1982 xj650 Maxim bogs under WOT acceleration

Good Day,
I have a 1982 XJ650 Maxim that i just picked up. Had to replace starter and bike fired right up. Unfortunately when you roll on teh throttle is bogs and will not rev up to red line. At WOT it bogs and sputters. Closed throttle under deceleration bike backfires. Previous owner had carbs rebuilt and tuned less then 6 months ago (had receipts). Bike does have pod filters, which I've read can make the bike run lean.

So my questions is would pod filters make the bike experience the issues I'm having??

 

Short answer, yes.

 

Ok, that make me feel a little better. I have a hard time believing a shop would rebuild and tune carbs and release the bike back to a customer knowing it cant go full throttle and has very obvious running issues which is why I ask. Previous owner said the pods were on it when it was tuned by the shop.

 

You will discover that there are a fair amount of people here who do not care for pods. Can they work? Yes, however it takes a considerable amount of time jetting, tuning, lather, rinse repeat kind of thing. I had the choice to run pods or reinstall the airbox, I went for the airbox and never looked back. While I realize that may not be an option for everyone. With the help, advice, and information here you can be the best mechanic for your own bike. Most shops don't have the information or the desire to work on a 35 year old bike.

 

Look up member kmoe and read the links in his signature. Read them, then read them again. This will start you on the road to getting your bike running well and more importantly safely down the road

 

Chitwood- Thank you for the point in the right direction. I just want to ride the dang thing already. Ill start by sourcing a factory air-box and go from there.

 

That's what I would recommend. Although you still may be into some carb work if it was in fact "jetted for the pods." I was in your shoes earlier this year and I am glad I found this site to steer me in the right direction on what needs to be done to a 35 year old bike.

 

From the way the bike runs I don't think it was jetted for the pods.

 

Pods = Problems .....Period....

Go back to stock airbox......do a full teardown of your carbs.....look at the pilot and main jets and you will know whether the shop jetted for pods.....

This site will get you thru the necessary steps to be your own mechanic.....

Shops will just take your money.....

Our vendor for parts is Chacal (Len).....click the logo in the upper right corner for a lot of information and his catalog

First rate OEM parts plus first class service

 

Please realize to check or change your jets you have to pull float bowls ...so carbs will have to be removed . Good chance your carbs are not jetted to run with PODS ... do yourself a favor put stock airbox in . Never trust what a P.O. owner tells you . On my bike he tried to tell me carbs were professionally rebuilt ... There were 2 different jets installed and when I did full tear down the shaft seals were all rock hard and 2 were cracked meaning they were NEVER replaced. When I hear folks say there carbs are spotless , but they did not "break the rack" ,they used a can of spray cleaner .... it will not cut it soaking is ONLY way to clean small passages. To replace shaft seals . carbs have to be removed from the rack, and butterfly plate removed from the shaft. Once a carbs are reassembled you do a bench synch , reinstall on bike and do a running synch . Carbs scare some folks , but they are quite easy to rebuild , and do not require exotic tools to accomplish . Cheers

 

Good Day All,

So got around to messing with the bike today. Pulled the carbs and took off float bowls to inspect the floats to inspect jet size to see if previous owner did the larger jets to compensate for pods etc.. Turns out in addition to a little petroleum jelly from the biking sitting for 6 months the main jets are 92.5 !!!!! The pilots jets are all 41 except 1 which is 40. Not too worried about the pilot as it does idle good and that's stock pilot jet size anyways (40).


My concern is what dumbass put in 92.5's in place of 110 (stock size - correct me if I’m wrong).


So now I’m really worried cause either

A. previous owner or someone put on none factory carbs (I hope not; please advise any distinguishing marks I can locate on carbs to confirm if stock or not)

B. previous owner didn’t know what they were doing and -- Insert what ever here ...................... Put in super small main jets.

And last, would having such a small main yet cause the engine to lean out so much it wouldn't reach max RPM as that is what started this fun run, was that the bike wouldn't rev past 5.5-6k and backfired on decel

 

I suspect the throttle slides are not opening all the way due to the missing airbox. Many mistakenly believe it is just a matter of getting the jets set up. You will likely need softer diaphragm springs now to allow the slides to fully open. I'm not sure why the PO went leaner with the jets, they could also be drilled open.

 

Simmy, thank you for your input. Inspected the jets and found no signs of it being drilled out via scratches/bit marks, and all jets are identical in appearance. (What does the jet number relate to in measurement? can't be millimeters... , perhaps a function of flow per hour/minute at X pressure?
Understand I'm coming from a strong position of ignorance, would "17.5" undersized jets cause the issues I'm experiencing regardless of proper air box?

 

Generally if you run Pods if stock main is a 110 you need to go up at least 2 to 4 to a 112 or 114 and same for pilot up at least 1 ...and run it see how it goes , if still not to liking pull carbs and change jets again...CV carbs are more difficult to make work with Pods , some have built their own airbox that uses a pod on both ends and may work better .

 

Update - Ordered 4 x 116 Mains and 4 x 42 pilot jets from chacal. Will slap those in and report back with issues (If any).

 

And let us know what shop never to take a bike to!

 

In a warm climate like Texas you may find 116 a bit rich, but let us know

 

All of them.

 

Update - Put in new main and pilot jets. Bike runs awesome! Pulls all the way to the red line and no backfiring or stubbling on acceleration .
Very Pleased with myself

 

As far as being too rich, if i get board again ill color tune and trouble myself with that later on down the road. Now its time to ride!!!