Hello everyone, new here and new to the classic Iron Head. I bought an 81 with 8000 miles on it for my wife after it sat in a garage for 19 years and probably had not been driven more than 100 miles or so a year since 1991. Having been 42 years in the auto and truck repair trade I figured why not, it can't be too hard to get this thing up and running and safe again. Put a new battery in it and it fired right up like it was running yesterday. That aside I went about going through everything from front to back before I started the engine again. All of us in the trade can do pretty much anything BUT, there are those who know one thing or another inside and out so I'm here to consult some experts. It's a lot easier to ask a specialist than it is to try to become one when you don't have to.

The rear brake is not releasing. The MC has been rebuilt. I am assuming I did not get the return port cleaned out properly. Opening the bleeder releases the brake. My question is: Is there hope of getting this issue resolved by disassembling and cleaning the MC again? It usually is not successful on a car or truck that's why I ask.

As for the carb (stock carb) have you guys ever seen the overflow stand pipe actually leak from the base, like between the stand pipe and the bowl? That is where I believe it is leaking. I took the bowl off and put some gas in it and it dripped from the overflow port. I put another bowl on it and the accelerator pump does not work. Yes it is in right, brand new, not cut, rod is moving. I assume the port or passage is plugged.

Also on the carb, can the low speed "factory seal" be removed to adjust the low speed mixture? I know on cars back in the 80's we were able to do it since the screws were just hidden under the "seals".

I released the rear brake and am using front only for road testing so there is no a load on the engine caused by the brake issue. It runs and goes down the road but as a runner I would say it runs just OK, not as good as it should IMO.

Also, in general, any advice on what I should check besides the obvious. Have already rebuilt both master cylinders, front and rear calipers, replaced brake hoses, new pads, carb kit, intake seals, tires of course, packed wheel bearings and replaced seals, end play is OK, changed oil and filter, changed trans/primary oil, new battery, new starter relay, new headlight, it just passed NYS inspection.

Have been told to check tappet adjustment "just because" and will do that soon. Any further suggestions?

Thanks in advance for any help you can offer.

 

buy the factory books parts and service

the rear caliper is draging the piston kits are cheap

amazon has USA carb kits - if you opt for a china kit **** on it instead as it might make it work better after doing that -- do the intake manifold o rings as they will be needed very soon with the carb over haul - have it sonic cleaned at a boat yard

remove the fuel pet **** / clean it // i would replace it as it will leak not if - and all new fuel lines at 50MPH you cant help being burned before you get it to stop

all the oil lines are a must as well it will drown the rear tire in oil in a turn at some point

valve adjustment is a must - welcome and good luck

 

I preach this all of the time but make sure you are using the proper type brake fluid. I am not sure about 81' but I know an 80' used type 5 and if you put type 3 in the rubber swells and causes the brakes to stick. I bet you can figure out how I know that.

 

You need both of these ...

99484-85 Factory Service Manual
99451-85A Factory Parts Catalog

Buy from a local indie bike shop or HD dealer. Or put the part numbers into the eBay and Google searches.

The rear brake the piston may be cocked in the bore. Dismantle the caliper then use compressed air to pop the piston out. This is the usual technique. With both fittings removed block one and use a rubber tipped blow attachment on the other. Catch the piston in a thick [bath] towel so it does not go flying across the shop.

I have refurbished a few of these and never needed a rebuild kit. I was always able to re-use the two rubber gaskets/seals.

The stock carb for 1981 is a Keihin butterfly carb with a 160 main and a 68 slow jet. You could easily install a 165 or 170 main and perhaps a 75 slow - with the usual testing.

You can remove the cap that is on the pilot jet passage. I have not yet had to do that myself but i believe the technique is to use a self-tapping screw.

Is the replacement bowl a new after market piece? It is unbelievable just how very very very bad the new after market parts are. Never! use any for transmission or internal engine parts. Used parts from eBay are the best choice. Well, new Andrews parts for transmission.

I have not seen that particular leak on the float bowl. It is surprising - usually carbs with the cap in place are undisturbed inside. Perhaps this is why the bike sat unused.

The acc pump jet is a press fit. You can remove it and spray carb cleaner thru the passage. try both directions altho in theory it should only go one way [i think ?]. There is a check ball in there. You should hear it rattle as you shake the bowl.

To remove the jet use a 1/4" drive metric socket. I forget the size, i just recall that it is an odd number like 7 mm or 9 mm. The 1/4" drive is the right size tool for the job - not too big so nothing will get wrecked. Do not use any other tool like pliers, vice grips, etc. Even tho it is a press fit, not threaded, it should unscrew.

When you re-install aim it so that the spray goes thru the middle of the cut out in the choke plate, with the plate open. I do this on a carb stand, a ~1' length of angle aluminum with two drilled holes, in a bench vice.

+1 on the DOT 5 brake fluid, and on checking the pushrod adjustment ...

 

Thanks for your reply. Have factory manual and I use online parts look up. Brake problem seemed to be a combination of brake pedal adjustment and tight brake pads on the pins. The pads are new and they did not move well on the pins. I checked the piston movement and determined it to be working properly. The pedal had no free play so I took care of that. Small round file in the holes on the pads to free them on the pins. So far it seems good. The carb bowl is OEM used. I'll remove and clean it well. I do not recall hearing the check ball moving around when I cleaned it up the first time. And thanks for the tappet adjustment video.

 

DOT 5 all the way. It appears that the person who owned it before me mixed 5 and 3 or 4 and made a very strange looking non-flowing brew.

 

Oil lines.... never thought of that. Will do seeing as how they are 34 years old. Any suggestions as far as type of line? Manufacturer? Fuel line is already done. That looked like a fire waiting to happen. USA parts all the way!

 

I should have thought of the pad pin holes. I always have to clean them out. A round file or a drill bit.

The correct lines are ...
vent 1/4"ID x 1/2" OD
oil 3/8" ID x 5/8" OD

Note that the OD is important. If you buy non-standard lines from an auto parts store, transmission lines, modern hi-tech lines, etc, they will be very difficult to run thru the tight spaces on the motorcycle without kinking. Especially under the starter motor. One counter guy actually pinched the line in his caliper to prove that they were correct

I buy mine at a local indie motorcycle shop. He always has the correct stuff on hand.

 

Yea, that rear brake was getting me a little nuts. Took a closer look at the MC and found it was just a simple MC, no residual pressure check or anything like that. One port, simple MC like a they run car clutches. So I went to the caliper and hooked the rear brake hose directly to the MC. Piston was free and moves back very slightly when the brake is released. The pads would not move on the pins though unless they were "walked" back from side to side. Took the round file to them, now all seems well. It dropped 30 degrees here from the 80's to the 50's so I have not taken it out to test yet.

Thanks for the tip on the line size. Automotive line should work I guess as long as the OD is correct but the newer stuff is thicker due to higher pressures mostly on trans coolers. Might be tough to find the right OD that isn't fuel line specific which I don't trust for high temp. I'll be over close to one of the better local indie shops today so I'll check with them.

Thanks for your help.

 

No rattle in the bowl. About half a can of some bad *** carb cleaner didn't free it. Finally smacked the bowl on the bench and out came the check needle. Cleaned things up good and back together it went. Thanks for the valuable info!!! All fixed and now the old lady can play a little. I had no problem playing with the throttle to road test oher issues but there's no way a novice rider can keep track of everything and fiddle with the throttle to stop it from falling on it's face. Thanks again!