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  1. mfro

    Lifan 140cc Top End on Honda 70cc cases

    Yes, the most important thing: it won't fit. Chinese cylinders/cylinderheads have a different stud spacing than Honda.
  2. mfro

    Oil Flow

    The cylinder liner is lubed by leak oil from the big end connecting rod bearing. Basically, oil from the oil pump is divided into two streams: the one to the head mentioned above and the other ("main stream") going from the pump through the clutch case to centrifugal clutch and the hollow-bored...
  3. mfro

    Jump in head first right?

    The only left handed thread I'm aware of at these engines is the one for the flywheel puller.
  4. mfro

    cold intake manifold and condensation...problem? Solution?

    Not familiar with Pontiacs - single carb V8? So it will be probably suffering from a similar problem: relatively long and cold pipes. Avoid long pipes (especially such with different length) and avoid closed to half-open throttle (this is causing the pressure drop). Both (especially the...
  5. mfro

    cold intake manifold and condensation...problem? Solution?

    Atomizing fuel isn't done in the manifold at all. It's sole purpose is to transport air and fuel spray to the combustion chamber. Atomizing is eventually done at the valve's stricture and combustion chamber squish. This, however, is a more than bright idea I'd seriously consider - a classic...
  6. mfro

    cold intake manifold and condensation...problem? Solution?

    On a multi-cylinder, single carb engine (even more on a "long" inline six like your Jeep's), where you have long distances between carburator and intake valve, this might be necessary as a compromise: the long distance would otherwise lead to condensating fuel on the cold manifold walls which...
  7. mfro

    Any electrical gurus out there?

    Replace the meter with a light bulb on two wires and you not only have avoided the risk of damaging your meter, but also have a clear visual indicator on what happens. Then start disconnecting things from the harness as described above until the light goes off - then you found the culprit (or...
  8. mfro

    cold intake manifold and condensation...problem? Solution?

    I'd say its more like the opposite. As long as you don't have a problem with icing. High humidity? If you have condensation on the outside, that just means you have vaporization (caused by pressure drop) on the inside which takes your intake charge air temp down greatly improving volumetric...
  9. mfro

    Dyno Run With Honda S65

    It doesn't matter which gear you are in for the dyno. You should get the same result regardless of gear (don't you learn that in school? :16:).
  10. mfro

    cam journal wear

    Shop manual (German SS50) says: replace head if journal diameter exceeds 29,06 mm (left and right).
  11. mfro

    Practical Eng advice Q:

    4c) is my preferred choice most of the time. Just drill away the head. Once you have the bolt head (and cover) off, you can usually remove the remaining stub easily with grip pliers. Most of the bolts resistance comes from head friction. Regarding "overhaul depth": once I have an engine...
  12. mfro

    Crank Question

    According to my documentation, the straight (last gear) transmission ratio of the 3-speed is 21:25 (1,19), while the fourth gear of the four-speed is 24:23 (0,95). Assuming my docs are correct, you'll need to compensate for that difference with the inverse change on your front/rear sprocket to...
  13. mfro

    Hondabond or no Hondabond, that is the question.

    IMHO, there are more disadvantages than advantages to use liquid sealant on these engines. With new gaskets and clean and unmolested sealant surfaces, bolts tightened to spec, those engines do not leak. I seriously do consider using sealant counter-productive: I've seen just too many engines...
  14. mfro

    Replacement frames in the 1970's

    To my knowledge, Honda never sold prebuild crate engines. Just individual parts. Your engine has probably been repaired with a new case.
  15. mfro

    Anyone have a Honda Nice for sale? Or where to buy

    Have seen sheered off main shafts (at the shaft recess where the clutch basket is supported) due to hard stress changes (probably because of weak springs and wornout rubbers).
  16. mfro

    Anyone have a Honda Nice for sale? Or where to buy

    That's the problem. Not much left and those that are were abused over decades. Most often not even worth the shipping fee.
  17. mfro

    Anyone have a Honda Nice for sale? Or where to buy

    I'm not going to say anything bad about ACT, but you should know that the term "reconditioned" generally has a very different meaning in Thailand than it has in the western hemisphere. Just to avoid frustration: reconditioned engines from Thailand very rarely meet western expectations and...
  18. mfro

    2sm vs 4sm heads for Nice

    I don't think so. 2SM is Honda Monkey/Dax/CT70 etc. (including Nice ZN110 engine) stud pattern 4SM first appeared with the old 138cc complete engine and large valves. It doesn't fit to Nice ZN110/Monkey engines because of its wider pattern which - on the other hand - isn't compatible to the CSM...
  19. mfro

    nice motor super clutch conversion help

    Not so easy, I suppose. The Nice crank needs the threads for the crank nut - the snap ring won't work there. It lacks the toothwork on the crank, there is only a woodruff key. That key alone wouldn't hold torque, therefore the primary gear must be bolted to the crank.
  20. mfro

    nice motor super clutch conversion help

    He didn't tell, but as far as I know he has a 66mm TJR Nice style stroker which I suppose he doesn't like to replace ;)