Engine running hot!

(Sorry for the cross-post. I put it in the "Mods" forum accidentally.)

Still a stone moto-newbie, but I finally started riding the bike a bit. I purchased it last fall, had the carbs cleaned out (http://www.katzinteractive.com/motophoto/index.htm), got some new fork seals, filled it up with high test and I've been taking little scoots around Brooklyn/Queens on it.

One problem I'm noticing is that the engine seems to be running VERY hot after 1/2 an hour or so (to the point of smoking slightly at stoplights).

I'm sure that this is one of those things that could be the result of just about anything, but I was wondering if there was any kind of a checklist to proceed through.

Oh yeah -- the forks had been leaking and oil apparently made it down to the pads as my braking power seems greatly diminished. Are the pads toast and do they require replacement?

Much thanks in advance,

Scott

 

It is possible that your smoke is nothing more than an oil leak. Clean the beast up good and keep an eye out for leaks (they do happen with these older machines). As for the oil on the pads, convention suggests that they are no longer usable. I have, and I don't recommend this to anyone, cleaned them off very thoroughly with brake cleaner and a steel toothbrush when I was too poor or didn't care enough to buy new. Manufacturers insist (and they are probably right) that once contaminated, the pads are junk and, as you seem to have noticed, braking power is diminished conciderably. This is because the oil contaiminate is "baked" onto the surface of the pads due to the dynamics of the pad on the rotor. I would suggest you replace them. But you are a grown adult and can make that call.

 

robert is right on the money. Replace those brake pads, and check for oil leaks!!!! if it is a white smoke, it is most likely an oil leak, as the engine (when it) drips, it drips right on the exhaust. Oil has a very disstinct smell to when burnt. Ask a mechanic to smell it, they'll know.

 

Thanks guys. I'll replace those pads before I Darwinize myself.
I'll clean the engine off, but it still seems like it's running hot to me. I can feel it through the seat, and in my very limited exposure riding other bikes it seems to be running considerably hotter.
Anything I should check first? The oil level looks fine through the window, and even though I might be burning some off on the engine I never see a drip leak beneath the bike when parked....

Scott

 

Just a question here to get brought up to speed. Are the fron brakes sticking. Front tire should spin freely, no binding. This could explain the smoking at the front brakes and the hot engine. If that isn't it then look at the spark plugs. Are they the correct ones for the bike. A hotter than normal plug will cause it to run hot and over time melt a hole in the top of the piston. I.E. Only use the right plug. Hope this helps.

 

Has the bike been used regularly? Often when the engine heats up it will find new areas of dirt and oil to burn if the bike has been previously sitting for quite some time.

They do get hot, My 550 you can splash some water on the heads and it will sizzle into steam. Burns your knees if your dumb enough to wear shorts.

Every now and then if I get stuck in slow traffic the engine will start smoking. Best thing to to is pick up some speed and get some airflow around it. There is not much you can do to lower the heat other than check it's not running too lean and has good oil flow to the top end.

 

Sounds like an auxilary oil cooler is in order there HG. Might be a thought for you too scogordo. I never noticed the heat on my machine, even in the summer down in San Diego. Plug heat range would be an excellent point to check. So would spark plug gap. You may also wish to look very closely at the areas around your valve cover, you don't need a whole lot of oil to have smoke, just a small weeping is all it takes.

 

Already got a cooler Robert.

Most of the smoking on my bike was related to the PO painting the engine with cr@p paint. It would "bake" as the engine got hotter and start smoking. Most of it has peeled of now but the temps don't get as hot now since the carbs have been tuned properly.

An old and tired engine doesn't help either. More friction = more heat.

Also a point worth putting in regarding oil is if you are travelling slow in traffic it's better to be in a lower gear and revving a bit higher than traveling in a high gear at low revs. A few revs keeps the oil flowing from the pump at a higher pressure and helps the cooling process a little.

 

A high idle might also contribute to a hot engine while standing still. When i first started to ride my XJ, it used to be real hot when stopped at an intersection. Sometimes it would get too hot and i would have to stand and move back a lil to get away from the engine. One day i looked down and noticed that the idle speed was at 1500 rpm. After lowering it down to about 1000, the bike is much cooler when im not moving around.

 

Thread-jumping here...

I seem to be getting hot at a long red light as well, or at least I think I am. It seems that the idle will start to bounce a little, and when the light does finally turn green, it's a sluggish start at best when this happens - and I'm required a higher rpm and more clutch-slipping to get it moving past this "bogging". Once I get going, it all seems to be fine again, until the next long red light.

I also noticed my idle when warm is at about 1500rpms.

I'll check the condition of my plugs tomorrow afternoon - but I'm assuming by the prevoius statement that a warm idle closer to 1000rpms is better? Or where? If so, that'll give me my first repair project!

 

Hired goon! i dont mean to be a jerk and contradict you. but i feel like the heat given off by more RPMs (=more exdplosions=more heat) would off-set any advantage gained by having a higher oil pressure.

 

P.S. spec. idle is 1250 ± 50 RPM

 

That would be correct Brian, but Wouldn't you rather have a larger volume of hot oil flowing through your bearing shells than a trickle of hot oil generating more heat due to less lubricating properties around your bearing shells and bores? Bit of a catch 22 but I will keep the revs up around three thousand rather than revs closer to idle. IIRC idle only create 4-6 PSI oil pressure. IMO not enough for a hot engine in traffic.

It's all a bit of a hypothetical question because I'm bored and thinking too much today. :wink:

Of course the best option is get out of the traffic, hit the open road and get some air around that baby.

 

You overheating guys need to look at my recent POST "Colortune Problems / Mixture screw?"

TUNE your bike to idle RICH ... RICH is COOL ... LEAN is HOT.

 

Yeah, I'ver got some of that going on too....

Scott

 

I feel I should chime in here on whether higher revs is better for cooling since I have a temperature guage! I realize we have different engines, but not by much! And besides, the friction and heat generation in general is probably the same.

When I warm my bike up in the morning with choke, it warms up much faster with revs at 3,000 than 1,000. About twice as fast.

When running down the street at 30-35mph:
If I run 2nd gear at 5K-6K, my temperature guage will climb up past normal.
If I run 3rd gear around 3.5K - 4K, my temperature guage will stay normal.

So, I don't buy the argument that more hotter oil is better. If you run quality oil, it should stick to surfaces anyway. And I imagine that 3-4K rpm is plenty of oil! 1K is probably down on oil, but these bikes were designed to idle! If you are running quality oil, don't worry about it.

When you are running air cooled engines, you want to keep the temperature as stable as possible, right? In that case, I would recommend idles of 1K and running revs 4K. Just my 2cents!

 

Sorry, I meant let your bike idle at what the manual says. I believe mine is 1100 rpm. I realize your bikes idle higher.