Xr650l decompression issues

[southjerseyhonda]

The bike starts fine, but at idle u hear the decompression engaging occasionally and sometimes on start up it seems to hang up and stay engaged???? Anyone have issues like this or replaced the decompression mechanism? I don't see much info on it, but see on the micro fiche it's a lil spring and round thing on the cam??

[brianhare]

More parts than that boss...........three springs and rollers make up the one way sprag clutch,,another small spring under that...there is a pin that wears that`s pressed into the cam too that tends to wear one edge off.........

 

i`d go on ebay,,buy a low miles cam if it was me..

 

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[southjerseyhonda]

I see a complete cam assembly new on Motorsport.com for 175$ maybe I'll go that route

[brianhare]

http://www.ebay.com/itm/Honda-XR650L-Camshaft-Cam-XR-650L-2009-Low-miles-J-/380900558141?pt=Motorcycles_Parts_Accessories&hash=item58af71453d&vxp=mtr

 

 

It`a a "best offer" listing...........the seller, i`ve dealt with before,i would definately buy from him,,i have him saved in my favorites on ebay,if he says 3000 miles you can bank on it..he parts out alot of XR650L`s and usually has the speedo in a listing somewhere to verify.....it`s an OE low miles cam....

 

make him a decent off........like 140 or something,,he usually will counter offer if too low anyway ?

 

B

Edited August 5, 2014 by brianhare

[XR650L_Dave]

Are you sure it's the decomp and not the one valve hanging, or a valve seat coming loose?

[southjerseyhonda]

It really sounds like the decomp mech, only does it at idle intermitinly grab some throttle and it goes away, the one time it did sound like the one vavle was stuck open as if the decomp was steady stuck open

And all this came about after I finally did a vavle adjustment and the exhaust vavles were pretty far out of spec

[southjerseyhonda]

Ok after talking to a few honda techs, I'm pretty sure my problem is the spring and pin that sit under the cam on the head and hold the decomp from turning at higher rpm's, seems like an easy fix and 15$ in parts, but for now turning the idle alil higher solved the problem, u can still hear it engaging when I turn it off and the rpm's die down, but it no longer does it at idle, hopefully I can milk it til winter and do a full topend rebuild, cus I know it's due, surprised no one else has had this issue, the honda tech talked like it was a common problem, the pin wears and the spring weakens, and all u have to do is pull the cam n throw in new spring and pin

[XR650L_Dave]

I have been riding the pig and reading/posting here and elsewhere since 2002, have never heard of this particular problem.

[brianhare]

The reason you don`t hear about the spring and pin wear...is most people just press the decomp off and weld the exposed hole shut so no oil is lost...having this work is important,Honda thought it was...just because removing it can be done,doesn`t mean it should..

 

i did say that in my first post.i also said the sprag roller clutch wears too....replacing the pin and small spring may fix your issue,or you may have to tear it apart again and replace the one way clutch rollers and there springs the second time...your call boss..

 

I am surprized that a Honda tech knew this,,,,,most Honda techs do not know squat about these older bikes,there are very few arround that actually diagnose anymore,,they are parts replacement techs..to be fair..it`s the same in the auto industry.throw a carb in front of most mkechanics now and they look at it in wonder,,no clue where to start first?

 

i advise most people to get a low mile used cam,,as most people do not want the hassle of popping the decomp mech off,without losing parts,,and pressing the sprocket holder back on..most people think rem,oving it is the best thing to do..as they either don`t understand the operation of it...........or someone posted somewhere it`s best to remove it ?

 

B

Edited August 7, 2014 by brianhare

[ElDorado650]

I removed mine on the rebuild - but I added a manual

decompressor as I installed an XR600 head.

 

I thought the auto decompressor worked fine, but it is loud sometimes.

It got on my nerves, so on rebuild I went the manual decompressor route.

I like it.

I would not run the bike without one or the other.

The 10:1 piston will stop the starter on occasion, usually when cold.

The manual decompressor deals with that just fine.

 

Just used a dual lever mount for the clutch/decompressor - identical

to my XR650R lever set up.

[southjerseyhonda]

Yeah I did see that in ir first post that's what led me to further investigate, thank you, I'm mainly jus buying time till winter, then I'll be doin a full top end rebuild with a new cam, just tryin to get the rest of the season out of it... If u welded it and removed it, the starter wouldn't turn the motor would it??

[ElDorado650]

Yeah I did see that in ir first post that's what led me to further investigate, thank you, I'm mainly jus buying time till winter, then I'll be doin a full top end rebuild with a new cam, just tryin to get the rest of the season out of it... If u welded it and removed it, the starter wouldn't turn the motor would it??

The starter will turn the motor - but not very well.

When cold - you have to use the decompressor.

When hot - not all the time.

It makes the starter happier if you use the decompressor.

Also - it can be kick started with the decompressor - not hard.

I did add the kick starter - only used twice - to see if it works.

But it is there just in case.

[southjerseyhonda]

Yeah I really wish I had a kicker, 650l's are electric only.. I really thought the spring and pin were the smoking gun, due to it still working, but engaging intermitinly at higher rpm's than it should, were if the sprage clutch setup was bad I thought it wouldn't engage at all?? I am no expert on these by far, just doin as much research as I can, I got the bike about six months ago and is my first 650, had mostly 2 strokes before this, would of been great if my cr500 had a decomp system lol

[brianhare]

Agree.......it will start the bike usually..without it...but harder on the starter,and if you get on the trail and dump the bike,it just may leave you stranded unless you have a kicker..

 

B

[southjerseyhonda]

But I bumped the idle up not even an 8th turn and it went away, the honda tech said if ur idle is too low it will cause this too, but u still hear it when u shut it down, it kicks in about halfway from idle to dead stop, is it normal to hear it engage on shit down?? I had never heard it doin that before I started having issues??

[southjerseyhonda]

I do have access to an older xl600, wonder if I could use that head and convert to manual decomp system ???? If so what cam do u run ? 650 cam without sprage clutch setup or 600 cam??

[heart_of_darkness]

An XL600 is a dual carb, so the top end parts won't swap. I think I have a 600 valve cover here, which will bolt on and give manual decomp.

Have you looked through the valve caps at the cam lobes to verify their condition?

[southjerseyhonda]

Not sure of what year but I'm almost positive it's single carb, I want to say it's an 89 xl600

[brianhare]

But I bumped the idle up not even an 8th turn and it went away, the honda tech said if ur idle is too low it will cause this too, but u still hear it when u shut it down, it kicks in about halfway from idle to dead stop, is it normal to hear it engage on shit down?? I had never heard it doin that before I started having issues??

 

Idle rpm is 1300 i believe...the decomp deactivates above 400 or 500 rpm..he is correct that a very slow idle will cause it,but on a properly operating system the engine should stall before that happens..

 

As for hearing it when you shut the engine off,,that`s normal as the rpm slows down.I`ve heard it before,,just don`t pay attention to it as it is operating right on mine..

 

I had mine apart and pressed it off and examined it a few years ago,chasing down a noise....it ended up being the Megacycle cam making the noise as it has very steep opening and closing ramps.....i learned that this cam will be noisy,as most performance cams are..

 

B

 

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[southjerseyhonda]

Mega cycle cam is aftermarket I take it? The motor seems all stock and virgin(never cracked open at all), it still had stock clutch plates in it, which is what I did when I first got it, friction plates were trashed, thanks for everyone's help and fast responses !! I'm goin to cross my fingers n jus run it with the idle up a bit and go from there, then next step would be the pin and spring, but hopefully it holds up another 4-5 months till rebuild time