93 750 performance mods

I have a 93 750. The bike is stock aside from a twin bros exhaust can. I am looking for some noticeable power increases. I have heard about going down a tooth up front (not a power increase obviously but manipulation) also air box drilling, jet kits etc. I have build other bike before but not messed with the VFR's much. What do they respond best to? Thanks.

 

Mods

1. Best mod, get the suspension tuned. Probably rebuilt forks and new shock.

2. Good tune-up and getting rid of entire PAIR system.

3. Small city accceleration increase from dropping a tooth in the front.

5. Rider training.

This bike is a GP bred all around good bike, but does not compete with gixxer's, etc. Expect about 100 BHP on a good day with good tune.

Of course, if you just want to mod it, you can go as crazy as your pocket can handle. Complete USD forks and wheel conversion. New shock from Ohlins, Penske, Maxton, Wilbers, or Jamie Daugherty conversions. Seats ar nice too. See threads by Safe-T, Fotomoto, etc, etc.

Larry

 

I'll got a 2 Bro's full exhaust, I've wrapped the header, Installed a jet kit, wrapped the entire air box with a foil insulation. Plugged the emissions system, and insulated the fuel lines. With the combo I've gotten 94.1 hp for it. My next change/upgrade may be to convert to a 520 chain, in place of the 530. The 520 is suppose to have less reciprocating mass, so it should accelerate quicker. I think it's more theory that fact, but I'm all for a faster bike!

Robert

 

Try -1 tooth front, +2 or 3 at rear. Wastes fuel but significantly improves acceleration at some sacrifice of ultimate top speed.

Also, jet kit would help some.
Remove snorkel from airbox.

 

Did they have the PAIR system in 1993?:...........:doh:

 

What is the PAIR system?

 

Also with the carbs I have now, I just rebuilt them. The bike was dirty inside so were the carbs. now valves and carbs etc are clean. The bike pulls much harder than before. However, the idle is a little rough, almost lopes like a camed up hot rod. Is this carb sync time? Also on decel the bike pop/ backfires slightly. This is air bleed adjustment correct? The book calls for 1 7/8 turns out for the bleeds. Should I go slightly ritcher?

 

the loping idle could be caused by poor synch or excessively rich condition or both.
synch the carbs first and the slight backfire may disappear.

 

turning the pilot screw counter clockwise richens the idle circuit correct?

 

what is the pair system referenced to the airbox?? Is it in the earlier models referenced above??

 

Not on my Canadian model at least. I read about it, got all excited about putting the old girl on a diet, and for the life of me couldn't find anything to toss in the trash :frown:

 

I would second everything that Larry (safetypro10) said above. I actually started suspension work just by changing the fork oil and setting up the preload/sag properly which is a good starting point if you're on a lower budget. Depending on rider weight you may have to upgrade front springs to get your sag right; on the 3g the rear spring is stiffer and was fine (for sag at least if not for damping) in its stock form for me (165# without gear).

If you want to get 'er handling a little quicker without the initial expense of a ride height adjustable aftermarket shock, flipping the rear eccentric made a substantial difference and allowed me to run less preload for a little more compliance in the rear, while still keeping the geometry relatively quick. I'll do a search and see if I can post up the link.

The only other suggestion I would have you already have (mostly) covered, the 3rd gen VFR is not a light bike and the muffler is a big culprit in this - a little weight reduction went a long way in felt power and also handling on my bike. Muffler, rear seat grab handles and bar (high up weight) if you're not carrying a passenger, passenger pegs and brackets if you want to fab up a little seat release bracket. You can go crazy with the little ballast weights in the footpeg brackets, taking off the fender-plate mount/light, aluminum/titanium nuts and bolts, smaller AGM optima battery etc... but there is a point of diminishing returns. I personally did not feel that the 520 conversion made any appreciable difference except for show, and making it really drone on the highway. I went to 16 (stock) front and 50 (+7 I think) rear, which was too much.

It's a great all round bike at a reasonable cost, my experience was that you go too far and you can easily compromise both of those.

 

Hope this isn't bad juju, like saying the ex-girlfriend's name in bed... the post in question is on VFRD, here:

4th Gen Two Brothers Exhaust On 3rd Gen - VFRD

snip of it is:
<snip>
In order to use a TBR RHS exit header in conjunction with the OEM center stand on my FP I had to (a) flip the eccentric (as shown in the first image--note the countersunk brake caliper mounting bracket and titanium bolts), space the centre stand down by approximately 35mm (as shown being tested in the second two images), and (as not shown) lengthen the side stand by approximately 25mm to correct the somewhat frightening lean angle.

The center stand mod requires the eccentric mod because, otherwise, the bike would ride too low in the rear to allow the center stand to operate. It is also required in order to get back some of the lost ground clearance. <snip>

Here's one pic showing the carrier. Only one bolt hole needs to be countersunk as the other does not pass under the hub in its whole range of travel. In the pic, JZH has replaced his with an allen head but the stock bolt works fine. Titanium is, of course, always preferable.....

It should be noted that he did this to allow the centerstand to be lowered and the an exhaust to be used, I did it for the ride height - by putting the eccentric at the bottom as opposed to the top, the wheel moved down w.r.t the swingarm by about an inch and provided about an inch of additional rear ride height. Combined with stiffer front springs, it solved my clearance problems and provided quicker handling.

The centerstand still worked, barely; the sidestand would have needed to be extended as it had a nasty lean to it.

 

Remove the cam gear silincers, you can save over 1kg from engine.will make it sound like a bucket of bolts at tickover-kinda ducati dry clutch cool.
lighten the flywheel.
what dont you use? i removed the grabhandles, pillion pegs?
Ray
and look here VFR 750 Tuning / Mods - Workshop - Technical Advice - In the shed - PB Magazine Forum i like the idea of an electric coolant pump.

 

Who sells the 520 sprocket????

I have a VFR swing arm on a non-VFR bike and the front sprocket is a 520.
Any info would really help,
Thanks.

 

Loose 20 lbs of that extra weight you been hanging on to Good for at least 10 horsepower

 

Sprocket Specialists, Sprocket Center, Sum Of All Parts, your local dealer, pretty much anyone if you ask them. Just tell them what you have front and rear, that you want a 520 conversion, and how many links.

 

Thanks....good info. I'll soon need that sprocket.
This is it, part CR125, part CR500 and part VFR.
Click on a pic for the full build:

 

Woo hoo! that looks like fun....
You may find that the CR fork is too long in travel and static height, and too lazy in its rake for what you want (although looking at the leading axle the trail should be less than one would think with it raked out like that). Have a look at what Roland Sands is doing with the 450 super singles and you might get an idea of what kind of geometry mods will make it handle for the street. 450 SUPERSINGLE


Cheers,

S

 

I should probably note that I used a non-hard anodized aluminum Vortex rear sprocket, and it was starting to show wear in under 5,000 km.

I have had much better results with steel sprockets but they don't have the same sizes available (or 520 conversions, or the bling factor); I have riding friends who have had much much much better luck (and who don't even lube as religiously as I do) with the titan tough hard anodized alu sprockets from Sprocket Specialists. Worth the extra $$ IMO after seeing how fast a cheap Vortex started to let go.

HTH,