Hard starting with new exhaust install


CB750 Enthusiast
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Denver, Colorado
1982 CB750K

I was finally able to buy the Delkavic 4 into 1 exhaust and install it on the bike this weekend. I was pleasantly surprised by the amount of weight savings I gained by removing the factory 4 into 4.

Factory Senkei 4 into 4- 46.9 lbs
Delkavic 4 into 1- 13.5 lbs
Total weight savings- 33.4 lbs

It could just be me wishfully thinking, bit the bike feels much easier to balance between the legs.

Anyways, the removal and install were both very straight forward.

However, getting the bike started seems to be quite the challenge. Before removing the stock exhaust, no matter warm or cold, the bike started right up (wouldn't even have to touch the choke). Now, I've only been able to get it started once. Im pressing the starter button and having to open the throttle about a third of the way to get it going, but if I let the RPM drop below 1,500 it dies. It also sounds like once I start to ease down on the throttle, it's not firing on all 4 cylinders. If I give it more throttle, all 4 are firing.

The one time I was able to get it started, it did all of what I explained but only for about a minute and then it purred to life and acted right. It seems easier to start with the choke pulled all the way out (as it should).

What do you guys think? Do the carbs need to be retuned for this exhaust? Is that something I could do here in the parking garage of my apartment building?

I van attach a video of that would help. The new exhaust sounds fucking incredible btw. :)
I put fresh new gas in it and wound out the gears out a few times and it runs much better now. Almost feels like something mightve been clogged and beating it's ass a few times was all it needed. Thanks for yalls help. 🤙