FJ 1100 motor into XS11 frame ?

[Dan Hodges]

FJ-1100= 96 Horsepower & 61 ft. lbs. Of Torque

The XS frame can be stiffened up with simple gussets and/or solid motor mounts in the rear can turn the "Flexi-flier" into a solid handler. also to go a step further would be to gusset the upper dual-tube backbone and around the tree.....Take a look at what member 79XS11F (Rob) is doing.....I just have the solid motor mounts in and you notice the improved feel of the bike in hard corners right off the line.....If you stick the FJ motor in the XS frame the rear motor mounts that have to be welded in would allow for even greater frame reinforcement anyway. Whoever sticks an FJ motor in an XS frame would have one sick ride, not to mention the 180 tire that the XS is lacking, and removal of the jack-shafting action that I don't like about a stock XS11.....

A box stock FJ-1100 was making 96-98 horsepower at the rear wheel and 61 ft. lbs. of torque and the 1200 was making about 5 horsepower more vs a stock XS-1100 which was putting down about 70-75. There are at least 3 people on here who made low to mid 90's with the XS me being one of them and it wasn't nearly as diffulcult as putting an FJ motor into the XS and I have seen more than a couple of these conversions over the last 20 years. Of course the FJ motor has a lot more potential than an XS and it's cylinder bore centers are wider than the XS and with sleeves can achieve 1400 plus cc's versus about 1300 for a sleeved XS but you were I believe talking about a stock FJ. An Eleven with a Wiseco kit, properly ported heads, a good Kerker or Super/Trapp header, a set of MegaCycle or Web hard weld cams and properly jetted stock carbs with a modified air box will make 96 plus horsepower and 72 ft. lbs. of torque. You can fetch another 2% by cutting the head .020. Maximan made esentially the same power as I did with an unported head cut .028 but he used the 36 mm carbs from an FJ and the 1196 kit whereas I used the stock carbs and the 1179 kit. People also forget that when you start putting stand up windshields on their Elevens they are killing the top end. In the mid eighties Cycle-World did some test on a V-65 Honda Magna and found that there was a difference of over 5 MPH on the top end simply by the rider sitting upright vs leaning over. A stock FJ is much better aerodynamically than a stock XS in naked form and the XS with anything larger than a fly screen type windshield is a dead player at much over 125 mph. A sharp early model FJ would pull red line in high gear which was 145 mph. In 90, Yamaha changed the sprocket tooth count and the over all gear ratio got higher and they got slower acceleration wise even though they had a bigger motor and more power. You can gusset the frame of an XS and use V-Max type rear shocks and with a fork brace and sticky tires it's a decent handler but it's not a 900 Ninja in the handling department and never will be. The rear of an XS wants to rise when you throw the coals to it and you need a shock that is stiffer on extension to control this however stiffer shocks will be harder on your tail bone so you decide what you want. You can equal the power of a stock FJ-1100 and it will get it on in a straight line but it's got a skinny fork and the wrong amount of trail for a sport bike. An FJ weighs 536 pounds dry vs an 81 1100 Special which weighs 557 pounds dry. The bottom line is, a stock 70 horse XS is a dog compared to a stock FJ-1100 but that dog can be turned into a "Teufel Hunden" and you members of the USMC might recognise the name of that very special breed of dog. Like all things though, there is more than one way to breed a "Teufel Hunden". Stand back non believers, the've fired their welders and anything can happen!

[FJ111200]

A homemade XJR?!That would be awesome.If this bike came my way I snatch it up like nobody's business!But short of a real XJR1300 a "replica" bike would prolly be just as niceMakes me wish I still had my FJ1200

Don't know if anyone's still interested, or whether this belongs here or in "other bike discussion", anyway, here's my homemade XJR1200 as the finished article.

[Elevenator]

Reality

A stock FJ is much better aerodynamically than a stock XS in naked form and the XS with anything larger than a fly screen type windshield is a dead player at much over 125 mph. A sharp early model FJ would pull red line in high gear which was 145 mph.

Reading through this old thread and found the above statement.

I'm pleased to find some of us rooted in reality. I've had five of these bikes (XS11s) and I have never been able to push a stock XS11 of any variety (standard, special, Maxim) beyond 130 mph(true speed). And believe me I've tried. The fastest I've ever gotten one under idea conditions was about 128 mph. And that was me laying down on the tank on naked bikes...no fairing or windshield.

I realize "Psycho Ward " (Cycle World) reported a top speed of 132 or some such. Maybe they had a hot sample? But 140 is not in the realm of reality for a STOCK XS1100.

The XS1100 is a great old bike. Probably one of the greatest bikes God ever allowed man to build. But I don't think you could get a stock version up to 140 if you threw it out of an airplane.

Thanks again for the reality check Dan.

[cafejunky78]

just wondering??

So did anyone ever do this or is this one of those cool Ideas that fell by the way side?

[Bigfoot]

It would be cool, and I do have an XS and and FJ. But both run too well to even consider tearing both apart just for a whim. But I know how fast that FJ is and combining that with the comfort and styling of the xs would be awesome.

[81xsproject]

Since this topic is up, for some reason I believe the FJ1100 as having the same bottom end as the xs...? I wonder (if this is true), if the top end could be modified to the XS... would be cool to swap in a 4 valve head.

[cafejunky78]

well I have looked at putting a chain drive on my xs anyways and I was looking at doing the hydro clutch, so when I read that a big bore xs motor with ported heads and a cam would be comparable to a factory fj11, I thought why not go the fj route at the stage I am at it just seems to make sence.