that has 4 valves per cylinder that might fit on the block of the 11? Something that has all the same styled cams, crank and all that but runs 4 valves instead of 2. If there is one would there be any benefit?

[fredintoon]

More horses?

Hi Audi,
I doubt there is and even if you found one, simply going to a 4-valve head won't do much without a whole bunch of other changes too. If you really want more power, first think big bore then think turbocharger. You can buy kits for those.

[trbig]

This was discussed recently. They said that these valves, especially the bigger ones from 80 on, move more air than these bikes could ever consume even after a big bore... so 4 valves would be of no benefit.


Tod

[audijunky]

Thanks for clearing that up. So if I have a 79 and do a big bore kit, would it be benificial to get a head off an 80 or newer?

[trbig]

Your 79 head will still move more than enough air, but it is said that you can increase your HP with a larger valve head and using 78-79 cams in it. I haven't seen any dyno proof, but my XJ has this setup and will accelerate quicker than a stock XS, even though I usually outweigh them by far (Me AND the full fairing) and the XJ is SUPPOSED to be slower. So... nothing scientific, but if you run across one cheap enough it may be worth trying.


Tod

[Dennyz]

I have heard rumors that FJ1200 top end will fit the XS block. I have not been able to find a FJ parts motor to try it out.

[pggg]

The FJ cams look like their cam sprockets might line up with the XS crank sprocket, but the studholes, what's the chances, the combustion chambers the same then the gaskets are close, also 4 valves means new 4 - pocket pistons too assuming by some miracle everything lines up and it's a stroll in the park swap, you're looking at matching some good carbs to the 16-valver too but actually swapping the cylinder head is the hard part ain't it, I get the XS11 combustion chambers spaced at 89.5 - 146 - 89.5 the studs 70 across, 81 between, but I'd be doubtful

[GNEPIG]

Find you an old wrecked FJ 1200 and just stuff the whole motor and all in your XS frame. You will already have the big bore and be well on your way to having a chain drive also.

[Geezer]

Originally posted by GNEPIG
Find you an old wrecked FJ 1200 and just stuff the whole motor and all in your XS frame.

I've often thought of taking a FJ1100 and stripping off the fairing and putting on some higher bars and a more comfortable seat... Sort of desporterizing it...

This way an old beat up guy like me could ride it more comfortably but I'd still have a bike that would take off like a rocket when I was in the mood.

On the other hand, I can't afford the speeding tickets...

Geezer

[AlanB]

Hi guys,

I have heard rumours about the FJ top end being close to a fit on the XS cases, But have not tried it myself; however, the XS runs "reversed".... Tight cam-chain run at the back.

As far as I know, the FJ is "conventional"..... Tight cam-chain run at the front. I would guess that some pretty clever work would be needed to sort that out.

AlanB

[audijunky]

The cam chain tensioner is on the lower section of the head right??? If so, cold you just flip that part around so the tensioner was no the back side of the motor. Not planning on doing this, just throwing it out there for conversation

[randy]

The tensioner is not part of the head.

[TADracer]

Remember our machines rotate clockwise which is opposite from most. So if you do find something that fits, it must be from a motor that rotates in the same direction. Cam lobe positions would most likely be a problem.

[audijunky]

Thats what I meant ,,Randy Goooosh I guess that area would be called the block? The part that sits on top of the low end(brain fart) but below the head???

[audijunky]

Do the Fjs rotate clockwise??