More Power from a Neutered California 3rd Gen

[tinkerinWstuff]

Many may remember that it was around this time last year when I picked up the 1990 VFR750 project bike. The motor was partially tore down and the plastics were busted up. As I evaluated the motor, I found it had a spun rod bearing and a proper rebuild would cost more than double what a used runner would cost.

TOE CUTTER was instrumental in helping me locate a motor on a tight budget. Thanks again to Bweiss and Cundalini for their help too. Those stories are told here:

New Project bike hits the stable - '90 VFR750
New ( or at least differant ) engine for TinkerinWstuff

So I took the 1992 motor from Sac-Cycle Salvage and put it in the 1990 frame. I used the 1990 49 States carbs with stock jetting to start. The motor was put in with all the stock equipment (PAIR valves, headers, collector, air-box, and snorkel). I normally like to see what I have before changing a bunch of stuff around and then chasing ghosts to find the problem. TOE pointed out way back then that his failing aged memory believed there was a difference in the cam shafts. This was confirmed in the factory service manual but I chose to leave the motor as it was.

In the following photo page 1-6 of the Factory Service Manual, you can see as much as 20deg difference in cam timing from 3rd generation to California cams. You can also see at the bottom that the 3rd gen uses 36mm carbs.


The following photo shows carb numbers and jetting for 3rd and 4th gen along with California. Page 1-7 of same manual.


This photo is the real doozy. Page 1-8 of the manual shows as much as .090 more in Intake cam lift over the California model.


So I got the bike running and purring pretty well. Rode it all summer but the more I got used to it I felt it seemed a bit pig-ish. I had a local racer who used to own a 4th gen jump on and see what he thought. His report was that it felt about right.

Winter came along and some prodding by TOE CUTTER finally got me to get off my ass and dig out the 3rd gen cams from the original motor. Up to the closest bike shop with a Dyno I went to get a base line run before making any changes.



For fun, we ran two pulls on the bike. One with PAIR valve operating as designed, and one with the hoses pinched. The graph below shows both runs over top each other. Statistically there shows no change with the charts virtually identical. This is taken at 4900 feet with stock jetting(49states), K&N filter, Yoshi pipe, California cams, and a reported 12,000 miles on the motor (unverified).


The numbers are far from impressive. Home I went to tear it back down. Here's a photo of a California cam and a 49states Intake lobe next to each other. Some local shops warned me that our altitude did not always agree with more aggressive cams. Since this is a factory camshaft, I was not concerned.


And so finally, here are the semi-final results. The 3rd gen cam set compared directly to the California camshafts resulted in approximately 5 additional horsepower and 2.5 lb/ft more torque. Another important thing to notice however is that the fuel mixture became more rich.


So, a direct swap was five more HP. But to honestly compare apples to apples, I'd have had to adjusted the jetting to bring the air/fuel mixture back to the same as the first run which would have given even more HP.

Since the last Dyno run, I've pulled the carbs and replaced my #130 mains with #125. I'm trying to bring the mixture closest to ideal for my altitude which is something like 13.1 The seat of the pants gauge says there's an even more noticeable gain than I had from the cams. The Dyno owner said he expected to see 5-10HP additional gain from fixing the jetting. We'll see when the latest cold snap passes. High if -4f tomorrow.

Initial Dyno run cost me $65 and the second run cost $40. I would highly recommend to anyone that they go see their local shop with the right tools (Dyno) to measure properly how your motor is running.

[jesusbuiltmyvfr]

Very, Very Interesting. I think I have recently become allergic to carburetors. Thats just me. Can't wait to hear the rest. Thanks.

[TOE CUTTER]

Aboot time you post this info, and remember California victims that he is at Colorado altitude so the gains will be better for those at sea level. 5000 ish feet if I am not wrong. I would ponder a guess of 5+ more than what Tink is posting just due to the thin air.

[milehigh331]

Thanks for posting Tink. Good stuff!

[crustyrider]

so I could swap out my cam. and gain 10-15 HP? thats amazing.....

[tinkerinWstuff]

so I could swap out my cam. and gain 10-15 HP? thats amazing.....

I don't think so. Did the 2nd gen have different cam profiles for California and 49states like the 3rd and 4th gen did?

[TOE CUTTER]

No , wont work for gen 2.

[crustyrider]

oh darn....... I really wanted to bump up the ponies on this thing...

[betarace]

well done! love threads that show the process, the facts and the D-Y-N-O results!

[tinkerinWstuff]

The shop lost my graph from the pull done with 49states cams and 130main jets (same setup I ran with California Cams). Fortunately I had it scanned and shown above. But, the pulls compared below are all California cams with 49states carbs & 130 main jets TO 49states cams & carbs with 125mains.

It appears that switching to 125 mains pretty much brought my fuel/air ratios back in line where I was when running Cali cams. I was told to keep going and put in 120 main jets. I'm a little puzzled by the fluctuation in air mixture and would be interested to compare to a stock pipe.

I gained another 3hp and 1lb/ft or torque with the jetting change. Overall, I'm up 8hp and about 3.5lb/ft torque. The really big teller though is a time comparison chart that we didn't do last time. Overall, I'm developing max HP about 2 seconds earlier than I was.

With more room to improve with I drop to 120 main jets. I'm not sure if I'll run any more dyno charts though. Here's another $40 folks.

Time comparison:



Fueling with 49states setup with Yoshi, K&N, and 125mains :



Overal HP and Torque changes; two runs on Cali cams, 49state carbs 130 mains, K&N, Yoshi - two runs 49states cams/carbs 125 mains :


Same four runs as above but showing fueling:

[jesusbuiltmyvfr]

Too bad you did'nt get to compare stock air filter to k&n. I wonder if they make "powernow" for carbed streetbikes yet? Something to look into.

[TOE CUTTER]

You should probably install a Dyno Jet kit.

[tinkerinWstuff]

You should probably install a Dyno Jet kit.

The tuner claims I should stay away from a dyno jet kit. He claimed that dyno jet kit's are designed to get more fuel in the mixture. Because of our altitude, he says fuel is not the problem and they normally end up removing the kits when tuning here.

Don't shoot the messenger. I've never used a dyno jet kit and am only repeating what I was told by someone with far more experience than I.

[thepimpdaddy]

The shop lost my graph from the pull done with 49states cams and 130main jets (same setup I ran with California Cams). Fortunately I had it scanned and shown above. But, the pulls compared below are all California cams with 49states carbs & 130 main jets TO 49states cams & carbs with 125mains.

It appears that switching to 125 mains pretty much brought my fuel/air ratios back in line where I was when running Cali cams. I was told to keep going and put in 120 main jets. I'm a little puzzled by the fluctuation in air mixture and would be interested to compare to a stock pipe.

I gained another 3hp and 1lb/ft or torque with the jetting change. Overall, I'm up 8hp and about 3.5lb/ft torque. The really big teller though is a time comparison chart that we didn't do last time. Overall, I'm developing max HP about 2 seconds earlier than I was.

With more room to improve with I drop to 120 main jets. I'm not sure if I'll run any more dyno charts though. Here's another $40 folks.

Time comparison:



Fueling with 49states setup with Yoshi, K&N, and 125mains :



Overal HP and Torque changes; two runs on Cali cams, 49state carbs 130 mains, K&N, Yoshi - two runs 49states cams/carbs 125 mains :


Same four runs as above but showing fueling:

I would think that you could bring the fuel-air ratio back in line also with a less restrictive exhaust, and K&N?

[crustyrider]

i FORGOT WHAT I was going to write but the four year old liked the letter M

[tinkerinWstuff]

I would think that you could bring the fuel-air ratio back in line also with a less restrictive exhaust, and K&N?

This might sound a little terse but;

Did you read anything I put in my post?

[vfourbear]

Good thread Tink......

[ridervfr]

BRAVO!!!! loved that stuff, well done Tinker. Never dynoed my bike, wonder what it would be at. Love the Gen 3 bikes.

[tinkerinWstuff]

BRAVO!!!! loved that stuff, well done Tinker. Never dynoed my bike, wonder what it would be at. Love the Gen 3 bikes.

To just throw it up there and do a pull, should cost you between $40-$65. Go for it!

[Lazy in AZ]

Running the Dyno in school was a blast. We only got to play on the fuel injected bikes like the CBR1000R, GSXR1000, and B-King. There were no tests made on carbureted models, so I have no experience with that particular part of it. However, I will say that what I learned in Clinic 9 was that there is SO much more to dialing in a bike to performance spec than just simply jet settings, air filters, and what kind of exhaust you are running.

The cam timing can be set to any of thousands of combinations (if dual cam) and the PAIR valves also have their own minute adjustments that can be the make or break point of the whole system. Of course if you change the exhaust and it's not specifically designed to match the harmonic resonance that your particular engine requires for proper scavenging then you have to make more adjustments. My instructor in Clinic 9, Manny Macias, was a tech on several championship race teams and his job was to get peak performance out of each bike ran by making all of these adjustments. He said that if you didn't do all the math first and just made a change to see the result you'd be chasing your ass for weeks trying to figure out where you went wrong before realizing that the first adjustment was just a hair off from where it should have been.

That was enough for me to realize that this particular part of the industry was not my cup of tea. Leave factory stock alone and just enjoy the ride has become my motto. They did all this R&D for a reason and with all the EPA guidelines, the minute you tinker with the settings your bike becomes illegal... not worth the risk in my book.

But to each his own.

Now, all that being said... I find it ridiculous that the cam timing and valve clearances on the same model are that much different on the same model bike just because of California emissions regulations. So, basically all the Cali bikes are toned down and just need some adjustment and capped the lines to make them as strong as the rest of the country. Stupid.

[tinkerinWstuff]

Now, all that being said... I find it ridiculous that the cam timing and valve clearances on the same model are that much different on the same model bike just because of California emissions regulations. So, basically all the Cali bikes are toned down and just need some adjustment and capped the lines to make them as strong as the rest of the country. Stupid.

I think you meant cam height or some variation of the same?

I doubt that most of the emissions EVAP stuff has much if any affect on the HP or Torque. Kind of like the PAIR system - very little affect if any on performance, just more complication.

[Lazy in AZ]

No, I meant the timing of the cams as in 10 degrees before TDC, ect. There are aftermarket cams that you can adjust that can offset the actual timing and yes, it just makes things more complicated.

You'd be surprised how much adjusting really needs to be done by simply putting an aftermarket exhaust system on, even if it's just a slipper exhaust. These engines these days are designed down to the last fraction of a degree internally with the intake and exhaust ports, diameter of the ports themselves, and sizes of the valves. Their all not the same size on different models because each combination creates a different output.

They took the joy out of motorcycles when they went all scientific on their approach on how to make it more fun to ride.

[tinkerinWstuff]

you said cam timing, and you said valve clearance. I think you meant cam timing and lift, not clearance. The valve clearances are the same.

And to your most recent post; I agree that the engineering and science that goes into these machines is far more advanced than many may realize. It's that much more important to use a dyno to verify results if you feel the need to dick around with a machine designed by teams of engineers.

[Lazy in AZ]

Agreed, Tink. And yes, I mixed my words... thanks for the clarification :)

[crustyrider]

Bad student...........you get a "D" on your communication skills...... back to english 100 .....