Home made 4into1.....

Gday all. I like making stuff for my bikes. If it isn't any good, doesn't work, or is just plain shite :biglaugh:, then I do it again, keeps me amused.
I wanted a proper 4into1, mainly because I reckoned it would sound cool, partially because my standard exhaust needed replacing, and I was hopeful it would have a preformance boost as well.

Didi it work? HELL YEAH!!!!
Sounds excellent, saves 11kg (24lbs), kept me amused for the last 3 weekends. Bit tricky for the pipe routing of course, but that's 1/2 the fun. It needs a re-jet, runs a bit hotter when cruising, and doesn't need as much choke to start, I'll get to that, but IT GOES!:eusa_dance: Damn it goes!

Please don't ask for dyno numbers, the nearest one is a 4 hour ride away, but I'll update the track times to see what improvements have happened. It's not very shiny, and certainly doesn't have the looks for everyone, but I like it, and it owes me $250, including the muffler.

Now the best bit is I can look at something else that works perfectly well, and see what I can do with that!

Pics of the build below.

awesome job man, must sound sweet unk: you gotta post a video of it when you can

How close to the same pipe length were you able to come? I am sure plenty of folks here would love an opportunity for a pipe like that. I can maybe help get them measured up on a CMM machine if you wanted.

Hey guys. I like the end result, I had to use a 4" vice on the dirt, a 4" angle grinder, and a gasless MIG, so over all I reckon it turned out OK!

Sean, all the pipe lengths are unequal, deliberately so. I'm sure 99% of "experts" would disagree, but it has always worked for me on odd-fire motors. That's why I wanted 4-1, not 4-2-1, due to the uneven pulses. 4-2-1 are sensitive to unequal secondary lengths too, so just went the "interesting science experiment" route. The pipes were a compromise set, just a stopgap to get me through until I build my 4-stepped 4into4's with megs, which should make more power, but over a narrower rev-range (obviously, up top). I wanted to make the 4-1 from scratch, but needed an exhaust, so used bits off the old standard system to get me rolling again.

Front right pipe --- 33" and few bends. Step to 1.5" after 29".
Rear right pipe --- 30" and 3 tight bends. Step to 1.5" at 26.5"
Both fire 180 after previous, looking to tuning pulses at the right time.
Front left pipe --- 40" and few bends. Step to 1.5" at 34".
Fires 250 after previous, so needed to be longer.
Rear left pipe --- 27" and 2 tight bends. Step to 1.5" at 24".
Fires 110 after previous, so needed to be shorter.
Right pipes are the same "effective tuned length" due to the bends adding time for returning pulses from the merge collector.

On an even-pulse (inline 4) motor of 1200cc, ideal exhaust tuning for torque peak @ 7000 with a 65/25 exhaust timing, I would build a 4-2-1, 1.3/8prim 10" long, stepped to 1.5" for 7"more, then 1.75" secondaries a further 15" long, into 2.1/4" collector 12" lomg (phew!), just for a comparison.

The lengths are OK for the tuning I wanted, but I had to use the standard 1.3/8 pipe for longer than optimal, so overall tuning is around the 6000 mark, not the 7000 I wanted. Feels like that too. A top gear roll-on from 70mph is MUCH stronger than before, even with the jetting needed.

Bottom line is, I had a great time (same can't be said for my long-suffering better half, with all my swearing out the back!), so performance effects are a bonus!:biglaugh:

The OEM primary pipes are 1.5" ID and the engines respond very well with the 1.625" ID pipes. Your same system in that larger size may find you making more power.

I think the 4-4 without some sort of crossover will kill your HP at all levels. You will be losing the scavenging effect that the normal conjoined headers make.

Gday Sean.
The 4-4's might just do that, yes, but on some engines in the past I've built them for, like Kwak GPz11's and GS11's, they made more outright power, but over a narrow range, so if I can figure out the diameter's and lengths I need, it might work on this engine as well.
The GPz in particular was great, picked up 5% from 9 to 11.........also lost 10% at 6! Being drag only with a high launch rpm it didn't matter really.
I'll get around to it one day I spose.

I had to use most of the original pipes due to time constraints, rather than my ideal diameters, but it still seems to work very well, just a bit lower in the rev-range than an ideal pipe. Probably giving up power too using standard primaries, but not all that much really.

There is a 10% gain in HP with the larger diameter pipes on average. There is a 20% LOSS in hp when doing the 4-4 (cobra's) and I don't think any amount of flow increase will gain that back. I have dyno sheets showing them out on our website. In a few cases the power loss is actually closer to 30%!!!

We made a 4-2 system 2 years ago and used it on a 1500 engine we built. We used the OEM front outer wall pipes! They were considerable larger then the stock and aftermarket systems even. I think you'll lose a bit of torque with that large on a stock engine.

Sean

Dale Walker spent over a year creating his with his in house dyno for testing and came up with the 4-2 system he has now. It's the two left cylinders into one muffler and two right cylinders into one muffler with NO crossover.

He said he tried every conceivable way and found it provided the most power where it was needed in a two can setup.

Chris

Yeah, I like his system, looks very balanced on the bike. The cans look good too.
Years ago I had a VF1000F, and had aa 4-2 on that, worked very well. With this system I used what I had around, but I'm still surprised at the difference it made, I wasn't expecting a noticeable improvement, just a system that didn't rattle!

After pulling the stock system off and installing Marks 4-2, I think I'll leave the design work up to you Gents ( Guru's ). You're so far over my head with exhaust theory it's not funny.:ummm:Congrats on your new system modnrod, it looks great and it's amazing to me. Good luck with future development too.

tugla said:

awesome job man, must sound sweet unk: you gotta post a video of it when you can

Click to expand...

yep - i also vote for video...