R2 with New Engine is slow!

[ROD]

New 4hp "Powersport" on a rebuilt R2. Comet Torque Converter.

35yr old minibike with 3 1/2 and a Comet TorqaVerter is quicker and faster.

New engine carb has smaller throat, no adjustment screws. I am tempted to put old carb on new motor, but then younger son would get really unhappy.

Any other ideas on how to give it more get up and go?

I understand the Dellotro is great, but they are not cheap. Any other options?

[T-Mack1]

Rod,
I'm running a fairly new Tecumseh 4 HP w/ a comet clutch (our Hustler). With my 9 year old on, it did 35-40 mph at the mini-bike reunion while the group toured the country side after the parade. I could barely keep up to him.

Things to check. Throttle linkage on engine should have a screw that acts as a speed adjuster. Make sure it is screwed all the way in. If you want more power, take the spring out too. But...that makes it fast for a kid then. You should be able to unscrew it enough for a small child to ride (or if yours is anything like mine "a wife")
Second thing to check is governor adjustment. My rebuilt 4 Hp (on the R2) dogged until I tweaked the gov. Here's the Tecumseh manual for static adjustment of governor. I have the manual as a electronic file but it's 3.3 megabytes. That's a long down load if you only have a modem. Let me know if you want if.

Big warning here!!!
Make sure you are the first person riding after adj'ing gov. It could be real fast. Also, make sure the kill switch works. You may need to shut it down fast. If adjusted wrong way, it will dog more. Make little adjustments (steps) to prevent over rev'ing engine.

Static Governor Adjustments
The purpose of making a static governor adjustment
is to remove all free-play between the governor
spool and the carburetor (see illustration). Any freeplay
here will result in hunting/surging or erratic
running. After completing this procedure, always
re-check the engine speeds using the steps outlined
in the following pages.
To set the static governor, do the following:
1. Be sure the engine is stopped or damage may
occur.
2. If equipped with a throttle control, place the
throttle in the high speed position.
3. Loosen the governor clamp or screw.
4. Hold the governor arm and link in the W.O.T.
(wide open throttle) position, then rotate the
shaft or shaft/clip assembly in the same direction
and tighten the screw.
5. If engine speed adjustments are needed, follow
the steps described in following pages.

T. Mack

[ROD]

I have ridden it with my finger on the linkage and hold the throttle wide, and it is still pretty slow.

I have been told that the new carburators have no adjustments and that the throat of the carburator is smaller. Does your have this carburator?

[T-Mack1]

Rod,
- Sorry for delay in reply. I had to get a friend to lend me the blub style carb to test.

- It was from a 3 HP engine and yes, I noticed it had a smaller throat. But bigger screw thing on bottom of bowl. I tried to swap a adjustable high speed mixture thing but couldn't.

- I got it to run but didn't like it. Speed was just a bit slower then the adjustable 5 hp carb on my 4 hp engine. Without the adj screws, I couldn't get the idle down low enough. It was just fast enough to engage the clutch most the time. Also, it was a pain to start. Even after it ran five minutes. And the low speed mixture wasn't rich enough to pull out quickly. (low speed should be rich and high speed lean)

- So, here's some measurements: with the 5 HP carb I got 35-38 mph down the street to the stop sign (300-400 feet) and 25-27 back up the hill. With the 3HP carb I got 32-35 mph down and 23-25 back up. I think since it is a smaller carb, the results were to be expected. I noticed that the 3 hp carb was full open coming up the hill and pushing on gov lever didn't do anything, where the 5 hp carb would.

To gage distance see pictures at www.users.fast.net/~tommack/mack-MB-Rally03.htm . On one, you can see the intersection.

-- It should be noted that Tecumseh got the different horsepowers by both "bore & stroke" and by changing carb's to bigger CFM's.

You can get adj. carb's from Sears on line parts store. The 4 HP runs about $65 +S&H (new!!!) or from ebay for used carb. I suggest new. My 5 HP is used and the low speed mixutre is not good. I got another carb from ebay of unknown HP and it's must be for a 6-8 HP because it carbons up the spark plug after riding for 1/2 hour (too much gas) even with mixture screws lean'd out.

Sears parts store is at: www3.sears.com/
Search for model HS40* or if you want a bit more power HS50*. Then view parts diagrams for engines with mini-bike mufflers. You can pay by credit card.

Tom M.

[T-Mack1]

Rod,
I got the new carb body. It wasn't a complete carb. I had to take the choke parts and the throttle shaft to get the little plate on top. BUT......it was worth the $64 bucks. Bike rides good and has adustable mixtures now.
I went thru three used carb's and they all had something wrong with them. One was from a 7 HP and used too much gas. Carbon'd up the spark plug. afdter 15 to 30 minutes Two had bad low speed mixtures.

T-Mack1