HELP: Can't get cylinder down on pistons

C

Cruzader

New Member
I have messed up my second set of rings trying to install the jugs on my motor. Both times piston #3 has gotten stuck.
I've tried installing pistons 2 and 3 first, I've tried all the pistons at the same time. It just wont make it in cylinder #3.

Any advice is appreciated

The ring on piston 3 is not broken, but it doesn't rotate easily in its place anymore. Am I correct in thinking that it is done for?
 
How about some back story? did you have the cylinders bored? honed? Have you tried fitting that piston to the cylinder by hand? The ring may be bent. Are you using ring compressors?
 
Probably need new rings for that hole. Use appropriate sized hose clamps to compress your rings on the pistons. Sliding the barrel down should transition the compressed rings into the bore.. Use some scrap wood to block up the pistons so they're not wobbling all over the place - dowel rod works. Make sure your ring gap is right first and foremost though. Good luck..
 
What bike are we talking about? Honed or bored? What rings? What pistons? It's a lucky guess to say anyrhing at this point..
 
lingo said:
How about some back story? did you have the cylinders bored? honed? Have you tried fitting that piston to the cylinder by hand? The ring may be bent. Are you using ring compressors?
Click to expand...

No, stock everything. 1970 CB750 K1. I haven't tried fitting the piston separately by hand if that's what you mean. The same piston got stuck with the same rings it had originally, and that's the only one giving my trouble. The other 3 pistons are going in fine.
I am not using spring compressors, because I am an idiot. Are there any one in particular that you would recommend?
 
You can go cheap like Montessa said about using hose clamp or try to find a band type ring compressor.

I am curious. Why did you pull the jugs in the first place?
 
Look for clamps like these...
 

Attachments

  • ImageUploadedByTapatalk1365212501.942436.jpg
    ImageUploadedByTapatalk1365212501.942436.jpg
    211.6 KB · Views: 653
lingo said:
You can go cheap like Montessa said about using hose clamp or try to find a band type ring compressor.

I am curious. Why did you pull the jugs in the first place?
Click to expand...

Yeah, I'll be doing that once I get another set of rings for that piston because I don't want to chance the ring on that piston being bent.

It all started when the camshaft tower came loose... Leading to me pulling the motor and separating the cases to clean out all of the metal and inspect the dogs and shifter forks in the transmission. The bike wasn't shifting very smoothly. I have replaced all the oil seals and believe that will help some since it has over 30k miles and the old ones were flat. I also replaced the chain tensioners and upgraded to HD head studs. I picked up the bike earlier this year and am making it my daily to ride to class

here's a shoddy before pic
get-attachmentaspx_zpsf111be19.jpeg


pic of me daydreaming it back together before the pistons were back in
get-attachment-4aspx_zps3521a5ef.jpeg



montessa172 said:
Look for clamps like these...
Click to expand...

Thank you very much montessa
 
I got around to trying the the t-bolt hose clamp method of installing the cylinder today. The same piston got stuck in the same way. I also used wood braces to keep pistons 2 and 3 square.

Next, I will try to install the piston by itself in the cylinder then attaching it to the connecting rod.
 
Cruzader said:
Next, I will try to install the piston by itself in the cylinder then attaching it to the connecting rod.
Click to expand...

I think montessa and lingo were advocating you try to fit the piston in on its own to ensure it does fit and moves freely. Then fit it to the con rod and install as you have been doing. Do you have the ring gaps spaced evenly around the piston say 2, 6 & 10 oclock if they are all inline or close to its bad news for sealing and sometimes makes it harder to compress them when they are like that.
Try a stiff feeler gauge to ease the ring in on the taper of the barrel.
 
I'm willing to bet that your cylinder has a "ding" or something in it. Very closely inspect the cylinder wall for any imperfections.
 
I realized that I hadn't gapped the new rings on the stuck piston. The second ring was binding everything up. The pistons then went in after a little bit of convincing with t bolt hose clamps, wooden supports and a rubber mallet

thank you all for your responses !
 
You must log in or register to reply here.

DTT Light or Dark

  • DTT Light

    • Spread the Love

    Back
    Top Bottom