HondaCB650

I recently got a 1980 cb650c. I've seen videos and pics of people with the pipes chopped just before the stock mufflers. Looking at my bike (I believe it has crosstubing exhaust[?]), I assume you would have to cut in front of stock footpeg placement. Is this correct? I know backpressure would be an issue, but I plan on rejetting for open pipes and velocity stacks (120 main and 43 slow?). I worry about cutting too far forward and getting cables, wires, etc. too hot. If someone could tell me where they have cut or where they know of to cut, it would be greatly appreciated.

NOOooooooooooo! Don't do it give them to me and I'll give you my four into two, chop them instead I'm only joking mate, I'm on the other side of the World

I didn't see this before I replied on my show it off post lol. I wish I could make a deal man, but shipping would be outrageous.

Yeah, I know It'd probably be cheaper to tow the UK closer to America

I can say dont chop at all!



Do you see the pipes on my bike? Those pipes is for HD bikes mainly and it's not good to use att all.
In idle the engine stutters and sneases and i have found out it's the end pipes fault.
Try to find pipes that really work on a 650 cc engine if you must chop.

Have you tried rejetting for your specific pipes? Changing baffles? Adjusting needles? Adjusting mixture?

Well i can say with the factory setting those pipes is no good and when i got the bike it smelled like i had the choke on when i was standig still at crossings or red lights. And i dont like those short pipes anyway, you can clearly see how black the rear brake shield is. I like to have the highest MPG possible so rejetting is no go for me.



I would rather have the pipes from that kind of bike.

But in you must chop do that behind of where the pipes from the engine joins together.

Thanks for the tips. By behind the connection, do you mean toward the front or rear of the bike?

CP, have you actually had this bike running properly? I would delay chopping your pipes until the bike is running fine so that if there is a problem, you can't blame it on your lack of back pressure from your exhausts.

It runs, but I still have work to do. Not chopping until it's been on the road for a little while.

That is one good thing about the CV carbs. They will automatically compensate for an exhaust change.

Edit: Just for clarity: Your bike does not have CV carbs (unless a previous owner changed them).

What's required to run CV carbs?

CPowell1994 wrote:What's required to run CV carbs?

A new cylinder head at least I've heard it said that only the spacings on the carb inlets are different between the CV and slide carb heads but there seems to be a bit more to it than that.
I know from experience that the head gaskets are different between the two but also, unless the gasket I had was somehow faulty (don't think so) then the head bolts are located slightly different.
More here-
viewtopic.php?f=4&t=14167&hilit=right+gasket+set

Gotcha. So I'm probably better off just rejetting for the straight pipes and v stacks. If that doesn't work out I may look into a head and CV swap.

CPowell1994 wrote:Gotcha. So I'm probably better off just rejetting for the straight pipes and v stacks. If that doesn't work out I may look into a head and CV swap.

CP, my point being that it may not be as simple as just the head swap, the bolts that hold the barrels on "seem" to be in different locations.
I have spare engines with both types of head but I haven't really got the time to dig them out and experiment at the moment.