Think about a head job

[Shane4371]

Can I get advise on head work done to my 86 fj,I want more power don't wanna change my bottom end or replace my head .

[FJmonkey]

Can I get advise on head work done to my 86 fj,I want more power don't wanna change my bottom end or replace my head .

Have you talked with Randy? He builds these engines for racing, he might have some ideas.

[fj1289]

I would definitely bounce it off of Randy -- although porting is one of his least favorite tasks...

I was very happy with the work, results, and price of a nice street/strip ported head I had done by Paul Gast (Fastbygast.com -- same place Randy sends transmissions for undercutting).  Added big valves and a mild set of cams.  May not really need the big valves - again, another good question for Randy.  And with a mild cam you can stick with stock FJ valve spring retainers and buckets - hard to beat (or even match!) the quality and durability of the stock Yamaha parts in a lot of cases -- but you will want to install heavier valve springs.   

There was also a guy in Ohio I think that was supposed to be real good with FJ heads - I'll have to see if I have any info on him again -- maybe do a lot of digging on the 'net.  He was one of the people I spoke to when I originally had the street head done - I spoke to Paul Gast, Superbike Mike, Star Racing, and they guy in Ohio.  Paul Gast was by far the least expensive and did quality work (and I guy I used to race with knew  him growing up) and is still actively involved in racing and winning.  I will note though, this was about 2 - 3 years before I "met" Randy on the net and talked with him -- I would highly recommend you talk it all through with him before you make up your mind on what way to go. 

Good luck!

[racerrad8]

Shane,

You really need to get all of the other issues you have going on addressed before you worry about modifying your cylinder head for more power.

You dyno numbers you posted recently were very low. You stated you had raw fuel coming out of the exhaust, fouling spark plugs and blamed that on being two jet sizes too large.

I see you also posted up last night about the vacuum advance on the vacuum box and your ongoing poor performance issues.

There are several post discussing the function of the Yamaha termed, "Boost Sensor", here is the first one I found: http://www.fjowners.com/index.php?topic=11690.0

Randy - RPM

[FJools]

My understanding is that the head is a very good design as it comes stock. For a road bike all I had done was a basic clean up and blue print when the stem seals were replaced, and the valve seats recut.
There are some photos on my thread:
http://www.fjowners.com/index.php?topic=15837.0

[JMR]

The ports on the FJ are not that good for a side draft design. There is also a lot of valve angle. An early GSXR1100 or 750 head is much better. A GS1100/1150 is also better.
Whatever you do put an oversize intake valve in there and bore the seat ID to 90% of the OS valve OD.....this will make a big difference in CFM. Also make sure the intake is heavily deshrouded.
The FJ head is a copy of the Honda DOHC pieces (750, 900 1100).

[Shane4371]

Shane,

You really need to get all of the other issues you have going on addressed before you worry about modifying your cylinder head for more power.

You dyno numbers you posted recently were very low. You stated you had raw fuel coming out of the exhaust, fouling spark plugs and blamed that on being two jet sizes too large.

I see you also posted up last night about the vacuum advance on the vacuum box and your ongoing poor performance issues.

There are several post discussing the function of the Yamaha termed, "Boost Sensor", here is the first one I found: http://www.fjowners.com/index.php?topic=11690.0

Randy - RPM.Your advise is highly appreciated, I was running 107 octane with fuel injector/carb cleaner mixed in my fuel also,I've since dropped my needles and went back to 112 mains,my igniter isn't working right.please advise which cdi/pickup ignition works best with my 86,

[CutterBill]

Randy - RPM.Your advise is highly appreciated, I was running 107 octane with fuel injector/carb cleaner mixed in my fuel also,I've since dropped my needles and went back to 112 mains,my igniter isn't working right.please advise which cdi/pickup ignition works best with my 86,

Think about it... your bike ran great when it was new.  So put everything back to stock, and get it running right.  THEN you can start playing with the idea of more power.

[racerrad8]

Randy - RPM.Your advise is highly appreciated, I was running 107 octane with fuel injector/carb cleaner mixed in my fuel also,I've since dropped my needles and went back to 112 mains,my igniter isn't working right.please advise which cdi/pickup ignition works best with my 86,

You options are finding a used replacement from 86-87 FJ1200.

There are several other aftermarket options that were available but they are no longer made and can only be found as used or N.O.S.

The only other option is the Dyna ignition system for the FJ1200. That is a complete replacement system.

Randy - RPM