78 Honda Twinstar CM 185

[Guest]

If the petcock is working properly it will stop the fuel from flowing when you pull the tank. Just make sure the lever is in the proper position. I'm not sure how that model petcock works so to test you have to do some research.

With the carbs off you will want to remove the floatbowl's and have a look. If there is any grunge then a full tear down is in order. If the carbs look very clean inside the float bowl then you will want to follow up by removing the pilot jets and holding them up to the light to be sure there is no blockage. This should be the absolute minimum you do.

Awesome thanks. The petcock is in the off position, so hopefully it does its job. I'm planning on doing a full tear down regardless of its condition just to get the experience since I've never done it before. I'll need to do this on my GS550 in the future at some point, so I might as well get some experience on this smaller engine that only has one carb. It also looks like I can buy a brand new replacement carburetor for around $20, so if I completely mess it up at least I have a backup plan

 

[Nessism]

One carb? Humm. A brand new OEM replacement carb for $20? That would be hard to pass up. You will have to source replacement O-rings and maybe a bowl gasket to do a proper cleaning job and you can easily spend that much with only a minimum of parts.

 

[Guest]

It's not OEM, but supposedly compatible. I'll keep investigating, it might not work at all.

 

[Jedz123]

The petcock is a conventional non vaccum operated valve. So there is on/off/reserve. Just make sure she's on off...

Yup those guys only had 1 carb. The Twin star I had had an aftermarket carb as well. I ended up swapping on a a mikuni unit for the quality was better. However I did put a cheap aftermarket carb at first and that cheap carb did work great with the bike. Just make sure the jetting is correct. As I recall I swapped in the main jet from the fouled carb in the bike to the new carb for they were different sizes.

Just a heads up

 

[Guest]

Got the carb off last night and disassembled. Holy cow these JIS drivers are night and day difference on these screws. The carb didn't have much gunk in it, but the main jet was clogged. Tossed the pieces in a carb dip for an hour or so and then cleaned everything up, made sure all holes were clear using wire and compressed air. Ordered all the replacement seals that I'll put in when they get here.

I'll be ordering a new battery today that should take about a week. Anyone have any advice for verifying I'm getting spark?

 

[Jedz123]

I'll be ordering a new battery today that should take about a week. Anyone have any advice for verifying I'm getting spark?

Pull the plugs out and install them to the wire. Hold the plug next to the block and turn the engine over. You should see a bright blue arc (or spark). I bet it's fine make sure it's 6 volt battery too, pretty damn sure mine was 6V.

 

[Guest]

Awesome,thanks. Yeah, it's definitely a 6V system. Should the kickstart produce a spark the same as the starter switch?

 

[Jedz123]

Awesome,thanks. Yeah, it's definitely a 6V system. Should the kickstart produce a spark the same as the starter switch?

It should... What I would do is remove both plugs in turn not allowing any pressure to build in the cylinders making the engine turn over very easily by hand. Just have a buddy help turn the engine over (you can juggle and turn the kick start and hold the plug wire) but you should see a spark as you turn the engine over.
Good Luck! I did have my battery go flat once and I kicked started it on a dead battery so I can't see why there shouldn't be any spark.

GOOD LUCK!!

 

[Guest]

Probably a noob question, but is there something specific I need to do to keep pressure from building in the cylinders when I pull the plugs?

 

[Big Rich]

With the spark plug (s) removed, you can't build pressure in the cylinders.

 

[Guest]

ah ha. thanks.

 

[Guest]

As I'm putting this carb back together with the new gasket and seals I'm confused about this float needle...thing.

The Honda service manual shows to make sure the plastic tip is in good condition, and it is.

But I was watching this video of a carb disassemble (https://youtu.be/HeMjppADyTM?t=573) and he mentions that some of these have a spring loaded valve pin on the other end that should move freely. If mine is supposed to move, it does not. It looks like a new one is about $20 plus shipping, so I?d rather not have to replace it. Short of holding that end in carb cleaner by hand for an hour and trying to free it up, anyone have any advice on getting it moving again?

 

[Nessism]

Stand it up with the end in carb spray (not carb dip). You may need to prop it up in a small shot glass or similar to keep the rubber tip out of the sauce. After soaking for a while you may have to try grabbing the tip with tweezers and moving it back and forth to free it up. Don't gouge the metal though or the needle is junk. If necessary you can get aftermarket tips. They are fine and not overly expensive.

 

[Guest]

Thanks I'll give that a try. Would brake cleaner work as a substitute for carb cleaner in this instance? Not sure what's open around me today and I know I already have break cleaner on the work bench.

 

[Nessism]

Thanks I'll give that a try. Would brake cleaner work as a substitute for carb cleaner in this instance? Not sure what's open around me today and I know I already have break cleaner on the work bench.

Should be fine. Remember, soak the spring loaded tip end and try to keep the rubber tip out of the chemical.

 

[Guest]

Local auto parts store was opened, so it's soaking in carb cleaner now. Fingers crossed!

 

[Nessism]

It will work. I freed up a bunch of those needles that way. Tape the jaws on some needle nose pliers or some tweezers and push the small tang in and out. It will come loose. After it starts to move continue to work it until is springs back easily and strongly.

 

[steve murdoch]

Have you tried some heat?
This seems too drastic to me without ruining the rubber tip but if the carb cleaner doesn't work it might be worth a try.
https://www.youtube.com/watch?v=P0egD-1XWN4

 

[tkent02]

Too much heat would ruin the spring as well as the rubber tip. It will come free with the carb cleaner.

 

[Guest]

Well, one hour of soaking didn't do it. I'll leave it in there overnight, maybe I'll get a working float needle for Christmas tomorrow morning.

Thanks for the additional suggestion of heat, if it's still not unstuck by tomorrow I'll try that. Though I don't have a torch. Maybe the gas stove could help though.