310 kit...whys it keep doing this?? Help!!

[LT250Racer609]

Ok i have a stock re sleeved L.A. 310 sleeve on my quad. Now it takes the normal paper gaskets and L.A. sleeve is the only one that sells them. I keep having a coolant leak problem. When i start it, it leaks a tiny bit out of 2 stud nuts. When i ride it, it leaks a little on the front side of the gasket right above the exhaust port on the head. I have tightened it fairly enough where it shouldnt leak at all. Once i start riding it, even out on the ice in 20* weather, Coolant starts to leak pretty good out of the radiator overflow tube and i dont have the antifreeze rezzy for it to drain into. Why does it do this?? The first time it did it, there was no head leak problems just all the coolant went out of the overflow and eventually went dry (i shut it off before it was out) and this head gasket is brand new...the head isnt warped either cause it was checked...there is a ****load of compression, could that be the reason why its forcing the coolant out??? this is on a 87 motor.

[fireburns99]

When using thin gaskets, such as a cr or paper thin one, it helps to get a can of gasket sealer. It comes in an aerosol can and jsut spray both sides of the gasket and let it sit for about 5 minutes, then assemble.

The reason that the coolant is overflowing is that the head gasket isn't sealing allowing the cylinder to pressurize the coolant system which then forces it out the radiator cap. The radiator cap acts like a pressure release valve, when to much pressure builds it vents it.

I hope this helps.

[86 Quad R]

what head are you using? is it chamber matched to the cylinders bore? have ya by chance paid any attention as to whether or not the cast iron sleeve is at the same level as the cylinder itself?

personally i DO NOT like using the paper gasket on a cylinder. especially one with higher than stock compression. i'd go with the 3 layer metal gasket and coat each side with the sealer as "fireburn" had suggested.

have any idea what the compressed thickness of the paper gasket is?

for reference..... the 3 layer metal gasket is approx. .050" - .055" thick.

[LT250Racer609]

Originally posted by 86 Quad R
what head are you using? is it chamber matched to the cylinders bore? have ya by chance paid any attention as to whether or not the cast iron sleeve is at the same level as the cylinder itself?

personally i DO NOT like using the paper gasket on a cylinder. especially one with higher than stock compression. i'd go with the 3 layer metal gasket and coat each side with the sealer as "fireburn" had suggested.

have any idea what the compressed thickness of the paper gasket is?

for reference..... the 3 layer metal gasket is approx. .050" - .055" thick.

Im using the stock head and it was chamber matched for the 310. The cast Iron sleeve is at the same level as the cylinder. Also, they only make a paper gasket for the 310, they dont make the metal one or else i would have gotten it. No i dont have any idea what the compression thickness is.

[LT250Racer609]

anyways....Update

since this post i went out and drained the anti freeze, took the head off and looked at the gasket. The gasket was perfect so it wasnt a head gasket problem. Anyways i Put the head back on and torqued everything nicely. Then i read on here to put in the coolant and start it with the cap off, so i did. I did a 50-50 mix and filled it up untill i could just barelly see it in the radiator. Then i started it. It started nicely and this time there was NO leaks from the head, anywhere. Not out of the gasket and not out of the stud nuts. I let it idle for about 2 minutes then i put a little more water into the ratiator, it bubbled a little bit then i added a little more anti freeze and put the cap on. I then let it idle for about 2 more minutes to get the cylinder nice and warm. I then put it up on my stand and went through all the gears (once i was in gear before, thats when it went out of the overflow)...i romped through the gears for about 2 minutes and still not a drip. Tomarrow i will go out on the lake and give it the real test to see if its 100% fixed.

[CorvetteZ06]

nice, let us know, hopefully it will be all good.

[sandspanker]

make sure that you ate using the acorn nuts and the copper washers. i had all of my studs leaking because i just had standard nuts and washers on my cylinder when i got it back.

[LT250Racer609]

theres no washers on my cylinder..infact, theres no washers on any of the 5 cylinders i own and none on my dads 250r as well...they arent leaking from the studs anymore anyways and that was the only time its ever hapened.

[Aceman]

Originally posted by LT250Racer609
theres no washers on my cylinder..infact, theres no washers on any of the 5 cylinders i own and none on my dads 250r as well...they arent leaking from the studs anymore anyways and that was the only time its ever hapened.

It wouldn't have been leaking past 2 of your cylinder head nuts in the first place if you HAD been using copper washers. It doesn't make sense to ask people for help when you know you clearly don't have your your engine assembled properly. Washers are there for a reason, use them.

[C-LEIGH RACING]

Stock 250R cylinders didnt come with copper washers but did have the cap nuts.
One reason a stock cylinder didnt leak coolant was because everything was new at the time & didnt have the high compression thats being run in them now to get the bottom end pull like everybodys wanting.

After modding the engine & upping the compression, those copper washers under each cap nut is a must have item.

Leaking head gaskets on the 310 big bore sleeved 250r stock cylinders is a age old problem.
You can only remove so much aluminum before you get into strenght problems in the areas around the head studs & then add to that the amount that was cut off the head to get the compression up & then you end up with these kinds of problems.

Only real way to combat the problem is being sure each mating surface is perfectlly flat & if useing the fiber gasket use a good amount of gasket sealer. This is realy only a get by sort of fix , but will last some amount of time.
A real good fix is the get a cool head with the o ring sealing. Those heads are thicher & hold their shape longer than a stock head.
Another + of the cool head, changing the compression is just a matter of changing out a dome.

If you wanted a then metal gasket for the stock sleeved 310 big bore cylinders, Cometic offers a top end set with that gasket, a number C7351 top end set with a 0.010 head gasket.

Copper Coat is a good sealant, but I have had the best results with Three Bond brand number 1211 sealant.
Key to any sealant on a gasket is allowing time for it to cure out completely before adding any coolant or running the engine.
Neil

[LT250Racer609]

thanks alot for all that info. I was actually looking at the cool heads and was leaning towards getting one actually.

[number5]

You cant go big bore without changing the head with it. I have been through this. Your going to leak with your compression up. Unless using a copper gasket or a steel wire seal (.032 safety wire) A stock head on a 72mm piston will make around 240psi depending on what thickness gasket. Like c leigh said use a sealer. I used copper spray on the felt gasket and let it dry.

[LT250Racer609]

like i said before, the head matches the bore....it was done by L.A. Sleeve, and it was on a 73.45mm piston. Im not sure on how much PSI that would make around, but it blew the paper gasket again so i took it off and put back on my 265.

[number5]

Ok if your head is cut to 73.45 Does it look like its enough sealing area? When I measured to 72 I didnt think that was enough. Im suprised its holding. I had mine cut to 71 and went .045 deep and continued with the conical shape. I would also like to try experimenting with a head and have it cut for orings. I think the studs would be fine as long the threads are siliconed to keep fluid working up (capillary action).

[LT250Racer609]

actually me and my dad were just talking about o rings the other night on the head. My uncle owns a machine shop and strictly does snowmobile/dirtbike and quad motors...he can easily machine in the grooves for the o-rings...do you think that would have an advantage over a regular head gasket??

[number5]

yes. You probably would go 40-41 for the inside and a 46-47 for the outside. Just going by my dial caliper only goes to 105mm Im guesing 115 for outside. For the area you have to work with since its been cut out to 73mm I would go with a oring no larger 3/32 w. As far as depth I would let your machinist determine that. Here is a oring sizing chart. I would think a standard buna-n would work fine. To be on the safe side you can counter sink the studs a tad and put small orings on the each of those it would be reverse to the head. You wouldnt have to cut each stud hole. If you do it I would like to hear how it works.

http://allorings.com/size_cross_reference_framed.htm