CB100 Project

[mharrington]

If your not looking to remove the paint but want to simply clean the gunk off the engine case here is what I did with my XS650 engines. After taping off EVERY area I sparyed the assembled case with castrol purple power in a spray bottle. It is caustic on bare aluminum but the aluminum on my engine case is painted and I dont let it sit but immediately scrub with brushes. For rinsing I bought 3 cans of brake parts cleaner- $3.99 per can. Now the case is clean. I will scuff with scotchbrite, wipe down with laquer thinner and paint with PJ1 engine case black paint. This is the third time I have done this.

[vedgar]

careful !

I did just that last year, emptied a couple of cans of brake clean on the engine and caught the dripping in a low flat pan. Whoooosh, the stuff caught fire because I was dumb enough to leave a space heater on. It was 20 feet away too. Thankful for close fire extinguisher.

[kevxs]

yikes, i might just leave it as is and call it 'patina'

[kevxs]

leaking float valve

so I'm still working away on this bike when I get the time.
I have it back together but the carb bowl is overflowing.
I take the bowl off and hold the float shut with my hand and it still leaks out of the float valve (float needle or whatever you call the valve that stops fuel from entering the carb).
Everything has been cleaned but how do I fix this issue?

[webbcraft2150]

Yur gonna need new needles and maybe seats. I'd bite the bullet and tear the whole carb down and do a super clean. Don't know how old your Honda is, it may have one of those pesky Klein carburetors.

[Bonz]

Is it a rubber Viton tipped needle or a brass tip? A lot of issues with rubber tipped needles are the ring that forms where the needle rests in the seat. It's not really an indent, but you get some buildup that causes the ring. Take some 3M label and adhesive remover or similar (this was shared with me by a guru on the ZRX forum) and wet a terry cloth then twirl the needle tip around in the cloth to get rid of the ring. Seems to work in my experience with rubber tipped needles for the ZRX, so should work for the XS as well. Also, polish the needles seats themselves to smooth anything out. A Dremel with a polishing pad tip and some rubbing compound does that trick really well.

If you have brass tips, finely polish them up lightly and again, do the same to the needle seats as above. Let me know how it works.

[motoman]

Is it a rubber Viton tipped needle or a brass tip? A lot of issues with rubber tipped needles are the ring that forms where the needle rests in the seat. It's not really an indent, but you get some buildup that causes the ring. Take some 3M label and adhesive remover or similar (this was shared with me by a guru on the ZRX forum) and wet a terry cloth then twirl the needle tip around in the cloth to get rid of the ring. Seems to work in my experience with rubber tipped needles for the ZRX, so should work for the XS as well. Also, polish the needles seats themselves to smooth anything out. A Dremel with a polishing pad tip and some rubbing compound does that trick really well.

If you have brass tips, finely polish them up lightly and again, do the same to the needle seats as above. Let me know how it works.

A Q-tip with some polihing compound on it in the end of a drill works wonders.

[Bonz]

Good tip Brant.

[kevxs]

looks like it might just be a bad gasket on the needle seat. I'll check if one came in my gasket set but if not what's the easiest way to make one? what material do I need so it wont break down from being exposed to gasoline?

[Bonz]

I am only used to o-rings used as seals on the seats like the 1980 and on XS 1100. If that is the case, Harbor Freight sells assortments of viton O-rings that I I'm pretty sure will have some that would work.

[kevxs]

an o ring did the trick, thanks!

[kevxs]

wont fire up

an update on my honda project, I had to tear down the engine to replace the head gasket. Its all back together now.

I've got good spark and compression. the carb is clean and full of fuel so I assume I'm getting fuel to the combustion chamber. I can't get any kind of encouraging noises as I kick it over. a couple back fires is the most i've gotten after kicking it many times. all I can think to do (and have done) is adjust the timing and keep kicking it over but I still don't get any response from the engine.

can anyone give me some more ideas on how to proceed? as far as i know i installed the cam correctly, i have 120psi compression so I know I haven't bent any valves at least.

I've never done a tear down and re assembly like this so is there any method I should follow to get it to fire up for the first time? the fact that i get absolutely no firing sounds from the engine is pretty frustrating. i've also put a bit of fuel directly into the cylinder and got one sad little bang but thats it.

[wingnut]

So if you pull the plug after trying to start it is it wet or dry? Also I'd check the spark by removing the plug and laying it on the head. Is it a nice fat blue white spark or a weak yellow one. When you did the carb did you do a complete disassembly? The passages in the jets are tiny. Only takes a little POS to keep them from working right. Also when you replaced the oring on the needle valve did you reset the float level to the proper setting?

[kevxs]

i have a nice big blue and white spark. sometimes the plug would be wet when I pull it out after trying to start it, last time or two when i pulled it out it didn't seem very wet. I had the carb pretty clean as I recall but I think I'll pull it off and give it another go though. also I'll check the float height.

thanks

[kevxs]

just working away on my old honda again.

I got it running good after adjusting the cam 1 tooth on the timing chain.

I then put a few more covers and things on and tightened some bolts and now I have hardly any spark. I can get a bit of a spark sometimes but it's not like it was. I also notice when I hook up the battery it says 6volts but when i turn the key on it goes down to 2.3v or so.

My grounds and main fuse seem to be clean so just wondering how I should go about troubleshooting this issue.

thanks