possible engine overheating

[rob carroll]

Greetings xs11 I don't know how active this forum may be at this time but seeing as though I've mananged to find a 79 special garaged since 1981 I could use some help to get this bike home in good condition. I'm from Noxon, Montana temporarily staying in Loomis Calif. where I found this special. I haven't ridden since 1985 and you can imagine the memories and thrill it's stirred to have the wind in my face once again. I really want to take care of this piece of good fortune and thus this letter.

I put the bike in the shop to completely revamp the carburation and fuel system. New fuel shutoff and vacumm diaphram gaskets.Complete carburator overhaul with new floats and main screws. New fuel lines, plugs, carb synchronization, tires, timing, battery and all oils. The mechanic indicated a compression test revealed the engine was still in the breakin phaze; he claimed compression readings of 190 in cylinders 1 and 2; readings of 200 in cylinders 3 and 4. In any case when he was done the engine ran beautifully. He was very impressed as he had never ran an 1100 and cautioned me about the power of the bike. I drove the bike a short ways to my loaction in Loomis. I was just plain estatic. That evening I took the bike out for a longer run; about 20 miles. On my return home I noticed the engine was slightly popping, maybe a mild backfire in the higher gears. Also it became sluggish, hesitant, when starting from stop in first gear. When I pulled up on the lawn after the ride the engine died of it's own. I may be wrong but the engine seemed to be radiating what I felt was excessive heat. I haven't had a chance to address any of these concerns as the next morning I was enroute for a three week job in saltlake, Utah; where I am posting this thread. Upon my return to Loomis my son and I want to switch off riding the bike for the 1100 mile return to Noxon, Mt.

The mechanic did indicate that one of the pilot screws was noticably shorter than the others but wasn't concerned as the bike performed well during his test drive. My main concern is how do I determine if the engine is running excessively hot? Does an 1100 just plain run hot? I don't want to damage or burn this gem up on the ride home fellas. I haven't found a thread on the forum which directly addresses this concern. I,d appreciate any advice or direction someone can offer.

Live Free

Rob Carroll

[trbig]

First of all, this is probably one of the most active forums around, So welcome!! Second, My first guess is going to be a pickup coil wire repair in your future. These are under your left front sidecover while sitting on the bike. The vaccum advance working back and forth over the years weakens the wires and eventually makes a break. You can do a search for this.. it's been covered pretty well if you care to read up on it.

My 2nd guess would be that the inside of the tank had some crud in it that made it's way back into your cleaned carbs. Do you have inline filters on the lines?

As far as overheating... only if you are sitting in a traffic jam in 110 degree heat. The fuel would probably start pre-detonating as it entered the cylinders and cause it to eventually not run before it did any internal damage. It is rough on oil and shiney header pipes... but shouldn't hurt the motor. An oil cooler will help also if you are scared of this. The main thing is just not to leave it idleing for extended periods.


Again, welcome to the forum. Great people and great info in here.


Tod

[prometheus578]

"So many clues, Watson, yet you missed them all."

The mechanic did indicate that one of the pilot screws was noticably shorter than the others

Now, fellow readers... what does this indicate on early model carbs?

but wasn't concerned...

Equally, what does this say about the mechanic?
Rob.. the early model carbs have pointy pilot needles. Pointy, like the head of that mechanic. Now, some other style carbs have blunted needles, but on the early ones of ours, they are pointed and sharp.
What this means is...someone adjusting the carbs years ago, screwed them in too tightly, and snapped the needle's tip off, which as we all know, is lodged and blocking the idle circuit orifice for that carb. The bike, now running on only three cylinders at idle, will "pop 'n' fart", which is what my sons call me, but this being Mother's Day, we won't go into that now.
Yes, it will die at idle because of it.
Interesting compression readings. Standard is 142lbs. Never checked one with low mileage, so I can't say.
How many miles on the bike did you say? (Oh, you didn't... please do)
TRBIG is correct in assuming rust from the tank may have drifted down to the carbs. Take the plastic cap offa a spray can of something and place it under the float bowls. Open the drain on the float bowls and see what comes out. Do this with the bike on the centerstand.
These things will throw off a little heat, but no more so than other bikes.
Sitting idle in construction zone traffic will heat them up. Never a good idea to run an air-cooled bike without air flow over the engine... always run a fan when toying with a running engine in a garage. While cherry red pipes look cool... it indicates things are really hot.
Trbig, I'm assuming this bike has really low miles... I don't think the pick-up coils wires are an issue, yet.
It's fuel related, everything he mentions.
And the bit about the shorter pilot screw raises concerns.
Rob, you may wish to have the carbs redone by a different mechanic prior to the long ride home.. or that long ride may be longer than you expect and may entail some walking.
Shame that you aren't near the bike to check things out yourself.
These are easy machines to maintain and work on.

[prometheus578]

Ok... you took a short ride home.. no problems, but on the longer ride later.. sluggish, hesitant, and then finally dying on it's own.
Uhm.. Not trying to be funny, but....
Short ride ok.. longer ride not...
Uhm... did you leave the choke on?
It'll run like a bat out o' hell. for a short ride... longer ride, will eventually start to act up as the plugs foul.

[TopCatGr58]

Hey Rob,

Welcome. Congrats on a great find!! BTW, Prom, I editted your note, see the bolded word, you had typed NOT after it, but I'm sure you meant "IS", not "IS NOT"!

Rob, a few more questions, is the bike otherwise STOCK, pipes and Intake air filter box, or did the PO or YOU put some mods on it, like aftermarket pipes, Individual filters?? These kinds of mods can cause it to run leaner=hotter!

Also, did the mechanic clean the carbs and put the old parts back in, the Pilot Jets, Main Jets, or did he use a "KIT". There are known problems with certain K&L carb kits with the incorrect pilot jets! You said new floats and MAIN SCREWS....did you mean Main Jets, or the big brass center Main Needle Jet=emulsion tube, and if the latter, where did he get them from??? What size were the Main jets? Also, what were the floats set at? Petcocks and Octopus were rebuilt, again, rebuild kits for the Octy=vacuum controlled fuel diaphragm have been known to not fit correctly and so not function properly!

As for the Xsive compression, has been mentioned before that it can occur from Xsive carbon buildup in the cylinders, possibly from the engine/bike being babied, not run at the mid/higher rpms, or very short trips, so that the engine temps didn't get up to full proper temp, incomplete combustion=carbon buildup!

Okay, new fuel and vacuum lines, but did you replace the rubber synch port caps on the intake manifolds....can harden and be a cause for vacuum leaks.

Can understand with a job that keeps you on the road, that it can be difficult to find the time to do the wrenching yourself, but hopefully you have some experience/skills, or just the desire to get into doing these things yourself. Most mechanics of this modern era are NOT familiar with the intricacies of the older bikes, carb tuning, etc.!!! No place to connect a computer to it!

[prometheus578]

"Thanks, T.C."

I was doing too many things at once... and not doing well with any of them.

[wa407mpp]

Air cooled engines are designed to run rich, the extra fuel which is not burned is used to help cool the engine, when it evaporates off, if for some reason, dirty tank, dirty carbs. wrong parts wrong assembly, wrong mechanic, your carbs. are running lean and will cause major damage if not fixed. If you can fix them on site do so , if not rent a trailer and haul it home, don't try to ride it home the way it is now.

[rob carroll]

Appreciate the responses.

trbig

no inline fuel filters, mechanic had a hard enough time squeezing in the new fuel lines. I purchased new in tank filters but they didn't arrive in time for the service. He tells me the exsisting ones were just fine. I'm afraid I'm not savy enough to understand what a worn pickup coil wire would do. In time I will.

prometheus

doesn't seem to pop and fart at idle but only at acceleration for a short period after starting from stop. If in fact there was a broken pilot screw tip lodged in the idle circuit would it have come out in the one hour vibrating bath the carbs recieved. The odometer was showing 2892 miles when I recieved it. The story was that it was garaged. It sure looks like it to me. The man I purchased the bike from gave me the paperwork for a carb rebuild from Sacto. motorcycle service; my mistake, the invoice indicates 4 new floats and 4 new float valves. The service was performed in february of this year. As far as the choke being left open I can't recall to tell you the truth. It's sad beacause if thats the case I'm lucky but stupid. It's getting harder to conceal my senality as I age.

Topcat

Everything is stock as far as I can tell. As for the carb kit I dont know. I didn't elaborate above but the previous owner paid to have the carbs rebuilt off the bike. The service I recieved entailed breaking the carbs down, cleaning them, synch. The mechanic said the floats were set incorrectly with the first carb rebuild. I don't know where the petcock rebuild kit was manufactered, only that it included the vac diaphram. I forgot to post that the rubber intake manifolds were new. The mechanic wouldn,t work on the bike unless I replaced them. The previous owner had put silicone on them. In any case unless the rubber synchport caps were with the intake manifold kit they are original. They looked fine to me. Backtracking again, the feb. invoive indicates clean and rebuild carbs off bike. The only parts listed were the floats and float valves which were $200. The total bill was $384

wa407

My instincts and legs tell me the bike was running to hot. The gas tank looked pretty clean but there were still some rust spots inside. I just figured thats as clean as the previous owner or anyone could get it.

Thanks to all

[XSrunner]

HI ROB
I'm not sure of the book temp for these bikes but i know on mine the cylinder head temp guage reads at 350 deg F.It will burn the hairs of your legs (beat's waxing HA!)with thin trousers on but it does have full faring. As far as the loss of power check the plugs on the end of leads i had one crook one snip off a little of the lead the put end on now its fine. this site is GREAT AND THE PEOPLE ARE VERY VERY HELPFUL working on these bikes is great fun and you will apreciate it more.if you do the work.

[TopCatGr58]

Hey again Rob,

OUCH!!$!$!$!$ It's amazing how much labor costs add to the cost of repairs/maintanence!!!! The synch port caps do not come with the new intakes. Even though they can seem to fit snugly, because of age, heat, similar to the old boots, they harden and don't always seal well. You can drop by a local auto parts store and get some new ones cheaply to put back on!

Also, possibility that the Vacuum fuel valve/Octy may not be supplying enough fuel, you can switch the petcocks to PRIME to feed the carbs directly without the need for vacuum operating the valve to eliminate it as a problem.

While you're at the auto store, pick up some small inline filters. Instead of keeping the fuel lines on the same side as the petcocks, folks find crossing the lines so that the left petcock feeds the right bank/pair and vice versa will provide more room/slack in the fuel lines. Put the filters on the 2 lines that are just next/connected to each of the carb pairs, that way they will filter whether you are using ON, or Prime bypassing the Octy!

Popping from low rpm starts could be an indication of too lean as well as a messed up Pilot Circuit! The Ultrasonic cleaner might have dislodged the broken tip, but it might NOT. The mech said he reset the float heights, but to what value?? 25.7 is stock setting, but if set higher, then that could also be causing a too lean condition. There are some large screws on the top front of the carbs...the pilot screws, they have a slot cut in their tops, so you can see/tell how many turns they are turned, and you might try turning EACH one out a 1/4 or 1/2 turn to see how it affects the low rpm popping....it will richen up the pilot circuit, but it won't richen the use of the main jets which are used at the 3500 and above rpm range. IF the floats are too high(upside down) then it could contribute to lean running and more heat.

One of the big pitfalls with oil changes is that some mechs/folks don't know that the middle oil is a different chamber and type vs. the main engine oil. Hopefully your mech knows about the Middle Gear unit, the 80-90wt hypoid gear oil it requires. With the bike being this "NEW" it probably had the OEM tool kit, along with the Middle and Final Drive plastic dipstick. Would be good to inquire that it was done, the middle drive can LOCK UP if it is run without oil, not fun at highway speeds!

Finally, no aspersions on your previous riding experience...of which we don't know...just that it's been 25 years since you last rode regularly? Also, don't know your sons experience either. Would you two be riding 2 up, or one driving chase car? Highway riding is relatively safer than in town, but that's a big ride for both of you on an otherwise unfamiliar and fairly powerful machine! Just wanted to bring this up for further thought! An MSF course might not be a bad thing to partake!?
T.C.

[GNEPIG]

The Thread Killer has arrived:

Hey Rob welcome to the site and congatulations on getting such a nice bike, after sorting out a few problems, these bikes make very good riders.

Everyone has some very good points about what could be wrong with your bike and I have some that I would like to share also.

It sounds to me that you have a fouled spark plug. I would pull out all of the spark plugs and set them down in a row in the order that they came out. While looking at them you will likely find that the plug that is black, is the one that came out of the cylinder with the carb that has the shorter adjustment screw.

This adjustment screw is shorter because at one time some one did over tighten it and the tip broke off into the hole. These screws are brass and it is easy to reshape them into a point. Most of the time the brass tip (the one broken off and still stuck in the carb) can be pushed out with a pin/tack/small nail, but sometimes they have to be drilled. When this is necessary the shape of the hole has changed- that and the shorter needle with it's new shape will cause a slight tuning problem with that carb.

It's not really a problem if handled correctly. The way the new shapes of the hole and needle are make them more sensitive, so instead of this needle being set at 1 and 1/4 turns out (like all of the rest), it now has to be set at 1/8 to 1/4 turns out.

Ok this is gittin real long, short ending= If this screw is turned out to much it will cause the spark-plug to foul over a matter of a few miles.

Now the part about the engine over heating:
When one of your cylinders stops working, the other 3 have to work harder to make the bike go down the road. So if you ride your bike for about 10 miles on only three cylinders, your bike will seem over heated and will not idle very good if at all.

By the way that you speak of the person that repaired your bike, it sounds like he is pretty good. I would take your bike back to this guy and let him help you.
If it is a problem that he overlooked and you are a nice guy, it will likely cost you nothing.

I hope this helps and look forward to reading about your excellent ride home.

[tarzan]

I have a '80 special that sat since 1983.I bought it last fall from an estate sale.It had 588 miles on it.I went through the carbs,
the octy,and the tank.Also replaced all the lines.I experienced the exact same problem you have.I rode it around the neighborhood and it seemed fine,took it on a little longer ride and it spit and popped and seemed to start to miss a little bit and even seemed hot(and a lean condition can makem run hot).And it turned out I got a fuel line a little kinked when I put it back together.(Its very tight under the tank). Well, I found the problem and straightened out the line and it fixed it.I have about 950 on it now and it is fine.Might be your problem and maybe not,but its worth a check.Good luck and have fun with that thing.

[GNEPIG]

Quote:
"And it turned out I got a fuel line a little kinked when I put it back together.(Its very tight under the tank). Well, I found the problem and straightened out the line and it fixed it."


Good one Tarzan: thumbs up