27.2cc Zenoah Engine 4.25+

Discussion in 'Performance Mods' started by dave1490, Nov 4, 2007.

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  1. dave1490

    dave1490 Guest

    some of the thing,s that can be done to an engine,and why.

    This custom-built 27.2cc Zenoah G260RC engine, available exclusively at DDM, offers simply amazing performance and legendary Zenoah quality. 27.2cc's of modified and fully ported power. 34mm bore, 30mm stroke. Get the high-revving benefits of a modified G260RC together with the increased low-end grunt from a longer crankshaft. Aprox 4.25+ horsepower, and 5.5+ horsepower with a tuned pipe. Available in black or chrome, and with or without inner clutch. DDM has taken the hassle out of getting a top-quality modified Zenoah G260RC-based 27.2cc engine - we've custom built them for you. The engine comes fully assembled and ready to bolt-on.
    So where does the power come from? We start with a brand-new Zenoah G260RC engine (34mm bore, 28mm stroke - 25.4cc). This is the largest bore Zenoah has available. But we want more displacement for more power, while still keeping the high-quality Zenoah cylinder assembly! So, the stock 28mm crankshaft is removed and set aside. We want a longer 30mm crankshaft for increased displacement and power! But the stock Zenoah 34mm G260RC cylinder does not have room for the long 30mm crankshaft, so ESP has machined out the proper spacing. This is a more efficient and reliable solution than stacking gaskets to achieve the needed space, as there is proper spark plug clearance, the piston ring remains in the well-plated area of the cylinder, and the ignition coil remains properly gapped to the flywheel. The squish band is cut so there will be .020"-.025" of squish (using the stock .020" cylinder gasket), and the combustion chamber is machined to get the compression ratio down to 14:1 for running on premium pump 91 or higher octane gasoline. The head geometry is reshaped to the proven standard 'hemisphere' shaped combustion chamber, and the squish area equals 50% bore area, for more efficient burning.
    After the ESP cylinder spacing modifications are complete, ESP then fully ports the engine. ESP completely tears down the engine and spends hours, cutting in great detail, the porting that will have you grinning from ear to ear. Detail like this is almost impossible to do on a milling machine - even a CNC milling machine.
    Compare this to other offerings on the market and you will quickly see that DDM and ESP put power in your trigger finger without putting a huge dent in your wallet. Portwork includes:
    1) Cylinder precision ported (exhaust, intake, and transfers enlarged and reshaped).
    2) Polished exhaust port (for smooth flow and low carbon build up) and superb rough finish on the intake, cases, and transfer tunnels for better gas/air mixing.
    3) Resurfaced intake, exhaust, and spark plug gasket surface on cylinder to insure no leaks.
    4) Perfectly matched cylinder transfer tunnels to cases and case gasket matched.
    5) Case porting to insure better flow into the transfer tunnels.
    6) Cylinder skirt work to aid flow into the transfer tunnels.
    7) New gaskets and piston c-clips.
    8) Easy to read carb tuning instructions to get the most reliable power from your engine.
    9) E.S.P. logo etched into side of crankcase.

  2. JemmaUK

    JemmaUK Guest

    I was looking at that engine until my bike was stolen - the problem with a rooted engine is that of durability...

    Unless the changes are engineered in from the start you can get reliability issues.

    for example - the Rootes Group 1592/1725cc engines ran from 62 to 85HP - the only difference between the two looks to be a different head and induction manifold ... up until you find out that virtually everything on the 85 hp engine was changed - and that 'designed in' strength allowed a final road output of 107hp (Alpine H120) and racing output of 160hp which for an engine designed at the back end of the 50's is pretty good. I know these engines are indestructable from experience.

    Its worthwhile looking round this and other forums whether other users of this engine rate it

    Jemma xx
  3. Jenna there is 'designed in' strength already in on most well build Japanese and Taiwanese engines like Tanaka and Zenoah compared to some of the cheap chinese build bicycle engines out there. However a high reving rooted engine as you say, also has it's own reliability compromised. In this case we don't know which would be more reliable. The proof is on the pudding. But that modified Zenoah sure sounds like a lot of fun.
  4. Just a quick question, was your stolen bke that one with the sprocket mounted on the disc brake and with a custom made expansion exhaust chamber and a Delorto knock-off? If so, Hope you get the ******* who stole it and get it back.
  5. Hi,
    Just a couple of questions about the engine....First what kind if $$ are we looking at?
    Is there a pic of the zenoah....Does it have the needed gear reduction or would a tranny be needed to work to get the proper gearing?...Also, what is meant by "rooted".
  6. http://www.davesmotors.com/store/product993.html g260 Zenoah 6+hp $699

    http://www.davesmotors.com/store/product1674.html g260 Zenoah 4.25hp $425

    http://www.davesmotors.com/store/product1610.html CY31RC ChungYang4.5+hp $399

    http://www.davesmotors.com/store/product1295.html GP460 4.2+hp $255

    And I think this last one is a good deal, 46cc so it has it easier; and it's peak hp is at only 11,000rpm, 2.3lbsft torque not bad.

    The stock g260 for comparison cost $214 + $5(w/clutch) and has 3 hp, 14000rpm, 1.4lbsft.torque
  7. Nice....if there was a gearbox to gear it down it looks really good...would a gearbox like on the tranny thread work?...if so which one would be the recommended tranny?
    The 6+ HP would be insane!
  8. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:IMO, with max hp and torque at 11,00rpm and 8,000rpm, the STATON 18.75:1 box, when used in conjunction with NuVinci hub, is the only transmission that would be able to successfully harness and make full use of ANY high-rpm engine.

    Besides, both components possess excellent long-term warrantees.

    No other transmission I've researched comes close.

    I might be wrong, but I'll post later with stats on theoretical mph/rpm range.s

  9. Waiting anxiously for your figures!.....I am just wondering tho....what does the manufacturer rate the HP of the gearbox and hub at....well, maybe 6 HP isn't too much...Maybe!
  10. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:Andy, STATON has a lifetime guarantee on the gears. In its gearbox are 3 gears and their shafts. That's all there is.

    NuVinci hubs are rated to handle 95.81 foot-pounds, which is more than a 1600 cc 60hp VOLKSWAGEN engine can produce.:shock:

    With 12t gearbox sprocket and NuVinci 36t sprocket, maximum speed in low gear is 5.91 mph at 8,000rpm and 8.13 mph at 11,000 rpm.

    Maximum speed in high gear is 20.57 mph at 8,000rpm(peak torque) and 28.3 mph at 11,000rpm(peak hp).

  11. JemmaUK

    JemmaUK Guest

    Mine was a zenoah based GEBE on a raleigh Apex MTB frame... new one will be another GEBE 2S using a 32cc engine on Schwinn deluxe 7 cruiser

    Jemma xx
  12. BS

    I'd like to know how they measure HP. I had a 138cc Whizzer motor that was only 2 HP before I did a major hop up. Even at 2 HP it was a LOT stronger than my GS 460 from DDM. I have their best TS head on that 47cc X-Can too. They say it is 4.2 plus HP. BULL!! They LIE!! I'm one dissapointed customer.....
  13. Could be torque vs HP....As an example my Cummins Diesel is rated at only 160 HP but 400 LB ft at only 1600 RPM....My gas Dodge has a higher HP level but the HP and torque arrive a lot later in the RPM band so depending on load.....the gasser may never get up to it's power band where as the diesel already there putting the power to the road.....My diesel truck pulls Soooo much better than the gasser plust it gets better MPG's..all with less HP but probably more usable HP to the road because I am not running the gasser to 5 or 6K RPM's all the time...FWIW some small RC nitro engines like the .21 CU IN 1/8 scale engines put out more HP than the happy times and in race tune probably around 3-4 HP but they do so at insame rpm's....sometimes 30,000 +.......but they wouldn't be real practical to run on a motorized bike....good power but at too high an RPM.
    PS - I have never actually used a pocket bike motor but I understand they are little screamers too.....have to rev pretty high to achieve max power where as the whizzer is probably is more "diesel like" comparatively.... i.e. low speed grunt
  14. JemmaUK

    JemmaUK Guest

    The problem isnt one of BHP its more one of wringing power out of an engine.

    There are two methods - one basically involves more power per revolution - aka different tune, breathing, timing, and in the case of multicylinder engines one carb per cylinder... turbocharging would come under this banner as well..

    The other method is that used on smaller engines which is design the engine with similar setup regards fuel etc. The trick here is raise the revolutions limit...

    A 98cc villiers engine produces 2hp at 3750rpm ... a 32cc Tanaka produces 1.6hp at 7/8000 rpm. Technologically they are fairly similar engines.

    Take a 25.4cc zenoah and build it to run at 11,000rpm - you'll get around 3-4 hp depending on carb and tune etc... on the bench.

    Trouble is you will hit a problem on the road because in order to get 3-4 hp out of the engine you have to get the engine up to 11k rpm under roadgoing conditions...

    If we assume the max revs available on a single speed drive is 7500rpm without LPA then with a normal spec zenoah you'd be looking at about 1 - 1.2hp. If you put the rooted one on the same bike at the same ratio you'd get the same rpms - but given the different powerband you would likely get less actual power to the wheel and also the torque curve would be difficult.

    in order to be able to use the extra power, you'd have to change the ratios in order for the engine to spin up to the relevant RPM's. Its the same thing as would happen if you put a new engine in a car but used the same original gearbox and final drive ... if the engine has been set up as a high revving engine and the transmission ratios dont allow it... then the extra power will not be available...

    Jemma xx
  15. 5-7HEAVEN

    5-7HEAVEN Guest

    An less-expensive alternate gear-reduction box!

    :cool:Well put, Jemma.

    As I stated before, the STATON rear chain box can harness ANY high-rpm engine, even without the NuVinci hub. A 10t/16t drive/driven ratio yields 1.6:1. Multiply that by 18.75 begets 30:1 final drive.

    With these gears on a 26" bike, an 11,000rpm engine can be harnessed to 4,000rpm/8,000rpm/11,000rpm speeds of 10.6mph/21.2mph/29.2mph.

    Higher or lower speeds can be adjusted by a simple $15 drive sprocket.

    That's after you buy the $240 STATON gearbox.

    Like the old saying goes, "Speed costs money. How fast do ya wanna go?"