cylinder head rework

chrism1 · 09-23-2008, 04:57 AM

On my last ride I broke off the upper exhaust pipe stud,flush with the head.Since I am having the stud removed at the machine shop,should i have the head milled while it is off? How much should be removed and what would the benefit be? It currently has a 9:1 compression ratio.
Thanks again all :?:
If the stud cannot be removed,I am having a hard time finding a replacement head........ :x

tigertamer · 09-23-2008, 07:48 AM

I'm not to sure about the compression ratio, but the stud extraction is a fairly simple task for a machine shop, especially with the low carbon steel the Chinese use for their fasteners.

Next time, consider a drill bit and "Easy-out" screw extractor, available for a few bucks at the hardware store...You will probably save a few bucks, and get it done faster and easier, without removing too many parts.

Just my humble opinion,
Tigertamer

red2003 · 09-23-2008, 12:22 PM

If you haven't already pulled the head, don't. The machine shop can get the stud out on the bike. No problem there. I would suggest you DO NOT have the head planed. The increased performance (if any) would not outway the need to run on premium gasoline afterwards.

knothead · 09-23-2008, 03:49 PM

Quote:

Originally Posted by tigertamer

Next time, consider a drill bit and "Easy-out" screw extractor, available for a few bucks at the hardware store...You will probably save a few bucks, and get it done faster and easier, without removing too many parts.

Just my humble opinion,
Tigertamer

I say stay away from easy outs, they break too easily and if they do it ust makes extraction all the harder.
Use a left hand or reverse drill bit on broken fasteners. You'd be surprised at how well they work.
A Dremel tool is always very handy too. Sometimes you can slot the end of the broken bolt enough to turn it with a screwdriver or tap it loose with a punch.

As for machining the head... unless you have used plastigauge to check the clearance between the valves and the piston, don't even think about machine work. Sometimes even low compression engines will have very little clearance between the piston and open valve.
Then there are other issues like the timing chain or gears on the OHC engines... I think the valve train of an OHV engine would be fine with some mild decking or milling of the head.

I have thought about doing the same to my engine, and I think it's a very doable and worthwhile mod. But it's like the old saying, "Measure twice, cut once.".
If you could bump the compression up to something like 11:1, port the head, add a pumper carb of about 32mm and a decent exhaust, I could see getting 22hp or more out of a Chinese engine. (But would it last?)

TeamCheap · 09-23-2008, 04:16 PM

I wouldnt shave the head either unless you plan on going thru the whole engine and reworking all of it.(not worth it in my opinion)

I havnt tried these but I may the next time I need to extract a bolt.
ALL-IN-ONE-extractor

Most of the time I can just weld a nut back on the nub of the bolt and with all the tools needed right there at the ready I can weld the nut and then wait until I think it has cooled enough and just turn the bolt out and on the bigger bolts the impact makes it even easier.
Of course you really have to watch what is around it that can be damaged by that much heat.

IronFist · 09-23-2008, 06:36 PM

Knothead:
"A Dremel tool is always very handy too. Sometimes you can slot the end of the broken bolt enough to turn it with a screwdriver or tap it loose with a punch."

Once again Knothead, I've done the exact same thing.

elroyjetsn · 09-23-2008, 09:09 PM

You can also use the Dremel to clean off all the carbon in the combustion chamber.

IronFist · 09-24-2008, 10:18 AM

I've worked close to 1000 pounds of soapstone with a dremmel 8O My shop is set up like a dentist's office.

elroyjetsn · 09-24-2008, 04:35 PM

Quote:

Originally Posted by IronFist

I've worked close to 1000 pounds of soapstone with a dremmel 8O My shop is set up like a dentist's office.

Hmm, wildlife scupting perhaps??

knothead · 09-24-2008, 06:44 PM

Quote:

Originally Posted by IronFist

I've worked close to 1000 pounds of soapstone with a dremmel 8O My shop is set up like a dentist's office.

Soapstone? Really? I'm sending you a PM!!

IronFist · 09-24-2008, 10:41 PM

Quote:

Originally Posted by elroyjetsn

Quote:

Originally Posted by IronFist

I've worked close to 1000 pounds of soapstone with a dremmel 8O My shop is set up like a dentist's office.

Hmm, wildlife scupting perhaps??

I'll post a pic in my album of the stone, just to prove I aint telling tales. Sorry for the Hijack.

http://www.chinariders.net/gallery2/...avId=xddeba81c

frostbite · 09-25-2008, 08:16 AM

You did the right thing taking it to a machine shop. It'll save you money and grief. Easy-outs should be banned for any engine work. If a bolt is seized so bad that it snaps from the extraction torque the chances of successful removal with an easy-out are very slight. What often happens is the easy-out breaks off in the bolt you're trying to remove and now you have a piece of hardened steel between you and the softer bolt you were trying to remove.

Case in point:

http://nbdsc.ca/forum/viewtopic.php?...broke&start=15

Learn from our mistakes. Easy-out = EVIL.

IronFist · 09-25-2008, 10:21 AM

A year ago I had a problem with a broken bolt, I tried the easy out from CrappyTire. I had no luck with it at all. I too got frustrated and went at it with the knothead method. It was out in 10 minutes and there was no damage to the case. I'm too city-fied to have a mig or tig or even an A/O torch.

Since the head of the screw was gone, I would have pulled the other 5 screws, pulled off the side case I was working on, and exposed the broken screw. From there I could have got at it with a set of vice grips.

I think it really matters where the screw broke and how much material there is to work with/ weld to. I did use heat, and lube, and I rapped it with a punch. If I didn't get it out myself I would have taken it to the shop. Not much else I could have done. Hypocratic oath, "Do no harm." The last tool in my kit is always to take my bike to the shop

tigertamer · 09-26-2008, 04:28 AM

SORRY AGAIN, for giving advice that has worked for me many times in the past! 8)

Don't try this at home, KIDS,
Tigertamer

VinceDrake · 09-27-2008, 12:45 AM

Just to jump in on the Easy-out thing. I hate easy outs. They break, they strip, they suck, on and on ad-infinitum. *BUT* If you can drill the right size hole, a decent Torx Socket, is about the best easy-out money can buy.

Better grip, and less likely to snap. Just hammer it in a little bit, and twist with ratchet. Works like an easy-out should have.

--Vince

09-23-2008, 04:57 AM	#1
chrism1 Join Date: Sep 2007 Location: Bevely Hills,Florida US of A Posts: 138	cylinder head rework On my last ride I broke off the upper exhaust pipe stud,flush with the head.Since I am having the stud removed at the machine shop,should i have the head milled while it is off? How much should be removed and what would the benefit be? It currently has a 9:1 compression ratio. Thanks again all :?: If the stud cannot be removed,I am having a hard time finding a replacement head........ :x __________________ Lifan LF200GY-5
	0

09-23-2008, 07:48 AM	#2
tigertamer Join Date: Jul 2008 Location: Wheeling, West Virginia Posts: 683	I'm not to sure about the compression ratio, but the stud extraction is a fairly simple task for a machine shop, especially with the low carbon steel the Chinese use for their fasteners. Next time, consider a drill bit and "Easy-out" screw extractor, available for a few bucks at the hardware store...You will probably save a few bucks, and get it done faster and easier, without removing too many parts. Just my humble opinion, Tigertamer __________________ 07 H-D XL883C 06 LF 200GY-5 Yin and Yang CAUTION Obey The Traffic Regulation. Always Wear a Helmet. Don't Ride After Drinking Wine. Before Operation, Read The Owners Manual Carefully.
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09-23-2008, 12:22 PM	#3
red2003 Join Date: Jan 2007 Location: Northern Vermont, USA Posts: 1,249	If you haven't already pulled the head, don't. The machine shop can get the stud out on the bike. No problem there. I would suggest you DO NOT have the head planed. The increased performance (if any) would not outway the need to run on premium gasoline afterwards. __________________ First Chinabike: 2006 Roketa RSX200E Current Chinabikes: 2023 Titan DLX & 2022 Lifan KP Mini w/ 210cc BRT kit, 22 RWHP!
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09-23-2008, 06:36 PM	#6
IronFist Join Date: Apr 2007 Location: Toronto Ontario Canada Posts: 2,585	Knothead: "A Dremel tool is always very handy too. Sometimes you can slot the end of the broken bolt enough to turn it with a screwdriver or tap it loose with a punch." Once again Knothead, I've done the exact same thing. __________________ IronFist ___________________________________ The "chain" of command is used for beating spammers. ___________________________________
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09-23-2008, 09:09 PM	#7
elroyjetsn Join Date: Mar 2008 Location: West Virginia Posts: 629	You can also use the Dremel to clean off all the carbon in the combustion chamber. __________________ Wayne Wildfire WF300-SP
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09-23-2008, 04:16 PM	#5
TeamCheap Join Date: Jun 2006 Location: directly under the earths sun............NOW Posts: 2,302	I wouldnt shave the head either unless you plan on going thru the whole engine and reworking all of it.(not worth it in my opinion) I havnt tried these but I may the next time I need to extract a bolt. ALL-IN-ONE-extractor Most of the time I can just weld a nut back on the nub of the bolt and with all the tools needed right there at the ready I can weld the nut and then wait until I think it has cooled enough and just turn the bolt out and on the bigger bolts the impact makes it even easier. Of course you really have to watch what is around it that can be damaged by that much heat.
	0

09-24-2008, 10:18 AM	#8
IronFist Join Date: Apr 2007 Location: Toronto Ontario Canada Posts: 2,585	I've worked close to 1000 pounds of soapstone with a dremmel 8O My shop is set up like a dentist's office. __________________ IronFist ___________________________________ The "chain" of command is used for beating spammers. ___________________________________
	0

09-25-2008, 08:16 AM	#12
frostbite Join Date: May 2006 Location: Fredericton, NB, Canada Posts: 1,744	You did the right thing taking it to a machine shop. It'll save you money and grief. Easy-outs should be banned for any engine work. If a bolt is seized so bad that it snaps from the extraction torque the chances of successful removal with an easy-out are very slight. What often happens is the easy-out breaks off in the bolt you're trying to remove and now you have a piece of hardened steel between you and the softer bolt you were trying to remove. Case in point: http://nbdsc.ca/forum/viewtopic.php?...broke&start=15 Learn from our mistakes. Easy-out = EVIL. __________________ Frostbite "The beatings will continue until moral improves"
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09-25-2008, 10:21 AM	#13
IronFist Join Date: Apr 2007 Location: Toronto Ontario Canada Posts: 2,585	A year ago I had a problem with a broken bolt, I tried the easy out from CrappyTire. I had no luck with it at all. I too got frustrated and went at it with the knothead method. It was out in 10 minutes and there was no damage to the case. I'm too city-fied to have a mig or tig or even an A/O torch. Since the head of the screw was gone, I would have pulled the other 5 screws, pulled off the side case I was working on, and exposed the broken screw. From there I could have got at it with a set of vice grips. I think it really matters where the screw broke and how much material there is to work with/ weld to. I did use heat, and lube, and I rapped it with a punch. If I didn't get it out myself I would have taken it to the shop. Not much else I could have done. Hypocratic oath, "Do no harm." The last tool in my kit is always to take my bike to the shop __________________ IronFist ___________________________________ The "chain" of command is used for beating spammers. ___________________________________
	0

09-26-2008, 04:28 AM	#14
tigertamer Join Date: Jul 2008 Location: Wheeling, West Virginia Posts: 683	SORRY AGAIN, for giving advice that has worked for me many times in the past! 8) Don't try this at home, KIDS, Tigertamer __________________ 07 H-D XL883C 06 LF 200GY-5 Yin and Yang CAUTION Obey The Traffic Regulation. Always Wear a Helmet. Don't Ride After Drinking Wine. Before Operation, Read The Owners Manual Carefully.
	0

09-27-2008, 12:45 AM	#15
VinceDrake Join Date: Nov 2007 Location: Southern Saskatchewan Posts: 491	Just to jump in on the Easy-out thing. I hate easy outs. They break, they strip, they suck, on and on ad-infinitum. *BUT* If you can drill the right size hole, a decent Torx Socket, is about the best easy-out money can buy. Better grip, and less likely to snap. Just hammer it in a little bit, and twist with ratchet. Works like an easy-out should have. --Vince __________________ "Sometimes it is better to say nothing, and let people think you're an idiot, than to open your mouth and prove it."
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