Ct70 with Nice 110 - considering installing a ct110 motir

Discussion in 'Modifications' started by RMHRC, Aug 9, 2020.

  1. RMHRC

    RMHRC Member

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    Being in Australia we have thousands of postie bikes so getting a motor and genuine Honda parts is easy for the postie 110.

    My ct70 was fitted with some parts I bought from city Honda about 11 years ago and i have used the bike on and off. The Honda nice engine has been ‘ok’ but Asian concepts i think sold me a bit of a dud - bolt holes stripped etc.

    I’m unconvinced about Thai quality engines versus Japanese hence my interest in the Postie 110 engine. The negative of the postie engine is that it’s semi auto and heavy. But as many know it’s as reliable as an anvil.

    So is fitting the postie 110 a matter of grinding the postie 110 upper mount down and drilling larger mount holes in the CT frame?
     
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  3. power6994

    power6994 Member

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    I think there were good and bad sellers of the nice 110. The postie motor is reliable yes, but the mount distance is bigger from the top to the lower mount. Some guys have made a bracket rather than drilling the frame etc.
     
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  4. racerx

    racerx Administrator
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    Asian Concept vanished years ago. Their "reconditioned" motors varied, early ones could be horrible, later ones were much improved but still nowhere near what most of us would consider a proper rebuild. They cobbled-together used parts, in okay condition; it's amazing how long some of these lasted. The CT90/110 motors were well-built and very durable, the Nice 110 more so...plus it makes more power and is a lot lighter. Fitting one of the earlier "postie" motors requires cutting the top engine mount down, to fit the CT70 frame and drilling the frame for the lower engine mount, along with adding bracings & modding the brake arm/pivot. Your sprocket choices will be limited, as the countershaft splining is different. Translation: no #420 sprockets are made for this engine. Easiest solution is a custom rear hub that can use CT110-patterned, or custom (plate type) sprockets; that's more time, engineering & money than you might think.

    Consider the years and miles the used lump has given you. It'd be less time, modifications and money to just do a proper rebuild of what you have. Starting out with a rebuild done right, you could easily get 30,000 miles out of the Nice with nothing more than timely oil changes & spinner cleanings. Repairing stripped threads is easy enough. From what I saw going through used Thai-sourced specimens, the most common wear items were first & second gear, plus oil pump. Worn shift forks, valves & seats, and even cylinders were rare to the point of being virtually non-existent. Guesstimating shipping (postage) costs to your part of the globe, somewhere around $400USD should buy enough new, OEM, parts to return this lump to mechanically new.
     
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  5. RMHRC

    RMHRC Member

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    You’re 1000% right. I’ll rebuild the Nice engine

    I love the manual clutch on the Nice110

    so anyone on the site or a sponsor sell the parts I need? Is there a manual to show me how to clean the spinner?

    What if I just wanted to bolt on a rebore just oversized head?

    I dealt with a great guy about 10-11 years ago at a Honda website who got me into the Honda Nice engine concept.
     
  6. mikejana

    mikejana Active Member

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    That's a good choice. Don't let go of a Nice motor. I've been looking for years for one.
     
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  7. RMHRC

    RMHRC Member

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    you can still source from Asian concepts or faddybike.
     
  8. RMHRC

    RMHRC Member

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    So Bob i think my engine has pretty decent compression (it was a rebuilt motor I paid for) so I think I might just replace the oil pump.

    Maybe new valves and seats so I have them.

    What would a 1mm rebore do you overall capacity? It would square up the motor even more wouldn’t it?
     
  9. racerx

    racerx Administrator
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    The base question is why you're planning to tear into the motor in the first place. Once that's been answered, it'll direct the rest of the what should be done.

    If the cost of an MJN22 carburetor is more than seems worth investing, then I'd focus on getting the motor as close to "mechanically new", ready for another 40,000 miles and optimizing the stock setup. Going to a 51mm bore just means using-up all the extra cylinder thickness and ending up with 4th OS. 113cc isn't going to make more power than the original 109cc. Power gains are really kinda underwhelming on the seat-of-the-pants-dyno, until displacement is around 140 and that's gonna need a bigger budget. There can be some decent hp gains but you won't really feel them below 50-55mph. From that speed up, the engine will just keep pulling, not leveling-off until the speedo reads 5-10mph higher than what you have. That kind of power could be made with the stock bore size...you'd need to raise compression and the rpm at which peak hp is reached, using a "hotter" cam. If your engine is making full power, you should be seeing low 60s (~100kmh) on the flat and be able to sustain 50-55mph, closer to 60 under ideal conditions.

    A head rebuild is pretty basic on this motor, the parts are inexpensive. They're also durable. I've not seen one of these heads with wasted valve seats. At most, a light cut, new valves + lapping was all that was needed. As long as the casting itself is sound, there's not $100 total in valvetrain parts. With the head removed, you have to decide whether the piston has to leave the bore. If there's no oil control problem and no scoring, then it's your call as whether you want to gamble that all of the lower end parts are in tiptop condition.

    Once the piston leaves the bore, you'll need to deglaze the cylinder and buy new rings, at the minimum. At that point, it'd be pennywise and pound foolish to not split the cases and inspect the lower end. On one hand, the lower end may need nothing. You spent an afternoon cleaning and end up with cheap peace-of-mind. Barring any surprises, I doubt you'd need to replace $150-350 worth of lower end parts...giving you a lower end that is literally good as new. It's still cheap peace-of-mind. A new motor is 2500EUR + shipping.

    The lone modification that might be worthwhile is some light port cleanup. Concentrate on the exhaust port...removing casting flash and working on the short-turn side of the port, to give more of a straight-shot from the vale to the port outlet. Keep the material removal to a minimum. Hogging-out a port, substantially increasing its volume, will kill flow velocity and result in soggy lower-to-mid range scavenging & performance. On the intake side, you just want to remove any casting flash; leave the port walls rough. The exhaust side, OTOH, can be polished if you like; that's not really worth the effort.
     
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  10. RMHRC

    RMHRC Member

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    No real reason other than setting a baseline on an engine. I didnt realise 1mm was a 4th over.

    My new Mikuni VM20 arrivs today with the TB manifold which according to the seller needs dremelling to match the gasket.

    This is the part I have arriving to fit the Mikuni:

    https://www.tbparts.com/product/tb-intake-kit-for-stock-70-head-or-race-head-all-models/

    Bob - in your fountain of knowledge do I have to dremel the TBW0273 manifold to make it work with a Honda Nice head?
     
  11. dirtbkr188

    dirtbkr188 Active Member

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    If the Nice bolt pattern on the head is 45mm, the TB Parts manifold will work, it is 45mm at the head end, and 48mm at the carb end. According to JetsRus HERE, The VM20 flange mount carb has a 50.8mm bolt hole pattern.
     
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  12. RMHRC

    RMHRC Member

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    6F887120-DA0F-4E52-B96D-FD2F9777A6AA.jpeg

    Carb just arrived

    So 188 are you saying it should fit? Sorry bit confused
     
  13. RMHRC

    RMHRC Member

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    2DFEBF54-96AC-44DA-9209-5D00E7FFFFDB.jpeg 7353518C-5FA7-4647-B43B-1E0B17B37982.jpeg Ok just did some measurements

    TB0273
    carb end appears like 22-23mm - 1st pic


    Above - engine side of Tb manifold is about 18mm

    carb itself is about 18mm

    460C2C80-E085-4F3C-951A-128D4A7920E2.jpeg
     
  14. RMHRC

    RMHRC Member

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    Hi again

    can you guys help me with the parts and where they go?

    gasket either end of the manifold?
    Also what’s the black plastic item? Seems weird

    any pics of install of this carb on a Nice 110 would be great

    6E1EAAB6-0C33-40FF-9D57-21AB9CACD441.jpeg
     
  15. racerx

    racerx Administrator
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    First thing to do is a dry fit. You may need to use the heat insulator as a spacer, between the head & intake, to fit the carb. I prefer locating the insulator at the carb end, that isn't always possible. There's very little cubic real estate to work with. At the head end, use the gasket(s) (and spacer, if needed), to establish port alignment. At the carb end, pull the slide then look through the venturi.

    The rule is that each ID must be the same size, or larger, moving downstream from the carburetor to the port. Any overlap, on the downstream side must be eliminated...that's where a die grinder (including the ever-popular Dremel) work comes into play.
    • Intake manifold inlet side...same size, or larger, than the carburetor outlet.
    • Intake port ID...same size or larger than the intake manifold outlet, gasket(s) and spacer (if used)
    Gaskets & insulators can have a slight offset that isn't noticeable until installation time. Always flip them and check alignment in both orientations.
     
  16. RMHRC

    RMHRC Member

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    So what end shoukd the insulator go on?

    ive never seen such a part before
     
  17. Gary

    Gary Well-Known Member

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    Some bigger Hondas had them- they went at the carb end,thats why they have that funny wing- it protected the float bowel from getting hot. You will have to check if you put it on the head end it might raise the manifold too high. If you try it on the carb end it will push the carb further back.
     
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  18. RMHRC

    RMHRC Member

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    Any pics ?
     
  19. dirtbkr188

    dirtbkr188 Active Member

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    That heatstop will only fit at the head side of the manifold, it matches the 45mm mounting holes. The extension goes towards the exhaust side when you test fit it in place on the head. Otherwise, when you bolt the carb up, the float bowl will hit it.
     
  20. dirtbkr188

    dirtbkr188 Active Member

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    You can see the heatstop in place correctly in the pic below...

    I3IQvS.jpg
     
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  21. RMHRC

    RMHRC Member

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    Wow nice looking bike DB188

    My next plan is to fit an oil cooler.
     

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