Collective,
So stupidly I tossed my complete factory 93 exhaust over 15 years ago. I am now assembling the parts to replicate aviationfred's system of factory header pipes, factory style (he used an english made XJR part) collector and Dominator mufflers. This will allow me to finally mount the complete Krauser K2 system that I have owned for 15 years. I bought a set of factory double walled (early?) header tubes and a perfect factory collector from my favorite used parts emporium. Pat mentioned to be careful cleaning the early tubes as the black chrome will come off. They are caked in very old bugs. Best cleaner? Second, being as they are double walled is the ID smaller and thus a restriction? I had put a post up looking for the later pipes and had no offers, these were too good to pass up dollar wise. If the later pipes perform better I can watch over time for a set. Next year after child support ends I am going 1350/1380 (not sure yet), I want to let the big pump breathe.
So thoughts on cleaning and performance of early pipes?
Thanks,
Daniel
Can't answer you questions but curious what year FJ's were double wall
It sounds like the 1100 was the double walled. Possible early 1200 as well.
I'm also curious what those little bings are for at the bottom of each header tube....some kind of air fuel ratio check port?
Quote from: 86FJNJ on July 21, 2025, 05:06:18 PMI'm also curious what those little bings are for at the bottom of each header tube....some kind of air fuel ratio check port?
Exactly Eric...The factory used those ports to dial in the air/fuel idle mixture, then they put tamper proof caps over the adjustment screws....so knuckle heads (like us) couldn't fiddle with them. Silly bureaucrats.
Daniel, yes, the double walled tubes were oem on the '84/85 1100's
In '86 with the 1200's they went to single walled stainless steel tubes.
At the time, the double wall tubes were considered a performance enhancement, keeping heat within the gas flow to help scavenging, much the same way wrapping the header tubes do today. I know the OD of the double wall tube is larger than the single wall stainless tubes....I don't know about the ID of the double walled tubes.
I do know they sound like Armageddon when the inner tube cracks and flails itself against the outer tube. Clang, clang, clang, clang, clang, clang, 800 miles of clang, clang, clang, clang, clang.
I scratched my 84's black chrome tubes by soaking the bugs then (I thought very gently) using a green scotch bright pad. Dumb mistake. I should have stayed with my trusty Simichrome and a soft cloth rag. There is a fine abrasive in the Semichrome, it just takes patience and elbow grease.
With all my polished aluminum, I buy a lot of this stuff
(https://fjowners.com/gallery/12/49-210725202528.jpeg)
Now that I have converted to stainless, any scratches or stains I can aggressively rub out...or take them off and use my 1hp buffer.
Cheers.
I had my '85 exhaust headers Jet Hot coated. They sand blasted them prior to putting the ceramic coating on. Apparently it was just enough to weaken the weld between the inner and outer tubes. Shortly thereafter, when at the rally in Tellico, the weld gave up the ghost. I thought for sure I had a rod gone south but the damn thing ran anyways! What to do? RUN IT, what else could happen? Anybody need a beautiful set of stock '85 pipes that are jet hot coated? Impress your friends with how stout your bike is that it can run with a broken conrod. :wacko1:
Pat,
I know Simichrome all too well. We had a family friend that had a collection of Stanley Steamer brass cars. I used to ride my bike to his house during the summer, I had a key to the garage. I would spend 2-3 8hr days a week polishing all of the brass. My fingers were black for a month. Do you know the shoelace trick? get a coating of polish on the tube then wrap a shoelace around and pull it back and forth. The good old days!
Daniel
Can the stock transmission handle 1350/1380?
Yes
Ok I see people posting that and selling bikes where 2nd gear is shot or the fork shifter broke so that was why I asked. The FJ is a great engine then, so is the Yamaha CP3 engine considered the modern version of the FJ engine in terms of versatility and reliability?
The early shift forks were shorter and would bend. This would damage the transmission engagement cogs and windows. Which in turn would cause it to come out of gear and get worse over time. Doesn't matter if 1100cc or 1380cc
I don't know anything about the CP3
Quote from: 86FJNJ on July 23, 2025, 11:29:22 AMCan the stock transmission handle 1350/1380?
Have a Gast undercut transmission in my 87 and it shifts almost by just thinking about it. Best transmission I have....better than the busa. Mine is just under 160 RWHP at 1314cc.
Mike,
Is Fast by Gast still around? They used to be the go to place for undercutting. Something tells me they are out of the game.
Daniel
Paul is still around, I had him do a set of dog rings for a Tex Racing t101 4 speed H pattern a month or so ago.
That's a serious piece of kit. What's it in?
https://fjowners.com/index.php?topic=21401.msg216495#msg216495
I hijacked this other thread already but we should have it in the dyno sometime next week or the week after to get a final tune in it and hit the track for shakedown in August 10th before the couple of competition events we are running
And I thought the full forged turbo motor I built for my son's Miata was zippy at 24psi. That's a whole nother world!
Originally it was a 1.6 turbo motor making 450 to the wheel at 30PSI on e85.
Then it was a LM4 5.3l with a 88mm turbo running 30PSI and making around 770-780HP to the wheel on e85. Can't find the dyno sheet but its in there.
We had an early Holley HP and it ran out of inputs for wheel speed sensors and what not to control boost per gear and traction control etc. So we went back NA with the LM4 it made 370HP with a ford 8.8" IRS rear.
We wanted a Wincters quickchange for easy gear changes for all the different size tracks we run. We we put the quickchange in it, the HP dropped from 370 down to 330 to the wheel. So then we went 6.2l LS3 make 470 to the wheel but now we are getting more serious into time attack we need more power. Got a decent deal on the LS2 with all forged internals and solid roller lifters but it was serviced out from the 427ci so we punched it out to 454ci and bumped the compression up.
Not the old engine builder but our neighbor who tuned the motor before our rebuild brought this over this afternoon. No info on the cam that was in it. (Didn't have a cam when we bought it), he thinks it had a Holley Hiram intake on it. Red is all motor blue lines are with nitrous.
We will be running all motor so piston to wall clearance is a bit tighter since we don't have to accommodate for the nitrous. Having a cam over .700 lift , along with bumping the displacement and compression ratios up. We are hoping to see 700-750rwhp maybe 570-600 fr lb torque. He has some dyno time coming our way next week or the week after for some horse trading we did. Fingers crossed!