I tested the sealing around the valve seat and...

[Steven]

I've got my cylinder head removed for my rebuild. The machine has been ridden hard now for three years so I decided to test the seal around my valve seats.

I don't know if this is the proper method to do so, but I sprayed carb & choke cleaner into the intake and exhaust ports so that about 1/4 inch of fluid was sitting in the valve pocket.

I've let it sit now for about 1/2 hour and I have some seepage around one of the exhaust valves. The other three valves have held back the carb cleaner.

So now what?

Lap the the old valves or get a three angle valve job on the SERDI machine with new valves?

Laping would be inexpensive I know... but I have an old aquaintance who will do a P&P and three angle valve job using the SERDI machine for $100. New valves and valve seals from service honda are $100... so thats $200.

How about aftermarket valves and valve springs... what do they cost?

What do you guys think I should do?

Steve

[BadA$$440]

When i had my head off during my 416 rebuild i d the test to. I poured gas into the ports and all the valves leaked. All i did was get a universal spring compressor, lapping tool, and some lapping compund and started lapping all the valves. Then i poured gas into the ports and i didnt leak one bit. So i would just lap them for now.

[Steven]

Ok, will a machine shop lap the valves?

If I buy new valves, can they just be laped or do they need the angles cut in them?

[BadA$$440]

No dont have a machine shop do it. It is a very easy job that you cant really screw up. Im a 17 year old kid that is new to working on 4 stroke motors and i lapped my valves no problem without help from my dad. the tools shouldnt cost that much. Not sure how much a universal spring compressor is but a lapping tool ( looks like a small toilet plunger ) is only a couple dollars, same with the lapping compound. Do you have a manual? If so it should show step by step how to lap the valves. With your head already off and with the right tools, it wil take about 15-20 minutes lap the valves.

[Steven]

ok, thanks... I'll look into it

[beerock]

well if you can get a p&p , 3angle valve job and install new valves all for $200 I'd say go for it. if the motor has some hard hours on it . that would freshen up the motor. heck, why not even throw some larger valves in it. you might as well buy a new timing chain too;)

why not even throw some larger valves in it. Cause thats where it starts getting expensive. Seems that if you start talking to anyone in this industry about larger valves in minutes you will be thinking cutting the new seats will take years of hard labor. :) but seriously it does add a few hundred to the usuall valve job and if your on a budget thats a lot, hey I wasnt and decided to stay with the stock size.

[Steven]

I called around a little.

The local machine shop who does all the Tampa areas's big ATV/Moto shops says $62.50 for the three angle valve job and a lap. They said the valve job will really renew flow and seal. The price seemed ok. But for a mere $38.00 plus shipping I can get the polish too. Hmmmmmm... decisions.

They will do the resleeve for $45 and the bore and ring gap for $40.

$147 for all the machine work seemd ok.

I'm thinking of getting new valves from honda for the refresh. Not decided yet though.

Steve

[Colby@C&DRacing]

just put new seals in it while you have it apart they are cheap $1.25 each

[Steven]

Colby, I think the intake valves might have been leaking oil anyhow. There is a nice think coat of blopey tar looking substance on the valves where the stem meets the base. I would guess this is cooked oil which leaked down the valve. Either that or its air filter oil???

[Colby@C&DRacing]

sounds like leaky oil seal to me:(

If your thinking on new valves consider this.

Honda claims the valves themselves can not be cut or ground, so if they are out of spec get some replacements.

The OEM ones are a multi piece type that the valve head can eventually fall off into your cylinder (not good)

I think the Black diamond ones I got were not that much diff in price than the OEM Honda. And they are a much better part by far. PM Colby @ c&d for a price.


I am now thinking that if I had moved to the Tampa area like I was planning a couple years ago I would have saved a bunch of $$$ on the machine work. Those are some pretty good numbers you were quoted.

[Steven]

I used to live in N.J. (Princeton). If you ever do come to Tampa, look me up.

This guy says he does 3 angles on 400ex valves all the time. You have head this can't be done with the Honda valves... YIKES!

OEM valves are $15 ea. for the intakes and $26 ea. for the exhaust.

What did your black diamond's cost from Colby?? He is where I get my parts from now. I ordered valve stem seals from him today.

Steve

[jb400exxx]

my 400ex smokes when it's cold, but after about a minute or 2 it goes away. does this mean i need new valve seals, or is it the rings? i think it's the valve seals.