Top end knock

[m in sc]

this.

whos almost burned their hand on a piston pulling it out....    

[2t Fan]

16oz to 5 gallons of gas, 40:1.

35ml of 2T per 1000ml of gas is fine for a lightly ported RD ? 

[rodneya]

this.

whos almost burned their hand on a piston pulling it out....    

Definitely been burned by exhaust and sparkplugs more than once.

[m in sc]

16oz to 5 gallons of gas, 40:1.

35ml of 2T per 1000ml of gas is fine for a lightly ported RD ? 

yes, typically its fine. it wont cause a seizure, that's for sure. I used to run my high strung yz on that ratio no issues. 

[Joshua]

Thanks all . . . Yes, I'm patient or made to be patient.  It took me almost 5 years to complete this project. . .lol.  Actually, I just sold my warehouse and changed careers.  This past year has been a year of simplifying, sadly selling off way too much I just don't have room to store anymore.  Next project I picked up is an RZ350 I'm dying to get to. . . . and it's sitting there staring at me . . .

Either way, I'll keep you guys updated, should have it apart in a week or two.

[Hawaii-Mike]

Nice looking bike, fenders might come in handy when it rains.

[Joshua]

Welp, here is my stupidity. Now that I've had some time to think, I believe when I lost my timing, I heated up the right cylinder, which may have caused some damage that I didn't catch. Then on my longer ride I did the rest. Great learning experience, sucks for me. Lol.

Couple questions so I'm not spinning my wheels here.

1– will I need piston, rings, rebore/hone. Is there anything else.
2– who can I send the work to?  I'm in florida, so I guess shipping would be fine.
3– is there anything I should be concerned with other than the obvious.

Thanks for all the encouragement here. Many times my first time through things I overthink and it freezes me to not just jump in and get it done. I'm learning . . .

[rodneya]

That doesn't look bad at all. You should be able to clean the cylinder up with muratic acid and then just a new piston.

[1976RD400C]

Could you post more pics of both pistons and what do you mean by it lost timing?

[Joshua]

I've got the vape ignition, flywheel slipped.

I have to pull the pistons off. Really just looks like one cylinder is down but I feel I should just replace both. I'm nervous when my timing slipped it caused some weakness in rings/pistons.

[Striker1423]

if timing slips on the vape setup, it would normally retard the timing. As the flywheel would slip backwards after firing the cylinder.

One thing to note when installing the vape. Heat the center taper of the vape flywheel with a heat-gun for like 60 seconds or so and then install it as quickly as you can. Give it a tappy-tap-tap with a plastic mallet and then install the bolt with extra thick washer from economy cycle. The taper is what sets the flywheel, but the extra few ft-lb's clamping down on it never hurts.

[Joshua]

I did this when I set the timing, I also lapped it before I reinstalled it. . . .

[m in sc]

do not lap it. theres a 1/2 degree difference which is what gives the interference.

[Economy Cycle John]

Make sure that longer bolt isn't bottoming out (it's been reported a few times), Add washers if it does. 18-20 ft/lbs of torque on the bolt.

[Joshua]

Got it, Chuck got back to me, so I'm in good hands. I sent him some detailed pics and he  suggested sending him the barrels, then once I get things broken in again I'll go and hang out and double check everything on the bike. Every time I go up there he is a wealth of knowledge. May even have some parts he needs from my left over pieces to keep one of you guys on the road. Things are working out. Just have to be patient I guess. Lol.