Newbie with pics needing advice.

S

SuperChris

New Member
So this is my first post and here is my bike
n4w8.jpg
It vibrated really bad so I got a Dax PK80 remapped the port timing to 157/ 117 degrees
ztt8.jpg

balanced and trued the crank
wd3p.jpg

and I stuffed the cases. I'm sorry for the large pictures, I don't know how to make them smaller. Am I missing anything? Like I said, I'm a newbie and this is my first piston port setup. I also have a Puch Hi Hi that is going on the lathe to cut the squish band out to bore diameter, What squish gap is safe for these engines?
 
Looks like you got it under control! I believe about .030 is proper squish, but you should wait for someone more into high performance to chime in as I've never really done any work on my ht's.
A lot depends on the head design and chamber shape. Fred at CR machine knows heads if you give him a call, but don't be surprised if you end up with one of his heads instead...
You should also look into a better top end bearing. Search box for the moped and chainsaw part links. Get one that fits better than the stocker, which can slide halfway out since it's too narrow, A full width bearing will oil much better with the extra area exposed to charge and it's cheap insurance for any stage build.
 
I agree with the .8 to 1mm squish as well, plenty enough clearance and good compression. .030" or .75mm is a really good place to set it and where I set mine to.
 
what is your current inlet duration?, Cutting the piston skirt to increase inlet duration is recommended, but easy to over do. 120 deg total inlet duration is usually recommended, a little more for higher revs.
Have not tried the titanium pin, but others say they wear fast with a bearing and should be used with a bush.
 
Agreed about the titanium pin... I'd use the bushing with that pin if I was going to run one in mine because of wear issues with the needle bearings. Titanium is strong and lightweight but hardened steel can still eat into it over time
 
get an sbp pipe and drive it before u acomplish more redundant band aid work. besides that hello :) you got the hi head and a wally carb so i expect 30-50 mph as soon as it is back together. get on it

.xx.
 
sub66 said:
i expect 30-50 mph as soon as it is back together. get on it
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Just smiles at the obtainable speed expectations on a direct drive.
Granted with a powerful enough engine you can mount a little sprocket on back for speed but your not going to get over 40MPH direct drive with stock sprocket no matter what you do to your engine.
 
KC, at the risk of starting another 'how fast can you go' thread, sorry to disagree but I have two bikes that will exceed 40. One has a 41T spocket and the other has a 40. Neither engine is what I would call 'built'. Just a little port cleaning and matching. No HP heads, no expansion chamber exhaust and I don't burn nitro. Yes, I'm a lightweight but even with my friend, 170lbs, riding them they both will do over 40. I'll admit that I never ride them that fast; I'm usually down in the 25 range but if I want it, it's there.

Now, 50 mph is to me a pie-in-the-sky figure that even if attainable is just downright dumb on a standard bicycle frame, wheels and bearings. You won't catch me riding one.

Just saying.

Tom
 
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2door said:
KC, at the risk of starting another 'how fast can you go' thread, sorry to disagree but I have two bikes that will exceed 40. One has a 41T sprocket and the other has a 40.Tom
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We are not disagreeing, the kits I buy have 44T rear sprockets and I've seen them up to 48 for a 2-stroke.

3 or 4 teeth may not seem like much but it is.
One good example is on some single speed coaster beach cruisers I'll swap out the back wheels 18T for a 19T and on a 2-stroke direct drive coaster brake the difference is staggering.

It is far easier to pedal start and the coaster brake works WAY better.

We don't disagree, just talking about different gear ratios, and if you are going to run a smaller left side drive sprocket for more top speed, it would behoove you to drop a tooth bigger sprocket on your pedal side rear wheel to get you going off the line better ;-}
 
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