Tight Valves

My sons 150R was having a hard time starting and once running was boging real bad. I had his bike looked at and was told by the shop that the valves were tight. They made some adjustments and it seems to start and run fine now. I was unable to talk to the mechanic that worked on it at the time. I dont know what would cause the valves to get tight.

A little help!

ooooo is this another addition to new generation 4-stroke valve issues?

ABM: If it gets hard to start again or the valves go tight, tell us.

What COULD be happening is the coating of the valve is getting worn off, and exposing the tender material below. Once that happens the valve face and seat deform and the valve sinks in, thus tightening.

Yup, if your valves tighten up once again, time for a top end rebuild!

How many hours are on it? The reason I ask, is because if it is low hours you couldve just broken the motor in and a lot of times the valves will tighten a bit, at least thats how it is on my 250.

Thanks for the info Guys.

The bike is a 2007 and has about 60 hour on it. Two weeks ago we went to Kennedy meadows and of course that’s when it started acting up. I know part of the problem there was the altitude. One thing that concerns me is that when we rode in KM the ground was really dry and super dusty and my son being 13 was third in line and the farther back the bigger the dust cloud. I brought an extra air filter for our bikes but at the end of the first day I checked his filter and it was wasted. If some dirt got through could that have caused this? After the first day of riding and even with a clean filter he had to rev the bike a lot or it would stall. We took it out today and it seems be running well. If i have to have the top end done what do you think that will cost?

Good intake filtration is one of the best things you can do for intake valve lifespan. When tiny particulates make their way past the filter many of them wind up embedded in the valve face and valve seat sealing surface. The abrasive surface created accelerates wear. This is a lot of the reason intake valves often go tight so much faster then exhaust valves.

I'm changing the air filter after every ride now. Next timeI go to Kennedy Meadows I will bring filter cleaner and filter oil. Does any one use filter skins?

Im wondering if they would be good for extra protaction especialy when it is super dry and dusty. One thing iI need to start doing is check the valves myself. I have slowly been doing more and more on our bikes myself but adjusting the valves i am not real confident yet.

ABM, filterskins do work and can help you to extend your ride times between filter changes. Compared to the cost of top-end damage, they are extremely inexpensive in price. I.M.H.O., 'skins should be one of the must-haves anytime you ride in very dusty conditions.

Do you have a filter skin recomendation?

I dont know what would cause the valves to get tight.

Wear. That is it. One might reasonably think that valves would get loose over time and with wear, but the opposite is true. Valves wear into the seat and will become tight with wear. The shops I know that replace pistons, put in new valve seats while they are in there.

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