XJ650RJ Running Rough, Seeking Guidance.

Hey all,

I recently brought the XJ back to life. To do so, I replaced the head/cams from what I believe is a Maxim XJ650 (snapped exhaust studs on the stock Seca head). I've gone through the shims, and everything is within spec aside from one valve (based on RJ specs, don't have the proper shim on hand to completely calibrate):

• 1: I: .18, E: .17
• 2: I .15, E: .14
• 3: I .15, E: .17
• 4:.I .15, E: .17

This bike also has pod filters, a 4-1 Jardine exhaust (with a moderately caved-in tube on the bottom), and a DynoTune carb kit with adjustable jet needles. This is how I bought it ~15 years ago, and it ran quite well, to my memory.

Below is a clip of the bike warmed up, idling and with light throttle:
https://photos.app.goo.gl/kQcVDxpfTq2HRPXW7

The carbs are amateur tuned (by me) according to 1:1 fluid vacuum method. I have a colortune, but need to gain some practice there.

Additional history: I split the case to replace the chain guard 10+ years ago; no leaks and the engine ran quite well after the surgery. The bike sat for many years between then and now. Swapped the head and valvetrain assembly from an uncoated engine, assuming Maxim. Parts looked good. Installed, but timing chain was off for some non-load runs to the point that the engine wouldn't turn over at one point. Disassembled, saw no damage, reassembled with correct timing alignment.

I guess I'm looking for a list of things to check, easy to difficult. I'm hoping the engine sound is a good indicator, but I'm a novice.

Thanks!

 

Does sound rough , sounds like you may have an exhaust leak , and carbs are not synched properly. Question have you done s compression check ? When was the last time carbs were rebuilt? I would suggest a FULL tear down of the carbs , breaking the rack and a full soak in Berrymans carb dip or similar. Replace the butterfly seals (see my post on why you should replace seals) ( XJ4EVER on top right of page has the seals or two doubled up number eleven buna O rings can be used ) note: spray cleaner cannot get into the small passages of the carb bodies, and if you soak carbs with any rubber seals , this will damage seals. One thing to check look at the plugs are they sooted up? You could have a plug not firing well , unthread the plug cap and cut off a little bit of the plug wire and rethread cap back on . I once had a Honda CB750 it was running on three cylinders , I pulled cap off it was full of green corrosion, cleaned this up snipped off a bit of wire put cap back on and problem solved. You might try a new set of plugs as well . Cheers

 

I haven't done a compression check. It's been years since a carb rebuild, but the bike hasn't driven in longer. Nonetheless, it has run stationary, so fuel has been in the carbs.

 

If bike sat for a long period and fuel stabilizer was not used , this can gum up jets if you pull the float bowls, you may find a greenish muck on the walls of bowl. The alchohol in the fuel can break down in short order , it used to be gas could sit for years and still be useable . You really should check the jets and the emulsion tube.

 

Sounds good. I picked up a carb parts cleaner kit (bucket, cleaner, basket). Can I simply pull the parts (bowl, needles, jets) out and soak them in the bucket for 30-60 minutes? One at a time, to avoid mixing parts between carbs. I'd prefer to avoid disassembling the rack, since I imagine resetting those springs will be a pain, but can dive in if that's highly recommended.

 

Nevermind, searching through older posts, finding some clear direction and recommendations.

 

Yes one carny at a time , make sure you remove ALL the rubber seals once fully tore down with butter fly shaft removed soak about half an hour . Wash carbs in hot soapy water with Dawn best let dry or blow out with compressed air , and reassemble with new seals . One important thing replace the O rings on the fuel interconnect tubes ( you do NOT want a leak after putting these back together, because only way to fix is break rack again...and fire hazard to boot. I recommend ordering new seals from xj4ever I just ordered some they are like 40$ for the butterfly seals and the fuel rail O rings well worth it.

 

Oh for a UK supplier on these - looking more like £100 to get them here.

 

Understood. Ordering those seals now.

 

You won't be able to replace the butterfly shaft seals or fuel interconnect seals without disassembling the rack

 

Yeah. After reading enough posts, I decided to go ahead with the full disassembly. Everything is baggied up and/or sitting in a carb clean bath right now.