Cryotempering Happy Time 2 stroke engine

[chrisnbush]

Update on cryotempering

Well I got the motor out after 48 hours at -109F (-80 c), and put it back on my bike - it runs !

Seems a bit weak, this is a DAX F80, I was quite happy with the power on my previous DAX, I think his series on that one was a D65 or something. A couple of observations:

1) they pick up considerably after break in
2) I have about 550 miles on my other new ride, rear mount DAX titan, and have gotten used to the low end torque
3) Cryotempering might have warped the head, possibly. But it looks fine, and after my 15 minute 1st run there is absolutely no leakage around the head gasket
4) Cryotempering could have damaged the magneto (I didn't take it out), although seem like it would fail or not fail. I will wait for 200 miles or so to see if it picks up.
5) Cryotempering could have weakend the magnet. I will check relative strength against the other 6 or so (!) I have in other motors using a screw driver or something.
6) I believe the F80 actually does have more CC then the D65 believe it or not. Wondering if I need to change the setting on my carb needle. Anyone have any experience with this ?

Well, my bike looks sweet, I came into a little money (sold some stuff on ebay) and got a new basket, touched up the paint job, put a 12 volt MR16 LED lamp on the front (I rigged up a 12 volt battery pack a couple of years ago with an LED taillight and wire to LED head lamp. The MR16 is only about a watt I think - going to get the one with 3 crees eventually - 300 lumens or something - 7 watts - it screams ! I will post an updated picture.

I will update with progress on my new motor. One step at a time. If anyone has any insight on a weak motor, particularly DAX F80, let me know. I will update mileage every couple of months

 

[GearNut]

Thankyou for the update.
As far as a weak engine, I have learned that all of the HT engines are pathetic untill broken in.
Let all the parts bed into each other, then assess the power output.
The DAX Titan is a very good 4 stroke. They are in a whole other class.
You can't compair them.

 

[Old Bob]

Cryo tempering is a waste of time and money. We did an engine, dynoed it before and after, no difference in power. Use good oil and an air cleaner to make it last longer.

 

[chrisnbush]

"Cryo tempering is a waste of time and money. We did an engine, dynoed it before and after, no difference in power. Use good oil and an air cleaner to make it last longer"

Did the engine last any longer ? Glad to hear you didn't lose any power in any event, my engine is weak after "treatment" but I think it is just one of the standard problems (clogged fuel filter, air leak somewhere, still breaking in, flashing blocking intake tube, etc.). Also, did you treat it with or without magneto ?

Thanks

 

[Old Bob]

Engine was disassembled, the crankshaft assembly, the crank case without bearings, cylinder and piston were done as seperate peices.

It wasn't a motorbike engine, but a small two stroke nontheless.We didn't see any difference in wear with the treated engine.
Cryo treatment done as part of the manufacturing process to stabilize steel components as part of stress relieve/ stabilizing BEFORE the final finish grinding or lapping does improve accuracy, but post treatment on engine parts does nothing.

 

[Egor]

If you want to get one of the HT engines to run good you have to port them. I just finished an experiment IE (tried to run one straight out of the box) no deal, Yea they run and they would last but, you fight everything. That thing that looks like a carburetor, they were made for an engine that just runs at a single speed, like a pump. I have a pump with the original design on it, not made to Idle. I ran the stock bike as long as I could, and just ran out of patience. The barrel is off for the porting, not necessary to do any more testing. I started porting in the 60's with my Hodaka. I take these engines straight away apart and do the cutting, you would like the results. I have ridden too many Yamaha's and Suzuki's to be tolerant enough to just let it be. I do not attempt to make a scalded cat out of them just make them run as good as anyone would like. They pull hills and take off with out using pedals. You could take off and get a bunch of speed out of them but then it would just fly apart and be no fun. Have fun, Dave

PS: Just get the CMA carb, or find a real Yamaha 80cc carb. I have made the HT carb work, but it is a bother.

 

[GearNut]

I still love Hodakas! Seemingly bulletproof and well mannered bikes.

 

[chrisnbush]

Good idea about the porting Egor, I might experiment with this sometime on a parts motor, using a dremel drill or something.

Well, I got the "cryotempered" motor almost up to the strength of what I expect right out of the box. At first I tried all the normal stuff (that I am starting to get tired of doing with these things) including ->

- setting carb needle lean, rich (I left it to lean as it seemed to run better)
- cleaning the air filter
- cleaning the petcock gas filter
- sealing around the input tube with gasket silicone
- running 32/1 on DAX recommendation (I always break in and run at 20:1)
- checking the exhaust pipe, looked clean so I didn't do anything
- maxing the throttle cable setting at the carb
- trying different plugs and gaps

Nothing seemed to help. What did seem to improve it was removing the air filter cover - a little.

So I did what I would knew would improve it - it is better to go with something you know works and go backwords sometimes. I took the baffle out of the exhaust, plenty of power and noise. So after looking at some stuff on th forum (thanks guys !) I decided to cut the tube off the baffle, just leaving a stub.

Now I am up to maybe a little less power than I would expect at 25 miles total (mostly up and down the road by my house peeing off the neighbors), and without the baffle tube there is hardly any more noise, the noise is just different - more of a popping sound, more like you would expect out of a two cycle. And I would say 20% performance boost.

I am wondering if the larger engines work that well with the one size fits all mufflers and carbs. I think I am finding that even a little carbon build up, like what was in by baffle tube, can have a large effect on the performance - maybe I could have just cleaned it out. Also "discovered" that there is spitback on these motors from the carb. If you remove the air cleaner and run that thing, you can feel the gas+oil mixture puffing back on your hand. People tell me this is normal, and I have noted that these crappy air filters actually can restrict flow, not because they actually catch any dirt (its all in my carb) but they collect the oil from the spitback.

So, obviously to many of you guys probably, I am finding that these motors are a close balance between the input and exhaust pressures. I would bet that a lot of weak motor complaints are due to too much back presssure for the motor, or not enough input air flow. I don't think lean or rich has TOO much to do with a weak motor. So the solution might be the grubee carb that is supposed to be designed for the "80cc" motor (spookytooth), and the tuned exhaust from SBP.

Thats what I am going to do in the future, I think. Now I just want to hold out to see how my power improves, and eventually if the cryotempering actually did anything (if I get to 2501 miles I will claim victory, as my best to date is 2500 on a centermount)

I think I got motor bike OCD, sorry guys



cb

 

[Egor]

Two kits and some Idea's.
I rode the one bike today with the stock engine I don't like it at all. the carb will not lean out at all, I have the clip on the top notch and it still 4 strokes. I lowered the float and still the same. So I cut the slide (changed the filter side cut) and it is slightly better just off the idle but you still cant go near the wide open throttle, and I am at sea level. I have not idea what someone would do at an elevated city. I am doing this to see what the engines would be like if I could not do any engine work.
In the past I have not run any of my engines stock I always take them apart and do the porting and check to see if the parts are in there proper places.
One thing I noticed straight away is that the two kits have quite a few differences, and I ordered them together. On the one I was so glad to find the gears not screaming, then the next one is a real screamer, so out with that. I like the new clutch handle then the clips on the bottom to hold the plunger in place flew out clips gone!. I had to do a lot of carving the get the muffler to run past the pedals, I change the angle of the outlet port on the barrel.
You know if they want to clone something to use on these engines they need to go get the old Tillitson carb, you could adjust everything from the outside, I think I only have one in my junk pile. LOL. These engines could be the best thing ever invented with just a few simple improvements. I wonder if the Russian version that was cloned to make the Happy engine kits were better? Well have fun, Dave

PS: I did all the mods on the carb and now it is again a little better, but I found the slits in the sides are so far up that it is letting air past and mussing things up. Sprayed cleaner on the thing while running, made the motor speed up.
PSS: I wonder if the cyrotempering would help hold the big end pin better, on the first engine of the two I think I twisted the wheels out of alignment. A high speed pass. With the porting you can destroy one in a minute. LOL

 

[chrisnbush]

Cryotempering Progress Report

I now have 300 miles on the motor, I keep a log. Running pretty good now, after making some mods in the muffler (matching ports, drilling holes in the baffle as above). I am thinking I will be getting the SBP tuned exhaust to increase my time "2 stroking", although hill climb ability is now excellent the way I have it.

I will post an update from time to time

Thanks everybody for your help

cb