Topic: boosted cb550 bobber bike build (Read 18956 times)

swansmaa · « **on:** August 19, 2013, 01:33:29 AM »

scored a rough old bike a wile back, and now im getting around to building something out of it. Its a 1975 honda cb550. The plan is to build a hardtail bobber, thats boosted with a draw through single carb setup.

got it stripped down and chopped up the frame a little

start of building the intake. making 1 of 2 flanges

made the intake collector. turned out alright

intake flanges

mmmmm pie

2 runners done. chop saw and angle grinder got a good workout

better shot of the collector. cut the pieces with a cutoff wheel and mig'ed em up

this is all the progress for now, gotta get some more steel tomorrow.

Ntrain2k · « **Reply #1 on:** August 19, 2013, 06:35:49 AM »

Well done!

92CXyD · « **Reply #2 on:** August 19, 2013, 09:12:00 AM »

Looking forward to progress on this build.

Well balance pr0n with turbo bike build.

dvst8r · « **Reply #3 on:** August 19, 2013, 10:41:22 AM »

I approve this message.

PhilStubbs · « **Reply #4 on:** August 19, 2013, 12:07:02 PM »

Text book newb post.

Reported

crxvtec91 · « **Reply #5 on:** August 19, 2013, 12:47:06 PM »

Well done

ratcityrex · « **Reply #6 on:** August 19, 2013, 02:47:50 PM »

Quote from: crxvtec91 on August 19, 2013, 12:47:06 PM

Well done

swansmaa · « **Reply #7 on:** August 22, 2013, 02:31:04 PM »

made a little more progress. bike is a roller now and I finished tacking up the other 2 intake runners. Also threw a 30mm mikuni on it

carkrazed · « **Reply #8 on:** August 22, 2013, 09:48:31 PM »

CB's are narly. Likin this build

swansmaa · « **Reply #9 on:** September 26, 2013, 03:01:21 PM »

made a little progress. built a more direct exhaust header, got the oil feed/return plumbed up, and the intake mani is off for powdercoat right now. also just won these little guys to let her breathe. 40mm flatslides (i only need one of them) 29.50 shipped

jabberwock · « **Reply #10 on:** September 26, 2013, 05:27:33 PM »

You may want roundslide. Flats are more likely to get stuck open when breathed on. Give the flat a shot though, something to think about if it sticks.

swansmaa · « **Reply #11 on:** September 26, 2013, 07:22:35 PM »

Quote from: jabberwock on September 26, 2013, 05:27:33 PM

You may want roundslide. Flats are more likely to get stuck open when breathed on. Give the flat a shot though, something to think about if it sticks.

ahh thanks for the heads up. i think ive got a pair of 38mm round slides that i can swap if its an issue.

rawr · « **Reply #12 on:** September 26, 2013, 10:17:10 PM »

I like the way bobbers look, but I wouldn't fucking ride one.

Do a wheelie

swansmaa · « **Reply #13 on:** October 01, 2013, 12:38:11 AM »

got the carbs in the mail today, and my buddy finished up powder coating the intake so i made a little progress.

new megaphone/log style header is all welded up, painted with high temp black, and wrapped in header wrap. Forgot to take pics while building it, but im happy with how it turned out.

got a buddy to machine me a steel oil galley plug with the metric male threads and an 1/8" pipe thread tapped into it. Much stronger than drilling/tapping the hollow aluminum plug. The T fitting feeds the turbo oil inlet and an oil psi gauge.

Intake is powdered high temp black and bolted up to the cylinder head.

new carb: gotta make a couple slight mods but it should work out well. 40mm flatslide mikuni, with plenty of main jets/ pilots/needles available thanks to the snowmobile world.

got a few more things to give some attention to, and i'll be pretty close to seeing if it will run.

PhilStubbs · « **Reply #14 on:** October 01, 2013, 09:09:53 AM »

Does that turbo have the proper seals(the actual name is escaping me currently) for a draw through setup or is this a "fuck the man" situation and just see what happens? I'm curious on the results either way. I have a cb750 that needs boost

92CXyD · « **Reply #15 on:** October 01, 2013, 09:50:00 AM »

Awesome the picture of the powder coated intake looks like some one MS painted it in.

Looking at the turbo manifold, does the rider have enough room for his legs to not get burnt?

In this pict:

The header looks to extend past the frame a bit.

Liken' this build, major Props.

PhilStubbs · « **Reply #16 on:** October 01, 2013, 09:57:15 AM »

With all of my miles of Harley riding with exhaust between your leg and engine, I think he will be fine

swansmaa · « **Reply #17 on:** October 01, 2013, 02:06:35 PM »

Quote from: PhilStubbs on October 01, 2013, 09:09:53 AM

Does that turbo have the proper seals

nope.

Quote from: PhilStubbs on October 01, 2013, 09:09:53 AM

or is this a "fuck the man" situation and just see what happens?

exactly.

Quote from: 92CXyD on October 01, 2013, 09:50:00 AM

Looking at the turbo manifold, does the rider have enough room for his legs to not get burnt?

it will probably be a little close, but shouldnt be a deal breaker. i'll probably get a couple burns and then learn to avoid it.

PhilStubbs · « **Reply #18 on:** October 01, 2013, 03:06:40 PM »

Quote from: swansmaa on October 01, 2013, 02:06:35 PM

Quote from: PhilStubbs on October 01, 2013, 09:09:53 AM
Does that turbo have the proper seals
nope.

Quote from: PhilStubbs on October 01, 2013, 09:09:53 AM
or is this a "fuck the man" situation and just see what happens?
exactly.

swansmaa · « **Reply #19 on:** October 02, 2013, 03:03:59 PM »

got the downpipe welded up. just needs a few little things and ill be close to making some noise hopefully

swansmaa · « **Reply #20 on:** October 03, 2013, 01:45:43 AM »

fucker runs. havent touched the jetting or anything yet, but it runs.
Cb550 turbo

yes. i know the vid. is shitty quality and sideways. heres some redheads to make up for it.

PhilStubbs · « **Reply #21 on:** October 03, 2013, 07:40:04 AM »

Badass, I need to start on my 750 now.

turbohf · « **Reply #22 on:** October 03, 2013, 09:07:30 AM »

gas tank looks road worthy.

swansmaa · « **Reply #23 on:** January 17, 2016, 05:46:09 PM »

https://www.youtube.com/watch?v=CaVHN-DM6GQ

well I haven't quite forgotten about this project, been fucking with it a little lately. got quite a few more things done, and im working on jetting. I can turn the fuel screw all the way in on the 40mm flatslide mikuni, and it does not stall out at idle. This should mean the pilot circuit is too rich. Stock pilot jet was a 17.5. I tried a 15 and a 12.5 today and they have the same results. I just ordered a size 10 pilot jet, and it looks like thats the smallest size offered. What do I do if idle is still too rich with a size 10 pilot? Am I doing something wrong?

ratcityrex · « **Reply #24 on:** January 18, 2016, 02:05:03 PM »

Quote from: swansmaa on January 17, 2016, 05:46:09 PM

What do I do if idle is still too rich with a size 10 pilot?

More boost!!

Random Hero · « **Reply #25 on:** January 18, 2016, 09:17:32 PM »

Quote from: swansmaa on January 17, 2016, 05:46:09 PM

https://www.youtube.com/watch?v=CaVHN-DM6GQ

well I haven't quite forgotten about this project, been fucking with it a little lately. got quite a few more things done, and im working on jetting. I can turn the fuel screw all the way in on the 40mm flatslide mikuni, and it does not stall out at idle. This should mean the pilot circuit is too rich. Stock pilot jet was a 17.5. I tried a 15 and a 12.5 today and they have the same results. I just ordered a size 10 pilot jet, and it looks like thats the smallest size offered. What do I do if idle is still too rich with a size 10 pilot? Am I doing something wrong?

You may have the slide idle stop screw set to high/far in and it might not be using just the pilot jet anymore. try moving the center needle in further (c clip up 1 notch)

swansmaa · « **Reply #26 on:** January 19, 2016, 12:58:51 AM »

Quote from: Random Hero on January 18, 2016, 09:17:32 PM

You may have the slide idle stop screw set to high/far in and it might not be using just the pilot jet anymore. try moving the center needle in further (c clip up 1 notch)

I have gotten the same response from others now, and this is making sense. If I drop the slide anymore it dies. Heres a video of what I can currently get for an idle:
https://www.youtube.com/watch?v=UkLiAaB0auw

swansmaa · « **Reply #27 on:** May 21, 2017, 02:22:24 PM »

well she's a runner. revs to a healthy 12+ grand and makes a good 14psi of boost once you're up there. starts boosting good after 7k. Bout 100 miles on it so far, starts and runs great but still has room to lean down the main jet a couple sizes.

https://drive.google.com/open?id=0B0tuIVPtbJTgUUNWSzJ0ZUJsclE

swansmaa · « **Reply #28 on:** May 21, 2017, 02:23:49 PM »

rawr · « **Reply #29 on:** May 21, 2017, 05:55:41 PM »

rad as fuck i'd ride it.

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Author Topic: boosted cb550 bobber bike build (Read 18956 times)