MTD Trail Flite info and parts (New mini bike owner)

D

Detour

Member
#41
#41
delray said:
factory cast steel will be just fine for what you want to do......:thumbsup:
Click to expand...
Do you know how many rpm the factory wheel will handle (if I raise or remove the governor)? If I remove the governor will valve float act as a low enough governor? I do not intend on running it at valve float, but know what that feels like and back off on other motors.

I went out to Symco with a friend on Sat. Unfortunately we got there to late for the drags. It was still a cool place to walk around. Thanks.

Any suggestions out there on a gas tank? I was thinking something that I can put on the frame vs attached to the motor. I currently have nothing.
 
delray

delray

Well-Known Member
#42
#42
stock cast iron flywheel can handle quite a bit of rpm's I would say 6000 is safe and I have seen VKE motorsports modify stock units and turns them 7500.
http://www.vkemotorsports.com/catalog/2010_VKE_web_catalog.pdf page 10

for floating the valves. it doesn't take much to float the stock ohh valves

one good thing about the rods in them they are stronger then the old hs-40 and hs-50's rods. I have one ohh motor with a stock rod that I ground and polish and it hold's 4700 rpm's easy. another member claims he can spin a stock rod ground and polish up to 5000+ and never broke one. but for 60 bucks you can get a billet rod and be real safe....:thumbsup:
depending what kind of head you have ? you could get some 16 pound animal springs and mill .040 off. do some porting in the bowls into the start of the runners only and find a ohh steel cam with the compression relief setup. most come with a plastic cam(junk) and install that with a good motorsports hot coil and hs-40 rupp style replacement carb and it will fly for a complete stock motor setup. except for the rod and springs(aftermarket).
 
D

Detour

Member
#43
#43
Those rpm sound reasonable. I did find your OHH build thread and read through it. It was nice to see how much success you have had with your Tecumseh motors considering how few parts are out there compared to the Honda clones.
 
D

Detour

Member
#44
#44
Well it turns out the Tecumseh has a warped head. The valves are straight (chuck them up and spin them on a drill) but they do not completely close, resulting in a large amount of blow back out the carb while trying to start it. Once fired, it does run briefly but however. Either way I do not think it is worth putting more money into this motor. Already spent money on a new carb, intake adapter for cone filter and exhaust flange to make my own exhaust.

I have 2 options for motors. A Honda GX200 for $100 and I found a 1989 roto-tiller with a non I/C Briggs flathead (no stickers, assuming a 5hp) for $50.

Opinions?
 
D

Detour

Member
#46
#46
Well I went back and the Briggs was gone. So now it’s the used Honda (not a clone) or a new Predator for the same amount. Giving myself the weekend to think about it.
 
D

Detour

Member
#47
#47
Well bad luck strikes again. In a hurry to get this little bike enjoyable before we run out of good weather up here I decided to go buy a Predator motor with the $99 coupon. I was able to get a Hemi version as well. A test fit was tight, having to remove the factory exhaust in order for it to fit in the frame. I then bought a manifold from OldMiniBikes and it does not fit either. It curves back and has the threaded end of a manifold. The problem is the curve brings it right up into your left thigh and into the seat. A muffler would not fit and there is no way my wife's leg would clear the pipe. I need something that stays tighter to the motor.

Wishing I had just found an old flathead with the rear exhaust port. Would have made it much simpler. Any ideas besides wasted money on the new Predator?
 
C

cfh

Well-Known Member
#48
#48
basically when ever i use a predator motor, it requires a custom exhaust. i'm sure there's commercial units available, but i haven't found any that fit well on 1970s bikes.

Likewise, i've had about the same luck when using tecumseh motors. short of a Taylor products muffler, i usually have to come up with something custom. On my MTD i was able to use a Rupp roadster style exhaust with minor modifications. But that's a rarity.
 
D

Detour

Member
#49
#49
What I have noticed looking at the Tecumseh HHO50 that came on the bike (warped head) and pictures of other engines, is that I need a rear facing exhaust port. Which the Tecumseh and old flat heads seem to have. So I am looking for a new head for the HHO50 or a flat head motor. The trouble I am finding with old motors are that many have 2 output shafts or are a tapered or short shaft. I believe I need a long shaft...?

Any suggestions on what brands or types of equipment to look for? I have been searching for cheap roto-tillers or snow blowers but I am nervous of buying another motor that either needs adapting or just doesn't fit my needs.
 
massacre

massacre

#50
#50
I like my MTD with hs50, if you buy a snowblower and it has 2 shafts, I would think you could get a regular cam and side cover and be fine?
I haven’t done the conversion myself but I’m sure someone here has or can fill you in on the details.
 
C

cfh

Well-Known Member
#51
#51
i just cut the short shaft off. start motor, and hold a hacksaw blade on the small shaft. cuts clean in about 30 seconds.
 
D

Detour

Member
#53
#53
Well I just bought an old go kart with the same OHH50 motor on it for $50. I was told that it sat for the last decade, but the engine looks in better condition and turns over easy. Will clean it up and open it after lunch.
 
D

Detour

Member
#54
#54
Today's motor find has 115 psi compression, and the ID sticker says it's a 172cc, where as the old motor that came on the mini bike is a 195cc. Does anyone know if the heads are different? Would it be worth putting the 172cc head on the 195cc block?
 
delray

delray

Well-Known Member
#55
#55
yes that chamber will be smaller and will increase your compression.


the head in the center is a 172 head and the head to the right is a 195 head

far left is a 172 too with bigger valves installed and the head milled.
 
D

Detour

Member
#56
#56
I now have all the old welds ground off and prepped to be re-welded.

It has become a bigger project than I expected but I hope it pays off in the end.

I do still need some sort of a gas tank for it. I like the look of the spun aluminum ones on eBay, but I do not like the high prices. Any ideas for alternatives? Most other tanks are designed for a single backbone.
 
You must log in or register to reply here.
Top