400ex deck height

[69zandar]

O.K. everybody i just finished mocking up my new top end on my 440 motor and measured my 12.5 wiesco at .087 down the hole. That seems like a hell of alot to me. i was thinking of having my cylinder decked .080 to play it a little safe but that still seems like alot. Has anyone ran into the same kind of numbers with that issue. Thanks

[Fanged03]

The only problem I could think of by decking it would be cam chain tension/slack and how that would affect cam timing. As far as the numbers I am not sure, haven't yet built my engine. When I do though I was thinking about doing the same since everyone says that weisco's comp. numbers a touch high as compared to reality.

Brent

[drew416ex]

Take the base gasket off and use a small amount of silicon (so you dont clog the oil ports). This will do the same thing as decking the cylinder. I have done it for years and it works great and its free. It does slightly advance the cam timing but I havnt had a problem with that or too much chain slack. Just check your valve clearances before your final assembly with some modeling clay. .060"- .065" clearance is a safe number for piston to valve clearance.

[69zandar]

Thanks for the reply, the base gasket is very thin, cometic, it only measures about .025 i wouldnt expect much of a gain by going to silicon and getting it shaved is pretty easy for me. Cam timing does have me a little concerned, i read somewhere that someone had slotted the cam bolt holes to get a little adjustment out of it. when we degree it ill see how far off it is and go from there. does anyone sell an adjustable cam gear for these? thanks

[F-16Guy]

When you mocked up the assembly, did you torque the cylinder down so that the base gasket is compressed? It might make a little difference. Here is the ultimate thread on the subject. It also goes over a couple different options for acheiving the proper deck height and squish (quench) band, and discusses cam timing issues:

http://www.exriders.com/vbb/showthread.php?s=&threadid=8316&highlight=decked+cylinder

[69zandar]

Very cool thread! ALOT of info in there im going to have to sit on all of that for a night or so and go back and double check everything. im wondering how i came up with .087 in the hole and everybody else seems to have about .040 ? also does anybody know the compressed thickness of cometic head gasket in the kit #c7826 the gasket itself is #ho402

[drew416ex]

faliconcranks.com used to make an adjustable sprocket. They might still make them.

[69zandar]

Thanks for the cam sprocket info. I think i found out why the piston is sitting .087 in the cylinder. I got to looking at the rod and it seems to have a nice little bow to it?:eek2: Well it all makes sense now.

[brokenmike]

faliconcranks.com still makes them. they are pretty cheap too.

[F-16Guy]

Originally posted by 69zandar
Thanks for the cam sprocket info. I think i found out why the piston is sitting .087 in the cylinder. I got to looking at the rod and it seems to have a nice little bow to it?:eek2: Well it all makes sense now.
That sucks. You have a couple of options. If you're going to have a modded engine, you'll probably want to get something stronger than stock. I bought a Carrillo rod directly from Carrillo for $175. If you can split the case and get the crank out yourself, it would probably only be another $75 to have the new rod pressed on. If you pay for it, it will probably be closer to $300. My lower rod bearing was in good shape, so I re-used it and haven't had a single issue in years. That is really your call, but mine had zero up/down play, so I rolled the dice and saved some $$.

You could also get a complete HotRods crank assembly. I've found them on eBay for really cheap. Either way, you're going to have to split the case, and that's where most of the labor cost comes in. If you get a manual and do it yourself, you could save some money, but it's not something you want to do twice.

[69zandar]

I was thinking of the hotrods setup, it comes with all the bearings, etc. i just hope its a good piece. Im not to scared about spliting the cases ive done a few 2 strokes and i think i can do the 4 poke.

[drew416ex]

Originally posted by 69zandar
I was thinking of the hotrods setup, it comes with all the bearings, etc. i just hope its a good piece. Im not to scared about spliting the cases ive done a few 2 strokes and i think i can do the 4 poke.

I have the hotrods stroker crank and its been great. I dont think you will have any problems with it.