So the age old debate of the F2 versus modern bikes I've found pretty obnoxious. It typically boils down to a few people throwing out numbers they found on wikipedia, a few people saying it's all about the rider, and then a few people saying it's all the technology and the F2 is just left behind.


Welp, how do you like these apples kids!



The Red: F2
The blue: F4i.

True power comparison: "stop light to stop light" the f2 demolishes the F4i with significantly more HP and torque prior to 11krpm. From 11k rpm onward to red line, the F4i continues to gain power where the F2 rolls off until red line and the F4i only gains due to overrev, IE: torque drops, but HP is torque multiplied by rpm / 5250 (hence all torque and hp readings cross at 5250 by the way).



End results: The f4i only stands a chance against the F2 if ridden constantly from 11k to redline. Outside of that range, the F2 delivers more power and torque and will pull away on the F4i EVEN WITH THE WEIGHT DIFFERENCE.

Given that with some moderate spending you can affix equivalent suspension on the F2 that will easily rival the F4i's setup (fox racing rear shock being superior), the F2 will compete favorably against the f4i. Not only will it compete favorably against the f4i, but in a contest with two riders who are intermediate to newer in skill level (standard 600 riders) the F2 actually delivers more "streetable" power.

"Making the F2 competitive to the F4i isn't cost effective": This is relative horse ****. Delivering the power above on the F4i requires a power commander ($300) and dedicated dyno tuning ($150). Without those two, the bike will deliver less power, and be even worse below 11k, and not deliver on top like the above tuned bike. So $450. $450 will get you a dynojet stage 1 kit easily, hell you could even pay some one else to install it for you for that price.

Given the price difference of an F2 versus an F4i ($1000-$1500) you could get an F2, get your suspension done up for $300-400 (springs, f3 fork internals, rear shock resprung) and still be way ahead on the F4i... and have a far more streetable bike for the average rider.





So there you have it. Only to a more advanced rider capable of keeping a well tuned F4i constantly above 11k rpm at all times entering and exiting turns, will they have an advantage over the F2. Some will argue that keeping the F4i above 11k rpm constantly at all times is easy... but until I stop passing kids on these bikes, I won't hear any of it.

 

Nice analysis and glad to seem some good results posted.

This was a tuned F2 to a tuned F4i right?

 

Interesting analysis, great post. Id like to see you post this up on the f4i page though Id like to see someone with their f3 dyno results also post up.

 

nice

 

Meh, anybody could argue the bikes potential either way still. One could say that the F4i still produces that much more horsepower while weighing a bit less. There's also a strong argument for the F2's streetability, as it produces more torque and power accross 85% of the powerband. Infact, I compared my F2 to a friends race prepped 636 with a full exhaust, fuel injection, and a power commander, and it's producing only 4 less torque.

The f2 is no mild mannered antique my friends. It was a monster in it's day, and still is a pretty powerful machine when tuned right and maintained properly!

 

^^^ I agree with Jesse. I know I have said it before, but a new bike is NOT going to make you a better rider. You must first have the ability to prove to yourself that you have the confidence to go faster and lower through the turns.

"It is not the bike that makes the Rider, it is the Rider that makes the bike".
-Lance Armstrong

 

how exactly can you identify if you have a Stage 1 kit already installed? What am I looking for?

when I bought my bike the kid had had it 3 months and laid it down 2 times. But somewhere up the line, someone loved it enough to do a K&N, Factory pro timing advance, full V&H header/exhaust, and paint it up in a SJR/Duhamel replica with a high quality paint job. I'd love to know if it has some other goodies in the carbs as well. I'm getting close to doing a sync/tune based off your findings anyway.

 

You really should do a sync just because it delivers the most amazing difference in how smooth the power delivery is. If it's gone down and been banged up a few times, not to much lots of miles, I'd highly recommend you do so. Also, a little carb cleaning goes a LONG way on these bikes if they were already well setup, but not addressed in a while.

As for how to tell if you have a jet kit, pull the pilot jet's and read the numbers off of them and report back. We'll let you know what you've got. The Dynojet kit also has you epoxy one of the holes on the slide ****. That should be another dead giveaway.

 

WOW... that is good to know.
I just sold my F4i for trials bike money and am back on the ol' F2.
I am not a good enough rider to push either one to their limit and I know that both bikes feel relatively the same on the old butt dyno. The weight difference is not huge but the feel of the front end is very different while riding (F2 feels heavier in the front and takes slightly more effort to turn in). Though I am sure with a very small budget (as stated above) you could get the front end to 'feel' lighter.

I miss my F4i simply because it looks way better

 

Tire profile will have a lot to do with that as well.

That's rad you're looking to get a trials bike! I dirtbike a ton, and trials bikes look pretty gnarly! I occasionally encounter them out on the trails, although they're generally farting around some really sketchy looking stuff, and I'm blasting hill climbs and jumping ****!