breakbeatz69
Banned
Hey everyone! So I’m new to the forum but not new to bike forums or metric bikes in the least. I’ve been building choppers and bobbers out of sportsters a little but my main bag of tricks comes from building choppers and bobbers out of the Yamaha XS650. I’ve done numerous xs’s with everything being done in-house by myself, I’ve had a couple bikes featured in magazines, and blah blah blah.
But now I’m tackling the one that always seemed to allude me, and that’s….you guessed it…a 1981 CB750c. I’m super stoked to finally do one of these bikes but I’m LOST when it comes to the DOHC style engine. I can tear down Harley Evos and Yamaha parallel twins like nobody’s business but this CB750 is a different monster entirely. I did order a Clymer service manual because, for one, I’m not an idiot that thinks I’m just gonna fly through this bike because I know a thing or two about motorcycles, and two, I know I’ll need it to understand this beast of an engine….so at least I got that going for me.
So to get into my first of many questions to come, I got my donor bike home today and got it in my shop and wanted to put it on my motorcycle jack right away but realized the 4 into 1 exhaust was in the way of the jack being able to sit on the lower frame rails. So I went to take the exhaust and headers off and when I did only 5 of these half moon shim looking things came falling out as I removed the headers. I checked the exhaust ports and there weren’t any stuck in the engine or on the headers themselves. So I have 5.
Now, I’m no mathematician, but with 4 exhaust ports having 5 of these things doesn’t make sense. So I looked online to find new ones to buy and couldn’t find shit in the way of any new ones. I did however find a set of 8 used ones on eBay and promptly ordered them since they were pretty cheap. Now, 8 makes sense to me, 2 for each header, but what in the fuck is the purpose of these things (whatever they’re actually called)??? I know there’s also gaskets that go into the 4 exhaust manifold ports, but what is the purpose of these half moon looking pieces? Are they some sort of weight support due to all the steel from 4 headers hanging off of the engine? Or do they serve another purpose? And are they necessary to have, or are they a part that can be deleted?
If you made it this far thanks a lot for riding with me until the end. My posts from now on won’t be as long winded now that I got my introduction out of the way and everyone has an idea of my experience level. Any and all comments/advice are welcome and thank you all in advance for your help. FTW!
But now I’m tackling the one that always seemed to allude me, and that’s….you guessed it…a 1981 CB750c. I’m super stoked to finally do one of these bikes but I’m LOST when it comes to the DOHC style engine. I can tear down Harley Evos and Yamaha parallel twins like nobody’s business but this CB750 is a different monster entirely. I did order a Clymer service manual because, for one, I’m not an idiot that thinks I’m just gonna fly through this bike because I know a thing or two about motorcycles, and two, I know I’ll need it to understand this beast of an engine….so at least I got that going for me.
So to get into my first of many questions to come, I got my donor bike home today and got it in my shop and wanted to put it on my motorcycle jack right away but realized the 4 into 1 exhaust was in the way of the jack being able to sit on the lower frame rails. So I went to take the exhaust and headers off and when I did only 5 of these half moon shim looking things came falling out as I removed the headers. I checked the exhaust ports and there weren’t any stuck in the engine or on the headers themselves. So I have 5.
Now, I’m no mathematician, but with 4 exhaust ports having 5 of these things doesn’t make sense. So I looked online to find new ones to buy and couldn’t find shit in the way of any new ones. I did however find a set of 8 used ones on eBay and promptly ordered them since they were pretty cheap. Now, 8 makes sense to me, 2 for each header, but what in the fuck is the purpose of these things (whatever they’re actually called)??? I know there’s also gaskets that go into the 4 exhaust manifold ports, but what is the purpose of these half moon looking pieces? Are they some sort of weight support due to all the steel from 4 headers hanging off of the engine? Or do they serve another purpose? And are they necessary to have, or are they a part that can be deleted?
If you made it this far thanks a lot for riding with me until the end. My posts from now on won’t be as long winded now that I got my introduction out of the way and everyone has an idea of my experience level. Any and all comments/advice are welcome and thank you all in advance for your help. FTW!