Author Topic: CB550 Track Bike (Read 41321 times)

Rocketman · « **Reply #75 on:** May 31, 2014, 02:55:34 PM »

Just started the motor for the first time!!!!

What a thrill!!! Here are some photos of how I got there.

Assembling the frame

Wrapped the frame in rubber roofing to protect the paint.

Motor in the frame with no damaged paint.

Details of the front brake splitter.

CB750 carbs and velocity stacks installed.

I managed to bend one of the bronze swingarm bushings. It as a tight fit and a little more force was too much! New set is on the way.

Using a hole saw to cut the center out of a tappet cover. It will be used to protect the threads in the cam cover when checking valve to piston clearance.

Checking valve to piston clearance. All is in order.

Accent ignition installed and adjusted.

Dyna 3 ohm coils and new wiring harness. Not much wiring on a total loss system.

Battery hooked up and ready to start!

I way under estimated how loud the megaphones are. Will take the motorcycle to a friends out in the country side to break in the motor tonight. Will take some video and post it.

SOHC4 Cafe Racer Fan · « **Reply #76 on:** May 31, 2014, 03:14:46 PM »

Quote from: Rocketman on May 31, 2014, 02:55:34 PM

I way under estimated how loud the megaphones are. Will take the motorcycle to a friends out in the country side to break in the motor tonight. Will take some video and post it.

Saw that coming in a good way. I can't wait for the video.

Hopefully, it sounds a little like the RC166. Check out the sound at :50

http://youtu.be/eaRop_ZMwo0

Tews19 · « **Reply #77 on:** May 31, 2014, 03:49:03 PM »

That looks sweet! Waiting for a video with lots of anticipation

Rocketman · « **Reply #78 on:** May 31, 2014, 07:54:45 PM »

I have posted a video on You Tube warming up the motor. The exhaust is a tiny bit quieter in my friend's shop with the overhead door open.

Changing the oil and wondering if I chance a back road run or do the smart thing and wait for the track. Many years ago I would break in my TD2 on a lonely country road. One of my favorite sayings is 'To be old and wise you must first be young and foolish'.
http://youtu.be/BN9k7j9-UCU

DustyRags · « **Reply #79 on:** June 03, 2014, 11:48:46 AM »

BRB BUYING A 550 AND MEGAPHONES!

SOHC4 Cafe Racer Fan · « **Reply #80 on:** June 03, 2014, 06:33:37 PM »

Sounds appropriately angry.

Tews19 · « **Reply #81 on:** June 04, 2014, 06:46:40 PM »

That is sweet.

Rocketman · « **Reply #82 on:** June 23, 2014, 07:06:24 PM »

Haven't been able to schedule any dyno time, but more progress to share. Bought a real nice cover for the points side from Joker Machine. Wasn't sure it could be done, but asked a machinist Friend if he could cut the alternator side off in his lathe. He was able to use a 4 jaw chuck in the inside.

Took it slow and was able to cut it down.

Cut a piece of aluminum plate down with a jig saw and files to make the cover.

I think it turned out real nice.

Here is the best part. My painter buddy finished the tank and seat. Here they are mounted on the motorcycle. It looks better than I hoped for. Need to finish the front fender then get it on the dyno and see what it will do.

bwaller · « **Reply #83 on:** June 23, 2014, 07:23:41 PM »

It does look great, well done.

I wish I would have thought about it earlier, I have an alternative left end cover I could have sent you.

Tews19 · « **Reply #84 on:** June 24, 2014, 07:16:34 PM »

BOTY possibly!

Rocketman · « **Reply #85 on:** June 26, 2014, 08:42:54 AM »

Just scheduled dyno time at Larry Pegram's Performance Center Saturday. Looking forward to seeing if the CB750 carbs work and what it will do. I'll post the numbers, good or bad. Appreciate the comments and suggestions.

Rocketman · « **Reply #86 on:** June 29, 2014, 05:38:58 PM »

Saturday was one of those one step forward and two steps backward days. Took a short ride around the neighborhood before heading to the dyno and found I have no second gear. I am generally very careful to check the gearbox when the cases halves are bolted together. I have made the mistake of assembling and installing a motor in the frame only to find the gearbox is not shifting correctly. I was sure I had all 5 gears when I last checked, so not sure what the problem is. Will do all I can before pulling the motor back apart as a last resort. Decided to roll the dice, loaded the cycle, and headed for the dyno.

Once on the dyno I warmed it up, made three 1/2 throttle pulls to 6,000 rpm, then shut it down to cool for 15 minutes. No strange noises or issues with the transmission so far. The second session was same as the first with the exception of three 3/4 throttle pulls to 8,000 rpm, then another 15 minutes of cool down. For the full throttle pulls the dyno operator took over, warmed the bike and tried to make full throttle pulls. No joy! The jetting was off the chart lean. The stock jets are 110 and the biggest I had was 120. Put the 120s in and put two washers under each needle. Back on the dyno, still way too lean, but at least on the graph at 17:1. Just for grins we covered half of the velocity stack opening with duct tape and tried again. The fuel air was 12:1 and you could hear the difference in the exhaust note. Best horsepower was 40.

I have 78 CB750 carbs which have no adjustment to the needles. Will need to see what I can find or keep adding washers. It seems to me that the 77 carbs had adjustable needles. Will need to do some research. Also need to go richer on the pilots which are pressed in. Another area to research. I'll see what I can find before throwing in the towel and ordering the smooth bores. More to come.

Here is a Youtube link to the 3/4 throttle pulls:

http://youtu.be/_-kQVdZCsng

Tews19 · « **Reply #87 on:** June 29, 2014, 05:45:57 PM »

Sounds so nice! Cylinder one seems to have flames coming out of the exhaust.

Rocketman · « **Reply #88 on:** June 29, 2014, 05:51:39 PM »

First four stroke "race" bike, but I'm pretty sure that is from the lean jetting.

bwaller · « **Reply #89 on:** June 30, 2014, 04:01:17 AM »

Pull the clutch to check there isn't an issue with the shift mechanism before you pull the engine. Those pilots are a nuisance. I've used tapered jet reamers to enlarge them, but you also really need something like gauge pins to check your work.

Rocketman · « **Reply #90 on:** July 16, 2014, 04:35:59 PM »

This is one of those better to be lucky than good stories. Before pulling the clutch cover to trouble shoot the no second gear problem I decided to pull the oil pan and see what had accumulated from the dyno runs. You can imagine my suprise when I found a shifter fork!

I'm thinking how in the heck did that get there and what sort of damage has occurred as a result. There was a little debris in the pan, but nothing out of the ordinary, such as gear teeth. I then pulled the clutch cover and the how was quickly apparent.

The shaft the shift forks ride on was out of place. I had installed the retainer for the shift drum backwards . The "thumb" that covers the end of the shaft was on the wrong side.

After carefully checking the shift fork and finding no damage, I laid the cycle on its side and inspected the transmission. I had dogged a huge bullet as there was no apparent damage there either. I was able engage the shift fork in the slot for the gear, rotate it into place, and slide the shaft back in. With the retainer now installed correctly I once again had second gear!

The new jets and needles for the carbs have arrived. I've scheduled another dyno run for next Tuesday and will post the results.

bwaller · « **Reply #91 on:** July 16, 2014, 05:54:21 PM »

Well Martin you know what they say.....you've got to be good to be lucky!

Now, cross your fingers & toes for me, we're off to the next race round tomorrow.

SF · « **Reply #92 on:** July 16, 2014, 08:08:40 PM »

Holy crap that's good news! Been following along and really like your bike

SOHC4 Cafe Racer Fan · « **Reply #93 on:** July 16, 2014, 08:20:26 PM »

Dodged a major bullet there!

Tews19 · « **Reply #94 on:** July 17, 2014, 02:34:53 PM »

Rocket you are missing a bolt by the half moon washer.

Rocketman · « **Reply #95 on:** July 17, 2014, 06:31:20 PM »

Missing Bolt!

LOL! My heart was racing for a few seconds until I spotted it. Actually that bolt holds part of the shift mechanism and was reinstalled. Thanks Tews19 for looking out for me.

In looking back through my posts I can see my mistake in a prior photo. (post #68)

Brent, Good luck at the races. Looking forward to reading about it in your blog.

Rocketman · « **Reply #96 on:** July 24, 2014, 06:24:06 PM »

Had my CB550 back on the dyno Tuesday. Worked my way from 150 mains, to 140, and finished at 130. The needles are from the 77 CB550, F205IE, started with the clips in the middle and ended with them in the lowest slot. It is amazing what getting close to the ideal air/fuel ration will do. There were some 20 HP holes in the power curve after the dyno runs a couple weeks ago.

Here is the air/fuel (bottom lines) from the 140 mains & clips in the middle(red line) and 130 mains clips in the bottom (green line) today and HP (top lines). Still lean in the midrange, will try shimming the needles first before changing them.

Here is the HP for the 120 mains (blue line) during the first dyno session and today's runs with 140 mains (red line), and 130 mains (green line).

Time to sort the suspension and get out on the track.

bwaller · « **Reply #97 on:** July 27, 2014, 09:13:18 AM »

RM, I know you mentioned JE pistons, what bore size? Are there any other jobs to complete before you do a trackday?

Rocketman · « **Reply #98 on:** July 28, 2014, 01:15:45 PM »

Hoping to do a track day at Nelson Ledges August 30. The only "must do" is the swing arm pivot. When I installed the brass bushings the total swing arm width at the pivot ended up wider than the pivot tube. May need to have a new pivot tube made or come up with spacers for the tube. The fairing is still in the works at this point. I want to put cartridge emulators in the Red Wing forks, but that will need to wait until winter. I guessed at 150cc of 20 wt fork oil and ended up 7" below the fork top when collapsed. A steering damper and catch pan are on my list, but think I can do a track day even if they do not get done.

Trad · « **Reply #99 on:** July 28, 2014, 01:50:08 PM »

What is causing the lean spots? It seems like 120 and 130 mains are really rich. Also, wouldn't the increased cylinder bore size cause more vacuum, in turn needing to bump down the main jet? Clearly my assumptions are wrong judging from the dyno info.

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Author Topic: CB550 Track Bike (Read 41321 times)