help! 22-cent mod renders motor non-running!?!?!? ('99 klr)

[James W. Flower]

John-  The one time the valves were adjusted since I've owned the bike, I let the local mechanic do it.  Next time I'll try it myself, but I'll study up first.  It seems more complicated and fussy than on my old SR500. I had a bigCee gravity petcock kit.  On the small chance that the vacuum setup was causing the problem (and because I wanted to simplify), I installed the gravity kit.  That didn't hurt, but it didn't help, the high-rpm miss.  Thanks- James On Apr 28, 2014, at 10:52 AM, "Cox, John" wrote:

Just so you know, in my case a weekend Tech Day adjustment of my valves turned into a complete overhaul when one of the valve shims didn t seat correctly and we didn t see the problem before turning the engine over to start it. Adjustment of the valves (replacing shims) on a KLR is not something you have to do often but it is a fairly intrusive operation which can easily expand. I assume you have looked at the fuel petcock and its vent circuit.  The stock petcock valve below the gas tank on the left side has a vacuum hose to the carb.  It shuts off gas if there is no vacuum (ie: the engine is not running.)  You probably know that this convenient feature has caused a great deal of grief when it malfunctioned. [b]From:[/b] James W. Flower [mailto:jwflower53@yahoo.com]  [b]Sent:[/b] Monday, April 28, 2014 9:46 AM [b]To:[/b] Cox, John [b]Cc:[/b] Fred Hink; KLR650 DSN [b]Subject:[/b] Re: [DSN_KLR650] Help! 22-cent mod renders motor non-running!?!?!? ('99 KLR)  Thanks John, will do.      On Apr 28, 2014, at 9:42 AM, "Cox, John" wrote: Your, local mechanic says this problem is caused by the valves being too tight.  Was this an armchair diagnosis or did he measure the clearances on your engine? Even assuming that your valves need adjustment I think you would be wise to look elsewhere and try to fix the missing problem before introducing possible new issues by opening up the head and adjusting the valves. I agree with others who recommended you make sure the fuel system is working correctly.  I strongly recommend you thoroughly check this before making any other changes. [b]From:[/b] DSN_KLR650@yahoogroups.com [mailto:DSN_KLR650@yahoogroups.com] [b]On Behalf Of [/b]Fred Hink [b]Sent:[/b] Monday, April 28, 2014 8:39 AM [b]To:[/b] KLR650 DSN; James W. Flower [b]Subject:[/b] Re: [DSN_KLR650] Help! 22-cent mod renders motor non-running!?!?!? ('99 KLR)  While it is true that tight valves can effect the starting and performance of your KLR, this issue doesn t come on all at once and is a very gradual process.  If your missing and starting trouble came on all at once, I doubt it is going to be your valves.  Usually when the valves are too tight, it may start and run normally while cold until the engine warms up and then it becomes harder to start and runs worse.  The reason this happens is because of the lack of clearance between the cam and the valve, which when cold still allows the valve to close but as it warms up and expands, this clearance goes away and the valve doesn t close completely loosing compression.  Eventually it won t even start when it is cold but that takes a long time.  Also running valve clearance too tight will over heat the valves as the valve cools itself when it contacts the head.  If the valve doesn t close completely it will get hot enough to cause damage to the valves and/or head . Fred http://www.arrowheadmotorsports.com

 [b]From:[/b] jwflower53@...[b]Sent:[/b] Saturday, April 26, 2014 6:49 PM[b]To:[/b] dsn_klr650@yahoogroups.com[b]Subject:[/b] Re: [DSN_KLR650] Help! 22-cent mod renders motor non-running!?!?!? ('99 KLR)  -A local mechanic says this problem is caused by the valves being too tight and needing adjustment.  The bike shows no other symptoms, but I shamefully admit it's been 9,000 miles since the last adjustment.  Better do that anyway, but could that be the cause of this particular problem?

I'm hoping for answers to these questions before I button it up and try it out to see if it still starts missing at 5000+ rpm.  Thanks again.-James