Author Topic: 1979 CB650 brat style first build. (Read 7875 times)

BollarNPS · « **on:** July 16, 2015, 03:48:42 PM »

Hello All,

Purchased my cb650 for 400$ and it ran when you put fluid in carbs. Pulled carbs and cleaned them a little not as well as i should have but to my defense i was not at my house and didnt have all my stuff. I intend on re pulling them and dipping them to get a real good clean job thoroughly shooting air through all holes. I have purchased pods as i want a clean look. I know that it will be a pain to tune but im willing to work with it. Im waiting on the pods to get started much more. I have order 42 pilots and 120 mains as i heard this is good to start with as im close to sea level. Thinking about purchasing a new master cylinder from china (the ones that are like 20$). Id like to hear the thoughts on this if you've used them before. I also plan on removing rear fender. Im thinking about chopping the front one down a little smaller but will wait till the end for this as i would rather keep it full if it looks good. Im waiting to do anything cosmetically until i get it running well enough for the road. New shocks, and new front fork seals. As this is my first build it may be slow but i love these bikes with a brat seat. Planning on black frame, white tank with red Honda logo. I have also been cleaning out the tank with apple cider vinegar. Ive fulled it and emptied 3 times now and its looking real good inside now. Here she is as i received her.

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SOHC4 Cafe Racer Fan · « **Reply #1 on:** July 16, 2015, 04:06:11 PM »

Bollar,

Congratulations on your purchase and welcome to the forum.

Soaking your carburetors alone will not get them completely clean. You will want to clean them with an ultrasonic cleaner with solvent to get the stubborn gas-turned-into-varnish to release. Then, you will want to vacuum synch the carburetors to tune them. In addition to jets, you may want to acquire some rebuilt kits with gaskets.

I would avoid buying a cheap $20 MC from China. They are pretty much crap. You can likely rebuild your MC with a rebuild kit, unless the corrosion is extensive. OR, you can buy a decent quality MC.

New shocks are a good idea, as are new fork springs, fork oil and seals. You can get some decent Progressive, Hagon or IKON shocks to replace the worn out stock shocks.

As for the brat seat, I understand they have an aesthetic appeal, but have you ever ridden a motorcycle for a 100 miles on a brat seat? It is like sitting on a skateboard deck. You butt will be sore/numb. You can use the stock seat and shave down the foam and re-upholster it with a slimmer seat with some padding. Your butt will thank you for it. If you insist on going with a brat seat, you may zip tie it to the frame BEFORE cutting tabs and riding the bike. It may look neat, but it is very uncomfortable not having a modicum of seat padding. If all you want to do is look cool and ride ten or twenty miles, bring on the brat. Just something to consider. . .

BollarNPS · « **Reply #2 on:** July 16, 2015, 06:44:15 PM »

Thanks for the input. This would likely be a ride around town bike. I plan on having some cushion just not alot. This bike will be my daily to work until i can finance a nice newer one. I will still keep this baby of course. I have a whole carb rebuild kit already. I also have a place that is willing to ultrasonic clean my carbs for 12$ and glass bead whatever doesnt come off. For the ultra sonic should i tear it completely down or can the rack stay together?

calj737 · « **Reply #3 on:** July 17, 2015, 04:24:46 AM »

If the place can ultrasonic ally clean them on the rack, leave them together. But do NOT glass bead them. Soda blast is fine, but glass beading is apt to open orificies that you don't want effected. Of course, you'd have to re-U/S clean them afterwards.

SOHC4 Cafe Racer Fan · « **Reply #4 on:** July 17, 2015, 07:37:29 AM »

Glass bead blasting is fine when you are going to completely disassemble and thoroughly clean a part. Of course, it also makes sense to disassemble first. Another option is soda blasting.

BollarNPS · « **Reply #5 on:** July 19, 2015, 10:19:14 PM »

Still waiting on my pod filters!!!!!! this is by far the worst ebay transaction ive ever had. In the mean time i dumped the cider vinegar out of my tank which still seemed a bit rusty but the inside of the tank is looking real good now. Since it is hard to get the last little bit of liquid out of the tank which i fear might have rust stuff in it i thoroughly shot a ton of water into the tank flushing everything out. Once the water began to come out clean i shook all of it out and replaced it with more vinegar to prevent flash rusting. Trying to decide if i should try to line in the inside of the tank or if i should fill her up with gas and just leave it. Also i tested compression which of course once i finished i realized i did it wrong which idk if it would have much effect. I have mechanical carbs and i did it with no throttle. My readings were cylinder 1 - 150 cylinder 2 - 145 cylinder 3 - 130 - cylinder 4 - 145. this was a dry test and i know there is room for improvement. the bike was not warm as i have no tank hooked up at the moment. I believe that these numbers will work for now just to get her tuned up.

Ravie · « **Reply #6 on:** July 20, 2015, 12:15:23 PM »

If it doesn't leak don't line it. No reason to just for fun. It's a #$%* to get it to stick right and an even bigger #$%* when it doesn't and you have to try to remove it. Run a filter inline to catch any extra gunk and don't worry about it; SO LONG as it doesn't leak.

Eh, you may not have done it right but you still got pretty consistent numbers. i wouldn't worry about it...it looks like it's probably plenty healthy in that respect.

BollarNPS · « **Reply #7 on:** July 20, 2015, 06:05:20 PM »

Finally relieved my pod filters. Installed them and the bike starts up with choke. Previous owner seems to have installed a 750 choke since it is a metal hook rather than a plastics one that I hear about. Need to some how rig up the choke knob as I believe a piece is missing because I have to pull the whole cable assembly rather than just the know I'll grab some pictures of it tomorrow. But bike seemed do be doing decent since I didn't change out jets. Gonna pull carbs soon and ultra sonic clean them and swap out jets.

BollarNPS · « **Reply #8 on:** July 22, 2015, 07:13:40 PM »

Ordering progressive springs and fork seals tonight so I can get that done. I'm going to put gaiters on the forks as well. I think I'm going to have the lower part of the forks powder coated black while they apart as well. Took the head light off today as well to sort out some wiring issues and wow I couldn't how much of the harness they shove in there!!

zekd · « **Reply #9 on:** July 23, 2015, 06:24:01 AM »

sweet ride. can't wait to see the progress!

BollarNPS · « **Reply #10 on:** July 25, 2015, 01:59:31 PM »

Currently cleaning carbs with this little harbor freight ultra sonic cleaner and boy am I impressed!!! Hopefully I can get the carbs back together lol.

BollarNPS · « **Reply #11 on:** July 26, 2015, 02:16:39 PM »

So took carbs all apart and cleaned them up with the harbor freight ultrasonic cleaner which i now speak highly for. probably ran that thing non stop for 3 or 4 hours yesterday. Its only 2.5 liters so i had to take carb completely apart which is for the best anyway. Most the screws were stripped already so i will wait to install the carb on the bike till Tuesday so i can go up to the hardware store and buy replacements. I rather have stainless allen caps anyway. It cleaned everything really good in my opinion youll have to look at the pictures and see for yourself. Accidently had black and white mode turned on so most the pictures are worthlesss for seeing how dirty they were at the beginning.
Before--

After ------

Im happy with the results and i found some issues to that will help me get the bike running better. Not one of the idle air screws had a washer or an o-ring, the PO had the slide for carb 4 in backwards?!?!? idk beats me how they did that one. Think i can re use this screw??

Also the boots were all cracked so i ordered some new ones.

Purchased new plug wires as mine were cut in spots and wrapped in electrical tape. Also after cleaning tank found that i have 2 pin holes in tank so i have caswell on order as well too. Will be posting detailed pictures while doing that to. Thanks for everyone's help on the site!!!

calj737 · « **Reply #12 on:** July 26, 2015, 05:33:42 PM »

It's fine to use stainless cap head screws, but be mindful: you should use a dab of antiseize, and do NOT over tighten them. They will tear the threads out of the carb body lickety-split.

SOHC4 Cafe Racer Fan · « **Reply #13 on:** July 26, 2015, 05:34:11 PM »

Very nice job cleaning those carb bodies. That was a good decision to get new rubber manifolds.

BollarNPS · « **Reply #14 on:** July 26, 2015, 05:59:00 PM »

might be a silly question but what type of metal is best for the screws then?

calj737 · « **Reply #15 on:** July 26, 2015, 06:34:28 PM »

Stock screws were zinc plated. Stainless is fine, just use care. Too many folks over tighten with the Allen wrenches and since stainless is harder than alloy, the threads tear out. Cinch them up, just no ham fisting them-

BollarNPS · « **Reply #16 on:** August 08, 2015, 04:05:15 PM »

Decided to dive into rebuilding forks today but figured I would polish the lowers before I rebuild so I didn't in anyway hurt the new seal once on. Needless to say it to much longer than I thought to polish the forks and they could still look better. Gonna do the fork rebuild tomorrow though. So does anyone have any tips or tricks I should use or need to know about? Anyway here's pics of forks and my motorcycle lift

Thanks for looking!!!

SOHC4 Cafe Racer Fan · « **Reply #17 on:** August 08, 2015, 04:33:46 PM »

Are you sticking with the air assist (not sure if the 79 had that) or closing the valves off?

CBJoe · « **Reply #18 on:** August 08, 2015, 09:12:32 PM »

Quote from: CB750 Cafe Racer Fan on August 08, 2015, 04:33:46 PM

Are you sticking with the air assist (not sure if the 79 had that) or closing the valves off?

The air assist didn't start until '81 if I'm not mistaken.

Joe

SOHC4 Cafe Racer Fan · « **Reply #19 on:** August 08, 2015, 11:13:15 PM »

Quote from: CBJoe on August 08, 2015, 09:12:32 PM

Quote from: CB750 Cafe Racer Fan on August 08, 2015, 04:33:46 PM
Are you sticking with the air assist (not sure if the 79 had that) or closing the valves off?

The air assist didn't start until '81 if I'm not mistaken.

Joe

I've only actually seen '81 and '82 models up close, so I'm not surprised.

BollarNPS · « **Reply #20 on:** August 09, 2015, 12:08:05 AM »

I don't believe I have anything like that

BollarNPS · « **Reply #21 on:** August 09, 2015, 02:10:17 PM »

So rebuilt the forks today was pretty easy besides getting those dang seals out but found that the wife's hair dryer makes it easier from the site. Put on some gaiters and then added new headlight brackets to lower the headlight. The goo that came out of the forks was dang near solid. And here are the pics!! Thanks for looking

And I decided to mock up a seat pan out of cardboard I refuse to cut the frame so if I can't make it look decent then I'll switch to cafe but I got a good feeling bout it.

I plan to just put a small layer of padding where the hump is and then cushion even with that all the way up. That still gives me about 2.5 to 3 inches of padding hope that's pretty decently comfy. The seat will end behind the hump and the left over frame there will be covered by a brake light slash license plate. Still waiting on my clubmans then I will lower the gauges and such to be more even with the new headlight position. Next I will conquer the gas tank.

BollarNPS · « **Reply #22 on:** September 30, 2015, 07:07:25 PM »

Been awhile since i posted on here but got a few updates. Instead of lining the tank itself i took it to a radiator shop where they welded the holes and used red kote. I chose to do this cause i wasn't welding the dang thing and they guarantee it will not separate for 12 months or they fix. maybe it just fails after 12 months and a day..... ha ha ha. oh well get to that when it happens i hope not though. I then changed out my plug wires and boots which fixed my issue of cylinder 2 not firing. Put the carbs back on the bike finally and started here up. I've never heard one of these bikes before so I'm unsure if it should sound this way. Got numerous electrical demons to figure out but it runs at the moment. Looking to buy tires soon. suggestions? idc what they look like i just want something that preforms and doesn't blow out on me. Bike is still smoking while running and i cant tell if its blue or gray smoke. could never tell the difference in the two. I also added clip ons as the clubmans were too far of a stretch for me. I like the position right now. Will also start on the seat pan soon. i will try loading this video of it running.

Please let me know if this sounds like total crap or what? thanks

BollarNPS · « **Reply #23 on:** October 29, 2015, 04:14:58 PM »

Soo little update. I ended up cut the rear frame cause i wasnt happy with how it was turning out. I decided if im gonna make this bike my own i have to commit to making it how i want it even though alot of people on here dislike this option. Got a frame hoop and seat pan from dime city and i welding the hoop on and grinded off some of the extra tabs. i also got it start and running even better than the last video ill try and load that one later. when running i didnt leave it running too long but i used a laser thermometer to check header temps and 1 3 4 are all between 110-115 and 2 is 95-100. what would cause this little difference in temp. i didnt leave it running to long so maybe it would even out? not sure. wires and plugs have been changed but the coils have changed the same. The turn signal relay is also clicking and vibrating when the key is turned out. i havent re done or cleaned anything electrical yet.

SOHC4 Cafe Racer Fan · « **Reply #24 on:** October 29, 2015, 05:23:56 PM »

The 1979 650 frame is much easier to work with since the frame rails do not dip as low in the rear as the 1980-92 frames.

Pics please!!

calj737 · « **Reply #25 on:** October 30, 2015, 06:14:28 AM »

Quote from: BollarNPS on October 29, 2015, 04:14:58 PM

i used a laser thermometer to check header temps and 1 3 4 are all between 110-115 and 2 is 95-100. what would cause this little difference in temp.

Most likely culprit is the #2 carb is slightly out of balance or A/F mixture with the others. It could be down to needing a vacuum synch, mixture screws, fuel level (floats) or worn innards.

BollarNPS · « **Reply #26 on:** October 30, 2015, 07:29:20 AM »

silly me! yeah thats what ill be doing today is vaccum syncing it. The frame hoop is still unpainted and im redoing the battery box as metal and relocating to the center so still uncomplete pictures in a bit. Just dont wanna get to much more into the customizing till shes ridable. Carb four is still leaking fuel through the overflow and ive adjusted the float about as much as possible so im thinking its the neeedle tips rubber is to hard and just isnt working good enough.

calj737 · « **Reply #27 on:** October 30, 2015, 07:44:56 AM »

Quote from: BollarNPS on October 30, 2015, 07:29:20 AM

Carb four is still leaking fuel through the overflow and ive adjusted the float about as much as possible so im thinking its the neeedle tips rubber is to hard and just isnt working good enough.

Remove the bowl, fill it with fuel. Does it leak? If so, the overflow tube may be cracked and its not an indication of fuel level issues.

BollarNPS · « **Reply #28 on:** October 30, 2015, 07:57:53 AM »

So I'm not great at welding so there is much more grinding to do but I'm gonna wait on that.

I'm not sure how to attach by the tank as it is obviously higher than everything else and I would like a flush fit.

calj737 · « **Reply #29 on:** October 30, 2015, 08:09:30 AM »

Well your pan needs to be shorter than it is to not interfere with the tank retaining bolt. That will create a large "gap" between the end of the tank and the seat, partly due to the style of seat, partly due to the configuration of the tank at the rear.

You could drill holes through the seat rail from underneath, then install a rivet nut into the pan, and screw the pan to the rail from below. Or do the same thing thru the cross brace at the mid point of the rails. Brat seats are tricky to mount in a clean and serviceable fashion.

BollarNPS · « **Reply #30 on:** October 30, 2015, 08:16:00 AM »

Yeah it's a fuel issue it will stay full. Maybe I could cut a piece out of the pan so it fits around the tank mounting bracket?

swleathercraft · « **Reply #31 on:** October 30, 2015, 11:29:05 AM »

Quote from: BollarNPS on October 30, 2015, 07:29:20 AM

silly me! yeah thats what ill be doing today is vaccum syncing it. The frame hoop is still unpainted and im redoing the battery box as metal and relocating to the center so still uncomplete pictures in a bit. Just dont wanna get to much more into the customizing till shes ridable. Carb four is still leaking fuel through the overflow and ive adjusted the float about as much as possible so im thinking its the neeedle tips rubber is to hard and just isnt working good enough.

I have this exact same problem on number 3 and 4 carbs on my 79 cb650. Still working it out.

Sgt.Pinback · « **Reply #32 on:** October 30, 2015, 11:38:19 AM »

Thanks for sharing!

BollarNPS · « **Reply #33 on:** October 30, 2015, 11:52:19 AM »

so for the Sgt. i just took the float out while it was still on the bike and replaced the float needle (not sure if thats the correct term) and this fixed the issue. When i rebuilt carbs i bought these but didnt change these as they seem to be in good condition. Try it out!

swleathercraft · « **Reply #34 on:** October 31, 2015, 02:14:09 PM »

Ok it was the float needles. I replaced them and the problem is resolved

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Author Topic: 1979 CB650 brat style first build. (Read 7875 times)