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G_Rapids

New valves have 0 clearance

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Posted (edited)

2002 CRF450r - Earlier this year i took my bike into the shop for a pre-season checkup, mechanic said valves need to be replaced as i have low clearance (around .003), i ordered a ProX SS intake kit and put new OEM exhaust component in. I did not have the valve seats cut, but reassembled everything to within spec (using the smallest shims i have - 1.20mm), was within spec, reassembled everything. Bike started first kick cold, ran great, i was happy until i was about 8 miles into a trail, then the bike started not wanting to run, limped my way back and the bike would not start at all.....got it home, tried starting it again, it backfired, now it wont hold compression, took off the valve cover and i have 0 clearance on the intake valve bucket. Took the head off and i don't see anything obvious wrong, piston still looks fine, valves and springs look fine, what the heck is going on??

Edited by G_Rapids

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Just now, galligar said:

Seats gone,you should of done both,maybe guides as well.

I've requested info from a few shops asking if they cut seats, but no one has gotten back to me yet. Wont cutting them create even less clearance though?

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new seats=bigger shim vs worn out seats =small shim .Cut the old  worn out seats not able to shim. You cut the seats to get a seal with the valve. 

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Posted (edited)
5 minutes ago, galligar said:

new seats=bigger shim vs worn out seats =small shim

That does not seem right, if you get the seat cut, it removes material and moves the valve closer to the camshaft lobe, the closer to the lobe, the smaller the shim should be...right?

Edit: nevermind, i think you're saying cut out the old seats and replace them, correct?

Edited by G_Rapids

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Performance shop says $360 for all 4 valve seats...Welp, this money hole just gets deeper and deeper....and deeper

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22 minutes ago, G_Rapids said:

Performance shop says $360 for all 4 valve seats...Welp, this money hole just gets deeper and deeper....and deeper

Call or email George at Pro1 Racing and get a quote for his copper alloy seats, guides, valve job and assembly with your parts. He quoted my $295 but that was a while back. Regardless, you'll have a bad ass set up that will last.

https://www.pro1racingheads.com/

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If you're going to keep this bike, I'd just put a brand new Big Bore thumpers head on it. A decent shop would be able to cut the seats, face a stainless valve and tip the stem to get back into shim range. Taking .012-.015" off the stems isn't a big deal. More than that can be as the bucket gets too close to the spring retainer.

 

Short Block Charlie can do that for you (Pro1) Same guy.

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On 8/19/2019 at 10:59 PM, Shawn_Mc said:

If you're going to keep this bike, I'd just put a brand new Big Bore thumpers head on it. A decent shop would be able to cut the seats, face a stainless valve and tip the stem to get back into shim range. Taking .012-.015" off the stems isn't a big deal. More than that can be as the bucket gets too close to the spring retainer.

 

Short Block Charlie can do that for you (Pro1) Same guy.

I'm just going to try to finish out the season with it and get a newer bike, i'm tired of these old bike problems, KRG Performance near Detroit said they will put in new copper seats for $80/valve, so i', just going to do the intake side and then get rid of the bike come winter. Big Bore would be nice, but $160 vs $600 to finish out a season. 

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On 8/19/2019 at 12:16 PM, HRC27 said:

Call or email George at Pro1 Racing and get a quote for his copper alloy seats, guides, valve job and assembly with your parts. He quoted my $295 but that was a while back. Regardless, you'll have a bad ass set up that will last.

https://www.pro1racingheads.com/

Was quoted out $395

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11 hours ago, G_Rapids said:

Was quoted out $395

yeah again.....

alloy seats are to make up for the poor thermal properties of titanium valves.

the extremely conductive alloy seats pull the heat out of the poorly conducting TI

with ss run em on the iron seats

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12 hours ago, EnglertRacing said:

yeah again.....

alloy seats are to make up for the poor thermal properties of titanium valves.

the extremely conductive alloy seats pull the heat out of the poorly conducting TI

with ss run em on the iron seats

That's a good point but as mentioned, this is a "season ending" bike, i just want to finish it out and i can redo it if needed. Also, iron seats? do you mean aluminum? The exhaust side would be hottest, and those are still SS, the intake side would be cooled from incoming air, and that's the Ti side. 

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7 hours ago, G_Rapids said:

That's a good point but as mentioned, this is a "season ending" bike, i just want to finish it out and i can redo it if needed. Also, iron seats? do you mean aluminum? The exhaust side would be hottest, and those are still SS, the intake side would be cooled from incoming air, and that's the Ti side. 

no the stock heads have iron or powdered metal ferrous seats.

you would be surprised to know intake valves under full load will glow red.

2062583697_glowingintakes.png.d533bf99994ca87d199fed5beaab02c1.png

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