Help please :) XJ650 Maxim

Hey all,
So today my buddy and I put back together my bike (1982 XJ650 Maxim) and took her for a ride. We just got done cleaning and rebuilding the carbs, changing the oil, new spark plugs, and new air filter. My bike was running great at first it seemed, but as the ride went on the idling was weird, and the throttle wouldn't rev properly. By the time we got back we basically had to keep it revving at 4k rpm and didn't dare stop or slow down because it would die. When we first started it there was some smoke, but it went away.. (I think it was just oil we spilled elsewhere, but who knows). We haven't vacuum synced yet, but I did do a bench sync.

Any ideas?
Thanks for the help.

 

A couple of things to look at...if your carb cleaning and rebuild was done correctly, did you wet set the float levels to spec? Have you checked for vacuum leaks in the intake manifolds? Are the caps on the vacuum sync ports pliable and tight? Also, check your throttle and choke cable for binding and correct placement. If you did not break the carbs off the rack, you may have the seals in the fuel rail leaking. It is going to be a process of elimination. Do one thing at a time and try to start the motor and see how it runs. Once you have it idling you will have to get your valves in spec BEFORE you do a running vac sync with the YICS ports blocked.

Assuming your bike still has the stock air box and exhaust system...

To help others to help you, put your bike info and what has been done in your signature.

 

Also, if you actually soaked the entire carbs in carb cleaner, then you will have to remove the carbs from the racks and replace all the shaft/fuel rail seals. Contact Chacal and he can hook you up with what you need.

 

Are the VALVES IN SPEC?

Next would be float levels accurately wet set;

then a good bench sync.

"Starts fine cold, won't run hot" is a classic symptom of tight valves or completely out-of-whack carbs. Or both.

 

Checked the valves and they are way off, so ordering new shims.
Then going to wet set float, we did dry set but I was a little confused about wet set still.

Quick question though, when setting the pilot jet, it is supposed to be 2.5 turns out. Is one turn 360 degrees? If so, my jets are barely hanging on by a thread after it gets to 2.5 turns. Or is 1 turn considered 180 degrees?

Thanks!

 

jets should be fully seated, the mixture screw should be started at 2.5-3 full 360 degree turns out.

 

Oh ok. So the mixture screw is the one on the outside of the carbs though right?

 

pilot mixture screw hole is the small one to the right...the other is the starter enrichment jet hole



The pilot Mixture screw, spring, metal washer, & O-ring...the the small hole to the right



The starter enrichment parts....in the large hole to left

 

Thank you! Definitely makes sense with a picture.

 

start with the pilot mixture screws turned all the way down....turn out (counterclock-wise ) 2.5 - 3.0 turns......1 turn = 360 degrees...

You will have plenty of room left after starting from the bottom and turning out if you do it right....

 

http://xjbikes.com/Forums/viewtopic/t=8 ... +bowl.html

Did you make sure the enrichment circuit was clear?

 

Okay so 3 of the enrichment circuits are good, but one is a little messed up. We can't seem to get it clean, and I think we may have broke off a very tiny drill bit in there... :/

Any tips or advice?

 

if you cant get the drill bit out of the enrichment circuit in the float bowl....I would say look for a replacement float bowl......you should have 4 clean & open circuits for easy choke starting in the mornings.....

Sorry your drill bit broke off......

 

you can try this...

http://www.lowes.com/pd_178820-47120-SG ... Id=3064233

Welding Tip Cleaning Files. Comes with an assortment of sizes and you might be able to push the broken part of the drill bit out.

And it is cheap enough...

Hope this helps

 

Not sure how one is going to push it out....no way of working from bottom up to push the drill bit out in the enrichment circuit well

 

Look at the drawing in Noffy07's link. See if a small, right-angle pick will fit through the bowl hole and "lever" the drill bit loose (if it extends that far down). You might also be able to use a length of metal-string guitar string (E-B-G, higher notes) as a clean out tool vs the drill bit.

 

OK, so we got it running tonight and it was still kind of fishy when we took it for a ride.

Valves are in spec now & float levels wet set and did another bench sync.

When we were out riding, sometimes I could get the bike up to about 45 mph max and sometimes it wouldn't let me get it above 20 or 25 mph. At the low end it seemed to have A LOT of speed and torque until it got to higher rpm. It seemed like after it hit 4k rpm it wouldn't go any higher really when it was in gear. In addition, it died a few times at rest because the idle would get too low. Or sometimes it would idle too high. We fiddled with the idle adjustment screw a bit but couldn't really get it right.

I think it's getting to the point where I should just take it to a mechanic. We were really hoping to get it running good on our own though. Not a big deal though if I need to take it in.

Could this be fixed by just a vacuum sync/colortune? I thought that was more once I get it running decent to tweak it to perfection.

Ok, that was a long one. Any advice is greatly appreciated!!
Thanks!

 

Absolutely..........your engine is acting schitzoid because it's "fighting itself" because it is out-of-synch. The bench synch you did was necessary to get the carbs at a setting where it would actually fire up and run under it's own power; at that point, the bench-synch has accomplished it's one-and-only purpose in life.

It is then immediately time for a running (vac) synch, and then once that is accomplished, you can start fine-tuning via the use of the Colortune (note: as each cylinder is colortuned, the entire engine should to be re-synched before moving onto the next cylinder). So the "colortuning" procedure requires 4 more engine vac-synch procedures. You'll get real good at it real quickly.....

You're almost there! 99.9% of your symptoms will go away with the first successful vac synch.

 

So, I bought a vacuum sync, yics tool, and colortune. We were trying to vacuum sync it tonight, BUT we are having a lot of trouble getting it to idle low enough to even get to that point.

We basically have to have the choke on or else it dies. The only way we really found to stay alive was choke on and idle adjustment turned up. However, then it is obviously idling way too high.

When it would die sometimes it would also make a loud POP noise that I figure was a backfire or something.

Why is this happening? How can I get it to idle stable enough to even start to sync it?

Any advice much appreciated!!

 

sounds like you are getting more air than you want. did you check for air leaks ?

 

Will check tomorrow and report back.

 

If the Bike runs with Enrichment Circuit Open, ... Stalls when Chokes are Closed ... You got a Fuel Supply / Delivery issue(s) to solve.

That it runs "Choked" means Pilot & Main Jet Fuel is NOT being supplied.
Which usually requires a thorough Cleaning with inspection of Diaphragms, their Bores, Jets and connecting Passages.

Before you dive-in,... Check.
You got Gas in it.
Try running it with Petc0ck Switch set to PRI.

 

It does have gas and the petcock switch was set to PRI when we were doing this.

 

So my neighbor is a mechanic and came and took a look at the bike. After listening to it he said it sounds like either the valve clearance is off or the timing needs adjusted. Since I am sure the valves are in clearance that leaves the timing. How do we adjust this? He said we need a service manual and I have one but I was wondering if you guys have any tips?

 

for now forget the broken drill bit, once the choke is off it's out of the picture.
the running sync is very important at idle but as the throttle is opened, not so much.
are the air jets in the right places?

 

The broken drill bit isn't an issue anymore i got new bowls from a local motorcycle scrap yard and cleaned them up really well. To be honest they were in better shape than mine when I got my bike!

I'm pretty sure the air jets are in the right places, is there more than one place I could have put them??

Any thoughts about the timing?

 

the main air jet with the smaller hole goes towards the air filter.
the pilot air jet with the larger hole goes towards the engine.
ignition timing isn't adjustable on these. valve timing could have jumped a tooth but i doubt it would run well enough to get out of the driveway and it wouldn't ever seem right, hot cold slow or fast

 

Hm... well now I am questioning myself a bit. I might have to open her back up and check the air jets.

 

Update: We are rebuilding the carbs again because we found out we didn't replace everything that needed replaced last time such as throttle shaft seals, idle mixture screw o rings, plunger valve seat dust caps, fuel supply tube O-rings. This time we are breaking the rack and hopefully once they are back together it will fix the issues we have been having.

 

Do a simple Mod while the Rack is on the bench.

Grind a few mm's off the Idle Adjustment Rod SPRING.

Add a Nylon Flat Washer to the Rod along with a Stainless Flat Washer.
Makes those Idle Rod Adjustment reach-in's a little quicker and the feel much smoother.

 

What order? Like this? (Might be a silly question)
Carb>>Nylon washer>>spring>>stainless>>screw

 

Put the Rod through the Bracket Grommet.
Next goes the Nylon.
Then the Stainless Flat.
Spring next.

You can also get a Nylon Bushing that fits the Rod thin enough to press in the grommet's ID, ...

 

Okay thanks for the tip!