Author Topic: building engine (Read 3406 times)

Loki · « **on:** December 17, 2009, 04:03:10 PM »

ok so i have my top end motor apart and im going to rebuild it, but i want to know what i can do to get as much low end torque as possible? i dont do too much high way with the bike. the engine is a 77 cb550 . im going to use the carbs from a 75 cb550.

Tnutz · « **Reply #1 on:** December 17, 2009, 04:43:43 PM »

buy a twin of some kind.....

sorry, nature of the flat plane crank 4 cylinder design. rev the #$%* out of it to make power.

go up a couple of teeth in the rear sprocket.

Loki · « **Reply #2 on:** December 17, 2009, 04:58:43 PM »

lol i love the sound of them thast for sure!, so besides a bigger cog in the rear. what can i do to the motor?

MötleyRöx · « **Reply #3 on:** December 17, 2009, 05:02:45 PM »

STROKE IT

Loki · « **Reply #4 on:** December 17, 2009, 05:07:34 PM »

sorry im not that knowledge in the meanings of these phrases. stroke it?....im thinking the wrong thing here.

Tnutz · « **Reply #5 on:** December 17, 2009, 05:08:03 PM »

yeh or that. someone may need to chime in more on that. but you may give up reliability..

MötleyRöx · « **Reply #6 on:** December 17, 2009, 05:14:25 PM »

Stroking means to lengthen the length that the piston goes up and down... this produces more torque... it is not a "I have the head off" type of operation.

Loki · « **Reply #7 on:** December 17, 2009, 05:21:50 PM »

ya im just looking to do a top end , and not bore out the cylinder.

MötleyRöx · « **Reply #8 on:** December 17, 2009, 05:28:03 PM »

boring and stroking are different projects.
if you intend to do engine work... you'll need to take more apart than the top end, usually.

mlinder · « **Reply #9 on:** December 17, 2009, 05:30:54 PM »

Onlyt thing you could really do is cam timing to change power characteristics, with just the top end off.

Loki · « **Reply #10 on:** December 17, 2009, 05:38:09 PM »

ok and what would be the process with changing the timing? i was told about putting a 650 cam in...is this a better option, or is changing the timeing give me more torque?

mlinder · « **Reply #11 on:** December 17, 2009, 05:41:01 PM »

The 650 cam will give you more of both low rpm and high rpm power.

Advancing your cam will will give you more low rpm power. TO advance your cam, you'd need to slot your cam gear, and know how to use a degree dial to advance your cam properly.

Loki · « **Reply #12 on:** December 17, 2009, 05:42:37 PM »

so its probly better to just go with the 650 cam? ..ok so what else can be done?

mlinder · « **Reply #13 on:** December 17, 2009, 05:45:17 PM »

Head work. Not terribly necessary for a bike that you want to trade high rpm power for low rpm power for.

Cam and cam degreeing, and ignition timing. that's about it.
You can deck the head a bit, add more compression. That adds power everywhere, too.

Loki · « **Reply #14 on:** December 17, 2009, 05:52:32 PM »

what are the process's for doing these?

mlinder · « **Reply #15 on:** December 17, 2009, 05:55:33 PM »

A machinist can deck the head for you. Simple process.
Id have one notch your cam gear if thats what you wanted to do, too.

You will be disappointed with the trade-off, in my opinion though.

You'll never get very much low end power out of a 550cc inline 4.

Wrong design for it, really. And you'll give up most of your top end for a small increase in low end.

MötleyRöx · « **Reply #16 on:** December 17, 2009, 05:57:18 PM »

Building on mlinder's post... you need a twin or single cylinder with more "stroke" for more torque.

Tnutz · « **Reply #17 on:** December 17, 2009, 06:07:24 PM »

exactly....when it comes to small CC inline 4's forget the words "low end torque"

My g/f had a 04 cbr600RR prior to her monster 696. The monster makes more torque at 3500RPM than that bike made at it's peak

Loki · « **Reply #18 on:** December 17, 2009, 06:18:23 PM »

ok so ill just put in a 650 cam, and call it a day?

Loki · « **Reply #19 on:** December 17, 2009, 06:34:31 PM »

woudl drilling out the exhaust holes do anything?

MötleyRöx · « **Reply #20 on:** December 17, 2009, 06:38:53 PM »

Just put the tools down and go kill yourself on an R1. I'm speaking figuratively, of course, don't go kill yourself!
Enjoy what Honda has given you.

Drilling out the exhaust, wherever you decide to drill, will not help you any.

Loki · « **Reply #21 on:** December 17, 2009, 06:44:06 PM »

lol i wanted an 03 r6, but i love the classics, and im young and dumb! lol. but i thought i heard that you can bore out the exhaust for better flow giving more power?

MötleyRöx · « **Reply #22 on:** December 17, 2009, 06:49:56 PM »

Quote from: kre-eper on December 17, 2009, 06:44:06 PM

lol i wanted an 03 r6, but i love the classics, and im young and dumb! lol. but i thought i heard that you can bore out the exhaust for better flow giving more power?

I'm glad you took that kindly... it was meant that way.
I would suggest a more free flowing exhaust for you.
It will sound louder, thus, make you feel like you are going faster!

Make sure to start it up between removing the exhaust and adding the aftermarket... it'll be fun, I promise!

Loki · « **Reply #23 on:** December 17, 2009, 06:53:00 PM »

but boring the cylinder head exhaust holes wont give you more power?

mlinder · « **Reply #24 on:** December 17, 2009, 07:08:39 PM »

Quote from: kre-eper on December 17, 2009, 06:53:00 PM

but boring the cylinder head exhaust holes wont give you more power?

The 550 head is not restrictive at low rpm.

Increasing valve size and doing a port job allow the head to breath more freely at high rpm.
Low rpm can actually suffer from too large of ports and valves, as power is dependant on intake velocity.
Velocity is created by restriction. You'd probably loose low end by increasing valve size and porting (well, porting for more airflow, not quality of airflow, theres a difference.)

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Author Topic: building engine (Read 3406 times)

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