Aftermarket carb

So as i understand. The stock carbs on the xj's are really sensitive?

So arent there any "new" carbs that you could buy for it and maybe have it working more smoothly?

Couldt find anything searching around so maybe im asking a rookie question

Much love
Proar

 

1. the stock carbs are not sensitive, they just require thoroughness when being serviced. Once serviced they are dead-reliable and provide excellent fueling characteristics.

2. New carbs will set you back at least $1000 US (for brand-new), and won't make the engine run any better than properly serviced stock carbs. Used carbs will have to be serviced, and then you'll have to mess around with jetting for a few weeks/months. This is not out of the question to do, but is (in my opinion) not the easiest path to take.

So, what's the issue that you are having with your XJ in the carb department?

 

well not a problem. but like many others i want to switch to pods. but as i read it this is a bad idea.

 

Yup......BAD IDEA

 

It is.
If you really want to have pods then you will need carbs with cable operated slides, or a fuel injection system. Bout will require fabrication and futzing to work, and neither will make the machine run any better that it does with the CV carbs (though cold startup will be a bit better with fuel injection).
If you want to ride this summer just get your carbs in order.

 

rookie question. but arent "all" carbs cable operated?

 

No

 

The thottle plates on the CV carbs we have are cable operated, but the slides are not. They are controlled by airflow. Alter the airflow and you alter fueling. Alter the airflow in an uncontrolable manner (as with pods) and you get crap fueling.

Carbs that have the slides operated directly by the throttle cable(s) can have alterations made to the airflow without altering fueling characteristics as much, but they also have other tradeoffs in terms of fueling (mainly with fuel economy and the tendancy to bog when suddenly bringing the throttle wide open).

Then there are carbs that are operated by other means...many other means, most of which aren't used much anymore.

 

Please don' t put pods on a stock airbox will allow the bike to run soooo much better.

 

ok where can i find a stock airbox for my 82 xj 750 maxim

 

eBay or port up in the For Sale/Wanted section.

 

I have a 1982 yamaha xj650 maxim. It’s my project bike. I’m a mechanic and I would even say change the carbs out for a smoother ride all around. If you go on Murray’s carbs you can find one for you’re bike. I got duel carbs. They come pre synced and pre jetted ready to slap on the bike and ride right away. Takes a whole 20mins to set up on the bike it’s well worth it. I noticed after I put them on it was smooth asf starts up right away. Adds about 5-10 more Hp. Take a look let me know.

 

Devil's advocate: I bought a parts bike (1982 750 Maxim, avatar photo) that the PO had sold the carbs and airbox (also the wiring harness) so I was forced to buy some carbs. I thought why not, ebay 4 x 34mm knock-off Keihin PWK flat slides. Really cheap at about $110.00 for 4 new carbs. Made a 4 into 1 cable pull and they fit very well. I did have to clearance the #1 carb float bowl drain plug not too difficult however. Installed them (they fit the stock boots perfectly) and fired up immediately, I was totally surprised, I'm now getting the idle and jetting just right although it pulls like a freeking train and the throttle response is amazing no lag or delay at all. My two test rides have been without air filters but I have foam individual filters. They look way cool and are actually much lighter than the stock carburetors by about 3# which is good for 1/2 hp. I had never ridden a XJ750 Maxim before and I'm very impressed by how quick the bike feels. Not the best close up shot of the carburetors but..
Cheers, 50gary

 

How did you manage the 4-1 conversion?

 

They make a 4/1 cable pull. Mine works very well, happy and simple. If there's a downside it's that it's not pull to open and pull to close
like a lot of modern high performance bike have. I could maybe take a close picture of the throttle pulls.
Cheers, 50gary

 

Very cool, i didnt realize you did that. I looked into mikuni carbs for my xj650 and the cost was 3k for a push/pull setup. I came close to buying them but then the pandemic hit. I am still rocking the factory carb and 3k richers.

 

For the carb kit from Murray’s carbs for a 82 yamaha xj650 maxim its $950 for the kit with the quick turn throttle

 

Does anyone know were to get different size jets for the stock carbs for an '83 XJ750MK? The parts list from Yamaha does not list alternate sizes for low speed or mains.
At some point smoothbores would be nice, but they are pricey.
For now the stock carbs, whatever brand they are, will have to do.

 

Jets R US has a variety of jet sizes .

 

A full stock carb rebuild kit and a set of carb synch gauges is much cheaper than switching carbs . I have rebuilt six sets of these carbs , not hard at all .