My rear F@ conversion.....

It's not really anything about stress on the frame or swingarm, it's really about overall chassis geometry. With older bikes the rear ride heights were set at very modest levels. We have since found that increasing the rear ride height makes an improvement in the overall handling of the motorcycle.

The F2 wheel/tire is indeed a little smaller, which effectively reduces the rear ride height. Since this is a step in the wrong direction, increasing the ride height provides a benefit. That said, the F2 wheel and radial tire make a big difference over the stock tire, even at the reduced ride height.

 

I road from Sacramento to San Diego and the only thing that didn't go wrong was the new tires, shock, and front end. Been riding my unmodified bike and I have to say they are 2 different pieces now. With the upgrade I'm more inclined to let loose with the right hand and give er a go.
The unmodified bike feels way loose when under extreme acceleration. :vtr2:

Not to mention changing the front end also changes the look and stance enough to make it look even MORE attractive.

 

id have to say at this point, GreyVF750F's explanation of altering the bike geometry has damned near talked me out of the idea of the F2 front and rear wheel conversions. if these will negatively affect the bike, then whats the point of doing it other than asthetics? Jamie, does the fact that your rear shock returning the bike to stock ride height help to correct/level out the negative affects of the F2 rear wheel, or is the handling just gonna be out of whack for good?

 

I would keep this on your clipboard! It is definitely worth doing and my post wasn't meant to talk anyone out of this. My point is that there should be an understanding of basic chassis design when tackling this upgrade.

I am closing in on a 17" wheel conversion (using CBR600F rims) for my ’84 VF500F. As a first step I installed an F4i shock conversion – quality built from Jamie D. I then used this in combination with a base drawing of the stock VF500F to calculate the effects of switching from the 16F/18R rims to 17's front and back. Based on drafting in different tire sizes (and not wanting to slide the fork tubes) I made my selection of specific tires that would get the bike back (or very close to) its stock geometry. Of course this is all theoretical and as Jamie has written it is best to see how the bike handles and then take it from there. For myself this project has been part of an education in frame and chassis design, all of which I have very much enjoyed.

I am sure not every rider wants to dive into this much detail and many would like to install a well made and designed kit without having to get out their slide rules This said I would bet that Jamie has done quite a bit of work on his scratch pad for his F2 wheel conversions and has based his rear ride height and tire recommendations on this.

I don’t think you can go wrong with the 17” wheel upgrade – more that when making the switch rear ride height should be considered an important upgrade as well.

Hope this is of help!

Wanted add to the thread author – Yonan – congratulations on your F2 conversion – hope you get many years of spirited riding out of this!

 

Also nicely said. Yes don't be afraid of changing things on your bike like upgrading the suspension and tires. Just don't believe it's going to be the hot setup out of the gate. You may get better handling but the ride is rougher on bumpy roads or the steering is real fast or slow now.

Get to understand the basic's and or have good observation skills to noticed what has changed and at what speeds or road conditions or whatever. That's the learning process even the pro's go thru. Using a known setup really cuts down any re-adjustment time that may be required after testing. Plus it's safer knowing if any, the bugs are worked out for the most part.

If you don't know the basics or how to figure things out, you may want to rethink what your doing prior to do it. Best way is to get someone who has done what you want to do to help you. Or come to boards like this for info you need and things you may not have thought about. If you hit it right on the head the first time consider yourself lucky. You may have got the proverbial free lunch.

Yes even a blind squirrel finds a nut now and then. (not to talk bad about squirrels that is)

 

Do not.... I repeat...... DO not count this upgrade out. The benefits FAR outweigh the negatives. There have been way too many examples of folks on here doing this upgrade for you not to find the correct set-up almost straight out of the box. And yes, a shock change correcting the ride height fixes the problems altogether.

Besides Chris, you have WAY too nice of a Gen II to not have this done. IMOP

 

Just to let everyone know. I have a built shock by Jamie I plan on installing, problem was it was an older Fox shock without ride hight adjustment. As soon as I modify it to raise my tail back up and figure out what to do about the 4 into 1 exhaust being in the way it will go on. BUT for now I could not be happier with the way it feels. Quicker turn in yes, a little bumpier on rough roads yes, but tracks better and the looks are amazing in my opinion. I was a little scared to do the swap, but other than the exhaust issue it really wasn't that bad.

 

Awesome. Congratz on a beautiful Bike.

 

Its funny how the 86 VFR750F still looks as modern today as it did in 1986 !!! ... WOW looks GREAT !!

 

great looking bike Yonan. and +1 on this conversion. I did mine years agoa and would throw those old wheels in the lake before I would even consider putting them back on the bike.

 

UPDATE. Did my first good ride with my new set up. Overall a major improvement. I still need to raise the rear a little bit, I think a taller side wall tire in the rear should do the trick. gonna go to a 70 instead of the 60 series. The bike handles pretty dam good. My buddies said i was definately faster today. It's turn in is very quick maybe too quick but not scary at all. Being a little low in the rear did lighten up the front end so I just scooch up to the tank a little more to get my weight more to the front. She comes up a lot easy, that part is fun. So in conclusion my friends. Would I do it again....................HELL YEAH!!!!!!!!!!!!!!!!!!!

 

Right-on Yonan. Glad to see it worked for ya. What kind of shock ya running?

 

Sweet!

Good to hear.

Ride safe out there

 

Its a fox twin clicker.Rebuilt by Jamie. Minus the ride hight adjustment. I think its an early model. Worked great today.So much nicer than the wore out original.

 

Good deal - I am glad the F2 wheel conversion is working well. I also appreciate your positive outlook on what it takes to dial in this bike’s geometry.

From your post it sounds like you are very close to having it where you want it. Congrats again and please keep us posted on how the taller rear tire works out.

 

I was worried when I 1st started reading this post but I kept going and learned a few things about my current situation ( I haven't been patient and learned how the bike responds to what we do). This conversion is next on my list so hearing it turned out good for you is motivating. Bike looks real good. I wish I had left mine RWB color scheme now but the wife says if I make rate I can get a new bike so the 86 will be my commuter, but right now I'm keeping it in the VFR family.

 

Where you able to fix the exhaust issue? what was your remedy?

 

I installed the shock as is without making it longer. So it clears the exhaust by .005mm just kidding its pretty dam close though. Its low in the back, but rides pretty good. I'm going to a taller tire after i burn this one up. Should be good after that.

 

Yonan / Tex - would you all know the length of the spacers used for the cbrf2 rear caliper and torque arm to work. after reading Tex's thread i know i need an 8mm to make up space for cbr caliper bracket to fit on axle. what size will i need for the torque arm to caliper bracket.

 

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