Honda VFR 750 XC Makeover

[XRGRIFF]

Fantastic job,will make a brilliant bike.
Exhaust primaries have to be the same length within reason,
the odd 25mm is not going to make much difference to power
output on that motor.
Keep up the good work.

[advNZer?]

would not be the first motor i would think of for an adventure bike but they are a nice motor for sure....extremley interested to see how this goes.

[Kai Ju]

I'll try to cut n bend n weld to make them fit, but as I remember the all exhaust pipes have to be same lenght, right?

[/QUOTE]


I don't remember who did it, but somebody got around that by making the shorter headpipe a larger diameter than the long ones.
I don't know if it could be calculated by volume, but might be worth a shot.

Love that frame btw. Nice build so far.

[DRjoe]

Unfourtunatley tuning an exhaust pipe is not about volume.
Diameter and length affect different things.

If you have a look at the exhausts on a lot of multi cylinder production bikes you'll see there along way off being balanced.
I'm not sure if it's done on purpose to spread the torque and power curve out or if they do it because it's easier and cheaper.

If your looking for peak power and torque in a specific rpm range then youll get better figures if all the pipes are kept the same diameter and length.

there are online programs for working out length, diameter and collectors to suit your engine size and valve timing but generally if you want a top end screamer go big bore short headers and if you want a tractor go long small bore headers.

Ill find the link to a realy easy to use exaust calculator that was designed by a legened of the motorcycle tuning and racing community.

[bk brkr baker]

Originally Posted by Kai Ju

I'll try to cut n bend n weld to make them fit, but as I remember the all exhaust pipes have to be same lenght, right?

I don't remember who did it, but somebody got around that by making the shorter headpipe a larger diameter than the long ones.
I don't know if it could be calculated by volume, but might be worth a shot.

Love that frame btw. Nice build so far.[/QUOTE]

Ducati did just that with , I think , the 999. The rear cylinders pipe was shorter and larger diameter. Supposedly it worked satisfactorly.

[Quacamole]

Originally Posted by DRjoe

Unfourtunatley tuning an exhaust pipe is not about volume.
Diameter and length affect different things.

If you have a look at the exhausts on a lot of multi cylinder production bikes you'll see there along way off being balanced.
I'm not sure if it's done on purpose to spread the torque and power curve out or if they do it because it's easier and cheaper.

If your looking for peak power and torque in a specific rpm range then youll get better figures if all the pipes are kept the same diameter and length.

there are online programs for working out length, diameter and collectors to suit your engine size and valve timing but generally if you want a top end screamer go big bore short headers and if you want a tractor go long small bore headers.

Ill find the link to a realy easy to use exaust calculator that was designed by a legened of the motorcycle tuning and racing community.

Thanks for feedback, I'll try to find these online porgrams.

[Quacamole]

Tried to bend 1.5mm wall pipes today, but impossible with hand bender - creates the wawes and flattens
the pipe. Also tried with electric bender but it has too large radius, so it makes quite large bends.

Result with hand bender



Electric bender with large radius



Waiting for the silencers to arrive then I'll continue with the pipes and fabricate the meeting joints, not the best looking result at the moment. Maybe I should use thicker walled pipe to be able to make smaller bends with hand bender?

[Kai Ju]

I know it's your build and you're doing an amazing job but it looks like you're using the headpipes for a skidplate

How about running the headpipes on either side of the sump ? That should also make the difference in length between the front and rear cylinder headpipes slightly less.

[sailah]

Originally Posted by Kai Ju

I know it's your build and you're doing an amazing job but it looks like you're using the headpipes for a skidplate

How about running the headpipes on either side of the sump ? That should also make the difference in length between the front and rear cylinder headpipes slightly less.

I like this idea. I wish I could have done this on the CBR but I had no room. Looks like you have the space.

I have a tubing bender as well but it's really hard to get those small radius bends in thin wall tubing. I ended up buying prebent sections from cone engineering and then using my bender to make up other sections where I needed an exact angle. The prebent sections are $$$ though. I used 0.065" tubing and with a 1.25" die could get very nice almost perfect bends to 180 degrees. 1.5mm is 0.059" so pretty close to what I am using.

I think for tight radius bends you pretty much need to go mandrel bent to prevent deforming.

[Throttlemeister]

[LukasM]

Wow, custom frame, that's pretty bad ass!! Looks really nicely done too.

What's your plan for the fuel tanks?

Will be watching this one.

[Quickv4]

For the pipes? Have you thought of the stuff-them-with-sand-and-cap-the-ends trick. Ive seen others do this with great success!

Great build, I LOL'ed at the term Makeover. This is a complte scratchbuilt bike!

[Quacamole]

Not much progress, still waiting for the silencers to arrive to continue with exhaust pipes.

Today got the 1150GS gas tank, bought from ebay. The tank has a dent on the right forward
side so it was quite a bargain. Don't know is it a standard 22L or larger 30L version, but feels
quite huge. Unfortunately it's not a straight fit and needs some modification. Still deciding, should
I keep the looks of the tank and lose some capacitiy or should I widen it by some heavy cutting and
welding!

The color kinda suits the bike



To loose capacity or...will loose alot I quess



Dent on the right side

[sailah]

With your fab skills, I'd seriously consider a tank from scratch. I've fought with modifying tanks before and usually the result is less than stellar.

You also could consider redoing the subframe and putting a couple gallons there by replacing the entire thing and plating in some tubes. I tried this on my last build and got 2.16 gallons under there. I'm thinking about making a new one with 4 gallons as it's my only tank.

You could make a slim tank on top with 4-5 gallons and get 3 under the seat.

[TerraRoot]

I thought the point of use the ktm as the start point was to bolt on the ktm bits after the engine was in?