Head Gasket Blown (I guess)

GoldenMotor.com

vhatley

Member
Sep 1, 2010
33
1
6
Oklahoma City, Ok. 73118
Hey, brand new to this forum...recommended by ajscooterclub on j.tv. Here's my issue. Fairly new (50 miles or so) engine, been getting a lot of leakage from the top of the cylinder. Now, I'm a v-8/6/4 automotive mechanic, so I'm no dummy, I tightened the head bolts, exhaust, checked all other things, Got the leakage managed so that I can get the thing started again, but it's still not right. I've decided to invest in a few parts (other than the obvious upper and lower cylinder seals. Here's the question...I don't have a lot, so where to spend, and what on, for the best purchase. I want max power and speed for around $30-$40. Also, engine- 66cc Chinese from boy-go-fast, head bolts 14mm, (I think that matters??) rather not crack the crankcase for this operation.

Thank you for your patience and reading,
Vic-Alternative Transportation, Okc.

P.S. I'm also trying to start a club in this area, contact me at my e-mail in my profile.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
252
63
up north now
Have you checked the spark plug gasket? They leak too sometimes. If you've re-torqued the head and it's still leaking, get the new gasket in there and it should be fine. Do you have a photo of the leakage?

Max power and speed? First don't run it at 16:1. Second, if you can find a tuned pipe for around that price, it would be your best bet.
 

vhatley

Member
Sep 1, 2010
33
1
6
Oklahoma City, Ok. 73118
Nah, good thought though. Leak is at the bottom of the cylinder head, not the plug. Noticed the carbon, gas, and crap on the frame a little bit ago. Before the failure though, 42 mph (police radar verified,) power was okay considering the 28 in tires. I'm used to 26's and the take off...well, you know. A perf. pipe is a good suggestion, but is there a larger displacement cyl. or possibly an extra good coil that would add?
 

Kevlarr

New Member
Jul 22, 2009
1,628
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0
Mi
Actually 42 is doing pretty good for an un-broken in engine. Add an expansion pipe and you should be set.

You mentioned that you're getting black gunk on the frame, check to make sure you're exhaust gasket isn't leaking.

Pulling the head to check the gasket is no big deal, just take off the nuts and check the gasket. While you have the head off dress it with a piece of 300 wet/dry on a flat surface like a piece of 1/4" glass.
 

KCvale

Well-Known Member
Feb 28, 2010
3,966
57
48
Phoenix,AZ
Hey, brand new to this forum...
Welcome ;-}
I want max power and speed for around $30-$40. Also, engine- 66cc Chinese from boy-go-fast, head bolts 14mm, (I think that matters??)
I have no clue who/what a 'boy-go-fast' is bud. Is their a motor make?

32:1 dollar store oil and riding hard for break-in was.. Well, not your best start.
We very widely here on this issue here, but I just go by the manual.

The Grubee motor manual says 18:1 for the first tank (~100 miles) then 25:1.
You can certainly go much higher ratios with good oil like Amsoil synthetic like 80:1 after everything seats properly, especially the rings and cylinder.

Grubee uses chrome cylinder inserts too, the cheaper motors use cheap polished steel.
You may not have a gasket problem at all but a warped head, warped cylinder, who knows breaking it in hard at 32:1 with $1 oil.

You might want to see if the motor is even worth saving before you think about trying to push it harder. Do you have the tools to measure for head warp?

But, if it's OK and you lucked out then there are some things.

An expansion chamber is almost within your budget, but if you are doing 42 what would help you more might be a jackshaft if you have a geared bike.
Well outside your budget at ~$160 delivered and a semi-rebuild but a world of difference, especially with 28" wheels. You would have your low end, and an awesome overdrive even with just a 3-speed.

To me a Jackshaft and just my 48cc and 3-speed hub shifter it is the difference between antenna TV and cable.
It completely changes the way you ride.

I truly hope hope you haven't destroyed your motor or cut its potential broken-in power in half already. That is a hard lesson to learn on a first build.
These things are not water cooled car motors, they are dirt cheap Chinese 2-smokers with not so much as a single fire up before literally shipping on a slow boat from China half way across the world.

Do you have a camera?
You can upload pics here, and they sure help.
 
Last edited:

corgi1

New Member
Aug 13, 2009
2,272
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KCMO
ask in the search bar at the top of the page also,when it opens scrool down and see the topics,,there is a world of imfo on here

Google Search Bar ,,,at the top of the page
 

vhatley

Member
Sep 1, 2010
33
1
6
Oklahoma City, Ok. 73118
Thanks for all the good, well thought out replies. I'll check the head today...and see about the pictures, got camera, but not such a good one. Hey, KC, thanks a lot...you're right about the little thing not being water cooled...oops. Pardon my error, I'm just a poor writer with automotive ex. Let yall know about the head. BTW KC, Boy-go-fast is an e-bay store that sells the chinese cheapies. (That's all I can afford yet, but aspiring to an Italian.
 

KCvale

Well-Known Member
Feb 28, 2010
3,966
57
48
Phoenix,AZ
KC, thanks a lot...you're right about the little thing not being water cooled...oops. Pardon my error, I'm just a poor writer with automotive ex.
There was no offense intended their bud, I read your experience in your post and didn't take you for a motor dummy, my point was just that you may not have been aware just how fragile these cheap little China smokers can be until they get 'seasoned', and they need to be 'slow roasted' and heavily 'marinated' as it were to get them there where the hefty water cooled V-anything with crank case motor oil your expressed experience was in are a lot more stout and forgiving ;-}

Hopefully Kevlarr's head dressing suggestion might get any head warp out for you and you'll motoring again soon.

Better plugs as mentioned do indeed help too.
Is yours a slant head for straight?
 

vhatley

Member
Sep 1, 2010
33
1
6
Oklahoma City, Ok. 73118
I understand, but it's true...I am a dummy in certain things. For example, I'm not sure how to upload the photos I took of a really BLOWN head gasket. Another little tidbit I need is do I need to replace the head studs, I already plan to replace the nuts. And for the last thing, can I reface the head cover with sandpaper and a sheet of glass...I think I heard that somewhere...anyway.

Thanks a lot for yall's help, I'm lovin' every minute.

Three people can keep a secret...if two of them are dead. B Franklin
 

vhatley

Member
Sep 1, 2010
33
1
6
Oklahoma City, Ok. 73118
Okay, I got it. I had to start a new post in order to get the photos on. Here is the name of the post: Solution to photos of my blown head cover. See what you think, I'll start looking for responses there.