I've had my 72 CT70 for almost a year now, previous owner went thru and rebuilt the engine and carb. First 9 months were great, last couple of months it's started running rough at 3/4 to full throttle, also randomly wouldn't start or would just die. Cleaned carb, still the same. Checked the spark, seemed weak to me so I cleaned and set the points. Still running rough, cleaned the carb again and found a little bit of metal in the idle jet and filter. Put it back together and ran like a champ... for about 10 minutes. Started running rough at 3/4 to full throttle and progressively got worse until it died. Now it won't start, checked the carb all looks good, new plug still no good. Seems like spark is weak but it's hard for me to see while kicking it. Tried starting fluid just for kicks, still nothing. HELP, I'm pulling out what little hair I have left.
72 trail keeps fighting me
- Thread starter wsurf4me
- Start date
OLD CT
Well-Known Member
:102: When you clean the carb, did you remove the emulsion tube and rod out the holes in it? And make sure the pilot jet and main jet is clean/clear. If not, do it again. Cleaning the points may not be helping, time for a ''new'' set. Also, what are you setting the points at?
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cjpayne
Well-Known Member
If you will go through this thread and follow the things I tried with my K1, you'll probably find the problem along the way. http://lilhonda.com/webboard/showthread.php?t=18010&highlight=
I did, that's where I did find some crud, I'll do it again. I have a new set of points, if I remember correctly the old ones are set to 0.012".
Thanks, I'll take a look. Hopefully we can get this thing running again.
cjpayne
Well-Known Member
OC is right. During diagnosing a problem, I will sometimes set my points @.014, just to make sure the setting hasn't moved causing a problem. Once you get the bike running great again, then set those points @.016. You'll find that the bike will have 5-10m.p.h. more than the points being set @.012. MY K1 sure did. New OEM points are the way to go too. Sometimes just adding new OEM points will be good for a few mph's.
Thanks, just finished reading your thread, there's a ton of good information in there. I'm going to check spark again - seemed weak to me, set the points at 0.016", clean the carb and check valve lash.
While the flywheel is sitting on your workbench, check the breaker point cam. If it's rusty/pitted, the phenolic plastic rubbing block (on the breaker arm) will wear rapidly, causing the point gap to close-up.
Rodding-out the emulsion tube orifices is the most overlooked and oftentimes most important task when cleaning/rebuilding a carburetor. Sometimes, they have to really be worked to get unobstructed flow through all of them. Have you inspected the inside of your fuel tank? If it's rusted, time to do something about it. These days, pump gas is loaded with crap. Installing in-line, clear, fuel filters is a cheap & effective way to keep that garbage from entering the carb in the first place.
Rodding-out the emulsion tube orifices is the most overlooked and oftentimes most important task when cleaning/rebuilding a carburetor. Sometimes, they have to really be worked to get unobstructed flow through all of them. Have you inspected the inside of your fuel tank? If it's rusted, time to do something about it. These days, pump gas is loaded with crap. Installing in-line, clear, fuel filters is a cheap & effective way to keep that garbage from entering the carb in the first place.
Went thru everything this weekend, carb looked good the emulsion tube orifices were all clean. It still wouldn't start, the spark seemed weak to me so I checked the points next. The gap was way too small, maybe 0.008" at best. The phenolic block was badly worn, the cam looks ok. I replaced the points, gapped at 0.016", put it back together and after quite a few kicks it started up. Runs much better, no cutting out although the idle seems a little rough - adjusting the idle mixture screw didn't seem to smooth it out .
So overall I'm getting close to where I'm happy with it, however I found a couple of other minor problems. First is there is a very, very small gas leak at the carb, it appears to be where the brass hose barb is pressed into the aluminum carb body - any suggestions on how to fix this?
Also I have a small oil leak at the head gasket, I assume the only way to fix this is to replace the gasket, not sure if it's worth it at this point. I will start by checking the torque on the head bolts.
Finally the rough idle, not a deal breaker but it would be nice if it was a little smoother, could this be related to the 0.016" point gap?
So overall I'm getting close to where I'm happy with it, however I found a couple of other minor problems. First is there is a very, very small gas leak at the carb, it appears to be where the brass hose barb is pressed into the aluminum carb body - any suggestions on how to fix this?
Also I have a small oil leak at the head gasket, I assume the only way to fix this is to replace the gasket, not sure if it's worth it at this point. I will start by checking the torque on the head bolts.
Finally the rough idle, not a deal breaker but it would be nice if it was a little smoother, could this be related to the 0.016" point gap?
Sounds to me like you have 3 separate issues. The points were the most substantial. Keep an eye on the gap. If it continues to close-up, you'll have to find out what and make the appropriate correction; otherwise, this will repeat at regular intervals. I have the feeling that your carb is still not 100% healthy. I'd be tempted to swap-in a brand-new pilot (idle) jet. If that corrects your idle, problem solved. If not, I'd verify the pilot air bleed is open and look for a small vacuum leak.
The brass fuel barb is pressed into the bowl casting. If you can't stop the leak by gently tapping it into its fully seated position, a little epoxy will do the job.
Verify the source of that oil leak. It could be at one of the cam covers, oil flow migrates with gravity. Solvent-clean the area(s) then look for new oil, at the highest point on the motor; that'll be the source. If oil is getting past the head gasket, the most likely reason is a missing, or ossified, O-ring. Head warpage is possible but not common. More likely, a P.O. reused an old gasket or missed something during installation.
The brass fuel barb is pressed into the bowl casting. If you can't stop the leak by gently tapping it into its fully seated position, a little epoxy will do the job.
Verify the source of that oil leak. It could be at one of the cam covers, oil flow migrates with gravity. Solvent-clean the area(s) then look for new oil, at the highest point on the motor; that'll be the source. If oil is getting past the head gasket, the most likely reason is a missing, or ossified, O-ring. Head warpage is possible but not common. More likely, a P.O. reused an old gasket or missed something during installation.
Well I used JB weld on the barb, got it 90% but still a very small leak. While I had it out I cleaned all the orifices in the carb again, put it all together and seemed pretty good.
That was a month ago, went to start it today and same crap, rough running, won't idle, had to choke it to even have a chance at running. This is getting old, I assume the carb is crudded up again it's the why I don't understand. I added an inline filter during the last go round, I assumed that would do the job. Could it be the tank liner or old gas? Here in Florida we do have issues but I only use non-ethanol gas and I shut off the carb when I'm done with the bike. I'm starting to think I need to drain the carb also.
Any suggestions? Also does anyone know where to buy a fuel petcock? Mine just snapped off when I went to turn the gas on.
That was a month ago, went to start it today and same crap, rough running, won't idle, had to choke it to even have a chance at running. This is getting old, I assume the carb is crudded up again it's the why I don't understand. I added an inline filter during the last go round, I assumed that would do the job. Could it be the tank liner or old gas? Here in Florida we do have issues but I only use non-ethanol gas and I shut off the carb when I'm done with the bike. I'm starting to think I need to drain the carb also.
Any suggestions? Also does anyone know where to buy a fuel petcock? Mine just snapped off when I went to turn the gas on.
OLD CT
Well-Known Member
Have you tried spraying carb cleaner around the base of the intake where it meets the head when it falters, to see if you have a leak? The idle will pick up, if there is. :106:
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kirrbby
Well-Known Member
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Just thought I'd post an update. First with the fuel leak, idle issues and broken petcock I decided to go ahead and purchase an aftermarket carb. I swapped it in, had to do a little tuning and problems solved. I have my old one set aside, at some point I will purchase some bits and rebuild it. I also have instituted the no ethanol, no fuel left in the bowl policy. I am lucky enough to have non ethanol fuel available but also run the carb dry when the bike is going to set for more than a few days.
The oil leak was traced back to the gasket between the cylinder and the crankcase. I checked the head bolts and they were loose, the previous owner had rebuilt the engine and either forget to torque the bolts or they worked loose after a few heat cycles. Ended up torquing them to 10 ft-lbs, a little high but was hoping to get enough squeeze to seal her back up. At first had a very small leak, but much to my surprise it has stopped after a few heat cycles. I rode it at a local swap meet yesterday, about 10 miles over the course of 3 hours, lots of stopping and starting. Everything is good, thanks to everyone here for all the advice.
The oil leak was traced back to the gasket between the cylinder and the crankcase. I checked the head bolts and they were loose, the previous owner had rebuilt the engine and either forget to torque the bolts or they worked loose after a few heat cycles. Ended up torquing them to 10 ft-lbs, a little high but was hoping to get enough squeeze to seal her back up. At first had a very small leak, but much to my surprise it has stopped after a few heat cycles. I rode it at a local swap meet yesterday, about 10 miles over the course of 3 hours, lots of stopping and starting. Everything is good, thanks to everyone here for all the advice.
Well the cutting out problem is back. The bike has been setting for about 6 months and it cuts out and sometimes backfires at 3/4 to wot. I've cleaned the carb several times with no effect. I did get it running good for one day a week ago, I filed the points and set the gap to 0.016" and replaced the spark plug as it was all sooted up. It was a warmer day with temps in the 80's and the bike ran great - topped out at 40 mph. Checked the spark plug after about 30 minutes of riding and it was a nice tan color. The next day was cooler in the 60's and when I tried to ride it I had the cutting out problem again, pulled the plug and it was all sooted up again. Any thoughts on what's going on?
Yes I have grease on the cam and the wiper material.
I checked the condenser with a multimeter and it seems to be ok.
Thanks for the suggestions, any thoughts on why the sparkplug keeps getting sooted up? Carb has a #60 jet and I've checked the clip that holds the needle in place, it's solid with just a tiny bit of side to side play.