02' 501 bike with 03' 650 auto decomp; question

Hi comrades,
I recently had some upgrades performed on my low hour/mileage 2002 fe501e including the addition of a double bearing counterbalancer, steel timing sprocket and new cam chain, 03' rockerarms and rollers, cam bearings, YTZ7s battery, new Denso Iridium plug and yes, an 03' 650 auto decompression device.

Current problem; bike kickstarts fine both cold and hot but will not light up using the e-start button. Until these "upgrades", the bike has always e-started just fine after a complete warm-up of the engine. She seems to turn over fairly well when I push the button and even sounds out some low volume pops but refuses to start.

I have thoroughly cleaned and inspected the carb, (original Dellorto phm 40) and have tried different pilot jets. I've been running a 38, tried a 48 then tried a 33 to no avail.

Here's the big question!
Could the addition of the 03' 650 auto decomp device be the culprit of my new-found e-starting woes? This part was added by my mechanic because my original was worn down and supposedly the 03' 650 part has more lift which in turn, releases more compression allowing the engine to turn over with greater ease. Seems many Berg riders have added a welded bump to their decomp to do just this.

The auto decomp device has the same part # for all models 2001 thru 2003 with the exception of the 03' 650. There is a "note" in the 03' parts manual stating, "auto decomp device should be calibrated with camshaft" as Dale Lineaweaver mentioned awhile back. What exactly does calibrated mean in regards to the camshaft? Does it perhaps mean, "only use the 03' 650 auto decomp device with an 03' 650 camshaft? Could this 03' 650 part have too much lift for my stock 501 or could the lift be timed just wrong?

I'm hoping for some thoughts and theories from the clan before buying another new part and spending a long day (for me) replacing it.

Thanks fellas!

Logjump
(Rick Norrander)

husabutt said:

Hi Rick:

Have you ever replaced the stator?

If its the original it could be on the way out.

The engine must spin at somewhere between 400-800 Rpm (someone who knows please post the required RPM) before the stator will even fire.

Will it kick start?

Take a look at the spark. If its weak or non-existent during kicking you will probably need a new stator.

Mine went out on my 01 470 without warning after working on it. It would pop a little during kick starting but that was it.

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Hi Eric,
No, I have never replaced the stator and it still produces an excellent spark. In fact, I can hold the sparkplug tip nearly 1/4" from ground and throws a very healthy spark while pushing the e-start button.

As stated, the bike kick-starts just fine.

Thanks,
Rick

husabutt said:

I would next leave the plug in the bike and put another one in the spark plug cap and retest for spark.

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Thanks Eric. Gave it a go and still get a sweet spark.

Gotta say she actually may not turn over as well as she used to with e-start. Seems to hit a wall of compression once in awhile and struggle to get over the hump. By the way, I did re-check the valve lash and all is good.


Rick

husabutt said:

Per Dale:

"The auto de-comp. bleeds only a fraction of the trapped charge engaging near 85 BTDC and closing near 15 BTDC with a peak valve lift of less than .040". "E" Cranking compression should be roughly 130 psi with said system active."

Do you have access to a compression tester?

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Cranking compression is showing only 75psi but that is taken with a rubber tipped tester as I don't have an adapter for my good tester that will fit the husa-hole!

Thanks,
Rick

nsman said:

I believe that it is not enough to just update the the auto de-comp device,you must also use the correct auto de-comp spring to match. If these parts are mismatched the auto de-comp device advances too soon and it is then ineffective.

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I appreciate the thought nsman but the parts manual shows the same auto decomp spring for all models 2001 thru 2003. I believe my spring was replaced when the decomp device was replaced.

Keep the thoughts coming guys. Is the 03' 650 auto decomp a possible culprit to my new e-starting woes? Sorry to be kicking a DEAD HU-ORSE!


Rick

husabutt said:

The "book" says your 501 has the 53 cam and the 650 uses a 08. There are only two different autodecompression devices. One for the 650 and one for all others. What are the differences between the two cams anyone?

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Thanks husabutt.
This is exactly at the heart of what I'm wondering. Is the 03' 650 decomp device mated to the 650 cam in such a way that it wouldn't be beneficial to use with other engine or (cam) applications as others may have previously thought?

Would love to hear Dale's thoughts on this.

I'd also like to hear if anyone has found a major success using the 03' 650 auto decomp device in a different engine application. Can't say I've heard of any other UHE members doing this modification.



Am I barking up the wrong tree? Does the 03' 650 Auto decomp even make enough difference to be causing my new-found e-start woes?


Thank you fellas,
Husa-Log-Barking-Dog

Where's Taffy? I am Husa-Log not LeFrog

dsducati said:

I must ask why not simply use the correct one and try it again.
Dan

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Hi Dan,
I may do what you suggest. That's what this post is all about. Just want to know ahead of time whether throwing more time and money at this particular issue will help me out. Was waiting to hear of someone who may have done what I've done and if they experienced success or not.

Thanks,
Logjump

dsducati said:

Couldn't answer that one. What are the thoeretical advantages of the 650 part that make it worthwhile to try it? Not being a wise ***, just am curious.
dan

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It supposedly has more lift which in turn bleeds off more compression making it easier for the e-start system to crank the engine over.

Logjump