Author Topic: 71 CB500 project. (Read 8739 times)

cafehonda500 · « **on:** February 12, 2015, 11:39:21 AM »

Hello everyone. This is my first post on here and I figure I should start out with my bike. Its a 71 CB 500f based off the numbers on the plates. bought it from a guy who claimed to work on it a little. It did run though. Wiring harness looks choppy though. After about 10min of idle it would die though. So something with electrical. It came with extra exhaust so put on the 4-2 sidepipes. Put uni foam pod on for air Intake (no hate please I know what mess I just got into). Had a guy drill out my jets. Idle to 42 and main to 120?(I think he said that. He knows his #$%*). New spark plugs. New Dyna 5ohm coils. New wires. New NGK 5ohm boots. Right now having carb issues. They keep leaking lol. Have *fixed* them many times still leak. Here's some Picts too. Sorry can't find my good ones of it.

rb550four · « **Reply #1 on:** February 12, 2015, 02:04:21 PM »

Hello and welcome.
Dies after 10 mins. of idle , carbs are leaking like crazy,and you suspect electrical?
Is it left to idle on the centerstand or the sidestand?
What part of the carbs are loosing fuel?
Have you cleaned the petcock to ensure proper flow? inspect the inside of the tank for debris and condition?
What have you done to the carbs so far?Have you done a proper cleaning?
Are all your pipes hot? Try it on both centerstand and kickstand , see if all the pipes are hot in each position. I'd suspect fuel starvation on the kickstand well before electrical being the trouble.
Why is the wiring choppy? I see new aftermarket coils,plugs boots and wires , do you suspect that or other wiring issues.
How well did it idle before the pods and jet drill?

calj737 · « **Reply #2 on:** February 12, 2015, 03:03:12 PM »

I'm siding with RB in this. Fuel issue, probably floats. Drilling jets is a major boondoggle! Best to straight up replace them and 120s sound awfully large. Problem with drilling them is, if you solve them Robles with float levels, then your jets are too large and now you will be fouling the plugs.

You should avoid just letting the bike idle away for prolonged periods unless you have a cooling fan blowing air over the motor (air cooled motor and all that)

Retro Rocket · « **Reply #3 on:** February 12, 2015, 03:09:33 PM »

Keep the airbox, you'll thank me later....

cafehonda500 · « **Reply #4 on:** February 13, 2015, 07:16:31 PM »

Quote from: rb550four on February 12, 2015, 02:04:21 PM

Hello and welcome.
Dies after 10 mins. of idle , carbs are leaking like crazy,and you suspect electrical?
Is it left to idle on the centerstand or the sidestand?
What part of the carbs are loosing fuel?
Have you cleaned the petcock to ensure proper flow? inspect the inside of the tank for debris and condition?
What have you done to the carbs so far?Have you done a proper cleaning?
Are all your pipes hot? Try it on both centerstand and kickstand , see if all the pipes are hot in each position. I'd suspect fuel starvation on the kickstand well before electrical being the trouble.
Why is the wiring choppy? I see new aftermarket coils,plugs boots and wires , do you suspect that or other wiring issues.
How well did it idle before the pods and jet drill?

thanks for the fast reply! Ok First off i guess i did not describe the issue properly. I could putt the bike up and down my driveway (1/4 mile) for once or twice at about 10mph if that. was low rpm in 2nd gear. The bike would start sputering and die. from what I could tell it was getting gas. would let it sit for another 10min and she fired back up after doing nothing to it.
Next. carbs were only leaking from 1 overflow stem. took it off made sure float wasnt horribly off (wasnt so i left it alone) put it back on now 3 carbs leaking out the overflow and even through my pods. wayyy overfull.
Carbs were taken apart and cleaned individual in an ultrasonic cleaner, new bowl gaskets, and re assembled. did a bench sync and had it idling at about 1300rpm.
I would normally test it on the center stand unless i was too lazy to pull it on than side.
it idled the same before i did pods as it does now with pods and jets.
I just did the new coils, wires, boots, and plugs last week. my thought was that the coils were going bad, thats why i replaced them.
harness looks choppy because it is spliced all over with normal blue and yellow autowhatever crimps. some wires are not even connected and some liike brittle/aged. sorry for rambling so much just wanted to try anwsering you properly. thanks for any help everyone!!

rb550four · « **Reply #5 on:** February 14, 2015, 06:52:36 AM »

Overflowing carbs are still an issue.
Do you have electronic ignition or points? If you have points have you checked on the condition of the spark advance while you were there to make sure it functions properly, are the points new, factory or aftermarket, have you set them properly with a light (on 1-4 and 2-3), are you sure the timing is correct? Are you using a fresh battery or trying to resurrect a dead one?
Have you cleaned the fuel system yet? Tank,petcock,fuel lines...are you running fuel line filters, do you have excess line, is there any hard bends or kinks in the line, are they running on a downward plain from petcock to the carbs and not wrapped around them. Are you sure you didn't get any crap in the fresh carbs from an unclean fuel delivery system.
Sounds to me like the carbs will be coming back out and blown out (at least), at that time you may want to recheck float height on all 4 and possibly change jets ( your call).
Are you going to purchase another wiring harness or will you take those crappy crimps out, solder the splices ,and shrink wrap each repair?
I would suggest doing only one of these things at a time so you can isolate the problem/problems starting with the fuel delivery.
And I didn't ask before but, is this fresh gas or gas that was waiting for the lawn mower, there hes been issues with shelf life on fuel.
Just trying to get a better picture of where you 're at exactly.

cafehonda500 · « **Reply #6 on:** February 21, 2015, 02:25:31 PM »

Update.
Me and my guy are working on the bike more. Tinkered with the carbs more. Learned the hight was about 1-2mm off on the floats. Also the float pins are kinda worn and causing floats to stick every now and than. We did get them adjusted and put back on and it fired up easily (heated shop). New coils worked great. But one float still leaks a tad due to the pin making it stick. We are currently working on getting new float pins but may end up with new carbs as he is seeing many worn parts that will need to be replaced soon. New floats and pins are $40/each so $120 needle and seat may be bad too. Might be looking at some Mikuni carbs for it now....
And suggestions on new carbs? I can do my own research on parts for the old ones but know nothing about what kind of new carbs to put in.

calj737 · « **Reply #7 on:** February 21, 2015, 06:37:28 PM »

It's probably cheaper to send yr carbs to member Harisuluv and have him rebuild them with all new stock parts. He has a listing in the Services section for contact info.

rb550four · « **Reply #8 on:** February 21, 2015, 07:16:40 PM »

+1 on sending out the carbs like Cal said.
All this tinkering with old carbs/ new parts or new carbs/no idea will be costing you big bucks, send them out , you'll be way better off.
It'll give you some time to clean the tank (and seal it if it needs)and petcock properly,get new fuel lines to make ready for soon to be returned clean carbs.

cafehonda500 · « **Reply #9 on:** March 06, 2015, 06:50:16 AM »

new update!!
first off thanks for the advice again guys.
so we worked on the bike again and we learned a few bad things. 1 the gas tank has a leak in it, can feel gas dripping on the seam. 2 the fuel petcock is bad. it is not giving enough flow for the carbs to work properly. 3 the floats in the carbs are bad. they are absorbing gas and getting heavy. here are a few pictures of the carbs, this is why im asking about new ones. as you can see there is some major pitting and chips around the main jet. carbs 1 and 4 are like this carbs 2 and 3 both look very good though. but other than these few issues we had the carbs adjusted near spec and had the bike running very well, it drank fuel though,due to the heavy floats, so we didnt run it too long but she sounded very nice. on a side note if your exhaust doesnt seal properly make sure you have the collars on the right way lol i blame the other guy, he blames me but who knows.

Stev-o · « **Reply #10 on:** March 06, 2015, 08:00:33 AM »

Sounds like your tank is rusting and your petcock could be clogged.
I recommend Caswell to seal the tank.

SOHC4 Cafe Racer Fan · « **Reply #11 on:** March 07, 2015, 07:55:47 AM »

Quote from: Stev-o on March 06, 2015, 08:00:33 AM

Sounds like your tank is rusting and your petcock could be clogged.
I recommend Caswell to seal the tank.

+1

cafehonda500 · « **Reply #12 on:** March 12, 2015, 11:15:24 AM »

First off thanks for the advice guys, you're all great!! So I ordered 4 new carb floats, hope this fixes it. Live in MN so im gunna have to wait a month or 2 so seal the tank up. few questions now. 1. Were can i find a nice fuel petcock for the tank? 2. What is the best tank sealer to the tank? I see a few liked Caswell. My guy told me to try Kreem but i read a lot of bad Kreem seals that dont last. 3. how do I prep the tank for the sealer? What works best for cleaning any rust. How can i attempt to seal the leak on the outside (if needed, idk if the sealer will do it)

calj737 · « **Reply #13 on:** March 12, 2015, 11:23:54 AM »

Caswell. Definitely.

De-rust: theres lots of options- Distilled White Vinegar works well and is cheap. Electrolysis works great, but takes a little tinkering. Acetone soak (like Vinegar, but more costly).

Prep for liner: Prep 'n Etch works very well. Not required, but helpful. After de-rusting, you can swish about a pint of Acetone in the tank, rolling and getting all surfaces completely. It will clean and dehydrate the interior. Then line it.

I personally prefer to pour the liner in thru the petcock bung. This way, the liner first hits the underside of the top, and as it drains, it covers the backbone well and oozes down the sides. Your choice. Perfect prep and installation is key for any liner job.

SOHC4 Cafe Racer Fan · « **Reply #14 on:** March 12, 2015, 11:34:26 AM »

Quote from: cafehonda500 on March 12, 2015, 11:15:24 AM

First off thanks for the advice guys, you're all great!! So I ordered 4 new carb floats, hope this fixes it. Live in MN so im gunna have to wait a month or 2 so seal the tank up. few questions now. 1. Were can i find a nice fuel petcock for the tank? 2. What is the best tank sealer to the tank? I see a few liked Caswell. My guy told me to try Kreem but i read a lot of bad Kreem seals that dont last. 3. how do I prep the tank for the sealer? What works best for cleaning any rust. How can i attempt to seal the leak on the outside (if needed, idk if the sealer will do it)

Buy a genuine Honda petcock; the cheaper reproductions sometimes leak. You will need Honda Part #16950-300-020 You can find one on ebay for about $45. http://www.ebay.com/itm/GENUINE-HONDA-PETCOCK-CB500-CB550-CB750K-KAWASAKI-KZ400-/201073426760?pt=Motorcycles_Parts_Accessories&fits=Make%3AHonda&hash=item2ed0e90148&vxp=mtr

I have had very good results with Caswell and very bad results with Kreme and Red Kote/Coat (clogged carburetors and rust). That was with proper application. I know some others might like these products, but that's just my experience.

Prep -- take your tank to a radiator shop to be cleaned and pressure tested. Acetone before coating. Sealer may work. If it is a small leak, you can braze weld it. If it is multiple pinholes with thin steel, you may have to cut it out and weld in a patch.

cafehonda500 · « **Reply #15 on:** March 21, 2015, 08:07:13 AM »

great news everyone, the bike runs and is drivable! the new floats did the trick. we still think the seats are a little off but everything ran ok. pulled off the fuel petcock and wow that thing was nasty. i plan on cleaning the tank soon here but would still like peoples input on a good tank sealer. with any luck i should be riding on the road in a few weeks!!

calj737 · « **Reply #16 on:** March 21, 2015, 11:10:52 AM »

I think Vinegar is probably the cheapest solution for de-rusting a tank, and awfully effective. Expect it to flash rust very promptly afterwards though unless you treat with Acetone prior to a liner.

I really like the Caswell liner. I've used it on lots of tanks and been very pleased with it. RedKote has worked too, but it seems to me to take much longer to fully cure. It does remain a touch "pliable" afterwards where the Casell is rock hard when cured.

jkminer · « **Reply #17 on:** March 23, 2015, 06:58:34 AM »

POR15 has a kit that will remove some light to moderate rust, etch, and seal the tank. Used it a few times, never on anything that had a leak though. It's taken care of some rotten tanks though.

https://www.por15.com/mobile/POR-15-Motorcycle-Fuel-Tank-Strip-Repair-Kit_p_60.html

SOHC4 Cafe Racer Fan · « **Reply #18 on:** March 23, 2015, 11:11:01 AM »

Quote from: calj737 on March 21, 2015, 11:10:52 AM

I think Vinegar is probably the cheapest solution for de-rusting a tank, and awfully effective. Expect it to flash rust very promptly afterwards though unless you treat with Acetone prior to a liner.

I really like the Caswell liner. I've used it on lots of tanks and been very pleased with it. RedKote has worked too, but it seems to me to take much longer to fully cure. It does remain a touch "pliable" afterwards where the Casell is rock hard when cured.

There are some members who swear by Caswell (me), POR15 or RedKote. I've had a bad past experience with RedKote and Crème coating on gas tanks. No bad days with Caswell. I have the tank cleaned and pressure tested by my local radiator shop before pouring in the Caswell right after.

cafehonda500 · « **Reply #19 on:** April 02, 2015, 11:25:08 AM »

Update.
ok guys i managed to find and solder the leak in my tank. it was a small pin hole near the seam NOT on the seam. to find the leak i added some degreaser and a lot of red food coloring so when i slowly turned the tank i could see a clear red leaking out. never seen this idea online so try it out if you cant find the exact leak. than threw in a handful of short/sharp screws and shook that around till my arms couldnt take it. lots of rust came out but i could see there was still some inside. than i found a product at Oriley, but can be bought everywere, its called EvapoRust all you do is pour it in the tank and it eats away the rust. i added 2 gal to my tank and wow its clean now. just got my order of Caswell tank sealer that i will be using soon. any tips on using Caswell? ive seen videos and it looks easy but id rather learn from others mistakes lol thanks yours your advice is making this easier

calj737 · « **Reply #20 on:** April 02, 2015, 02:30:42 PM »

I prefer to pour into tank from petcock to insure coverage on underside. Split the product and do two coats.

SOHC4 Cafe Racer Fan · « **Reply #21 on:** April 02, 2015, 02:55:27 PM »

Quote from: calj737 on April 02, 2015, 02:30:42 PM

I prefer to pour into tank from petcock to insure coverage on underside. Split the product and do two coats.

Excellent idea. Do you do half from the top and half from the bottom, or both coats from the bottom/petcock?

calj737 · « **Reply #22 on:** April 02, 2015, 03:15:30 PM »

First coat from petcock, second coat from filler neck. I try to get coverage on the entire tank with both costs, but I do concentrate on the surface in that order.

SOHC4 Cafe Racer Fan · « **Reply #23 on:** April 02, 2015, 03:40:52 PM »

Quote from: calj737 on April 02, 2015, 03:15:30 PM

First coat from petcock, second coat from filler neck. I try to get coverage on the entire tank with both costs, but I do concentrate on the surface in that order.

That makes good sense.

cafehonda500 · « **Reply #24 on:** April 16, 2015, 10:48:19 PM »

Update.
So I have sealed the leaks in the tank and used Caswell to seal the inside of the tank. This is the first time I have ever used a tank sealer but it was very easy to do. I didnt have a funnel to pour from the petcock so I just poured from the filler neck. I did two coats because after the first I could still see small spots that did not get coated. This stuff hardens like a rock!! I poured all the extra I to a cup and after it hardened I couldn't break it stabing with a screwdriver. Bike no longer leaks nor do I worry it will again. I also bought a manometer and properly synced my carbs. Finaly after 2 years I road the bike on the road for the first time. Man did this feel amazing!! It runs decent and I had a blast. I did however notice that it ?surges? At around 6000rpms. If I slowly accelerate to it it will almost free rev for a second than I have power again? Not sure what would do this. My guy said try closing the choke a little but that did nothing. Any ideas what would cause this issue?? Does not make the bike unrideable just very annoying. Thanks guys. With your tips I got my bike running and am enjoying it. Have also learned a lot along the way

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Author Topic: 71 CB500 project. (Read 8739 times)