PLEASE HELP! Problem is driving me crazy!

[MomentSurf]

Any suggestion would be appreciated. This problem is driving me nuts. I got a 1985 xl600r used. It was sitting in this guys yard for years and he wanted it out. Its a dual sport, great looking bike. I bought it home, got a new battery, cleaned out the crabs and got it running within two hours. The problem is, occasionally it runs as if it were half power (if you ever drove a two cylendar bike on one cylendar...thats what it feels like). The bike has one cylendar but two carbs/two exhaust headers. I can be cruising along at top speed then bam, it looses power. Sometimes for a second...sometimes for a while. I've tryed so many things. Gas tank is clean, feul filter added. Carbs clean. New piston and valves.
The problem is so sparatic...it never happens at the same time. Some times at top speed, sometimes at idle, sometimes just taking off from a stop. Sometimes it will run for days great...then bam, half power. I just noticed tonight...when it runs at half power, the exhaust headers glow red.
Is it electrical?
Something clogged in the muffler?
Carb jets getting clogged?

Suggestions? Thanks so much guys!!!!!

A rid I just took. Started it up..it was running great. Drove to the end of my block (1/8mile), it lost power (like a two cylendar bike on one cylendar). Drove it about 1/4 mile...power came back. Went another 2 miles..lost power. Drove about a mile...noticeed the header was red hot. Pulled over to shut the bike off. Let it sit for a few minutes. Started it up, ran fine...drove it 5 miles home. Whats the dam problem!!??

[robertc729]

be patient while waiting for a reply, alot of members aren't very active on the weekends as some of them only visit the site from work.

[GregR1]

headers glowing red? only one of the header pipes, or both? always the same one? it sounds like it might be running lean, so one of the carbs keeps cutting out and not delivering fuel, or the float bows run dry and don't refill properly.

[Aussie Steve]

How many valves does this thing have. It sounds to me like a valve sticking open and either letting half combusted gases out or fuel being burned in the header. Does it backfire when losing power? I definatly would not ride it till I found out what is happening...you may be heading for a seizure...the bike that is! How is the timing set up on those? you may be getting an intermittant timing problem. Also do you use duel spark plugs...even if one is not firing they must be of the same heat value or you can crack the head....please do not ask me how I know that!

If you had to clean crabs out are we to assume its been under water????






sorry just joshing you!


Oh btw welcome

Steve

[MomentSurf]

Originally Posted by GregR1

headers glowing red? only one of the header pipes, or both? always the same one? it sounds like it might be running lean, so one of the carbs keeps cutting out and not delivering fuel, or the float bows run dry and don't refill properly.

Your idea sounds like the most likely!
The part that glows red is where the two header pipes combine, before they are connected to the muffler. One cylendar, but two carbs...my thought is that one carb isn't acting right. I'm going to try to take the carbs off again and see if i can find a sticky float or something - but they have been off three times, my hopes are droping.

Can it be something as simple as a loose baffle or clogged muffler? This bike sat for about 15 years with out being started.

Thanks for you reply!

[MomentSurf]

Originally Posted by Aussie Steve

How many valves does this thing have. It sounds to me like a valve sticking open and either letting half combusted gases out or fuel being burned in the header. Does it backfire when losing power? I definatly would not ride it till I found out what is happening...you may be heading for a seizure...the bike that is! How is the timing set up on those? you may be getting an intermittant timing problem. Also do you use duel spark plugs...even if one is not firing they must be of the same heat value or you can crack the head....please do not ask me how I know that!

If you had to clean crabs out are we to assume its been under water????

sorry just joshing you!


Oh btw welcome

Steve

It has four valves. Two exhaust and two intake. I actually suspected the valves at first, because it also has a decompression lever to ease kicking the bike over. But the head was just rebuilt, new vavles/spings/guides and new piston/rings. I'm still having the same problem as before I did the work. And I also rulled out the decompression valve.
No, it doesn't really backfire when it looses power. Some small quite pops if you put your head down and listen when driving, but no huge backfires.
Its an overhead cam. One chain runs from the crankcase to the head. Timing consisted of lineing up marks on the camshaft while the piston was at TDC. Pretty simple and I don't think it could change once done.
One spark plug.

The bike was sitting in this guys yard, half covered with leaves. The headers were lying next to it. He said about 15 years ago he put it there because the sparkplug threads are stripped. I took the bike for free. The threads are fine! It was a challenge to get the plug out because of where it is located... but the threads weren't stripped. The guy had about 20 half finished projects in his yard. I gently layed the bike on its side (to move stuff stuck under it, and water came out of the cylendar. Haha, but she still started and ran two hours later. Now its giving me hell! It runs so great...3/4 of the time!

[DaveMc]

Another thing you might want to check are the plug wires. If one is bad (broken wire making intermittent contact between the broken ends; or a bad connection at either end of the wire), it will send power to the plug intermittently; may work fine once its is warmed up (wire expands and connection is made), but vibrations, etc. could still cause what you describe. Just a thought.

[eb77k]

I know quite a bit about these bikes and you are right to suspect a clogged exhaust. Mouse nest? The other issue may be moisture in the fuel system. A small bubble of water in the float bowl can be a tough one to diagnose. Next time if acts up try turning off the gas from the tank and removing the plugs on the bottom of the float bowls and take a look. Try adding some gas line deicer this is mostly alcohol and will absorb the water and let the engine burn it. The red headers is a lean mixture symptom so check the jets etc. I believe it's carburation related. There are plenty of flat tracker around with the RFVC Honda motors and they are pretty reliable.

[omegajim]

and don't rule out the obvious, replace the fuel lines.

[MomentSurf]

Great responses! Thanks so much. Sorry I haven't replied sooner...I was layed up in the hospital for 5 days. I stuck a screwdriver through my hand (between the pointer finger and the tumb) about 12 days ago. It felt fine for a week...the night after I posted the first post my hand swelled up and my health went south. Ends up I have an infection in my blood strem. No good. Home now but on IV for a couple weeks. Rediculouse. Well, once I can use my arms again...I'll let you know what I find. Thanks so much for the hints...

[MomentSurf]

Getting back into things.

I had a few minutes to spare so I took the muffler off tonight. I hear some rust particles (sounds like sand) floating around in there. Nothing will come out either end or the trap. Is there a way to test if its clogged?

It seems ok other than the old rust inside.

I'll pull the carbs off tomorrow.

[GregR1]

if the muffler is clogged, the bike won't run for more than a few seconds. if it's partly clogged, it'll run decent at low rpm but want to die or lose power at high rpm

[Easy Rider]

Originally Posted by DaveMc

Another thing you might want to check are the plug wires. If one is bad (broken wire making intermittent contact between the broken ends; or a bad connection at either end of the wire), it will send power to the plug intermittently; may work fine once its is warmed up (wire expands and connection is made), but vibrations, etc. could still cause what you describe. Just a thought.

Also plugs and boots. I'd sure check this (easier) stuff before pulling the carbs apart.

Then again, the loss of power and glowing pipes might both be carb related or it might be two different problems.

With 2 carbs and 2 exhaust pipes......are we sure there is only one cylinder?
How many plugs?

[94gsxr750]

lets see if i can help...
has any one thought to sinc the carbs... i had the same problem with my 94
gsxr and it turned out to be that i wood also make shure your plug wires are
not tuching and flot levels are set right..i wood try that because it sounds
like one carb is running rich and one is running lean

[gull]

Hi,
I've got a similar problem with my diddy aprilia rs125, with the unexpected loss of power that is. I can ride around 5-6 miles before the revs drop, and i finally have to stop. I wait for around 1 minute, and shes fine again for at least another 5-6 miles.

At first thought it was the fuel filter or tubing, but cleaned all out and seems to be fine, the only thing i've noticed when the revs start to drop is a considerable more amount of smoke. May be the same problem? Any suggestions?

[lavy]

sounds like crankshaft seals leaking and pulling in oil from crankcase causing loss of power and smoking