Creating More Low-End Power

Red Fthr

Red Fthr

"Man is born free, and he is everywhere in chains"
So I haven't done much to my Honda CB500 F k0 to increase performance minus utilizing pods, free flowing 4-2 exhaust , and the proper jetting to go along with it. I've also installed new piston rings and kibble white "performance" valves. In addition, I've also upped my gearing to a 17 front, 37 back.

The little work I've done has increased my top-speed to 120 mph + from the stock 102 mph. However, the bike doesn't start really pulling until around 7,000-8,000 rmp. What should I do to hit that sweet power spot sooner? I'm not trying to do wheelies or anything, I'd just like to feel that juice around 5,000 if possible. Bigger rear gear? Or would a 4-1 exhaust with more back pressure increase my mid?
 
nothing you can do besides a change in cam timing will make that much difference, 5000 rpms is not gonna pull no matter what it is in the cam
you have it geared too tall gear it back down to stock or a bit lower if you want more poke
it will put the gears closer together, don't be afraid to rev it
what kind of pods are you running ?
 
I'm using Uni pods at the moment. I figured with a larger rear gear I might loose some at the top but gain something toward the bottom. Is that not correct?

I'm new to tuning and creating more power that never existed before, so be patient with me haha.
 
The Honda I4 engines arent built for low end power. As stated, you'll need some internal motor work to get anything really special. Or buy a twin ;)
 
Noted. Still stoked I got a little more juice out of it than stock. Guess I'll just get a twin. All though I feel like all the old 60s I4s (referencing the rc181) did a great job at getting around quickly. I would have to assume that was a very different 4 though.

If I were to get the most out this bike, like, let's say I wanted to race it, where would I begin to create more power? Or is that about as good as it gets?
 
River City Rocker said:
I'm using Uni pods at the moment. I figured with a larger rear gear I might loose some at the top but gain something toward the bottom. Is that not correct?

I'm new to tuning and creating more power that never existed before, so be patient with me haha.
Click to expand...

Also it should be said that changing sprockets does nothing to change the power produced in different RPM ranges, they just change gearing either for acceleration at the detriment of top speed or vice versa. Most people either change sprockets to increase acceleration around town or to lower revs at highway speeds.

Your bike will produce it's peak power in the same RPM band regardless of sprocket size.
 
I already read most of that article and, all though very insightful and well written, it made my brain hurt REALLY bad haha. I'll revisit it. I was hoping there would just be an easy/ affordable answer. Like, oh, tweak this, shave that . Idk.

Also, for now, straight up (and I know this is preference) should I just stop what I'm doing to my four and try again with my twin? I have a 175 that I was going to make into a little euro cruiser, and I was going to make my 500 as race worthy as possible. And I did this thinking that if the 500 is bigger, it should be able to go faster. Can I make my 175 plenty fast into the 100 mph range? Should I be doing what I'm doing but to the opposite bike?
 
First mistake is trying to compare the performance of your 70s street bike to anything Honda built for the track in the 60s. Those bikes were purpose built racing machines. It's like comparing a Ford Mustang to a GT40. Unless you want to spend a small fortune and handle a lot of re-engineering, one will never be the other.
 
i agree, accept both bikes for what they are
go 100 on the 175 ? you must be joking, you aint gonna do anywhere near that without huge aero help
if you want a fast bike get something more modern and just ride it
what kind of racing will you be doing on the 500? some vintage road racing ?
 
Have you checked with Dynoman Performance in Austin Texas? I don't know if their still in business, they had stage 1 and 2 performance kits for the CB500. The bore kit was 4mm over which made it 60mm @ 10.5-1 compression from 9-1. Compression makes a good improvement in low end torque, 1.5 is not much of a bump though. The engine then is 572cc. I haven't had any experience with these guys, maybe someone else here has.
 
jack up the engine and slide a cb650 motor into it

you will need to find a rt rear engine mount plate off a 550

and go from 48-63 hp
 
The 500 is a beautiful high reving engine, I would not do anything to ruin that. Just use the trans to stay inthe powerband and enjoy that sound. If it were my bike and I had the dough I would put a big bore kit in it and get some nice carbs.
 
"Race worthy" is an expression I'm using to convey my passion for getting as much out of my bike as possible. I want to learn as much as I can and produce as much as I can with the resources I have. I don't know how much you can get out of these bikes. I guess that's what I'm asking. Where is the wall? How far can a 500 be pushed?

I do fancy old 60s Honda race bikes. And I feel like trying to make a stock street bike perform as close as possible to what was on the track back in the day is the very essence of cafe culture, is it not? All I aim to do is give a hardy attempt at getting as close as possible with the resources I have. I'll save money and learn what I need to. If it takes me a decade then so be it.
 
Just checked out Dynoman Performance. I wish I had an extra $3,000 to burn! CR carbs and one of those packages would be tits. I wish I would of known about this before I rebuilt my top end.
 
If you want low end power without sacrificing the high end, you only have two real options: More displacement (big bore) or more compression (which you can also get from big bore).

You can also change the gearing to make the bike pull harder, but your top speed and fuel economy may suffer and you'll be shifting a bit more. A milder cam (not sure if such a thing exists) will also help you to hit the power band lower in the RPMs, but that lowers the effective redline as your engine will get asthmatic in the higher RPMs.
 
Have you read about the "gentleman's express"?
Seek out that article. Should be able to find it on sohc4.net

Nothing wakes up a sohc4 Honda like head work though.
That is the weak link in the power department.

Pods are 95% a downgrade and come with to many trade offs.
 
I guess what you have to do is decide how much money you want to spend and then check out the options that you have. A big bore kit should give you more power from bottom to top, head work and bigger carbs will not usually help your bottom end but rather mid range and top end. You might be able to mill the head for more compression, I don't know what this engine allows for. Higher compression helps from top to bottom as well. Just like Sonreir has said and he knows a lot more than I do but I would challenge him to a rock trivia duel. I would love to make a 60's race replica with this bike too!
 
Power is made in the higher rpms.
You seem to be looking for more low end torque, which you really aren't going to find in that engine.
I have a 400F and an SR500 (and the xs650) , the torque difference is incomparable.

There is plenty of power to be had in the cb500, you just have to ride it differently.
It's not a cruise along amicably kind of bike. It is made to be revved and flogged.
My 400f rarely ever goes below 7000 rpms.
You just have to learn your bike and keep it in the power, and dont be afraid of revs.
I used to be, a few years ago I sold a cb350 because I thought it was revving dangerously high at higher speeds, when it turns out that's not going to hurt it at all!
I rode my 400f at 10,000 rpms for 30 miles the other day without a thought or a hiccup.

My rambling point is Learn to Love the Revs!
 
Thank you for all the constructive feedback guys. Since I've started this post I've learned to begin accepting the bike for what it is while trying to achieve optimal performance. I have been scared of revs, but I have noticed the bike likes it. You can tell that it doesn't really sound like it's really working until it reaches higher revs. I always thought there was something wrong with it and my bike was going to blow up any day. After talking to you fine gentlemen, I know that's not the case now.

I'm really excited about my new found winter project. I think I'm going to start by utilizing a big bore, a different cam, and if I ever have the money, some CR carbs to go along with it. I'll document my project as much as possible and let you guys know what happens on my build thread.

http://www.dotheton.com/forum/index.php?topic=60116.0
 
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