Running Hot?

[mschor]

Just started up my 81Special after 20 years. Spent 3 months doing carbs, brakes, tank, fluids, etc. It's smooth, starts in an instant, but it seems to heat up pretty fast. Wondering if that's normal. I let it idle only about 45 seconds and the pipes are HOT. Smoking a little off the #4 pipe but that is probably just burning off whatever was on it. I'm just wondering if this is normal for it to heat up so quickly or if I should be concerned about oil not circulating or something else. Blows a little dark smoke if I rev it. Good response though! No hesitation/blips

[motoman]

Just started up my 81Special after 20 years. Spent 3 months doing carbs, brakes, tank, fluids, etc. It's smooth, starts in an instant, but it seems to heat up pretty fast. Wondering if that's normal. I let it idle only about 45 seconds and the pipes are HOT. Smoking a little off the #4 pipe but that is probably just burning off whatever was on it. I'm just wondering if this is normal for it to heat up so quickly or if I should be concerned about oil not circulating or something else. Blows a little dark smoke if I rev it. Good response though! No hesitation/blips

Sounds like you BOUT got it! I say BOUT, just because it doesn't stumble or have any 'blips' just free revving it could REALLY change that when you actually ride it under load. If that changes under load, you seriously need to set idle mixtures correctly FIRST, then sync. the carbs. This SHOULD be done anyways, even before one of these scoots is EVER ridden.....specially having no real knowledge of what or whoever may or may not have ever tuned them.

[TopCatGr58]

Hey there MSChor,

Yep, if it's running right, the pipes can heat up pretty quickly. A test for if the engine us running right is to spritz the headers with water and if it sizzles on all of the pipes, then it's burning on all 4 as it should. Down there in FLA, even winter can be pretty warm, so be sure to have a good box fan blowing across the engine/headers to help keep it cool while doing the tuning processes.

However, Yamaha did set the jetting quite lean for EPA requirements, and that can also cause it to run a little warmer as well. Also, if you've changed the intake/exhaust like POD filters or aftermarket pipes, that can increase the air flow that could also have helped to lean it out a little more.

After sitting for 20 years, the rings may be a bit stuck/stiff, and so it can take 500 miles or more to reseat the rings, and then you may not get as much smoke out of it. But also the valve guide seals may have hardened over the years, and they can also leak allowing oil into the combustion chamber. There's is an oil treatment you can put in to help soften up the valve seals, but don't know how it may or may not affect the clutch plates. Others may chime in with more tips. Marvel Mystery oil, a few ounces in the oil can also help to loosen up the rings, remove varnish/gum from internal parts, Greg/BA80 has used it in his bike without problems/damage, I don't know if IT will soften the rubber seals??

T.C.

[BA80]

You might need to ride it a little and clean 20yrs worth of crap out of it before you can get a good tune. Just sayin'.

[Bonz]

The time frames mentioned aren't enough for anything serious to go wrong with the engine. Think about the header pipes. You have a hot gases from almost a minute of internal combustion at 1100 RPM heating them up. They're going to get hot and quick. Normal.

Guys who ride their bikes regularly and ride 1000 miles or more in the heat of summer to GET to Colorado, still have smoke come off their engines sitting in line to get on the road to climb Pikes Peak the past two Colorado Rally's.

Right Greg?

[mschor]

Thanks for your input y'all, I'm going to switch to putting the brakes back together, put some tires on it, sync and idle mixture before I put it on the road.

[DiverRay]

I'm going to switch to putting the brakes back together

Good first choice! If you still have the original rubber lines, I would say pick up a set of Stainless Steel lines while you are doing brakes. Yamaha in the handbook said to change the rubber lines every five years. The OEM lines on your bike are 37 years old? They DO break down from the INSIDE, and you probably noticed the brake fluid was black or grey. That is from the rubber off the lines!

[BA80]

The time frames mentioned aren't enough for anything serious to go wrong with the engine. Think about the header pipes. You have a hot gases from almost a minute of internal combustion at 1100 RPM heating them up. They're going to get hot and quick. Normal.

Guys who ride their bikes regularly and ride 1000 miles or more in the heat of summer to GET to Colorado, still have smoke come off their engines sitting in line to get on the road to climb Pikes Peak the past two Colorado Rally's.

Right Greg?

Ha ha ha ha.....I'm glad to have made that climb. It's off the bucket list.

If I do it again it'll be on a weekday when there aren't so many tourists.

My engine never fully recovered from getting that hot.

[motoman]

Well, that's a good thing.......keep'er warmed up if your planning on going to the Kremmling rally. That scoot will be at everything from 8,000ft. to some 11-12,000ft. over Trial Ridge Pass in Rocky Mountain Nat'l Park down to Estes Park, if that be one of the day rides. May wanna consider leanin' it out a tad(, as many last year really noticed the rich smell coming off the exhaust when following you.....and Harry. Just for G&G, needles drop one clip position is equivalent to half a main jet step.

[mschor]

Definitely getting stainless lines. I would like to just do two lines up front with no splitter, and one direct line in back to cut out the solid section. Have you all done this? Would like to get measurements for this that have worked so I don't order something too long or short. I know there are a few threads on this, but I haven't seen any measurements. It's a little challenging getting the front measurement since they're going through the splitter currently. Thanks again for your help, it's been a great learning experience

[Bonz]

Hey Greg, what do you mean by your bike never fully recovered? Are you saying that some what in jest? I hope that's the case.

If not, are you down on power or using oil between changes, etc? Man, if that's the case I'm really bummed that happened.

[donebysunday]

Some like it hot

When you start using the choke you are introducing extra fuel to the engine. The engine may not be able to handle all the excess and some will burn past the engine and into the exhaust. The fuel burning in the head pipes will cause the head pipes to heat up nicely basically warming the engine faster. That is normal, typically these bikes are lean from the factory to meet EPA regs..
What pipes and air filters are you running ?

Just started up my 81Special after 20 years. Spent 3 months doing carbs, brakes, tank, fluids, etc. It's smooth, starts in an instant, but it seems to heat up pretty fast. Wondering if that's normal. I let it idle only about 45 seconds and the pipes are HOT. Smoking a little off the #4 pipe but that is probably just burning off whatever was on it. I'm just wondering if this is normal for it to heat up so quickly or if I should be concerned about oil not circulating or something else. Blows a little dark smoke if I rev it. Good response though! No hesitation/blips

[mschor]

Ok, it's all stock. I was running it without the airbox though, in case I had to take the carbs out again.

[TopCatGr58]

It's been many years since I did my SS lines, I did run just the single line in the rear bypassing the OEM solid line. Just take some string and trace the path from the MC to the caliper. Depending on where you get them from, they should tell you whether to include the banjo end fittings in the measurements. For the front, I would jack up the front of the frame to extend the forks to their max travel, and then measure the length to allow enough length for the full extension for bumps and such.

The Y splitter junction uses a longer banjo bolt to secure the 2 lower tubes, and so you will want the same for securing them at the front MC.

T.C.

[mschor]

Cool, thank you, I found a shop nearby today that will make them, I'm going to bring my old ones to them in the morning, hopefully will be able to put it together in a couple days, pretty excited to get this bike rideable