PlanetMinis Forums banner

1 - 10 of 10 Posts

·
Registered
Joined
·
80 Posts
Discussion Starter #1
Hi all,
Back in late February I picked up a 71 CT. It was in pretty rough shape but most are when you can get one at a somewhat affordable price. The bike started up and ran ok. Definitely needed tuning and clutch work. Well, I’m getting ready to rebuild the engine from the ground up. I’m doing a complete tear down and rebuild and after scraping off some dirt and grease I just noticed a crack on the back side of the case. The bike was filthy when I picked it up and the rear part of the engine sits under the frame so it was hard to see. I honestly don’t know how serious it is or if I shouldn’t bother rebuilding.. Here are the pics. Let me know if you think this case is garbage.

7C3C7A6C-35D1-400C-A1F8-A02562168F55.jpeg
7C3C7A6C-35D1-400C-A1F8-A02562168F55.jpeg
CDC982A4-12D6-474A-A617-CDFC8C3CC53F.jpeg
 

·
Registered
Joined
·
80 Posts
Discussion Starter #2
Hi all,
Back in late February I picked up a 71 CT. It was in pretty rough shape but most are when you can get one at a somewhat affordable price. The bike started up and ran ok. Definitely needed tuning and clutch work. Well, I’m getting ready to rebuild the engine from the ground up. I’m doing a complete tear down and rebuild and after scraping off some dirt and grease I just noticed a crack on the back side of the case. The bike was filthy when I picked it up and the rear part of the engine sits under the frame so it was hard to see. I honestly don’t know how serious it is or if I shouldn’t bother rebuilding.. Here are the pics. Let me know if you think this case is garbage.

View attachment 272741 View attachment 272741 View attachment 272742
Hi all,
Back in late February I picked up a 71 CT. It was in pretty rough shape but most are when you can get one at a somewhat affordable price. The bike started up and ran ok. Definitely needed tuning and clutch work. Well, I’m getting ready to rebuild the engine from the ground up. I’m doing a complete tear down and rebuild and after scraping off some dirt and grease I just noticed a crack on the back side of the case. The bike was filthy when I picked it up and the rear part of the engine sits under the frame so it was hard to see. I honestly don’t know how serious it is or if I shouldn’t bother rebuilding.. Here are the pics. Let me know if you think this case is garbage.

View attachment 272741 View attachment 272741 View attachment 272742
It’s possible I may have reacted too quick. After pulling the counter shaft oil seal I don’t see the crack in there. Maybe it a flaw in the castings??

2449DB4B-1BDF-4AC3-80E9-8B8E40C62000.jpeg
BD1DC21A-4C41-4000-B651-04F6F5B14122.jpeg
 

·
Registered
Joined
·
1,132 Posts
Flaw in the casting. It's very common. You can know for sure as you break down the engine. This one is the scariest looking one that I've seen. But I do think it's a outie, and not a innie :)
 

·
Registered
Joined
·
80 Posts
Discussion Starter #4
Thanks Kirrbby. I’m hoping the same. I’m tempted to break the motor down and confirm this but I’m trying to decide the best approach to clean this entire motor the best I can before I tear it down. I was actually considering taking to to my friends house and glass beading the entire engine while it’s assembled so I dont get any glass inside the case. I know the glass will leave a slight texture on the case. I figured I can smooth it out with some light sanding hoping the result will be a nice clean case.
 

·
Registered
Joined
·
3,962 Posts
If you use fresh glass bead and keep the pressure low (45PSI or lower,) it will look very similar to the original finish. If the beads are not new it will have a little texture that looks OK, but not as shiny.
 

·
Registered
Joined
·
929 Posts
I ran into this when tearing down my first Motocompo. I thought my engine was trash and all the avid scooter guys just told me it's completely normal with Honda castings. It's apparently how they save money! Sanded it down even tho you can barely see it when it's on the bike and it's good to go!

 

·
Registered
Joined
·
1,132 Posts
I'm planning to get a small cheap blast cabinet...brand new so its perfectly clean, and dedicate it to walnut shell blasting. Walnut shells are supposed to be soft enough as not to profile aluminum. I can't say first hand how well it works tho...yet.

Trick is to put only clean castings in the cabinet so you don't introduce sand and rust and such into the blast media.
 

·
Registered
Joined
·
80 Posts
Discussion Starter #8
I'm planning to get a small cheap blast cabinet...brand new so its perfectly clean, and dedicate it to walnut shell blasting. Walnut shells are supposed to be soft enough as not to profile aluminum. I can't say first hand how well it works tho...yet.

Trick is to put only clean castings in the cabinet so you don't introduce sand and rust and such into the blast media.
I have looked at the smaller harbor freight blast cabinet. I even went and purchased a 26 gallon air compressor from Lowe’s because I wanted an air compressor and I figured I would get something with a decent capacity so I can blast for more than 10 seconds. After doing some research I realized I need a lot more CFM. The compressor I purchased is only 4.5CFM at 90PSI. Correct me if I’m wrong but I think I need a lot more CFM to achieve good results with walnut or glass.
 

·
Registered
Joined
·
1,132 Posts
You might get good results with a, too small, air compressor. But it might take a while and be frustrating having to wait for more air all of the time.
I think it would be a massive compressor to keep up with a blaster at full power. 4.5 CFM definitely it too small...but I think it will work well when the tank is up to pressure.

Thus far, I've only used the blast cabinet at my work. It's powered by a magic, unwavering, air supply. So I don't yet know for sure what is needed to run a small counter top cabinet. My old compressor has crapped out on me. It was 12cfm at 90psi...60gallon. I don't think it would have been able to keep up with a blaster either...I'd have been waiting on that one too.
 

·
Registered
Joined
·
3,962 Posts
7
You might get good results with a, too small, air compressor. But it might take a while and be frustrating having to wait for more air all of the time.
I think it would be a massive compressor to keep up with a blaster at full power. 4.5 CFM definitely it too small...but I think it will work well when the tank is up to pressure.

Thus far, I've only used the blast cabinet at my work. It's powered by a magic, unwavering, air supply. So I don't yet know for sure what is needed to run a small counter top cabinet. My old compressor has crapped out on me. It was 12cfm at 90psi...60gallon. I don't think it would have been able to keep up with a blaster either...I'd have been waiting on that one too.
I use an IR 7.5 HP 80 gallon compressor, and on a full charge, it blasts less than a minute without re-starting. It can keep up with the cabinet, but anything less would be running almost constantly. Not a huge deal, but the big ones are more noisy and create a bunch of heat.
 
1 - 10 of 10 Posts
Top