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Coop355

XL600r Semi-Hot Start Problem

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Posted (edited)

Hello, I am having trouble chasing an issue on a new to me 1986 XL600r. Delivered non-running. Currently starts first kick cold (with a bit less choke than I would expect but we'll get into that in a moment), If it's hot and and shut it off or stall it'll restart first kick within a minute or two after shutdown. However if I take it to the store, 5-10 minutes inside, and come out it is a bear to start. Takes about 10-20 kicks, with voodoo magic in between to get it to fire.

What I have done and checked:

All of the ignition system is within spec, except for the pulse generator which is slightly off. New plug, coil, & boot. Spark appears a bit weak.

Carbs have been reasonably cleaned.

Valves are reasonably within spec. No more than 1 size on the feeler gauge.

Pilot screw I initially had 3.5 turns out when I was chasing some other problems, but currently have it about 1.5 turns. The throttle linkage is kinda iffy (can't really figure out what the issue is, but has no resistance from about 0 - 1/8th throttle plus the idle adjust cable is broken) making it tough to reliably set idle and to dial in the pilot screw. Haven't noticed much difference between 3.5 turns out and 0.5 turns out except it takes a bit more choke from cold.

Where should I focus my attention? Thanks

Edited by Coop355

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Usually that's a ssymptom of the valves clearances are tight.

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As soon as you mention heat and time to start again .................... that screams pulse generator

However if you were not the one to clean/rebuild the carbs that ............. maybe the problem

Does it start cold every time?

Is this happening every time all the time? When you start it and ride for a while then stop as you describe?

Can you ride it for 1/2 or 2 hours straight amd have no problems till shut down?

How does it run on a simple ride? vs Does it run well mid to full throttle?

7 hours ago, Coop355 said:

Hello, I am having trouble chasing an issue on a new to me 1986 XL600r. Delivered non-running. Currently starts first kick cold (with a bit less choke than I would expect but we'll get into that in a moment), If it's hot and and shut it off or stall it'll restart first kick within a minute or two after shutdown. However if I take it to the store, 5-10 minutes inside, and come out it is a bear to start. Takes about 10-20 kicks, with voodoo magic in between to get it to fire.

What I have done and checked:

All of the ignition system is within spec, except for the pulse generator which is slightly off. New plug, coil, & boot. Spark appears a bit weak.

Carbs have been reasonably cleaned.

Valves are reasonably within spec. No more than 1 size on the feeler gauge.

Pilot screw I initially had 3.5 turns out when I was chasing some other problems, but currently have it about 1.5 turns. The throttle linkage is kinda iffy (can't really figure out what the issue is, but has no resistance from about 0 - 1/8th throttle plus the idle adjust cable is broken) making it tough to reliably set idle and to dial in the pilot screw. Haven't noticed much difference between 3.5 turns out and 0.5 turns out except it takes a bit more choke from cold.

Where should I focus my attention? Thanks

 

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17 minutes ago, EarthCruzn said:

As soon as you mention heat and time to start again .................... that screams pulse generator

However if you were not the one to clean/rebuild the carbs that ............. maybe the problem

Does it start cold every time?

Is this happening every time all the time? When you start it and ride for a while then stop as you describe?

Can you ride it for 1/2 or 2 hours straight amd have no problems till shut down?

How does it run on a simple ride? vs Does it run well mid to full throttle?

 

I've only had the bike for 2 weeks, haven't even got the legit plate for it yet. I have only ridden in in short 10-30min bursts around the field, to the store, etc. Bike runs perfect. Starts right up after a stall or shut down. Only when going into the store and coming back do I have the problem. I'd like to take it further, but not until I can count on it starting when I want it to. 

I didn't go too far into the carbs. Only took off the bowls and removed the jets and sprayed the passages, but everything was clean so I wasn't too worried about it.

I actually have a new pulse generator (purchased before I found the immediate cause of the initial no start problem), but would rather not put it in unless I have to or really can't find the problem. I think I am going to play around with the pilot screw. Maybe get it to where it'll only start cold with full choke since I'm having trouble setting it the correct way.

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Posted (edited)

Its a air screw....................

you have a slow jet ( pilot jet,) main jet ...................needle and a

"air screw" that is adjustable........................... (if its on the other side of the carb its a fuel screw) on later models)

so the air screw is 1 1/2 to 2  (stock)- 2 1/2 (moded bikes)

BUT you have 2 carbs and the Main carb is your friend right now................... not the enemy I think.

Replace the Pulse Gen.

Then move on if needed.

It is important when working with the two carb system that you do one adjustment at a time then check how it runs.................

Main carb idle to mid range and 2nd for mid to top.......................... the carb bowls are different................ be careful here

33 minutes ago, Coop355 said:

I've only had the bike for 2 weeks, haven't even got the legit plate for it yet. I have only ridden in in short 10-30min bursts around the field, to the store, etc. Bike runs perfect. Starts right up after a stall or shut down. Only when going into the store and coming back do I have the problem. I'd like to take it further, but not until I can count on it starting when I want it to. 

I didn't go too far into the carbs. Only took off the bowls and removed the jets and sprayed the passages, but everything was clean so I wasn't too worried about it.

I actually have a new pulse generator (purchased before I found the immediate cause of the initial no start problem), but would rather not put it in unless I have to or really can't find the problem. I think I am going to play around with the pilot screw. Maybe get it to where it'll only start cold with full choke since I'm having trouble setting it the correct way.

 

Edited by EarthCruzn

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Posted (edited)

Ive been watching that video series since before I bought the bike lol. Thats why I initially put the pilot to 3.5 turns, spec is 1-2 I think. I have it set at 3/4 turns and I'm going to see how that goes. Starts easy with choke, but wont stay running cold without it. I'll take it to the store tomorrow and see what happens.

Edited by Coop355

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Posted (edited)

I took my stator off to inspect, didn't really see anything out of the ordinary but tighted up the grounds and stuff. Seems to be a bit better now, but I need to take it for a few more rides. I hate the "will it start?" anxiety though!

 

EDIT: Runs good and starts pretty reliably using the following method:

Manual decomp depressed, full throttle, spin motor 3-4 times.

Let go of decomp to TDC, decomp 1 click past, smooth hard kick.

Can get it to start in 1-3 tries now which is pretty good!

Edited by Coop355

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Posted (edited)

Finally got the bike fully registered and took it for a longer (30-45 min) ride. Ran pretty good. Except I stopped at a store and it wouldn't start hot! Ended up being stranded for 2.5 hours, but got it going. Ran a little worse on the way back. Ordered a new ricky stator and hot shot CDI. Seemed to act like the secondary carb wasn't working occasionally, or it has a carb insulator leak (Occasional poor throttle response, low power, back firing). Maybe that's a symptom of poor spark. Glad I made it back, but going to need more work. I have the insulator orings so I will replace those and fully inspect the boots when my new stator and CDI come in. Only thing left might be the pulse generator, but I will start here.

 

Love the bike and the power when it works. Like a rocket! It's certainly more of an adrenaline rush than my 250! Loving the tunnel vision sensation from a 35-65mph pull!

Edited by Coop355

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Something to check, the primary carb has a cutout in the slide. The secondary carb has a straight slide, no cutout. That could be why you have freeplay in the first bit of travel. 

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11 hours ago, Busdweller said:

Something to check, the primary carb has a cutout in the slide. The secondary carb has a straight slide, no cutout. That could be why you have freeplay in the first bit of travel. 

What specifically should I be looking for? If everything is lined up correctly?

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Looks like you already ordered one.  Mine had a similar issue, turned out to be the stator.  Apparently, the windings were braking down when getting hot.  My pickup coil is also out of spec. runs like a top though.

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Posted (edited)

Check to make sure the slides didn't get installed in the wrong carb. The left carb is the only one that has an idle circuit. It gets the slide with the cutout. I robbed this from ebay, see the cutout on the needle side? The right side is straight.  I've run across this more than once, the first time was a bitch to figure out. 

s-l400.jpg

Edited by Busdweller

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Got my parts today and installed new Stator and CDI. Cleaned all connections with contact spray and applied dielectric grease. I hadn't noticed before, but the previous stator wires appear to have been cut by the chain and re-attached. They look like high quality butt connectors so its probably semi-unrelated. Didn't have time to get into the carbs.

 

Anyway, bike rides and starts great now! Even dropped it offroad and it fired back up first kick. All the weird issues are gone - occasional back firing, popping on decel, surging power, lack of power, bucking and I attribute that to poor spark. Whether it was the CDI or the Stator not quite sure. Still not 100% sure I trust it to not leave me stranded yet, but we'll get there!

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