Building Big Bore FJ1100

[Flying Scotsman]

I am building a engine for my 1985 FJ1100.
I bought an engine that lost oil pressure and it will be my base for the build.1250 motor bored out to 1314cc with a ported head.
It came with cams but they had been swaped out and needed set back up.I had never done cams so I used the cams to do a test fit.I bought a used set of cams that I was going to use and they should be here soon.Meanwhille i am digging through some parts and i found some old cams.2 sets and one set  has had some work done to them.Cam lobes measure about .060" bigger than oem and have altered profile.Cams have #s on them if that helps.(I can get #s for you as there in the car)

QUESTION IS

Should I use the modified cams or the oem cams.I am leaning towards the moded ones if they will improve performance.

I havent opened up the cases yet to see why it lost pressure that comes next.


It will still sport 1100 stickers  no need to advertise the FJ1314 sleeper.
I will be working on it when I have time and when the weather allows I can use the 85 1100 and the 90 1200 for donor parts when needed.

[ribbert]

QUESTION IS

Should I use the modified cams or the oem cams.I am leaning towards the moded ones if they will improve performance.



[/quote]
One of my favourite subjects. I have removed many "hot" cams over the years to restore engines to a useable condition. Hot cams alone generally change power delivery rather than add to it ,to mostly high rpm only. In most cases the kick in the pants power band is more perceived than real because of the loss of torque at lower rpm.  My view is hot cams should only be part of package of mods to increase power, not a stand alone one. I also believe their are many more people that have the tools to grind cams than understand the process. As a rule I would suggest that hot cams are best left to racing machines, you wouldn't want lose that monster torque!  From V8's to bike engines I've never seen a road vehicles useable power enhanced by modded cams.
And finally, one might ask why, if the cams were an improvement, aren't they installed in a motor somewhere?
Noel

[andyb]

If you're making the engine bigger, the cams need to get larger to retain the character of the motor.

Depends on what you want, really.  I don't see any purpose in going to a huge piston if I'm not going to open the valve long enough to let it work harder!

[Flying Scotsman]

Cams have

26800-DY
11   .   91

on them

[RichBaker]

Probably these guys...... MegaCycle Cams

[Flying Scotsman]

Thank you megacycle cams they are.

[JMR]

Thank you megacycle cams they are.

Those are nice cams and work well with a 1314. They are a little hotter than the old Yoshimura Stage 1 pieces. The hardweld produces less friction and lasts much, much longer than any billet cam. Those cams do not have a lot of duration so you maintain good torque. I would set the lobe centers to 105....you will need slotted sprockets. I highly recommend springs too.

[Flying Scotsman]

Thank you megacycle cams they are.

Those are nice cams and work well with a 1314. They are a little hotter than the old Yoshimura Stage 1 pieces. The hardweld produces less friction and lasts much, much longer than any billet cam. Those cams do not have a lot of duration so you maintain good torque. I would set the lobe centers to 105....you will need slotted sprockets. I highly recommend springs too.

I do have slotted sprockets and a box of valves and valve springs.I dont know if there stock springs or not.I dont have a load tester but I can count # of turns and measure length and thickness.Who knows I might get lucky with the springs.

[racerman_27410]

i would recommend getting a brand new set of valve springs.... preferably aftermarket.

reusing old valve springs will cost you a bunch of horsepower.


KOokaloo!

[Flying Scotsman]

Cold here brrrrrr.I got to work on my motor today though.I found out my oil pump was shot.Gear on it was spinning free.Splines were stripped.That would explain why there was no oil pressure.New pump is in.I need to find some bolts I need to remove a cam chain tensioner from one of my bikes for the 1314 I used a tensioner with no bolt and spring to set up my cams.I need to do something with the extra oil ports in the head either plug them or get a top oiler kit.Im going to a use double spring set up in the clutch.I also need to check valve clearance. Then its time to drop the engine from the 85 so the 1314 can go in.

[fj1289]

Top oiler kit not needed - especially for a street bike.  Also, there is VERY LITTLE room next to the frame to make it happen.  I did it for a dragbike using an aftermarket block I couldn't get to seal the oil passages.  Not worth the effort for a stock style block!

With the oil pump loss, what shape are the bearings in?  Any damage to the main or rod journals on the crank?  Spin a bearing in a rod?

Also consider upgrading to XJR rods (talk to Randy at RPM) - stronger and lighter than FJ rods.

Good luck and keep us posted on the progress!  Pictures of the build in progress please - I'm having withdrawls...

Chris

[racerrad8]

Like Chris said, the head oiler is not needed and will not fit without major modification as it will hit the frame.

You do need to make sure the internal oil passages have not been blocked off on that head you are planning on using which is a common practice by a lot of engine builders.

Secondly, if you have a 1250 head it will not fit in the frame of the FJ. The FJ head fins have a curvature to them and the 1250 head is square. You will need to match the fin profile of a FJ head if you are planning on using a 1250 head. You will only need to match the intake side as there is no interference problems at the front of the head.

Randy - RPM

[racerman_27410]

Randy,

I happen to have a complete 1250 engine in my 86 frame.... granted  it is tight, and there is a trick to getting it in place but no modifications were required to fit it other than modifying the chain cover.


KOokaloo!

[Flying Scotsman]

Pulled the 1100 motor last night.I could have used an extra set of hands but its out.

[racerrad8]

Randy,

I happen to have a complete 1250 engine in my 86 frame.... granted it is tight, and there is a trick to getting it in place but no modifications were required to fit it other than modifying the chain cover.


KOokaloo!

Well there ya go, I was running the valves on a 93 yesterday and by looking at it I did not think it would fit. I looked at the space on my 86 as well and I wouldn't believe it.

But since it has been done, he should be ready to go.

Randy - RPM