| How to Make a Monster! |
| The following page details the creation of one of my racers, a 1972 F8/9. Now covering almost 12 years of building, testing, and evolution. |
Foreward: Ok. Yes I race the bighorn. It seems a little out of place at the AHRMA events. Most of the guys have SHOW quality Huskys, or Elsinores. My 'horn is FAR from a show bike. THe other classes are full of Maicos, and CZs. Pure racing machines. So why am I running a cumbersome stripped down enduro?
Dick Mann says (in a nutshell) the purpose of AHRMA is to preserve the sights and sounds of yesteryears racing. Believe me, not everybody who raced MX back in the early to mid 70's was running a Penton, or Husky. I represent the common man of those days, who scraped enough to spend $800 on an enduro only to rip the lights off and go racing. To quote a Cycle World review of the 1970 Kawasaki Bighorn Enduro
" The Bighorn is the only bike we have tested that we would feel right about taking it to a race just the way it came from the factory.....gobs of stump pulling torque that rivals any 500."
INTRODUCTION: (JAN 2003)
Kawasaki made a series of enduro bikes .....Back in the day, they actually made a full MX version of the F8 250 Enduro called the F81-M. While they never made a full MX production version of the F9 or F5 350s , Kawasaki did offer the "Factory Speed Kit" for the 350s which came with a new cylinder, crank, carb, expansion chamber, intake disc, and more. The installation of these parts got you all the tricks they used on the MX production model 250s, but with an extra 100 cc's worth of grunt.
| The 250s and 350s all shared alot of parts, and you can interchange top ends freely. All the bottom end parts are the same as well. The only difference was the bore size. Same stroke and everything, so even the cranks will cross over. |
| What I did was purchase a 1972 F8 250 Enduro and turned it into a pure 350cc racing machine using some original speedkit parts as well as a highly modified cylinder and intake disc. I replaced the fenders with NOS Preston Petty items, and the gas tank is a NOS Windsor Products tank. New bore and NOS WIseco piston kit also. NOS Barnett Clutch and springs. Speed kit carb, and a ground out rotary valve. |
| I also replaced the breaker point ignition with an electronic unit from an F5. The engine is putting out somewhere in the neighborhood of 40 to 45 horsepower. Laugh if you want, but I bet it could keep up with a modern 250 on a nice flat fire road, or a drag strip.Stock specs for the rotary valved 350 were 33 hp. The addition of the "Speed Kit " Parts (again acoording to Kawasaki)upped it to 45 hp. I have gone a bit beyond the kit specs as far as the porting and intake timing goes. So I got to at least be making 45 anyway, even if my tweaking hasnt made any more power beyond the speed kit claims. |
| I actually have the original book that came with the speed kit, and it is a gold mine because it lists all the part numbers and even more importantly, it has diagrams and specifications comparing the stock versus the kit parts. In the hands of a qualified machinist, you could take this info and turn stock parts into kit equivalents. I havent had to do that yet, but I could. THe cylinder I am using was ported by an old friend of mine who has since passed away, and when I am done boring it, I will have it resleeved. If I have to pay $300 to get it done I will because it is the sweetest, fastest 350 Ive ever riden! |
| Read on and see how it came together..... |
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| It must have been almost 4 years since bighorn the first was stolen from my old garage in Woodlawn. Since then,I had aquired my good old Honda, and put a lot of effort in it, and it was a nice bike. But, the thrill was never quite there. The Honda never scared me, although it did break my leg once. Meanwhile, I picked up any interesting bits and pieces I could find for a bighorn. I kept looking for a bike online, and found a few, but they were either $3500 museum pieces, or else located halfway across the country. (I would NOT pay $200 to ship a $200 bike!!!) Finally, I found a bike on Ebay, a 1972 Kawasaki F8 250. This was essentially the same as a bighorn, only the top end was smaller. (The 350 top will drop right on the gearbox, although more about the tech stuff later.) It was located an hour away from me also!!! I won the bid at $262.50. It was basically in original condition, with 4700 miles on the odometer. There were some things missing but nothing I cared about. It's condition was just perfect for me. It was nice enough to make a great starting point, but it wasnt so nice that I hated to tear it down and make a racer out of it. Putting it back to stock and riding it on the road would of been a pain in the ass, but had it been a couple of points nicer, I just might have. So, Im gonna start work right away. I dont know which way to go immediately, but eventually, Im gonna put a new 350 top end on it, as well as a Torque Engineering expansion chamber. I also have a NOS Windsor Plastic gas tank for it!!! Ive got new cables too! All from Ebay over the last year or so. The 72 F8 had breaker point ignition, but I have a complete spare CDI setup left over from my 350, and I am going to try and fit that as well. I may even try to ride it as a 250 for a while, as I collect a few more bits I need for the 350 conversion. I will post pictures as I continue to work on it. I will update this page as I go, and I will post some pics as well! |
| This is an actual pic from the Ebay auction that I won, so We'll call this "before" heh heh..... |
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| Progress: |
| 7/17/01 Update: I had the 'ol girl stripped down to a bare frame in 1 week. Some suprises: The head set had only 5 balls left in it, so Ill have to get some new balls. Heh heh...The swing arm bushings were smooth as butter! Someone took care of this bike at some point in it's life. Ill have to get some wheel bearings, but no big deal. A little secret here: just go to an industrial supply house to get bearings. MOST of the ones on your bike are standard sizes used in other machines. I bet I'll pay about $6 for wheel bearings this way. (As if you COULD get them from the dealer, anyway) After peeling away years of crud, I treated the frame to several coats of Rustoleum semi-gloss black enamel. |
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| 7/25/01 I got the swing arm back on, and also installed my choice of rear suspension: Gas charged, oil dampened KYBs! Another goodie I snagged last year. Gonna raise the seat height a couple of inches, but thats ok, I always feel like the front end on those things point uphill in their stock form. As well as providing some relief on hard landings, the new shocks ought to go a way towards keeping the front wheel on the ground. |
8/15/01 Ive got my NOS Windsor Products plastic tank mounted, as well as the seat.
8/31/01 Well, Ive got the new bearings for the steering head, and I put the triple clamps back on, as well as the rest of the front end. I also put the motor back into the frame, because I am happy with the bottom end, and although there is more work to be done to the engine, I can do it all with the engine in the frame. I fitted my Torque Engineering Expansion chamber, then removed it since I have to tear the top end off anyway. I also hooked up the handle bars, and cables. Now Im waiting on some parts, and Ive got a new source of distraction, ANOTHER project!!!!! a Basket Case 1993 KX 250!!!! Oh my I will never learn. That and schools about to start, and the weather will turn cold....somthing tells me progress will slow a little....
9/15/01 Hmmm. got the clutch case half off, and got set to torque the clutch basket off, and the nut just came loose way too easy. Turns out it must have been a little loose, and the inner housing got a little dinged up. THe thrust washer took most of the damage. Had some funky aftermarket springs in the clutch, I guess whoever put them in didnt torque the basket down enough. The clutch itself was pretty much fried, so Im gonna replace it. Got the rotary valve off, and Im going to modify it slightly. I actually ran the engine to see what it was like, and it sounded VERY noisy up top. I pulled the top end, and man Ive never seen such a worn out bore. The piston was doing some serious slapping in there. Luckily, the crank seems solid, all the plays are within spec. Lets face it, they dont exactly turn 13000 rpms like some more modern bikes. Keep enough oil in the gas, and your set. Ive got a new 350 top end for it anyway so I didnt care that the 250 was so worn out. Now, Ive got to locate a head for the 350, and get a clutch, and that will be about it for the engine.
As you can see, Ive got the front fender on, and both wheels. Here I am switching out the ignition system, from
the stock breaker point unit to an electronic setup that I had left over from my earlier involvement with these
things. You can see my S2 Triple in the foreground. (Its almost done, but has been for about a year now) I like RED dont I? You would figure Green would be it, but no....heh heh...ny KX is green however...
The electronic unit bolted right up. I figured it would. The original unit is to the right. Switched flywheels too.
Update: 10/14/01
I got my head in the mail, and it was is great shape. I bead blasted it nice and clean. I found an NOS barnett clutch set for it, and that should be in the end of next week. Ive got a new gasket kit in as well, and now I just need to have the cylinder bored.
10-18-01
Well, I got the NOS Barnett clutch in place, and the case sealed back up. I dropped the cylinder off to have it bored, and it should be ready next week. I have all I need for the top end, so by the end of October it will be all together. Then, on to some little things, like rigging up a choke, and idle speed adjuster. I am hoping to take it out for the first time in mid November.
11-01-01 Bottom end is together!! Another view
My cylinder is finally going to be ready tommorrow, and Im gonna put the top end on this weekend. My friends are planning to go riding next weekend, and If Im lucky, Ill be able to take my bighorn. Im gonna take my tools, and some spare parts, and try to dial everything in. (Dont want to piss the neighbors off!)
11-20-01 UPDATE!!!
I had it out for the first time Saturday! It took me about 2 hours to get the carb tuned in how I like it, and then I put it through the paces to see how it was gonna be. I took it to a newly opened MX park that has several different tracks to practice on. I chose the "beginner's" track which had alot of nice table tops, and a little step up jump. The track layout was sort of cramped. A turn, 2 jumps, a turn, 2 more jumps, etc....Even on the longest straight-away, I could barely get into 3rd gear. HOwever...in between fouling plugs due to my extra rich oil mixture (Break-in procedure) It ran great! When nailing it on the straight away, the bike wheelied in 1st, 2nd, and 3rd gears!!! Putting along in 2nd, you could get thrown right on you ass if you cracked it! Its making all its power up high, which I like, because low end grunt is no problem for these machines naturally, so If you tune it toward the top with the porting and jetting, you still have plenty enough down low to pull like a tractor. And, I was like riding around doing 5 mph, and waiting til I was at the bottom of the jumps to nail it, and it had no problem making power right away. I did wish I had some wide open ground to stretch the thing all the way out, but there was nowhere there to do it.
The rear suspension is great! I just hope it turns out to be vintage class legal. (Have to check the travel specs) The fronts need some tuning, they were hard on the landings, Im gonna take the oil level down a bit. The goofy foot pegs have to go also. Got a sore on my big toe 'cause thats the only part of my foot that would reach the shifter! Got to find some stock pegs. Need to hook a choke cable also! A bastard to start without it! Kick starter is sloppy, got to buy another one. So, I found some things that need doing, but that was the purpose of this trip for me. I got the engine where I want it, as for the rest of the little bugs, well they'll probably wait til after the holidays. I took a bunch of pics, and Ill post them as soon as theyre developed..
Here are the pics. Keep in mind it's far from done. Still got the original Trials tire on the front! Ive got a few
months to put the finishing touches on her...
Well I wondered if this project was gonna fly...
This was the day of the official test ride.
The beast as she is...needs a llittle finishing...but man does it run!!
Rear Shocks:
DAMN!! remote reservoirs are ILLEGAL in sportsman 500 class....gonna hafta run the stockers for the Vintage MX......yeah.. I could buy some "works performance" spring shocks...but jeeezus! $300 for 4 inch springers?!?
Yeah right! Thats almost Half of what i got in this bike TOTAL...heh heh heh...not me...
Heres some pics of the engine....took a lot of scrounging to come up with all this crap!!! 100%new top end!
Radical Baldwin Stage III Port job also!!! BrrrrraaaaAAAAAAkkkKKKKK!!!!!
This aint your daddy's bighorn!
Oh man...gotta get thru Xmas now........gotta finish the KX........my work is never done.
2/15/02 UPDATE:
Got a new front tire on it, and a real number plate. Got some foot pegs on the way.
3/01/02
Got the foot pegs, and repaired the sloppy old kick starter. I had to drill thru the threads at the end, and put a bolt all the way through, then had to grind most of the head off to clear the case when kicking, also I put some fiber discs in between the boss and the bolt, then welded up the end that I had to grind. So, it stays put when I fold it up now!
9/14/02
First race! An AHRMA event, in Easton, Md. It was about a 1.5 hour drive. I raced sportsman 500 class. It was a weird day to say the least, but I learned some lessons, and it ended well. To start, it was leaking gas out of the overflow, and I had to tear the carb out of it and clean it out. Then, my clutch was stuck and wouldnt let go. I Went out at pratice, and took a few laps. Clutch finally let go after the second lap. The course was VERY long. Difficult as well. Lots of jumps. Im talking doubles, big table tops, etc. I never got out of 3rd gear! My arms were dying! Then, it was time for moto 1. My kill switch kept jolting me somehow or another!! We were told to take a parade lap, and half way through it I thought my chain broke! Turns out, the axle came loose and the tensioners fell around, and the chain jumped the sprockets. If I had had a wrench on me, I could of started moto 1, but as it was, I got a big fat DNS for #1. I went back to the truck and removed my kill wires! Then, moto 2. I had wired up my kick stand, but it broke through and I got black flagged. Someone geve me some more wire and we wired it up real quick. Then it was back out there. Dead last overall, but would you believe I got first place in my class?!?! They were running all the sportsmans together, the 125s the 250s and the 500s. Turns out I must have been the only SPortsman 500 novice there, or if there was anyboy else, they had a worse day than I did which is pretty hard to imagine. The trophy looks good in either case. I felt like I deserved it after all the crap I went through!!!
The bike ran great. Ive got to clean out the carb again and get a gas filter. The forks are working well with the new fluid, but I need some seals. The stock pegs suck!!! Boots kept slipping right off of there. GO to make up some kind of spiky metal pegs! The next race is in WV, and I am going to run that one if I can!!!
I took some pictures, and Ill post them when they are developed!
Here she is on race day!
Dig the Pro Tapers! Had to make some special mounts, but they feel GREAT!
Here she is. I would call this one "done". I dont plan to do anything else to it besides ride it and race it.
I plan to take the Mid Atlantic Series Sportsman 500 Championship for 2003!
I will continue to update with race photos, etc...
Race #2: Budds Creek Vintage Nationals 2003
Well, the weather was questionable to say the least on the way down there. The practice was just plain muddy, and Moto1 was a little sketchy. However, by the time Moto 2 rolled around, the sun was out and the track was in perfect condition.
In moto 1 I got a 6 out of 9, even after stalling out at the bottom of a hill for about 2 minutes. However, I broke down on the line in moto 2. Gas was pouring out of the carb cover! The thing flooded out badly and stalled. I kicked and kicked until the light went red again, and that was it. After taking the carb apart, I learned what had happened. My floats had filled with gas, and sunk. I had left the carb dry up until race day, so thats why it ran for moto1, and then eventually as the floats filled, it crapped out. Thats what stalled me in Moto 1, and why it died on the line at moto 2. Ive got to get some new floats for it or at least a good used set.
Here she is at Budds. Got my official number as well.
Whats Green and Red and goes 30 mph? Me in moto 1 ! Jim Pomeroy was on hand! GODSPEED JIM!
Well, Thanks to the YZworks for transportation and support. Visit their site if your into old YZs!
http://yzworks.tripod.com
Next for me will be Inwood, WV in June!
MAybe by the end of the year, Ill have the bugs out of it, and maybe I can make a serious run at the points next year. Got to get some more practice as well. 20 years of riding doesnt mean much if you only ride 4 times a year ya know?
Well Ive made some spiky pegs using the old trick of removing the rubber covers. Then I sawed some teeth in some bar stock and bent it up into shape, and bolted it on. MUCH better. I also repaired the kickstart boss by welding some metal onto the spots where the swivel had worn down. Use alot of amps, and some thick rods, and you can easily build up the metal. Got a race in Sept. in Easton Md, we'll see if I can finish BOTH motos this time~!
UPDATE: 3/05 Well, it's 2005. The season is almost here. (Last season was cut short by a hand injury....surgury and months of recovery. See my Yamaha page for details on that one.)
First race is at the mighty Budd's Creek. I have changed the front end around, using a 21 inch Yamaha wheel that has really nice brakes. Im worried about the change in rake. If i had the time, Id cut the stem and angle it down a little. Im not a good enough welder to trust my life like that anyway.I am currently working on a Yamaha but it will not be ready for the first race at least. Im gonna see what I can do on the Bighorn. I would like to at least get a full season in. I think I could take a championship if I can make it to enough races. We will see!
UPDATE MADE 2012:
2012: theres a 7 year gap here. I have been racing the bighorn less now that I have three bikes that are active so to speak. Last winter I went thru the bighorn pretty well, I cut out the rotary valve and raised the exhaust port a bit. Its scary fast now, but it lost some of it's low end tractor like pull which is a shame. It wheelies alot more, and the clutch just couldnt handle the new power, it started to slip. I think I will go back to a stock rotary valve when one comes along cheap. I put new Barnett clutch plates in and new springs...long story, but the F8 I started with had one less friction disk than the F9 should have had. So I did manage to get the clutch to stick with the new motor mods. I got a new rear sprocket and chain, some new tires etc. I was ready for a nice run at Budds Creek in April of 2011, but I had a rash of bad luck. The bike fell over in the pits, and that ended my day because the plastic throttle tube just broke in half after that. I havent raced it again since although I am still working on it.
I am fitting the aluminum rims from my failed KX420 project to the bighorn, and I got some real MX shocks for it. They were old ones I had in storage from years ago. I dont know what brand they are, but they are beefy, and they are rebuildable. I was able to get some seals for them. I've got the stock Hatta forks back on it, and I wish I could think of a nice set to upgrade them with. So, I plan to race it some more this season (2012) but we will see. I made a seat for it. Yes made one. The pan is from an old toy snow board and the fabric is some marine grade vinyl that I stitched together by hand with heavy weather proof thread.
I cracked a piston also after a wreck that pinned my throttle and dazed me too long to kill it in time. I am now at 60 over. I have the 80 over wiseco set ready and in a box for when that day comes.
The white plastic tank in the pictures above didn't last too long. The metal that the cap screwed into all but rusted out and broke. Now it has a small red metal tank from a KD80. LOL....things haven't changed that much since my childhood I guess. Whatever works!
Now, I have to finish my KX250, and my S2.
Here is a link to a youtube video, a dash cam on my bighorn. Not the best video or my best performance but neat anyway. Deep rumble at 9 seconds is the Bighorn!
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