New Valves without Re-cutting valve seats???

[polarbear]

I was just curious of all of you have who have replaced your valveshow many of you had the valve seats re-cut and how many of you didn't? Also, how long did the new valves last with or without doing the re-cut? And who re-cut if you did, and for how much?

[Throttlejockey]

Definately recut the seats. Most guys that didn't had more problems shortly after.

[letmein]

I didn't recut the valve seats, but I put in kibblewhite steel intake valves and lapped them in. I got over 500 hours out of them before I replaced them because I was doing a major rebuild. I once again did the same routine and currently have 162.6 hours on my hour meter and haven't adjusted them once!

If you are going to put in titanium you will have problems if you don't cut the seats, because the metal is much less durable.

[crf-f crf-r trx cbr]

I was just curious of all of you have who have replaced your valveshow many of you had the valve seats re-cut and how many of you didn't? Also, how long did the new valves last with or without doing the re-cut? And who re-cut if you did, and for how much?

pm ron hamp-----best bet

[polarbear]

crf-f crf-r trx cbr man you are a quick responder! Almost every post Ive ever written you are always quick to reply.

What does this mean???? "but I put in kibblewhite steel intake valves and LAPPED them in." Lapped??? what is that???

Its obvious that Ron Hamp Re-cuts valve seats. But has anyone tried someone different???

[DPR250R]

I didn't recut the valve seats, but I put in kibblewhite steel intake valves and lapped them in. I got over 500 hours out of them before I replaced them because I was doing a major rebuild. I once again did the same routine and currently have 162.6 hours on my hour meter and haven't adjusted them once!

If you are going to put in titanium you will have problems if you don't cut the seats, because the metal is much less durable.

When you lap them in what valve do you use?

An extra TRX intake?

An extra Kibblewhite?

Or the valves you are actually installing?

[XR6's_rule]

use whatever valves you like, but in addition you MUST recut the valve seats. I recently revalved an '03 CRF450 of a mates' and his seats had gone slightly oval, the fella at the machine shop who did the work said with just replacing the valves, the bike wouldnt have lasted more than 10 hours running.

[LocoP]

It is not all in the valve seats. The guides have to be in good shape. If the guide is too loose the valve will not land on the seat strait and cause the valves to wear faster. If the guides are in manufacturer specs than I would think about lapping the valve for a second. Than have the seats cut. Just my 2cents.?

[Shawn_Mc]

Typically when guys just throw new valves into the same pockets, the go about 10-15 hours, then they'll need an adjustment, then you get about 5-8 more and they're dead again. Putting the stainless ones in may get you another 5-8 hours on both ends, but its still not the best move.

[polarbear]

I am still wondering what "having your valves lapped" means???

And, how much does it cost to have them inspected and/or cut??? How much more to have them put the valves in???

[MXof21]

I did not have my valve seats cut and I rode hard all summer on my new valves and they stayed in spec. I suppose it is because I replaced the stock intake with Ron Hamps stainless valves long before it would have been necessary, I adjusted the stock intake valves twice then replaced them. Unless I am wrong lapping a valve is when you use valve grinding compound on the seat and spin the valve in the seat with a special suction cup on a stick tool, can't remember what it is called. In any event I did this procedure to my seats using the valve that was being installed and never had any issues but I may just have been lucky.

[LocoP]

I am still wondering what "having your valves lapped" means???

Lapping is when you take the valve and use a lapping compound (abrasive) and spin the valve in the head to mate the valve to the seat. This works on low PRM engines (daily drivers) that will not see sever driving conditions. The Bad part to lapping the valve to the head is it removes material from the valve and head. Do not lap Ti valves or any valve with a coating this will remove the coating.?

[motoal88]

I installed Honda stock valves on my 450 without recutting the seats and they made it 70 hours, now one intake keeps losing gap

[LocoP]

I have seen that happen a lot. Some times the seats are not perfect from the factory. You should check them befor installing new valves.?

[moabrules1]

Some one who really knows what they're doing should do us all a favor and post pics of good vs bad valve seats. I'm currently replacing my intakes and the seats look good to me. As a check I took the head to a local shop and had a mechanic look them over. He concurred with my assessment. I'm still a little weary. My shop manual provides a spec for the width of the main sealing band where the valve seats. I plan on using some dykem on the new valves to check this. Still, I'd like some good pics on what bad vs. good looks like.

[moto_x2005]

i gotta find my camera, currently on my head i have three good seats and one bad i wish i can show u guys

[moabrules1]

Please do, I think it would help everyone here.

[polarbear]

That would be nice, at least then we would have less questions on "valve seats".

Hey, you who have said you had put in new intakes... looking back, if you were going to do it all over again would you have done all four valves and cut the seats and put stainless in. Or are you happy with only doing the intakes? I am currently needing to replace my left intake, it zero'd out. The right intake is fine still, and the exhaust havent budged. Im just trying to see if I should not worry about the exhaust valves or if it would be worth it to just do everything all at once with stainless...??

[moabrules1]

That would be nice, at least then we would have less questions on "valve seats".

Hey, you who have said you had put in new intakes... looking back, if you were going to do it all over again would you have done all four valves and cut the seats and put stainless in. Or are you happy with only doing the intakes? I am currently needing to replace my left intake, it zero'd out. The right intake is fine still, and the exhaust havent budged. Im just trying to see if I should not worry about the exhaust valves or if it would be worth it to just do everything all at once with stainless...??

I'm pretty sure the exhaust valves are stainless steel. Like you, my exhaust clearances haven't moved and I think you'd have a hard time finding many posts regarding issues with these. My issue is opposite of yours as my throttle side intake went to zero. Last year the clutch side intake went. So, long story short, I'm cool with replacement of only the intakes since the Ti material of the stock valve isn't long for this world. Of course, I'm replacing the pair of intakes as it only makes sense since the bike is torn down.

[mattsnow24]

currently doing intake vavles and having the same issue. I've got into a dark room and shined light into about the intakes and can deff see some light passing through. Also, I bough kwhite stainless vavles, springs and seals. Am debatting on having the seats cut because I hear so many mixed reviews. This is a stock 06 yz250f mind you and since the recall in 06 this will be the first vavle replacement. Any ideas guys?

Edited December 29, 2012 by mattsnow24