1979 Xs750 Rejetting: Pod filters and a Delkevic exhaust.

[750triples]

Hi everyone, this is my first post about my first ever motorcycle, hoping to get some help from yall!

The previous owner of this bike had the genius idea to gut the stock exhaust (I guess a loud engine that runs like trash was what he was after) without doing any tuning or rejetting. I could immediately tell by the way the engine bogs down when I open the throttle that the jets are struggling to give the engine enough gas. For some reason he also decided to gut the air filter inside the stock airbox?? I don't exactly understand the reasoning behind that. Since the stock exhaust is already in bad enough shape, I've decided to go with the Delkevic 3-to-1 exhaust, plus some pod filters (yes, I've made sure to get the ones that don't block the pilot circuit). I saw another forum post saying a 135-137.5 main and 45-47.5 pilot jets should be good enough for this. the stock jets are 130 main and 42.5 pilot.

Hoping to get some extra opinions on this, thanks!

 

[650Skull]

Ditch the pods altogether, (they are also harder to tune because CV carbs don't like swirling air), and if you really need to put on, non factor filters, ................go with uni-filters.

If you still have the filters and the foam is shot, they can be wrapped with filter foam for reuse. Lot of us do this with our XS650's

 

[Grimly]

My recollection of my '79 XS750 was that it was running on the ragged edge of lean all the time, from the factory. So much so, that even the rusting out of the silencer baffles made it run like crap and hard to start. It would have really benefitted from up-jetting, even as standard.
Otoh, it returned a steady 48mpg (Imp) no matter what way I rode it, so there's that.

 

[jetmechmarty]

I ride an XS1100 Special. It has a stock airbox with a K&N filter in it. It has a Jardine four into one exhaust. My jetting is correct and it’s stock or very close to it. It leaves me to believe the filters/airbox are more significant than the exhaust. My bike runs as if it had EFI.

 

[750triples]

Ditch the pods altogether, (they are also harder to tune because CV carbs don't like swirling air), and if you really need to put on, non factor filters, ................go with uni-filters.

If you still have the filters and the foam is shot, they can be wrapped with filter foam for reuse. Lot of us do this with our XS650's

I ride an XS1100 Special. It has a stock airbox with a K&N filter in it. It has a Jardine four into one exhaust. My jetting is correct and it’s stock or very close to it. It leaves me to believe the filters/airbox are more significant than the exhaust. My bike runs as if it had EFI.

I’m more of a tinkerer than a rider, I’ll probably stick to pods. I bought a screwed up bike with the intention of upgrading parts, and learning along the way (which is why I’m trying to include rejetting in the process). Thanks for the uni filter recommendation. I just need to know if the jets I mentioned will be able to handle the airflow.

 

[650Skull]

I’m more of a tinkerer than a rider, I’ll probably stick to pods. I bought a screwed up bike with the intention of upgrading parts, and learning along the way (which is why I’m trying to include rejetting in the process). Thanks for the uni filter recommendation. I just need to know if the jets I mentioned will be able to handle the airflow.

I did recommend. Any one who has TRIED to jet for pods...
....well nevermind.

Good luck, enjoy your tinkering.

 

[Tony Harrell]

Ditch the pods altogether, (they are also harder to tune because CV carbs don't like swirling air), and if you really need to put on, non factor filters, ................go with uni-filters.

If you still have the filters and the foam is shot, they can be wrapped with filter foam for reuse. Lot of us do this with our XS650's

Where do u get replacement foam. Is there threads about this?

 

[Vincenthdfan]

Where do u get replacement foam. Is there threads about this?

Post #87 on down:

https://www.xs650.com/threads/reunited-with-xs650sh.63667/page-5#post-788071

 

[Kevin Werner]

I’m more of a tinkerer than a rider, I’ll probably stick to pods. I bought a screwed up bike with the intention of upgrading parts, and learning along the way (which is why I’m trying to include rejetting in the process). Thanks for the uni filter recommendation. I just need to know if the jets I mentioned will be able to handle the airflow.

Jetting varies with intake and exhaust flow changes. Your jet selection may be in the ball park but do not expect any recommendation to be perfect unless it is from someone who has the exact combination you are running. There are some good posts in the tech section on this forum but you need to remember most are geared to the XS650 experience.
Remember to move one step at a time after you establish a baseline. By their nature, CV carbs a very tolerant of being jetted wrong so study it carefully..
Many of us change our float bowl screws to allen head fasteners to facilitate rapid disassembly and reassembly during a jetting change using a 2 inch allen bit. I do wonder whether my fat knuckles would reach a CENTER carb for a jet change, something I have never done on mor than 2 cylinders.
Welcome, Cheers

 

[750triples]

Jetting varies with intake and exhaust flow changes. Your jet selection may be in the ball park but do not expect any recommendation to be perfect unless it is from someone who has the exact combination you are running. There are some good posts in the tech section on this forum but you need to remember most are geared to the XS650 experience.
Remember to move one step at a time after you establish a baseline. By their nature, CV carbs a very tolerant of being jetted wrong so study it carefully..
Many of us change our float bowl screws to allen head fasteners to facilitate rapid disassembly and reassembly during a jetting change using a 2 inch allen bit. I do wonder whether my fat knuckles would reach a CENTER carb for a jet change, something I have never done on mor than 2 cylinders.
Welcome, Cheers

I’ve already taken apart those carbs so many times dealing with other issues that I can do it like an F1 pit stop at this point lol. Just got my bike back running today after dealing with some phantom issues (my other post), so I’ll probably rejet within the next few days.