Since they surfaced the head it is certainly possible that the piston might be hitting it or the valves might be hitting the piston . Depends on how much they surfaced it . When building an engine with parts I have not used before, I put clay on the top of the piston then assemble it with the old gasket or just light torque on the new gasket then turn it over then take it back apart and look at the thickness of the clay etc.
I also use the MLS gaskets in some of the high perf engines I build . Cometic makes them.
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You can use a few cylinder base gaskets to put the cylinder were it needs to be .
Make sure you have zero up and down play in the lower rod bearing when you take it back apart.
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Thanks guys. Shortline, since you've used the .435" megacycle cam in the past, what do you think the bottom end would be like on a stock geared 200 with the 12:1 wiseco? I'm definitely thinking the .370" is a better fit for my application, but I know you spoke highly of the other on your 185 build that I saw. I even think I remember you tried a couple different ones?
The 435 lift cam is awesome in combo with a high compression piston and will give you gobbs of bottom end power , my only worry would be you milled to much off that head and would have clearance issues.
78 atc 90/180cc Dickson Full Suspension
76 ATC90/180cc Nicholson
77 atc 90 Dickson Full Suspension
84 KLT 110/123cc Powroll Racer from 80s
87 atc 125m stock
84 atc 200x Curtis Sparks
84 atc 200x Powroll My race bike from 80's
83 atc70/108cc Powroll blue Xmas Special
81 atc185s HP-ATC full suspension
Performance Shop is Open PM me for Service
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I appreciate the info shortline. I know they only leveled the surface on the head and cylinder. They didn't take any more material off than they had to. I plan to tear it down over the break. Once I get to the bottom of things, I'll make my cam selection. Hopefully I have the clearance for the bigger cam. It sounds like it will be the ticket if I can run it.
So tonight this happened:
And it turns out all speculations were correct.
So, now that I found the sound, I need to figure out the best way to deal with it. I feel like I have several options here that I'd like to get opinions on.
Option 1: Double stack head gaskets to gain the extra space needed. I've heard of this being done before, but I need to do more reading as to how often this method causes sealing problems. Also, if I did it this way, which type to use? As I stated in an earlier post, I pulled off an MLS and replaced it with a regular style. I'm wondering what the crushed differences of the two are? If the replacement I installed is thinner once torqued down, I know that is not helping my situation.
Option 2: Take a little material off the piston or out of the combustion chamber. I think this would work fine, but I'm not crazy about it. Especially because I don't know if the valve clearance will be enough to run the big .435" megacycle cam, which is what I'd like to run if possible.
Option 3: Buy a new cylinder or head, or both. This would probably be the proper way but I have mixed feelings about this. The main thing is cost. My cylinder has just been bored, and since everything looks great with it, I hate to throw that money down the tubes. If I did go with a new cylinder, I'd like to snag one off a 200X for the longer cooling fins. I know that would be a good idea. I think the bore was $40 so that isn't the end of the world either.
On the cylinder head I have mixed feelings also. My brother just put the time and effort into porting this head for me. But, with only two ports to do, and the fact that we didn't get wild with it, his time investment isn't huge. Is it true that the 200X came with a larger intake valve? If so, that would draw me to this option a bit. If I keep my original cylinder head, I really should either replace my intake valve or go with an oversized intake valve. You can see in the pictures how far the intake valve is pulled up the head. Not only will this maybe cause me problems later on, it also can't be good for flow.
How do I go about checking the tolerances on the rod bearing? I didn't see anything about it in the service manual I got online from oscarmayer.net but it's probably in there and I missed it. I definitely can't feel any up and down play which I did check before I slapped everything back together. I was concerned about the side to side play that the rod had, though. It seemed like a lot, but I've never dealt with that style rod bearing before. The bottom end sounded smooth before so I said to myself, it must be fine. Looking back, I should've done more due diligence before assembling it, but hindsight is 20/20.
I guess I'll be splitting the cases on this baby anyway. I have an oil seal that has leaked pretty bad whenever the engine is running.
The seal looks damaged like someone tried to replace it but couldn't get it out.
Where is the best place to buy the HD timing chain and what brand should I be looking for?
Thanks for the help guys. As you can see I'm a newb when it comes to these small engines.
Oops, after making that long post, I reread shortline's post about using multiple cylinder base baskets to get everything where it needs to be. This is the way to solve my problem. I hadn't even thought of this as a possibility, but that's why I'm here. To learn from those with more knowledge and experience than me. I'm used to working on engines that don't have cylinder jugs separate from the rest of the block. That's why I came up with the solutions above.
Last edited by C-lab; 12-25-2016 at 12:35 AM.
An old school thick copper head gasket and 3-4 base gaskets should get you up to were you need to be .
Btw that's a great price on this gasket kit . You will know when your about right when your compression is about 200-220 .
78 atc 90/180cc Dickson Full Suspension
76 ATC90/180cc Nicholson
77 atc 90 Dickson Full Suspension
84 KLT 110/123cc Powroll Racer from 80s
87 atc 125m stock
84 atc 200x Curtis Sparks
84 atc 200x Powroll My race bike from 80's
83 atc70/108cc Powroll blue Xmas Special
81 atc185s HP-ATC full suspension
Performance Shop is Open PM me for Service
My Feedback http://www.3wheelerworld.com/showthr...ck+shortline10
Alright, I went ahead and nabbed that gasket set.
Did you get your rocker arms hard faced with the .435" cam? I saw where someone ran the .370" megacycle cam without it just fine. I know I'll need to upgrade the springs.
Factory rockers IMO don't need to be hard faced . I have put a lot of hours on a 435 lift cam and never seen excessive wear
78 atc 90/180cc Dickson Full Suspension
76 ATC90/180cc Nicholson
77 atc 90 Dickson Full Suspension
84 KLT 110/123cc Powroll Racer from 80s
87 atc 125m stock
84 atc 200x Curtis Sparks
84 atc 200x Powroll My race bike from 80's
83 atc70/108cc Powroll blue Xmas Special
81 atc185s HP-ATC full suspension
Performance Shop is Open PM me for Service
My Feedback http://www.3wheelerworld.com/showthr...ck+shortline10
ok, i will try to simplify my post somewhat.
200X HEAD
shortliune10 can probably tell you if a 200x head has bigger valves etc . he knows a lot about these
STOCK VS HARD WELDED ROCKERS
I have seen wear on stock rockers with stock cams and stock springs but the hours and oil type were unknown . Hard welded rockers will last longer than stock rockers but as shortline10 implied, stock ones won't wear out "quickly so you can decide if the extra expense is worth it to you . Good oil with high levels of Zinc is a good preventative measure against premature wear . Also changing it fairly frequently and cleaning your air filter frequently will help.
PISTON HITTING CYLINDER HEAD
The angle on the side of the piston crown/dome and the head is approximately 45 degrees . This means that for every .002" you raise the cylinder or head, you will gain around .001" in clearance between the head and the gasket . Since nothing broke and it ran, it is likely that the clearance between the head and the cylinder is very close to 0 as opposed to an interference fit which is a good thing as far as that goes . You should have at least around .015" clearance on the sides of the piston crown to allow for piston rock and rod stretch and piston pin, rod and crank bearing clearances etc . This means that raising the cylinder or head .030" higher than it was with your previous base and head gasket should give the minimum amount of clearance you need.
For long term fixes for problems like this on a 4 stroke, I prefer to use either a metal shim under the cylinder with one base gasket on each side instead of several base gaskets (although you may never have a problem using several base gaskets instead), or a thicker head gasket.
HEAD GASKET THICKNESS
You can call Cometic and ask them if they can make a gasket thick enough for your app so you can use just one base gasket and ask their opinion on doing this since they know their product . They do make different thicknesses for automotive apps and I have often used a thinner one than the stock thickness to help correct excessive quench/squish clearances . There are also some mfg's that can make a copper gasket in the thickness you need however, unless they already have a pattern for your app it can be fairly expensive.
COPPER VS MULTI LAYERED STEEL HEAD GASKETS
An MLS gasket will typically seal better than a copper gasket because they are designed to continue to seal if the compression is so high that it lifts the head slightly, however, they need a fairly smooth finish to seal properly . If your finish is fairly rough like it was surfaced with 80 grit sand paper, you will need to make it smoother which is fairly easy to do and I can post one method for doing this if you want.
COMETIC MLS GASKETS 800-752-9850
CUSTOM COPPER MOTORCYCLE HEAD GASKET MFGS
http://www.coppergaskets.us/MCG.html
http://www.gasketstogo.com/examples.htm
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They must have taken quite a bit of material off that head unless you got the cylinder decked as well. I trust what shortline is saying, he's the man. If it were me and the cylinder was stock height I would get a used head and start over. I only say that because your are going to be doing a lot of checking and re-checking with clay or squish solder to ensure your UCCR is correct....or I guess you could just run race gas once you prevent the piston from hitting the bowl.
Thank you barnett468 for the detailed explanation!
yaegerb, thank you for your help as well. You must have missed earlier where I did say they decked the cylinder as well, just to level it, not as an attempt to raise compression. I definitely didn't need that! He said that the cylinder must have gotten very hot at some point because it was warped significantly. Looking back, I should've asked him how many thousandths he removed, but like a dummy I didn't. I am also already running race gas. I figure that during the cold months if the tuning is right I could sneak by on 93. I'm not taking any chances right now.
I did already purchase the gasket kit shortline recommended. I plan on using it. Barnett, do you know where I could get a base gasket shim? I'll go ahead and google it but I'm not sure what my success will be.
Also, since I'll be using the copper, I can measure the thickness when I get it, but I know that isn't really the important part. I need to know what it will crush down to. I'm not sure how to go about this since I think once it's crushed and removed it's junk. I'm also thinking that you're right about there basically being zero tolerance, not an interference fit. I couldn't feel anything strange when pull starting. It ran okay other than the noise that made you cringe. Obviously the oil was clean since this wasn't creating any metal shavings.
So about checking the rod bearing. I don't feel any up and down play, but I didn't have the crank locked in place while I checked it. I'm sure that isn't really a good test. It has enough side to side play that it feels excessive. Bottom end sounded great, but I know that only means so much. I'm going to scan the manual again for the specs on the side play, but I didn't see it listed the first time. I wasn't in search of that before and I probably skipped right over it.
Also, the D.I.D. cam chain looks like a good replacement. Thoughts?