Assorted F11 questions.

[Nathan S]

In no particular order:

1. What size carb should it have? Is the original carb flange mount, or the normal 'slide into a rubber boot' type?
2. I recall (but could be wrong!) Doc saying that they handle well, but are slugs. Does anyone else have an opinion?

I've got one (thanks jimson!). Its a roughy but pretty much complete (carby aside, of course).

No idea of what to do with it. Any suggestions?

[211kawasaki]

Nathan
they do handle well and can be made to rip, the engines are very strong. I wouldnt put bigger than a 34mm carb on it untill you get it sorted then try a 36 but they lack crank case pressure. You will always find the clutch plates if left for a few weeks are stuck together but will free quickley when you ride - common Kawa problem dont ask me why?
The bike in the day were a bit of a hot ticket in DT and regardless of anything else are a rare and interesting thing that deserves to get out there. You will be suprised just how good you can get it moving.
Dave

[DR]

agree 100% with Dave's comments Nathan. When I say they are a bit of a slug I mean they are no more powerfull than any other traily of the era 'but' the engines leave themselves open to many modifications that as stated can turn the F11 into a misslie. I've performance upgrade specs if you'd like a copy. (courtesy of JC) The stock carb is a VM30SC. Consider the MX version the F11M only used a 32mm carb and utilized much the same chassis. It only weighed a touch under 94kgs. The F11 could be brought back to very near this weight also I'd reckon which puts it right in the ballpark but the bonus is it will out handle near any other pre'75 250

[firko]

Here's another slant on the Bighorn. This one recently reappeared at the Nepean pre '75 day. The frame is a cut and shut original built by Geoff Parry using geometry copied from an Astro back in the day. It's such a good job it looks like an aftermarket item.
           
One of the downfalls of the bighorn is the horrible Hatta forks. Kawasaki advertised them as multi tunable and fully adjustable and they were...the only problem being that they were woeful in every setting. Paul Bastick fitted a really well modded Bighorn engine to a Yamaha TD1B road racer chassis a few years ago and it whooped the opposition, even TZ350s. I believe it was similar to the bike that Yvon du Hamel rode in the 350 class in '72/73.

[DR]

  you think the Hatta forks were horrible Mark you oughta try std TS400 forks..they were so woeful I replaced them with a pair of Hatta forks and things improved out of sight but they were still woeful

[Lozza]

With a Big Horn 350 50HP is a pipe and a jet ski rod/piston away , you can set it pretty much any way you want to 32-36will work a treat. Ditching any points and going to a cdi will be a bonus.
Good friend of the Institue,Scott Clough in the US built Dave Crussells' Big Horn and it loses out a bit on the banking at Daytona but anywhere else is right there with the best 350's.

[AjayVMX]

A guy had a fast F11 at the Heaven Buladelah meeting a while back...

[Lozza]

Dave Crussel's Big Horn road racer

[DR]

why the holes in the mag cover Loz?

and AJay, I recognize that green F11 from a local Bris guy who's name evades me at present. (hate that!) anyway, he was normally #35 and I believe the owner/rider won the pre'75 250cc title not too many years ago on that particular bike. It did go well when I saw it run at Nudgee

[jimson]

Nathan what ever you do with the old girl just make sure you polish the triple tree as it looks like its begging to be seen its a lovely looking triple tree    jimson

[Lozza]

If you (or someone you know) is down at the Island Classic next weekend you can ask Dave yourself Doc(although I think he brought the triple) I'll ask Scott Clough who built the engine. Pipe makes the tyres look very skinny............

[firko]

As nice as the Crussel bike is and I'm sure it works a treat, it's no way as nice as Paul Basticks TZ/F9. He's retired from racing these days and has sold off all of his road race bikes but couldn't bare to part with the 'green frog' . He's retired to Port Maquarie and is building a 360GP Husky for CD7 these days. I've emailed him, asking for photos and some information on what he did to the engine to get it running so strongly. It only raced for one season but won nearly every race it went in and held the Oran Park 350 Post Classic record for a fair while. I can't remember the name of the guy who rode it but it'll come to me.

Talking with Paul had me convinced that the Bighorn 350 was the best kept secret in racing. My small Hindall frame was originally the actual American Dirt Bike magazine Project Bighorn from 1972 and we made a plan to build a 450cc version of the F9 and fit it to the Hindall to blitz the pre 70 class but I had my crash, he had a heart attack and the idea never got off the coffee table. I hope he remembers the theory of making a 'Biggerhorn', it'd be an interesting project.

[JC]

Nathan,

Doc & Dave T's posts are spot on. I have the porting & pipe specs from the F11M manual to make an F11M hotter if you want them, but you can go much better than that these days if you want, esp on the pipe. Also have 2 other porting specs for F11 in Enduro use. One was Carl Cranks specs when he rode one in an ISDT qualifier in US (circa 73)

Std 30mm carb is spigot mount (push-in) into bolt on flange. Stud space is same as TS/TM250 Suz IIRC

Std F11 frames are quite heavy, as are the wheels, but swingarm is light. Yam conical front hub & 130mm rear hub save a lot of weight. F11 tank is huge - too fat & too long for MX. Smaller lighter G5 tank (or early F7 tank) is much better, is similar shape, & w a lighter narrower seat moved forward gives much better seating position for VMX IMHO (I'm 5'10"). KX450 platsic tank is another option.

If yr engine # is above 16500 you should have a semi-close ratio g'box. Flywheel is fairly heavy & is points ign. I have an F81M/F11M ign for mine, but I'm fairly sure the DT2M ign fits too, which may mean a YZ one would too.

Thats some ideas of what can be done anyway

The green F11 (#35/135) above is Steve Cox's. It has George McKenzie porting & pipe, but fairly mild I believe. Last I knew it still had the wide ratio bottom end which Steve understandably found a bit of a pain.

Mark, beware the 450 bighorn. Its been done before - unsuccessfully. Somebody sold such aftermarket kits back in the day. Tranfer tunnels too small & strangle it IIRC. Also, for MX use, the inlet breathing limits the bighorn, even in 350cc. When you have to keep the carb cover on, its apparently v difficult to get it to breath sufficiently well. For RR use where you can run it w'out the carb cover - no probs.

[firko]

No Problems John, Project Biggerhornis as now far away from my plans as my chances of scoring with Sandra Bullock. It 'aint gonna happen. Interestingly, Paul came to the same conclusion about the carby problem but he found a way around it. Pity I can't remember what it was.

[DR]

Ah! Steve Cox that's him!!..thanks JC
Ram Tube Induction would eliminate the carb cover issue.  I rode my F11 at CD6 as you'd remember John, it was stock as a rock but it handled Connondale superbly. Maybe it's because I'm used to TS's and the likes but I didn't even notice the 'big' tank and the bike didn't feel overly heavy at all. It cornered like it was on rails and never put a wheel out of place the whole weekend. Nathan if I were you I'd build it stock, ride it like that and then decide what you want to do next. I reverted from the F11M ignition to the std magneto for CD6 because I'd thought it was going to be a little boggy from the rain, in hindsight I actually prefer the flywheel/mag ignition as the the drive out of the corners is instant which on the twisty green park track allowed me to keep ahead of many full on MX'ers. Build it stock, ride it and see..I think you'll be surprised