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Discussion Starter · #1 ·
I just changed my head gaskets about 100 miles ago and I blew the gasket agin on the front cylinder. I thought I was having tuning problems with my carb but I now think it is due to another blown head gasket. You can see a mist in the front spark plug side of the head when I go to start the bike, I an using compression releases but I forgot to use them once and the bike didn't like that to much. I just bought these heads about 500 miles ago and installed them and I blew the head gasket and changed it every thing was all good then this morning a big cloud of smoke and a hiss and I knew it did it again. Any ideas. I am running a 95 ci set up 10:5:1 Wiesco Pistons with 258 SE cams SE Heads and I am using SE high compresion head gaskets. I asked for some help before and it was mentioned to get the cometicc head gaskets, which ones should I try. I also an having a problems with a off idle ping could any of this be related and can some one point me in a good direction to get started on this bike back on the road?
 

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If I read it correctly, you say 10.5:1 pistons so I assume they are domed. You also say SE heads .. would those be performance heads? If they are, they are setup for 10:1 with flat tops ... now add to that 10.5:1 hi comp pistons and you might be over 11.5:1.

Only a guess from what I read.
 

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what procedure did you use to tighten down the headbolts. Did you clean the threads, and then lightly oil them? Also which torque procedure did you use?
 

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Discussion Starter · #4 ·
More Informantion

2002 Softail Duece
SE Pro Twin Cam Heads PN16952 W/ Compression Releases
Big Bore Cylinders (95 CI)
Wiesco 10:5:1 Pistons (with a slight dome)
SE-258 Cams (effectiovely brought my comression down from 195 to 165)
SE stud kit
SE Rocker supports ( I had to resize them so my rocker arms would fit way to tight)
SE big bore high performance head gaskets
Mikuni 45
Crane HI 4TC ignition
Fueling oil pump
Delkron cam plate
and Thunder Headers as of next week when they get here.

I will start my tear down again in the morning but I need to know the best head gaskets type and thickness.
I hope this helps you help me!
 

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i have also found with the multi peice head gaskets do the first step twice the second step twice giving it a couple of minutes between and then the final some of these expec. the se will back down like the coating is thick and needs to squish out or something
 

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Discussion Starter · #6 ·
I used the procedure in the tech manual,
starting with spark plug side forward, I first torqued them 9ft lbs then 11ft LBS the 15 and then 17 waited about an hour and made sure they were still at 17 then I marked them and torqued them 90 degrees.
 

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I gotta agree with springer on this one. You have alot of comp. there with that setup. By chance you aren't trying to use the o rings on the head gaskets are you? BB's don't use them.
 

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IMO, If you use the SEHG or the Cometic MLS HGs, you should torque to 42-45 lbf, instead of the 17lbf + 90 degrees. Before just replacing gaskets, take a few minutes to check the surfaces involved. You may have to do a skim cut to get them perfectly flat. While you're at it, double check installed height and tightness of the SE cylinder studs; if they're too high, or loose, you'll continue to blow gaskets. With the setup you currently, have, if I'm reading this right, yields 11.5:1 CR, and 210 CCP. Switch to flat tops, and you're back to 10:1
 

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I can only ask if the procedure on the SE gaskets are different then the original?

I always use the gasket manufacturers recommended torque method, what I have been told by more experienced then myself. I was also always told to build both cylinders at the same time to torque one do the other back to the other and so on, I always assumed this was for things to set, glad to hear I got that right.

Other then that I would trust the others on the compression issues, and make sure of the components compatibility, that that is what is truly in your bike, and then the remedy Springer and others may suggest.

Did you do a compression test?

As a closing I have had snot out of my compression release in my rear head, turns out a seal was nicked. The difference on a leak down was front head 3% and on the snotting head 9%. Head got off, re freshened, and back on less then a week and that was to NRHS in Colorado and back to PA.

I hope you get it sorted out and I know Spinger and others will help you. Might just need a "simple" piston swap, not sure how you would get the compression down on the heads alone. Spinger?
 

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If it is a compression related issue, then the chamber could be opened up but I would be more inclined to suggest porting the stock heads and replacing the SE perf heads. This would yield a 10.2-10.5:1 ratio. More in lines of what I believe you intended as far as compression is concerned. The stock heads can be ported to perform equally as well as the SE perf heads. The other option is as suggested, change the pistons to a flat top. The instructions for the SE head gaskets state to use the method described in the appropriate manual for the bike.

The 258 cam is a long duration if I remember correctly and that helps but I am not sure how much it is effecting you. If you did port the stock heads a spring change would be in order.
 

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Spinger how much ccing would have to be done to get him to the desired compression. I do realize it depends on the current heads, but do you have an idea what they are, and what they would have to be?
 

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LAF said:
Spinger how much ccing would have to be done to get him to the desired compression. I do realize it depends on the current heads, but do you have an idea what they are, and what they would have to be?
The SE Perf heads should be around 72cc .. to drop it from 11.5 to 10.5 I think it would be around 9cc. So open it to around 80-81 cc. But theoretically I would guess the 10.5:1 pistons would assume a stock combustion chamber size of 85cc's so using that it is a difference of 13 cc's .. But I can never get HD's number to come out right so I would say 9cc.
 

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Discussion Starter · #14 ·
I go it on the Torque and I will use a digital torque wrench this time too. If I do infact have 11:0:1 now I will need to change the pistons. I sent an e-mail requesting advice from Wiesco and I hop I get an answer soon. My Compression when the engine is warn is 168 psi both cylinders.
 

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Discussion Starter · #15 ·
I think I know what I need to do now.

I will get me a set of flat top pistons and have the cylinders bored .10 over and this should work. man this is costing me some good beer money. I will take it apart today because I want to get the heads checked out and the cylinders boared and honed to fit the new pistons.
 

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Boatswain said:
No O-rings but I am using the SE Metal Gaskets, should I go back to the Harley .40 95 ci gasket?
How thick are the SE gaskets? If the .040 gaskets are thinner that will only increase compression. You could try the Cometic gaskets and use their recommended torquing method.


168 psi doesn't sound like too much ... hmmmm ... you might just try the cometics as suggested above before replacing the pistons .. and yes, check out what rigidthumper suggested also
 

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springer- said:
The SE Perf heads should be around 72cc .. to drop it from 11.5 to 10.5 I think it would be around 9cc. So open it to around 80-81 cc. But theoretically I would guess the 10.5:1 pistons would assume a stock combustion chamber size of 85cc's so using that it is a difference of 13 cc's .. But I can never get HD's number to come out right so I would say 9cc.
Thank you Springer it helps me put into perspective of chamber size vs compression. And yes, on my heads, 85cc, and the domed pistons are assumed 10.5:1, 195 ccp

Now you said better flow from the stock heads with correct porting and I am a firm believer is redoing stock heads but at this point, in this case, wouldn't it be better economically to just send the SE's to Big Boys, cc the chambers, clean them up and send them back? And as a follow up, is there a particular place on that head, or any head for that matter, that needs ccd, where there is metal to take off? I mean I would think it would be hard to do it in the entire bowl area and keep them both symmetrical? Or is there a "bathtub" shaped CNC machine that you can just cc the head and tell the machine to cut xx from it?
 

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LAF said:
Thank you Springer it helps me put into perspective of chamber size vs compression. And yes, on my heads, 85cc, and the domed pistons are assumed 10.5:1, 195 ccp

Now you said better flow from the stock heads with correct porting and I am a firm believer is redoing stock heads but at this point, in this case, wouldn't it be better economically to just send the SE's to Big Boys, cc the chambers, clean them up and send them back? And as a follow up, is there a particular place on that head, or any head for that matter, that needs ccd, where there is metal to take off? I mean I would think it would be hard to do it in the entire bowl area and keep them both symmetrical? Or is there a "bathtub" shaped CNC machine that you can just cc the head and tell the machine to cut xx from it?
The only reason I mentioned porting the stock heads in place of opening up the combustion chamber has to do with maintaining the stock bathtub shape. 9-13 cc's of material is a lot to remove and the stock heads are already there. The stock heads can flow comparable to the SE heads with porting and would retain the correct combustion chamber ... if you wanted to drop the compression say .25 then opening up the chambers would be relatively easy.
 

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Thanks again Springer.

Not the easiest fix with new pistons in my opinion. With jug boring, new pistons, labor to get it down that far, I would just box the stock ones off to have ported.

I think you point, just my long way to it#[email protected]
 
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