Zed Head

I don't think that he has checked the timing yet, or tried adjusting it. It is very close to the very first thing that is done when starting an engine that has been apart and reassembled. Engines are all about timing. I'm always happy to offer an alternative path for people who don't want to try the well-worn one. He'll have to check the timing eventually. In the meantime...carbs.

I'm not an SU expert but I know that intake vacuum controls the position of the piston in the carb that controls the amount of fuel allowed in to the air flow. So your problem is probably related to what happens from start to engine running. The piston is in one spot at start, its resting position, with zero intake vacuum then moves, or is supposed to move, as intake vacuum develops. The new position causes the engine to spit and die, or the piston is stuck and doesn't move and this causes the engine to spit and die. I'd focus on making sure the pistons are moving like they should, with correct oil in the damper. Seems like you're getting a "lean" kickback, which implies that the carb pistons aren't moving, or aren't moving fast enough, which would keep the needle low in the jet making things lean. Engine starts, goes lean, kicks and dies. This is from my latest understanding of SU's, developed as I read your post and also pondered what little else I know about them. The throttle blade controls the airflow, the piston position controls the fuel mixture. The kickback sounds lean.

Isn't that the same video from Hybridz? Did you do the stuff that was suggested over there?

...

...

Bultaco. Never had one. Rode one once, a 250. Just like seeing the name in print. Spanish made, hard to believe. I did a Google and learned something. https://newatlas.com/bultaco-rapitan-sport-resurrected/32117/

Posting to remove the awkwardness! There is a web site though. Our Mission Boobs are complicated.

Just wanted to share. Seems like multiple wrongness but I can't put my finger on what exactly. This is a real ad on the site.

Did you check the numbers? Just curious. You might fall in to the trap of thinking that the PO used all correct parts. @jitenshakun

At the end of all of the discussion I don't think that anyone is going to pay more for a "Black Pearl". The car salesmen will use anything to promote a car. You might even find Jon Voight's pencil in the glove box.

Some of the transmissions we've seen on the site have been incredibly damaged inside. Often the owner didn't even know until they changed the fluid and found a collection of metal parts on the magnet. A failed transmission is almost unheard of. They die very very slowly.

...

And the two stroke cylinder had the tapered opening so you could get the rings in. CO built what is essentially a two stroke engine cylinder. Maybe the same for the four strokes.

Slip the slip yoke in to the end of the transmission and wiggle it around. You should also check the slip yoke surface for wear, it can get grooved if somebody let the seal wear out. I haven't seen a spec for play, I think it's kind of a gut feel thing. It will feel looser without the seal in place.

It might well be that ensys doesn't realize the effect his writing style has. Plus he's still worked up over the inability to post images. But, still, a problem was solved.

...

I was actually asking madkaw. But your info is good too. Do yours fit the perches? @Soedward11

Just thought of this - don't lose the preload shim in the countershaft bore in the front cover. It might be stuck in there, hidden, but you'll need it and the odd sizes aren't available anymore.

Bummer. Who did you order them from?

Here's a good read about doing transmission work. It also shows a sealed bearing used on a 71C transmission. Looks like it came from Nissan that way, the guy bought a brand new 240SX 5 speed. It's the front main shaft bearing though, which wouldn't see much fluid splash probably. He has some good tips for reassembling. Put the transmission in gear before reassembling otherwise you can get two gears engaged at one time as the shift rods are accidentally moved. This is where I learned about Hylomar Blue also. A non-setting sealant. http://zhome.com/ZCMnL/tech/240SX5spd/transmission.htm

If you can find an area of paint that has metallic black then it was a Black Pearl, apparently. Probably what we used to call "metal flake". Check the back of the gas filler door.

How about oil instead of fuel? A bad valve seal or oil scraper ring maybe. Are the DCOE's easy to swap? Swap it and see if the problem stays with the barrel.

This site says that "Black Pearl" is paint, stripes, an extra mirror, and a louver. So, look for holes or witness marks where the mirror and louver was installed. https://classiccars.com/listings/view/910782/1978-datsun-280z-"black-pearl"-for-sale-in-beverly-massachusetts-01915 Here's a picture that seems to show the bottom brackets for the louver.

Never mind, I'm wrong. I think that "Black Pearl" is an urban legend, isn't it? Or some sort of ad copy that got blown up in to a thing.

p.s. if you can find the number on that bearing you might be able to look it up to see what, exactly, it is. I'm sure it's fine, but just curious. The number's probably engraved on the side of the outer race. Here's a link to browse the different types of bearings. There's a bunch for all kinds of different applications. Looks like Dave and Chas were right, best to have good lubricant flow through yours. It's not what I thought it was. https://www.vxb.com/Sealed-Ball-Bearing-s/198.htm?searching=Y&sort=13&cat=198&show=15&page=2 2nd edit - and just to fill out the bearing saga, a page showing a "rubber molded to a steel plate" seal https://www.grainger.com/product/35JC49?gclid=EAIaIQobChMIkqvpqK_S6QIVUtbACh2EvQbAEAQYASABEgK_dPD_BwE&cm_mmc=PPC:+Google+PLA&ef_id=EAIaIQobChMIkqvpqK_S6QIVUtbACh2EvQbAEAQYASABEgK_dPD_BwE:G:s&s_kwcid=AL!2966!3!402184946084!!!g!439044420138!