XR650L - Many questions after snapped sub-rocker arm

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Jack Stone

Puppy
Joined
Oct 17, 2017
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Bike
Honda XR650L
Howzit guys,

New rider and new to bike maintenance and repairs, been lurking here for a bit and now hoping to tap into some of the knowledge and experience here,

Have the XR650L service and owners manuals, the Honda common manual and a fairly technical mind, searching for somebody with more experience and confidence with these engines,

Bike
===
- Bought as (I believe) 3rd owner at 24 000km (+-)
- Had an aftermarket exhaust FMF Powercore 4 (no maintenance done here yet),
- Had a twin foam air filter (regularly cleaned and oiled by me, seamed to have been fairly well maintained, some oil on when I got it, intake tract clean)
- Had a carburetor air/fuel mix screw tab and float bowl unmolested, I'm guessing the jets are stock too
- Had a XR600R front sprocket

- The first oil change yielded about a 1l of black but smooth oil, I have since flushed the system and kept oil changes well within service manual specification of every 3000km.
  (By the way, the XR600R manual recommends oil changes every 1000km, why the difference?).

- I have noticed that the bike is using a fair amount of oil, it's my only form of transport so it is used on the tar for short distances, and sometimes longer distance when finding some gravel roads. I keep my eye on the oil levels and top up as necessary, will start keeping logs but I reckon it's a bit excessive, it would almost certainly run dry if left between suggested 3000km service interval.


The Problem
========
Suddenly developed loud ticking from right hand side at the stop light. Got it trailered back hone. Opened the valve covers, noticed right exhaust valve extremely loose, tried to tighten it back to spec and run it again to make a video, the sound was muted but there, I opened the cover again and now noticed that the sub-rocker arm had snapped off (still right exhaust side here),

What I want
========
A big red pig that will take me from Cape Town to Kigoma (Tanzania) and back, a long way around, and without anything more than valve adjustment done on the engine. And it will have to take some punishment before that, and must last after that. I will add oil and fuel regularly, might even keep the air filter clean....

The plan
======
1) To ensure at least that the top end is in good condition, I will pay some attention to counter shaft and clutch plates soon enough (what you don't know doesn't bother you?  :ricky: ),
2) that oil is being delivered optimally,
3) that the the bikes air/fuel mix is not causing excess heat,

According to the service manual this can all be done with the engine in the frame.
I have already removed the head cover which gives me access to replace the rocker, no problem;

Everything else looks to be it top condition to me so;

1) Should I try to run a leakdown test before going any further? 
2) Or do I remove the head and test the valve seats for leaks?
3) If any leaks are found take it do a shop to redo the seats and clean up the valves?
4) And replace the valve stem seals? ( have already purchased new seals, if they aren't required I will keep until I replace the piston rings, want to log "normal" oil usage for reference)
5) Do I remove the piston and measure up the the specifications? Hone a given while in there? New piston because cylinder is honed? New rings if cylinder in honed?  Or if it measures up nicely do you just put it all back together? With new rings for good measure?

So once that is all taken care of and the oil strainers and passages are cleaned up, pump wear parts measured and the engine put back together again...

I've still got an untouched carburetor on my desk;

6) Do I make adjustments as desired, put it all together and start her up?
7) Or do I just clean it out and put it back on to check that the bike will idle? Or run through to wide open without unusual hesitation? Or full run-in time perhaps?
8) Or do I leave it untouched, put it back on and and test first?


Regarding the carb mods as per "Dave's carb mods"...

1) Clean and rejet to recommended 55/158 jets and modify the air/fuel screw to be adjustable - any suggestions or info?
2) Shim the needle and drill out the slide - any suggestions or info?

All information much appreciated,

If there is anybody out there with the time and knowledge to assist in person please give us a shout (based in Cape Town, Northern Suburbs). Willing to pay for professional services, perhaps a mobile mechanic to run a leakdown test etc. Anything that can give me more knowledge and confidence is good,

Also keen to get an idea of the costs of taking a cylinder for hone/rebore and taking a head in for a valve job after testing for leaks? And who do go to for this?

Thanks,
D
 
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