Jump to content
Sign in to follow this  

Valve issue hypothesis

Recommended Posts

Here is some food to chew on......... :cry:

There have been many a discussion regarding how to break in your bike..... the issue being, break it in hard or easy. It got me to thinking if there was a direct link to the valve issues that some are having?

People with valve trouble:

did you break it hard or easy?

I took the easy route. So far, no issues (knock on wood).

I truely am considering selling my time bomb.

And I think I should have listened to friends who said...

"do not buy the first year model".

Great bike, but don't have the time for the issues or worries (not at this age).

You may now throw your stones. :cry:

Share this post


Link to post
Share on other sites

Have there been more problems with the X? More problems with the ca emmisions model? If so, could the overly lean condition in which the bikes come be creating a higher than desired combustion temperature, thus contributing to premature valve failure? In that case and easy break in until jetting change could help. My son has an X and although its still fairly new, the bike has not experienced any of the problems that have been posted. My opinion on valve issues is that the vast majority of valve problems on internal cumbustion engines are usually a result of valve float(via overreving) or too much heat. :cry: M in M

Share this post


Link to post
Share on other sites

I think you are on to something here. There are two RMZ's and one KXF i know of(first hand) can give contact numbers etc. Both ridden by pro riders, at the same tracks and temp and altitude. The RMZ's have both been out of action for three months as they both dropped valves requiring major head work etc. These are both stock in jetting. The KXF is run way richer on the needle (where most of our riding is done not on the main) and has not moved clearance at all in 10 months of racing and practice. The guy who rebuilt the rmz's has since put them back together and rode them with there current jetting and said that both are way lean. Changed to his own specs, and performance was better, and hopefully so will longevity.

As a side note for all in OZ - if you pay more than $52 for new inlet valves you are getting ripped - honda has dropped the price, make sure your dealer passes it on. I got mine at Redwing Honda in Melbourne, I did not know them at all, just walked in and asked for two new inlet valves and nearly died when he said $104 for both - I paid $120 each last time I put new ones in. This pissed me off as I have been out of action for 6 weeks now waiting for stainless kits, had i known it was only $100 bucks I would have just put new Ti ones in.

I also got a set of dual springs (available from serco) similar to what KTM put in there 450sx to solve their valve problem. They come with an inner damper spring to eliminate harmonics - thought they might be worth a try (not cheap, but after only getting six rides off my last valves I am willing to try something).

Share this post


Link to post
Share on other sites

Simon Are bikes sold down under performance challenged by restrictive emission standards as they are in the U.S. We in california are even more restricted than the 49 state model that the rest of the country gets. As you mentioned valve harmonics ie, valve bounce, float, etc is a unwanted condition caused by the fact that in order for the four strokes to perform like their two stroke cousin, the manufacturers have to make a powerplant that will rev higher and rev up faster than conventional four strokes. The natural way to do this is to lighten rotating and reciprocating components especialy in the valve train. Ti valves being light are more prone to develope harmonic vibrations thus causing a hammering effect on the seat. (I believe). SS valves being heavier should reduce this part of the problem. But I like the idea of controling harmonics with springs, be it different size, coil diameter, materials etc. As many people that have had a problem its got to be legit, but I still wonder why ours shows no signs of failure. Remember this bike has been jetted richer (considerably) and I believe doesnt reach as high rpm by a little as a result. I believe when peak rpm is reached and load on the motor is decreased by momentum that a leaner condition would actually raise rpm,s slightly and surely raise combustion temperatures. When this bike was stock jetted you could wind it up to it cutting out slightly, now that its richer that doesnt seem to occur. Of course all this doesnt mean shiii if the material components arent up to the task, which is possible as ours is still fairly new but has been ridden fairly hard :cry: M in M

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×