RE: MT70CC TWIN
 

Mis alignment of the cases is possible..Chinese engines have no corner on bad QC[:o]....I have an Air Hobbies 4.2 here with the front bearing bore .015 higher in the case than the rear...It couldn't be assembled that way, so someone ground the rear crank by hand so it was smaller than the bearing bore...The person I talked to at AH said it wasn't possible...I'm a machinist, had a granite surface plate and indicator to check it with...It's still here...It could be fixed by putting a sleeve in the rear bore, then boring it to size in the right location...Then the rear crank extension would be too small and have to be ground smaller and a new sleeve pressed on it...Hardly worth the trouble for an overweight 4.2....

RE: MT70CC TWIN
 

Air Hobbies definately had their issues. I remember a twin crank being twisted from new. The crank would hit the case when turning the engine over. Not the kind of thing to build customer faith and loyalty.

RE: MT70CC TWIN
 

Any aftermarket prop bolt available to use a center bolt spinner?

RE: MT70CC TWIN
 

looks like the shiznit has hit the fan,,,,i emailed tommy when i first recieved my engine and suggested he ,do certain things,and apparently he didnt believe me or decided not to do too many changes to meet ,,what most of us would expect,,even something simple as supplying instructions,,heck,,even  one of those balsa gliders you see at the toy store comes with instructions,i really think tommy means well ,but as planecrazee stated,,good intentions dont go far without some action.well the ball is in his court,and i know he reads this post,so ,,lets see what happens.

RE: MT70CC TWIN
 

I'm sure Ralph (Antique)or Bill (BCCI) would make you one. Pretty sure I can chuck one up, drill and tap in my lathe too.

RE: MT70CC TWIN
 

Well dle 55 it is. Oh well I can always buy one of these later. I want to go flying.

RE: MT70CC TWIN
 

Tomy has offered to replace the engine realizing it was a mistake to sell this engine as it was. His offer was to run one at the factory and make sure it was ok before he sent it out. I responded that I would rather get one that hasn't been run but has been checked for quality, fit, piston height etc. I want to see what a good off the distributor shelf MT70 runs like. We'll see how this turns out. I have been in contact with other MT70 owners who received engines that turned over smoothly from the get go.

RE: MT70CC TWIN
 

mine did,besides the things that ive mentioned,,,if tommy does the same on every engine,and sends instructions ok ok im beating a dead horse,im not going to tell the man how to run his biusness,,,,,,,,but mine ran like a clock from the first start,,im actually having to lean the main needle,and fuel consumption is dropping,and ive never heard the engine miss in transition,all my airframe glue joints and screw connections shaken loose like with singles,its actually quite nice ,,but really if every engine is qc,,,d correctly and prerun,,i can say for sure ,,i would be glad to spend more for the peace of mind,,and then wrap the engine in plastic ,,like others do,,and ship it...with instructions,,if i had the computer skills id gladly compose an instruction manual,and have a paper copy with every engine,,

RE: MT70CC TWIN
 

We have done all of what you describe with the 35, the 70 will get there, just takes a little time.</p>

RE: MT70CC TWIN
 

Owner's manual ?? UHHH...What is so different about one two stroke compared to another...
OIl ? A few thousand posts here, more than anyone needs to know...
Prop size ? Hey, it's a 70cc, look around...
Ignition battery ? Don't use over 6.00000 volts...
Owner's manuals are GENERIC....Read any one you can, they're all the same...

RE: MT70CC TWIN
 

Ralph,

You said follow the manufactuers recommendations, there are none regarding oil or prop size.

I'm running Pennzoil at 32:1 for break-in.

What size prop do you recommend for a 70cc twin? I have a Vess 24A and Zoar 23x8 laminated for a start.

RE: MT70CC TWIN
 

Ralph

Did I read somewhere that you said a G-62 prop bolt adapter would work with this engine?

RE: MT70CC TWIN
 

Point is, ALL two stroke gassers have ball bearing cranks, needle bearing rods, plated aluminum cylinders...Any good two stroke non synthetic oil at 32 or 40-1 will be just fine...
Synthetic oils should be mixed at the oil manufacturer's recommendations..
There is nothing rubbing in the two stroke gasser except the bearing seals and piston rings, breaking in is making the rings seat to the cylinder...Bearings don't break in, they're good to go right from the start...Seals are neoprene, some might be tighter than others, so friction is less as the engine gets time on it...Heat cycling ? I guess, Tired Old Man has more documented time on two stroke gassers than almost anyone else on the planet, I believe what he says but all mine are set to run best right from the start...Never had an issue that was caused by not doing a prolonged break in...
The G62 uses a single 10mm fine thread bolt, it's tapped 5mm for a spinner, can be re tapped 10-32 for a Tru Turn...There is no grade marking on the 62 bolt, don't tap a metric grade 8.8, it's not strong enough...I THINK the 62 bolt is metric 12.9, same as our grade 8.
I deal in FACTS, but the above is just my 24 year dealing with two stroke gasser OPINION...
All you moderators can chime in with yours, seems to be a bunch of you guys here...;)

RE: MT70CC TWIN
 

Please reaad this thred and you will see that I have already posted that a Zenoah G-62 prop bolt pre taped will work. Thay can be purchased pre taped from Horizon hobbies. The size is M10 x1.25x50mm can be cut to 45mm if needed.

Thanks,
HCE

RE: MT70CC TWIN
 

Nothing rubbing but piston skirts and other parts that don't fit quite right or are tight. This two stroke appears to have a ball bearing/needle bearing crank. The bearing in the rear would have really small balls, it's barely larger than the crank.

RE: MT70CC TWIN
 

The rear main bearing is a roller.

RE: MT70CC TWIN
 

Real caged or drawn cup with little teeny rollers and no lube slot ?

RE: MT70CC TWIN
 

                  ralph i would agree with you about ,all the engine instructions would be generic,,but when dealing with this particular engine,,things may be different,, such as  ,,one needs to wash out their engine prior to assembly of the reed and carb block,,and also to check all engine bolts,because they have been found to be loose,,,then some ignitions can use 2 cell lipos,,my point is this,,if instructions came in the box,,then one wouldnt have to search forums or bother the manufacturer,for info.and unfortunately everyone isnt as sure as others in their knowledge of engines,and if they are,, the manual,will reassure those that do ,and reaffirm ,what they do know,,its kinda what one would expect,with a new motor,,of course ,with my gasser experience ,i dont need an owners manual,once again when i first recieved my engine ,i did have questions,such as do i mount this thing on standoffs?or should i use hardwood blocks? i did pm tommy and explain what we are used to seeing in the box over here in america,and thats what we would expect,,i also explained that crcc pro sells engines that require assembly,and have never been pre run,and most people avoid such engines,not knowing what the end result may be,so yes i do agree with the facts ,,but lets just say mr shen  qc ,ed all outgoing engines and sent a manual ,then a lot of negative commentary would be averted,,then people dont get engines with missing carbs,poorly cast cylinders loose bolts ect,,all this needs to be caught and rejected at the factory,before it makes its way to a customer,i personally know for a fact you would never send out something in that manner,and thats all im asking,,and of course not you but ,mtengines ,my first concern as a early mt 70 owner was the plug placement,,that was addressed immediately,lets see if our other concerns get addressed.

RE: MT70CC TWIN
 

Right on.....Gonna make it to Rabbit this weekend ?

RE: MT70CC TWIN
 

yes,i will ,as a matter of fact ,the waether is supposed to be great,,,theres a system blowing thruogh right now,and should start clearing ,by tomorrow,, ps they charge for acess to el mirage now,,so im sure rabbit is the spot,plus as i had said in my previous pm that they were dragging the aux,runway at rabbit,,hope to see you there and i will be flying my mt70 powered yak ,on the other side away from the racing...

RE: MT70CC TWIN
 

Cool, I'd like to see the 70 for myself...
Donnie might bring his 39lb 222 powered Extra just for kicks...;)

RE: MT70CC TWIN
 

Got the engine running. Ran for about 40oz below 3500 rpm, it really didn't want to stay running if leaned at all. Today ran just enough to tune needles for transition and little rich top end. 6700 rpm Zoar 23X8, peak hot was 6800. Now it will idle down to 1400 rpm but would set flight idle to 1600 -1800 to ensure it will take the throttle. The engine is running much smoother than a DL 50 now.

The front bearing is puking grease, either the seal was bad or there is too much case pressure getting to the bearing seal (loose case fit around shaft according to a trusted engine guru. These photos were taken today after I had already wiped the grease off yesterday.

Tomy said they are checking everything we have talked about here and is considering running all engines at the factory to ensure that there are no problems. These will be the best engine in the class once these issues are resolved and the 2 into 1 header comes out.

RE: MT70CC TWIN
 

I also had some grease come out the same place. It stopped now and only just a little of oil will come out. (very little)

Give it some time to run in my engine seems to get stronger after very few flights.

RE: MT70CC TWIN
 

No one local has a longer 10x1.0 grade 8.8 or 12.9 bolt. There's only about 5 threads holding the prop on.

RE: MT70CC TWIN
 

Buy the 70. You will be happier with it in the long run. Or you can buy my DL50 for $250.00. :D