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600 Missing through the RPMs. What else to try?

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96 XR600  has issues accelerating. Starts and Idle's well using the manual decompressor, engines seems to sound good won't bog and die while idling. Hop on and the Low Rpms and Higher RPMs it feels like misfire and chugs. gets to be noisy except when in the mid range of rpms. won't let me cruse on the road in 3rd or whatever gear. Frustrating.

 

Engine Work:

Recut/ seated exhaust valves & new Kibblewhite valves

new timing chain and tensioner

clutch plates

XRonly choke plate

Baja Designs Lighting kit

new Ricky CDI box

replaced ignition coil

iridium spark plug

Supertrap exhaust

 

I run higher octane fuel, jetted at 142 Main for my elevation in Leadville (10,200')

 

I don't know what to try next to get this bike running smoothly. Looking at the Cam the auto-decompressor seemed to be getting work and was thinking of replacing it, but would this cause running issues?  I believe the bike is set to correct valve specs and Timing (this i'm not entirely sure of though, a video link would be sweet)

 

Thanks for being there TT community my bike has come so far already just need the little extra help.

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Forgot to mention, I have pulled the carb multiple times to try different jets, needle positions and cleanings and nothing seems to make a drastic change. Currently on clip position 3.  Two questions about the carb. The slide has an opening where the needle holding arm screws into it and the hole can either be mostly covered or open. Is there a correct way?  Other question refers to a plastic main jet holder that just slides over. Is it a required part in the carb and is there a correct position for it to be in?   

 

I have tried so many variations that don't make a big difference, maybe my whole combination is wrong :confused:

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Not sure exactly what the issue with your auto decompressor is by what you said but yes, the decompressor can cause running issues. A little more info may be helpful as to whats wrong with it.

As for the plastic jet holder thingy, are you talking about the slosh baffle that goes around the main jet? It just slides on and then twists a little to kind of lock itself above the hex portion of the jet usually. A bike will run fine without it but may have issues on rough terrain or leaning over. It shouldnt cause the issues you describe.

Was it running like this before the valve work and new timing chain or is this a new issue after completing the work?

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A better description of the autodecompressor system's issue is that the lobe has play in it and makes a consistent click sound when spinning the motor. I have heard of these parts wearing out after a while and causing faulty engine performance. Could that piece be opening my exhaust valve while running thorough the RPMs? 

 

If so i'm ready to order a Hotcams Stage 1. Would this require me to change valve clearances?  And what about the oil system does this require me to change anything (such as pull the springed pin that sits under the stock autodecompressor system?)

 

Thanks Backwoods Bomber for identifying and explaining how the Slosh Baffle works, much appreciated i can rule that out.

Edited by MXJonWeed

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Mine was doing the same thing, turns out one of the valves sunk a little which swiped out my cam and all the rockers pretty bad. Check the valve clearances, proper oil level and proper operating temp. BTW my valve clearance on the exhaust side kept closing. NOT GOOD. Good luck, mine is still under the knife(waiting for gaskets).

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1st thing i would do is chuck the iridium plug and put an NGK in it. I have never seen those iridium plugs work in ANY engine.

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Just call me 'Sparky'... first thing I would ask is how good is the spark?

A weak spark will cause those symptoms.

Should be a healthy blue spark at kick-over..

. This sounds like a recorded message :-)

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I had my exhaust valves re-cut and sealed, would this change my clearances?

Yes and no, you're setting the clearance via the feeler and it will be correct if done properly. Lots of you tube vids. I've seen coils work great one day, the next nothing. Ohm it out or do a swap out. I bought a '91 cause the guy couldn't figure out why it wouldn't start. Cheap aftermarket stator(Moose).

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1st thing i would do is chuck the iridium plug and put an NGK in it. I have never seen those iridium plugs work in ANY engine.

 

Got an iridium in mine Jayson......and it pulls like a freight train :lol:

 

The plug isn`t the issue unless it`s defective...

 

B

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I had my exhaust valves re-cut and sealed, would this change my clearances?

 

Hell yes.......cut the seats/cut the valves.....everything moves up in the head and closes the clearances,,,,running it will wipe the cam out and possibly burn the valves...if you didn`t reset the valve clearances after the work was done..........then recheck at 600 miles..

 

B

Edited by brianhare

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Just call me 'Sparky'... first thing I would ask is how good is the spark?

A weak spark will cause those symptoms.

Should be a healthy blue spark at kick-over..

. This sounds like a recorded message :-)

 

+1         Good blue strong fire,,check the resistor in the cap for corrosion,pull it and replace with a piece of copper rod,,or get a new cap if the plug cap has any corrosion in it..

 

B

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Well I went ahead and installed a Hotcam because power and no more autodecompressor system (which had too much play). 

 

Now the float needle is malfunctioning and pissing gas causing issues. Turns out this could have been the problem all along. Parts and report to come

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New float needle did nothing to solve my problem other than help me move onto  the next thing.

 

So again, the issue is here:  Bike is sputtering and sounds like it's missing spark at any throttle position other than idle or cranking on it. Starts 1st kick, bunch of new parts and I ride at 10,000 ft.

 

hotcams stage 1

recut/ new kibblewhite exhaust valves

new timing chain

new chain tensioner

142 main jet, needle position 3 (playing with carb has little improvement)

supertrapp exhaust

new CDI

New ignition coil (didn't replace spark plug cap)

 

 

Bike appears to have good spark when kicking over with plug out, I am really stumped on this and just want to Ride!

 

 

 

Could someone please direct me to a video/ article on how to properly time an XR600? (finding compression stroke, how to get chain over sprocket properly . . .)

Also, how do i check my stator to see if it's pumping out enough OHMs?     

 

I hope to report good news soon I just seem to be in over my head and running out of ideas. Thanks again for all your help TT!

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Don't toss the Iradium, I switched to them years ago and they end any sparkplug issues I've ever had. Currently in 11 motors right now, all run great. Just the fact that he says to change to NGK (they make an Iradium also) shows no knowledge, iradium is a material NOT a brand, Denso, Champion, NGK , ect.. all make plugs out of the stuff.

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So again, the issue is here:  Bike is sputtering and sounds like it's missing spark at any throttle position other than idle or cranking on it. Starts 1st kick, bunch of new parts and I ride at 10,000 ft.

I have the same issue. other possible problems I found:

 

- bad stator

- air leakage

- bad contacts at CDI connector

 

 

 

complete list of possible failures I connected:

- Air leak at Insulator

- CDI
- CDI connector contact problems
- Stator / stator cable
- loose ignition coil (bad ground contact)
- loose needle clip

- fuel line clogged

Edited by kawamaha
  • Like 1

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Bike appears to have good spark when kicking over with plug out, I am really stumped on this and just want to Ride!

 

My bike had this same problem when I got it and after chasing many red herrings, it turned out to be a loose spade connector on the coil. You seem to have the mechanicals sorted out, so I think it's in the ignition system.

No one mentioned checking the pulse generator. Do that too.

Could someone please direct me to a video/ article on how to properly time an XR600? (finding compression stroke, how to get chain over sprocket properly . . .)

There are lots of threads here about setting cam timing. It's fairly simple; the hardest part is holding the chain tensioner spring in a compressed state while putting the chain and sprocket on the cam. Other than that, set the piston at TDC via the mark on the flywheel and ensure the dots on the cam sprocket are aligned with the head's gasket surface.

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I have the same issue. other possible problems I found:

seems it runs fine now after checking some stuff. I didn't have neither time nor a garage,

so no step by step operation, means I don't know what exactly was the reason...

 

carb

cleaned with comressed air

fuel line checked

Air Cut Valve checked

float level raised from 16mm to 15mm

insulator to cylinder sealed with Hylomar

ignition coil and CDI connectors cleaned and sprayed with contact cleaner

new spark plug connector/line

new spark plug

air filter contact face sealed

valves checked

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Well, new RickyStator, float valve, Hotcams  and still the same issue. I can't understand   :(

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The whole thing just wreaks of ignition to me. It has to be electrical with the symptoms you describe.

Do us a favor and just start over, we know what has been done so far, so just describe the exact issue in better detail. You have ruled a lot of issues out so a fresh start may help find the problem.

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