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Post by bob123456789 on Feb 19, 2017 17:09:24 GMT -5
I have a Linhai 257 cc to which I am changing the head and the piston and the rings. I am just putting things back together and am at a point where I could use the help of the good people on this board once again for two issues.
The main issue I am having right now is that I am getting slight liquid leakage from some of my gaskets. It looks like antifreeze. I think is mainly coming from the joint between the block and the head. When I put it together I used a torque wrench and torqued it to the specs in the manual. I used new gaskets with no RTV and cleaned the old gaskets off good. There are three things I can think of doing. The first is do torque it more than the specs indicated (I don't want to damage anything). The second is to wait and see if the gaskets might swell a bit on there own. The third is to pull it apart and use a new gasket and/or RTV.
How do I solve the leaking?
The next issue is when I turn it over nothing happens with everything together. It doesn't ever fire. When I pulled the air box off it will fire and run briefly if I hold my hand over the air intake on the carb. This indicates to me that the air/fuel ratio isn't correct on the carb. Is my thinking right? When I then put the air box back on and moved the a/f screw to several positions I could never get it to fire.
How do I get it to fire with the air box on?
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Post by tortoise on Feb 19, 2017 17:39:57 GMT -5
There are three things I can think of doing. The first is do torque it more than the specs indicated (I don't want to damage anything). The second is to wait and see if the gaskets might swell a bit on there own. The third is to pull it apart and use a new gasket and/or RTV. Another consideration.
One downside of using RTV sealer in an engine is that fragments may obstruct oil passageways.
Verify timing by inserting a probe into sparkplug hole to determine piston top-dead-center, then observe if flywheel TDC mark is aligned, and if rocker arms are oriented at bottom of cam lobes.
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Post by rockynv on Feb 20, 2017 6:50:29 GMT -5
You do not use RTV on a head gasket. Maybe on a base gasket but you would have to be extremely careful to not plug up the oil feeds to the head. For head gaskets you spray them with Copper Coat at best. Just spray the gasket and let it dry, don't bother trying to mask the cylinder or head and trying to coat those surfaces. I hang the head gasket from a light gauge mechanics wire from the upper timing cover bolt hole to ensure its not one with oil pressure or coolant near it. Helps keep the head and valves cooler to due to the increased heat transfer it provides. Apply a few coats without going too insane and let it tack off before installing. I will coat the gasket and let it sit overnight before installing it. www.permatex.com/products/gasketing/gasket-sealants/permatex-copper-spray-a-gasket-hi-temp-sealant/
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Freshman Rider
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Post by bob123456789 on Feb 20, 2017 9:38:47 GMT -5
Just to be clear I did not use RTV on either of my head or base gaskets. I have a very small antifreeze leak that I need to solve. I used new gaskets.
The main issue I am having right now is that I am getting slight liquid leakage from some of my gaskets. It looks like antifreeze. I think is mainly coming from the joint between the block and the head. When I put it together I used a torque wrench and torqued it to the specs in the manual. I used new gaskets with no RTV and cleaned the old gaskets off good. There are three things I can think of doing. The first is do torque it more than the specs indicated (I don't want to damage anything). The second is to wait and see if the gaskets might swell a bit on there own. The third is to pull it apart and use a new gasket and/or RTV.
How do I solve the leaking?
The next issue is when I turn it over nothing happens with everything together. It doesn't ever fire. When I pulled the air box off it will fire and run briefly if I hold my hand over the air intake on the carb. This indicates to me that the air/fuel ratio isn't correct on the carb. Is my thinking right? When I then put the air box back on and moved the a/f screw to several positions I could never get it to fire.
How do I get it to fire with the air box on?
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Post by dollartwentyfive on Feb 21, 2017 0:09:18 GMT -5
The next issue is when I turn it over nothing happens with everything together. It doesn't ever fire. When I pulled the air box off it will fire and run briefly if I hold my hand over the air intake on the carb. This indicates to me that the air/fuel ratio isn't correct on the carb. Is my thinking right? When I then put the air box back on and moved the a/f screw to several positions I could never get it to fire. How do I get it to fire with the air box on? my guess would be the slow jet or not enough fuel. your engine should run with, or without an airbox or uni filter. these chinese rides can give you screaming fits in trying to diagnose them, simply because of the shortcuts the chinese make. for example, an iffy ignition switch can drive you crazy trying to figure out why it died or won't start. bad connectors only compound the problem. the first and foremost thing i would do is make sure my electrics was solid. in my case that included that critter called an autochoke. the PDI in this case is definitely worth it. not only do you catch a great many problems, you get to know your ride, and not get freaked out when it does break so, judging from the standpoint that your electrics is good, i would check out the slow jet. it seems you could clean it with a guitar string, i doubt a bread tie would be stiff enough.
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Post by bob123456789 on Feb 21, 2017 10:23:49 GMT -5
Thanks Dollartwentyfive. I pulled the slow jet and soaked both it and the main carb cleaner. This made no difference when I tried to start it. Both jets looked relatively clean before I cleaned them. I posted a video in post 15 of this link showing the fuel provided by my fuel pump. Does it look adequate? itistheride.boards.net/thread/9999/linhai-help-removing-vacuum-head?page=2The big issue for me right now are the leaks from the head. I have confirmed it is both antifreeze and oil. When I put them together I torqued the nuts to 16 foot pounds and the bolts to 7 foot pounds. The main issue I am having right now is that I am getting slight liquid leakage from some of my gaskets. It looks like antifreeze. I think is mainly coming from the joint between the block and the head. When I put it together I used a torque wrench and torqued it to the specs in the manual. I used new gaskets with no RTV and cleaned the old gaskets off good. There are three things I can think of doing. The first is do torque it more than the specs indicated (I don't want to damage anything). The second is to wait and see if the gaskets might swell a bit on there own. The third is to pull it apart and use a new gasket and/or RTV. How do I stop the leaking from the head gasket? Any good ideas folks?
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Post by dollartwentyfive on Feb 21, 2017 11:11:56 GMT -5
i can't tell you what is adequate as far as fuel flow goes. i only know that a 6 inch vertical drop is adequate fuel flow for my 244.
as far as your leaking head/ crankcase, i can only guess that there is some kind of contaminant in the joint, insufficient torque, or you have gouged the metal, which is uber easy with aluminum. it could also be a manufacturing defect.
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Post by rockynv on Feb 21, 2017 13:31:12 GMT -5
The Copper Coat would be the next step after verifying that the dowel pins are not too long. Sometime replacement heads are machined a bit shallow so shorter pins are required while other times the heads just are not flat and won't seat no matter what you do aside from haveing a machine shop true them up however the vender that sold the head should make good if its defective.
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Post by bob123456789 on Feb 21, 2017 15:31:13 GMT -5
Would torqueing the bolts more than the specs say to try to get the gaskets to seal be a good idea or a bad idea?
I'm just not sure what I've done wrong. I have definitely taken my time and tried to do it right.
I was pretty careful with the aluminum.
How do I tell if the dowel pins aren't too long? I used the old ones. I have two new ones. Should I have used them?
I have a new head gasket that came with the head. I had used head gasket that came in a gasket kit. Should I get some Copper Coat and try to replace the head gasket with the one that came with the head and use copper coat?
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Post by dollartwentyfive on Feb 21, 2017 19:31:56 GMT -5
Would torqueing the bolts more than the specs say to try to get the gaskets to seal be a good idea or a bad idea? I'm just not sure what I've done wrong. I have definitely taken my time and tried to do it right. I was pretty careful with the aluminum. How do I tell if the dowel pins aren't too long? I used the old ones. I have two new ones. Should I have used them? I have a new head gasket that came with the head. I had used head gasket that came in a gasket kit. Should I get some Copper Coat and try to replace the head gasket with the one that came with the head and use copper coat? maybe you have done NOTHING wrong. if the above is true then you must assume some sort of manufacturing defect, either with the dowel pins being too long, or their cavities being too shallow, or the mating surfaces aren't exactly true. i do not recommend overtorquing aluminum. i would give those dowel pins a going over. or, make sure there isn't some kind of contaminant inside the dowel cavities. also, are you sure you got the headbolts back into the holes they came from? i don't see how this would matter, but leave it to the chinese to make it happen though. added to that, are you sure nothing fell into the headbolt holes? if you MUST modify the head, then document why and then return it as a manufacturing defect. i can't overstress that, although aluminum engine blocks aren't pure aluminum, aluminum is very soft. i do not recommend any type of metal scraper be used when removing gasket material, unless you are very, very, very careful. even sandpaper can have very bad consequences. from the above, it seems obvious to use gasket sealers that are easily removed. or maybe none at all, although i have never replaced a gasket without some type of sealer (even just a film of grease)
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Post by rockynv on Feb 21, 2017 23:22:22 GMT -5
Do not over torque as that could pull the studs from the engine case or crack the head. Time to pull and measure to see if the head is reasonably flat and the machining for the dowels seems adequate then Copper Coat the head gasket and try again. I have had some replacement heads come in with gas inclusions in the castings making them porous so coolant or oil seeps right through the casting.
If the head gasket was creased or deformed in any way that is one other thing that could cause it to leak. What type of head gasket was it? My Piaggio uses a spring steel gasket while others use a laminated composite gasket.
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Post by bob123456789 on Feb 22, 2017 9:29:00 GMT -5
If I look at things objectively the odds are pretty high that it is something I did incorrectly. The head is new. It is my first time and I was working on it alone. I did follow a shop manual step by step. However I did not use the gasket that came with the head. I used one from a gasket kit I bought.
I will not over torque the nuts and bolts. Do these seem like good next steps? 1. Pull the new head off the block apart using the shop manual steps. 2. Inspect the block, the head, the head gasket and the dowels for any damage. Check the dowel pin fit in the new head. 3. I have a new head gasket that came with the head. Use it. 4. Spray the new gasket with copper coat. 5. I have one new dowel. I will use it. 6. Put everything back together following the shop manual.
I only have one new dowel pin. Should I get another before trying the steps above?
Should I use anything other than copper coat on the gasket?
dollartwentyfi The head has four nuts and two bolts. I am pretty sure that I didn't put them in the same order they came off. The head is new so there shouldn't be an junk in the dowel pin holes. I don't recall seeing anything in the dowel holes in the block. Four of the six head attachments are nuts so nothing fell in them. I did carefully use a razor blade and gas to remove the old gasket from the block which is steel.
RockyNV I am not 100% sure what the gasket material is. I think some kind of plastic.
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Post by rockynv on Feb 22, 2017 12:40:05 GMT -5
Is the head gasket that came with the head a bit thicker?
You may have better results with the head gasket that came with the head.
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Post by bob123456789 on Feb 22, 2017 15:25:38 GMT -5
rockynv. I compared the head gasket that came with the new head and another gasket that came in the gasket kit I bought and they are very similar in thickness. The one that came with the new head may be just a bit thicker.
It is hard to say for sure since the one that came with the gasket kit is still on the engine.
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Post by dollartwentyfive on Feb 22, 2017 16:01:43 GMT -5
3 or 4 thousands of an inch could very well make all the difference in the world.
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