clone side cover gasket blowing

saychz316

saychz316

New Member
#1
#1
Please see picture below.

My Harbor Freight motor is eating this gasket alive. Right where cylinder head meets cylinder. You can see the gasket sticking up above the threaded bung in side cover. At first i thought it was me not tightening the side cover down, as i did that once before and sprung a leak on bottom of block. I removed bolts and side cover and they were tight. I thought it was a crappy gasket. So I replaced it again, torqued to 20ft. lbs. red locktite, and it did it again after 5 minutes of test and tune the other night.

My question is this for those who have been dealing with these motors for some time now:

Is this a crankcase pressure issue? (this has happened 2 time now, and in the same place on the side cover gasket)

Is this a casting issue with the block / sidecover?

Is this a balance issue with crankshaft / rotating assembly? (motor does shake pretty good with my setup)

Do I need to change from bolts to studs on the side cover and torque tighter? I am using quality arp bolts now, just wondering if studs would help)

I have a couple more side cover gaskets here, but i would like to know what to do before I use them all up chasing the problem.

Thanks - Kevin

Motor specs:
arc stock length rod and flywheel.
honda flat top piston, rings, wrist pin, clips
honda gx 200 level 4 head from nr-racing ported with single 26lb (will probably change to 55lb soon) springs .065 milled off, 27.5 intake (wanted to keep compression down so i dont have to run race fuel, for now anyways!)
honda .010 head gasket
nr-racing 274 cam
nr-racing 1.3 billet steel rockers
.100 shorter chromoly pushrods
honda gx200 lifters
nr-racing billet guide plate and honda rocker posts
arp side cover and head bolts
tillotson 304wx carb (runs on gasoline)
6* advanced timing
pretty much only thing left that is lifan is the case and crank.
block has not been decked, it has the factory deck height from lifan.

 
C

C9H13NO3

Active Member
#2
#2
Might be too much crankcase pressure. I can't really give a definitive answer, but I am willing to bet MDB or one of the other "go-fast" guys could.

Sidenote: Nice Clutch :rockon:
 
Strigoi

Strigoi

#3
#3
that's pretty much exactly what i'm working on building except with GX200 parts, bigger cam and it'll be running on alky. :laugh:

sounds like it may be a good idea to do something to vent the crankcase when i get it built.
 
125ccCrazy

125ccCrazy

Well-Known Member
#6
#6
could be a warped side cover or block....pull the cover off and see if it lays flat on a smooth flat surface...also check the block for straightness...If those check out ok try drilling and tapping 1 or 2 extra vents in the top of the cover...
 
jprice

jprice

OldMiniBikes.com
#8
#8
you are very close to my setup, except im close to 13.0 on the compression side.
and have no problems sealing,
like 125 said look into straightness of the side cover, or maybe them new bolts are a tad longer then the stock ones? just a guess
 
125ccCrazy

125ccCrazy

Well-Known Member
#9
#9
jprice said:
you are very close to my setup, except im close to 13.0 on the compression side.
and have no problems sealing,
like 125 said look into straightness of the side cover, or maybe them new bolts are a tad longer then the stock ones? just a guess
Click to expand...

yep thats a possibility also, I had that happen on a 3hp briggs headgasket, a couple of the head bolts were just a few threads too long and didnt compress the gasket and when I started it, poof..gasket let loose....

good point JP :thumbsup:
 
saychz316

saychz316

New Member
#11
#11
125ccCrazy said:
[/B]
yep thats a possibility also, I had that happen on a 3hp briggs headgasket, a couple of the head bolts were just a few threads too long and didnt compress the gasket and when I started it, poof..gasket let loose....

good point JP :thumbsup:
Click to expand...
good point, but i did check that. bolts are perfect. i ran the bolt all the way in, measured the distance from the head of the bolt to the face of the block, and the side cover is thicker by way more. i'm good there. at first thats what i thought was happening, but not so. :shrug:

redgokart said:
dowel pin issue :confused:
Click to expand...
nope. got solid steel dowel pins in there.

good suggestions guys. keep them coming. i am still looking into this. going to have to take block and cover to a friends shop to check for square.
 
cncd11

cncd11

New Member
#14
#14
more then likely it is a crank pressure issue. there are many cures for this. Look at some pics of mdb's bikes and it will give u a few ideas. a couple things i suggest getting... NR RACING, get pn#12310-ZE1-842 it is the valve cover eith the nipple on the end and second...Catch Can, www.bmikarts.com : BMI Karts & Supplies : Go Karts Parts : Racing Go Kart Parts : GoKarts : Versailles, Ohio : USA : Indoor Track : Tips thid catch can. Here is what i did, i took the new valve cover and removed the baffle system out of it you may have to drill the spotwelds on the inside but i was able to just get a screw driver and pry it out. This eliminates the possibility of the baffle sticking next hook up the catch can to eliminate any oil or anything from getting on your mini bike, now third. Before you do anything though check for warpage on the side cover. Also while the block is apart open up the oil drain back hole in the block, it is located between the lifters, I think i used a 3/16 drill bit for that. Get all new gaskets and dont reuse, they are cheap enough so just replace them. I have done these mods to mine and have not had an issue since and have a whole season of riding with no issues.
 
cncd11

cncd11

New Member
#15
#15
couple other things you said you are running a head from Nr-racing? I know Russle likes to use 18cc heads and you also stated that you have had it milled .65 which means you bumped your compression up. If you have the 18cc head then you are somewhere around 12.3-1 compression ratio with the flat top piston. which tells me you might have some detonation going on. What octane gasoline are you running? You may need to bump up the octane. Dont use octane boosters, get a higher grade of gas, what i like using is Aviation fuel its 100 octane leaded gas, and have no issues. Now with this being said hows the cylinder wall look? Is it all washed out and glazed over? You may need a new set of rings. Get the file fit ones and tighten up the ring gap to about .003 this will help blow by. If you have the proper tools check cylinder bore taper to make sure that is ok also. Just some food for thought....
 
C

chindo

New Member
#19
#19
Id assume you would use a catch can to vent..... at least thats what i do on my turbo car... these small motors dont have turbo but does have oil in those lines :thumbsup:
 
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