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Z462 X5 539 Barker YFZ FCI trimmed FCR 42.5 185M.PNG



Displacement:
462cc +4 bore cylinder works cylinder, +4 Hotrods crank, High compressioin CP piston (The old VCP 14.25:1 piston from Venom with slight modifications bringing it down to 14:1)


Compression ratio:
14:1

Valvetrain:
Custom Web cams, +1/+1 Ferrea valves, all from CFM Motorsports, Kibblewhite springs

Induction:
FCR 42.5 with the carb to head boot from a 05 TRX 450R, the intake is a Fuel customs intake for a carbed YFZ, and it has been shortened about an 1.5"


Porting:
The head is a +1 head from CFM Motorsports, which is in bad need of an update. The airflow is not on par with with my current heads

Exhaust:
Barker Full System

Ignition:
Dyna Programmable ignition box, curve #1,
Stock coil, CR8E

Flywheel:
DRZ

Tires used:
Big heavy 20" Duro street tires on steel rims. (only non knobs I have sitting around)

Gearing:
13/38 JT sprockets, RK X ring chain





Watch for updates, as I don't think I'm finished with this yet. I tried a lot of different cam and intake combinations before landing on this one. It's been as high as 59hp, but it gave up too much torque. It's been as low as 54 hp with a little more torque than this, but this was the best compromise, averaging the most power.

The intake cam is very close to a Megacycle X-5, but it's timed different. The exhaust cam is a Web 539. I had a FCR 41 and a FCR 42.5 on during this testing, and the 42.5 was marginally better. I wouldn't be afraid to skip the carb boring if you found a 40 or 41 for this setup.

The biggest changes to the curve were actually with the variety of intakes. I started with a Honda TRX 450R boot from an 04/05 model. It wasn't bad, but the length was a little out of sync with what the engine wanted. I remember from when I put it on, that it felt like a big improvement over the 400EX boot that I had on there prior. I did not have it on the dyno at that time.

Don't be afraid of a foam filter. The K&N style filters did allow for a change in the main jet, so there is a difference in airflow, which I knew, but that didn't translate to more power on the dyno. When I switched to the FCI intakes, it really didn't make more peak power, but it did make more torque in certain areas where the intake was in tune. The intake itself was responsible for the changes, due to the changes in resonance tuning. The filter had little to nothing to do with the changes.

You can still see a slight dip in the torque curve. There were 3 of them, and they were worse, when I started with the full length version of most of the FCI's, and with the Honda boot. Intake resonance tuning is simple, but complicated. If you have ever slapped your hand over the end of a pipe and heard the sound, that's basically what is happening in the intake. That pressure wave bouncing back and fourth can have advantages and disadvantages to the engine, based on when the wave gets back to the valves. So in certain parts of the rpm range, it will help, and in certain parts, it will hurt.

The longer the intake, the lower the frequency, and the lower rpms where the effect will be helpful. The opposite is also true. So first I found the FCI that was the closest to right, which was the one for an early YFZ. It's also a nice fit in the chassis. I cut a half inch off of the carb side, and tried it again. It improved. The peaks in the torque moved up in rpm, and started filling in the dips. I cut another half, and it followed the same trend. I cut another half inch, and The only dip left is still shown in this curve, and it's half as deep, if that.

This ended with a really great, usable curve for just about anything. 40 ft lbs of torque is huge from a 462, and when you drop the clutch on a start, you have that monster torque to keep you from dropping below the powerband, or to keep you from having to down shift when you climb a big hill. Even with all that torque, it still pulls hard all the way to the limiter, and when you shift, the shift drop puts you right in the heart of that other bump in the torque curve around 7500-8000 rpm

As I said, in the beginning, watch for updates. The head on this is from a long time ago, and it is not on par with my newer stuff. I will be making changes to the head when I can find the time. I think this thing can see 60 hp.
 

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::3 Pump Chump!::
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amazing work like always! 57hp out of a z is crazy.
 

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Discussion Starter #3
Thanks Tyler, it's a really usable power curve too. It would be at home anywhere from an XC race, to the dunes.
 

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Wow, thanks Chuck. Especially for filling in the details on the intake changes. Nice to see the theory put to the test. A lot of work on your part, buts that the only way to wade through it. Makes we want to put my thin base gasket back in , and throw some big cams in, just because..😀
 

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::3 Pump Chump!::
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Chuck that power curve is a really steady curve, which just like you said would be great for any style riding.
Thanks Tyler, it's a really usable power curve too. It would be at home anywhere from an XC race, to the dunes.
 

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Discussion Starter #6
Wow, thanks Chuck. Especially for filling in the details on the intake changes. Nice to see the theory put to the test. A lot of work on your part, buts that the only way to wade through it. Makes we want to put my thin base gasket back in , and throw some big cams in, just because..😀

It was a lot of fun working over the 462. Mine has always been my back up machine. It was literally built out of spare parts that I have amassed over the years with my white Z. (although they were pretty nice parts). But I never found time to get it on the dyno. It just wasn't a priority.

It was pretty good right out of the gate. It pulled 58hp, but when I was on it, I always missed the torque of the big 490 when I was riding it. Every change I made was an attempt to gain torque without giving up horsepower, or at least not much. The work was all worth it! I just took it for a ride about an hour ago. The before and after is amazing! It's making just as much power as some of the national Honda builds I did a couple years ago. I can't wait to get it back to the dunes with all this new torque!
 

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Discussion Starter #8
What do you use for a carb to head boot with an FCR?
I like the 04-05 TRX450R carb to head boot. It's slightly longer than the DRZ boot. It makes the issues at the top motor mount a little easier to deal with.
 
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