I've just had 2 intake valves replace(valves hammerd the seats) by a local atv shop,and a piston ring set(upper one fired up) and the dudes said that it was because of the octane was not high enougth.(always ran the 91 octane in my ds) when also said that most 4-storkes have to use lead substitute(says that it reduces wear on valve and the seat) in thier 4-storkes engines. He said that was the main cause my vavle miss up. Is that true on 4-storkes have to have the lead substitute? Anyone running that in thier DS 650??????

 

I think your dealer is full of it. With all this talk of cleaning up atvs and the like, do you really think bombardier would make a relativly new atv run dirtier then they could? Lead substitute is usefull in engines originally designed to use leaded fuel. Lead sub. is also uselfull in motors using solid lifters, but most vehicles post 1970 have had hydrolic lifters. So, your ds does not need lead substitute, maybe an octane booster though.

 

what do you think caused my intake valves to get hammured(I took it apart myself, and saw that that two intake valves were hammured, so as the valve seats(got that regrinded)? Just got my engine back two days ago, just had no time to work on it. When it was still running it had to get valve adjustment very 50 hours, because the valve keep get tight(would't start until it got adjusted). Now I'am on the smallest valve shim(2.00). And still is on the smallest shim. What do you think I should do to prevent this form happing again? Would octane caused this?(always ran 91 octane)

 

yeah, there is no way you need to run more lead, i see your from arizon, if your running a K&N in that dry dust you probably are sucking way to much particles through the engine, may be a factor?
Jetjock16

 

I've notice that with my stock one, so I replaced that with the UNI filter (got one that gos back in the air box)

 

is your timing correct?

 

should be, it starts right up when it got the valve adjusted (after 50hrs. or alittle more it would have a hard time starting, because the valves would become tight again. Do you think alittle bigger valve would help this problem

 

I agree with whatwasthat, your dealer has cranial-uppus-rectus, lead was used in old motors as a lube and because the valve seats were not hardened like the motors made since the early 80's. Octane has no bearing on valve wear (unless you run pump gas in a 12:1 motor,then they burn) Find a new dealer or shop to work on your quad. As for the cause of you valve damage, not quite sure about the source,you say your valve keep getting tight, are the correct springs in there? high tension springs would make the valve snap back harder,but you didn't say if you were running aftermarket cam or springs. But to sum it up, NO modern four stroke needs a lead additive, your dealer is a dimwit, don't listen to him. The only thing I own that needs lead in the fuel is my old Farmall 504 tractor, it was made in 1963 !!

 

crazydemon, I've been running trick racing fuel(leaded). the lead was building up the valve seats and I had to readjust the valves every third trip to the dunes. switched to trick unleaded and the valves are staying within spec. just my .02 on leaded fuels.

 

Just a little history. lead was originally put in gas as a cheap way to boost octane. It also performed a secondary function that nobody really knew about until the gov banned the use of lead in 1974, it coated the valves and hept them from melting and sticking to the valve seats. Back in those days valves and seats were made of a softer material and needed the lead to survive.
Nowadays, after the lessons learned in the early 70s valves and seats are made of a harder steel and in a properly running engine they will survive without any problem.
It appears that your mechanic is a throw-back to the early 70s when everybody was buying lead additive to keep their old valves from burning. He sounds like a good mechanic but even good mechanics have their quirks. Your valves definately don't need lead and all it will do is build up in your engine and cause other problems, don't use it.

It does sound like your engine is detonating (the air/fuel charge is igniting before the piston reaches TDC) Which will cause extremely high cumbustion chamber temperatures and the damage you speak of. This is caused by low octane fuel. Even though you pay for 91 octane you may be getting less. Where do you buy your gas?
I noticed that if I buy my gas at the cheep station or even Texico my enging runs like crap. Add octane booster and noticed an improvement. I buy my gas at Chevron or Union76, they are the only ones I trust to have true 91 octane. It doesn't hurt to add a little octane booster to the gas, especially if you ride in the dunes, and it will bump your octane a couple of points. Just stay away from the boosters that have lead.
Hope this helps.