EXC525

I dedicated Saturday to my long neglected dirt bike.
Really haven't ridden it much in the last 2 years but hope to change that.
I couldn't figure out why the electric starter struggled to turn the motor, relying on the old-fashioned kick lever.
At 63 I need the push button, kicking a 500 is a beastly task even for the young.

I had already changed batteries and tried boosting it so that was not it. A mechanic suggested the auto-decompressor malfunctioning so I looked there.
After pulling the entire valve cover off I had a good look at this.
Many bikes & ATVs have similar arrangement, the cam shaft has an eccentric tab which protrudes and keeps the exhaust valve slightly open at zero to very low RPMs. As RPMs increase centrifugal force tucks the tab in place and compression is restored.
Very simple stuff so I put the cover back in place and went to rechecking the valve clearances, this is done by small removable covers over the inlet and outlet valves.
I found all the valve clearances were too large. After putting the clearances in spec (threaded adjusters) I tried the starter and it spun like new, awesome.

What I conclude from this is that the clearance was large enough to negate the auto-decompressor.
I'm waiting for a water pump gasket so I haven't had chance to test it yet.

Spent another 2 hours converting it into super-motard, haven't ridden it in that config for a few years.

 

Thinking about this some more, that was my stupidity adjusting the valves last time.
You can’t just position the cam past the lobe like an XJ. A motor with an auto compression release must be positioned exactly TDC on the compression stroke so you’re not sitting on the auto-decompressor. That’s obviously what I did last time.
The auto-decompressor opens the exhaust valves on the way to full compression, but once at full compression the valves are closed again.

 

I agree with you on the bikes that are kick start. I refreshed a XR650 a few yrs back, 1989 model that had the two carbs. One being the chock ckt and the primary jet and the other carb just for the main jet after half throttle. If that bike had an electric start it would still be in my stable.

Went back with a 1st Gen KLR650 and put a 685 kit it it. That bike was sweet. I think my days of riding any of those dirt or on off bikes is behind me. I sold the KLR this spring.

 

I just rode my KLR to work this morning. My brother turns 70 this year and he still rides a KLR, KDX and YZ250.
As long as he rides off-road I need to keep up.
I have a cousin 64 still running competition enduros, he is crazy.

 

I forgot what 50 hp and <300 lbs feels like on the street, can’t be legal

this is my school from grade 1-4
Not even sure it’s public anymore

 

We’ll here’s a first, last night my bike was eaten by a squirrel, said no one ever LOL

I bought this tank 20 years ago
Just found out Clarke is still in business and replacement caps are $18

 

Mmm... yummy plastic.
Weird how some rodents love some plastics.
Some of them cause house fires because of that, too.

 

I rode the bike all day Friday, then went out dirt riding with my son today so I left it outside in my backyard Friday and Saturday night.
The city squirrel wanted gasoline.
Glad he chewed the cap instead of a corner of the tank

 

I have a mechanic friend of mine that says same happens to the cars. Mice like to chew on some cars wires and others they leave alone. I remember reading that some of the coatings and or plastics have some chemical or compound in them our chewing pests like. Nature is weird, all them pets have to chew or their teeth will grow to the point they can't eat anymore.

Sorry for the cap but yes good thing it was not the tank.