Things what DO work: Tanaka "HP" carb upgrade

Discussion in '2-Stroke Engines' started by AlphaGeek, Nov 10, 2008.

  1. AlphaGeek

    AlphaGeek Member

    As I've mentioned in previous posts, I have a GEBE mounted Tanaka PF-3300 that I'm upgrading one step at a time to quantify the effect of each upgrade. I was pleasantly surprised that my previous upgrade (to an ADA cylinder-type air filter) made a significant, measurable difference on a stock engine/carb/exhaust setup.

    Since my last post on upgrades, I changed out the original 13T drive gear for the 14T gear. I ran on this for a while without any power upgrades other than the air filter, and definitely noticed the motor struggling in the middle RPM range on hills, and topping out on the flats without sounding like it was anywhere near max RPMs.

    Yesterday, I swapped out the stock carb on my Tanaka 33cc for the "HP" (high performance) carb packaged with the performance pack. This was a bit more of a project than I thought it would be, though it was certainly not at all difficult for me. The main reason for this was that the upper end of the intake manifold shipped with my carb had the 10.5mm bore suitable for the stock carb, not the 12.5mm bore appropriate for the HP carb.

    Fortunately, while the main bore is slightly more complex in shape than a simple cylinder, it does run straight through (no curves) making it easy to modify with basic tooling. After carefully measuring everything several times with the micrometer calipers, and verifying that my original manifold was exactly the same as the new one in case I screwed up, I clamped the new manifold in my drill press and reamed the bore to 12.7mm (aka 0.5in). It's worth noting that the manifold appears to be made of wood fiber, which does NOT machine like high-temp plastics. Be sure to use high speed and a sharp bit.

    I used the Dremel with a small sanding cylinder to clean up the newly-enlarged bore, then gave the manifold a good cleaning. I also used a protective oil on the newly-exposed wood surfaces inside the bore. After that, everything went smoothly. I had to reuse the original carb-to-manifold gasket, but fortunately mine was in good shape and was fairly easily trimmed to match the new larger bore size. I was VERY happy to find that the HP carb had only one adjustment screw (not two as I had read) and that it was correctly preset to run perfectly on my motor.

    Performance:

    These are initial impressions only, will update again after a full commute to/from work tomorrow. Today's ride was 8.5 miles with a LOT of wind, but I was able to form some subjective impressions:

    * More power available at WOT to keep my speed up above 28mph even when beating against a significant/gusty headwind

    * A small but moderately steep incline (highway overpass) that previously caused my speed to drop from ~30mph to ~22mph caused a much smaller drop to ~28mph today. Very nice!

    * Top speed in good conditions (i.e. calm or slight tailwind) was up by 10%. Specifically, I was hitting 34.7mph on level ground, up from ~31.5mph pre-upgrade.

    I expect that I will see an even bigger increase in top-end power on the big downhilll coming home tomorrow night, since the HP carb should be able to flow 41% more air/fuel mix than the OEM carb. That plus the 14T gear could see me pushing 40mph on the downhill. Whee!

    Summary: HP carb upgrade for Tanaka engines (with air filter upgrade) -- DEFINITELY worthwhile. Easy and hassle-free (if you get the right parts, sigh) and produces measurable and useful power gains.

    Next up: tuned-pipe exhaust upgrade. As soon as my *&&)(*& vendor sends me the right exhaust manifold pipe. But that's a whole 'nother story.

    -AG
     

  2. JemmaUK

    JemmaUK Guest

    With mine all I have done is fitted up a tuned pipe from Tanaka which was designed to be used with carts.. so it needed a little bit of cutting/welding/adjusting


    Performance:

    These are initial impressions only, will update again after a full commute to/from work tomorrow. Today's ride was 8.5 miles with a LOT of wind, but I was able to form some subjective impressions:

    * More power available at WOT to keep my speed up above 28mph even when beating against a significant/gusty headwind

    Between 30-32 mph against headwinds which usually dropped me to about the same speed or even lower

    * A small but moderately steep incline (highway overpass) that previously caused my speed to drop from ~30mph to ~22mph caused a much smaller drop to ~28mph today. Very nice!

    A hill that previously dropped me to 20mph I could do with the #13 at 28mph - terminal speed at the end of the incline - 25mph with the #14

    * Top speed in good conditions (i.e. calm or slight tailwind) was up by 10%. Specifically, I was hitting 34.7mph on level ground, up from ~31.5mph pre-upgrade.

    I have had 35.5mph out the bike with the tuned pipe fitted... it will run along at around 30mph on an almost closed throttle. With the #14 gear fitted I have had 36.6 and that was with the engine wanting to give more

    I expect that I will see an even bigger increase in top-end power on the big downhilll coming home tomorrow night, since the HP carb should be able to flow 41% more air/fuel mix than the OEM carb. That plus the 14T gear could see me pushing 40mph on the downhill. Whee!

    There may be a problem with the #14 gear as it tends to stop the engine winding out to full power. It might also be worth running the motor a little richer on carb mixture while adding a little more oil to the premix... because higher revs = more heat = more friction

    Jemma xx
     
  3. AlphaGeek

    AlphaGeek Member

    Get this, Jemma -- the vendor sent me the manifold pipe from the cart kit, and the rest of it was from the scooter kit. The spring-attachment hoop on the manifold pipe doesn't even match up with the main pipe in any rational way. I'm a bit peeved at the vendor as it is taking weeks to get this resolved.

    I am looking forward to putting on the tuned pipe, though. Some more upper-midrange power to get over the big bridge would be nice to have. Even with the HP carb and intake, I'm still having to pedal to keep speed above 25mph on the incline.

    Good point on tuning the oil/petrol and fuel/air mixtures. I'll have to read up a bit on the HP carb to make sure I turn the screw the right way. :)

    -AG
     
  4. shawnshank

    shawnshank Member

    Do you know where to get the performance pack (pipe and carb) for the 40cc tanaka engine?
     
  5. mishle

    mishle New Member

    I sure would like to know also.

    and has anyone tried this yet on the 40cc tanaka

    mishle
     
  6. bamabikeguy

    bamabikeguy Active Member

    The Tanaka-USA web site wants you to order through a Tanaka Dealer first, they have a list.

    http://www.tanaka-usa.com/index.php?section=132

    Tanaka Engine Parts Books

    Our downloadable parts books contain illustrated drawings, part numbers, and descriptions so you can quickly identify the Tanaka engine part you need. To order, go to our dealer locator and contact your nearest dealer. If your local dealer does not have the part you need, call 1-888-4TANAKA.
     
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