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Hello, I found a new old stock 4 H.p. Tecumseh power sport for a mini bike that is about four years old. The question is. All the 4hp. I have the exhaust is to the right of the intake looking from the rear. This one is on the left side of the intake like a 3 1/2 H.P. on down. The intake is real short like a 3 or so also. A guy told me tecumseh probably threw a 4 h.p. sticker on the 3 1/2 who would notice. Any ideas. I would buy it but I am skeptical now. What is the difference in a 3 1/2 and the 4 h.p.

Submitted: 34 days and 20 hours ago.

Category: Small Engine

Value: $13

Status: AWAITING CUSTOMER ACTION

Posted by Curtis 34 days and 20 hours ago.

Answer

The difference between 3&1/2 and 4 HP on a single cylinder engine may just be additional weight on the flywheel. The additional rotating mass would easily increase power that much. I doubt if a manufacturer would misrepresent their product by stating it was something it's not.

34 days and 20 hours ago.

Reply

Well , Why are the older ones so different. I am not really satisfied with the answer. The intake ports and intake are way different also. With the economy the last few years who knows.

Accepted Answer

The fact of the matter is that the older 3.5 probably has more usable power than the 4.
In the mid 80 the EPA started to get involved with the small engine industry.
All models started to come under environmental revue. That simply opened up a can of worms for the consumer.
The EPA took the manufacuters word on HP. Most engine builders (Kawasaki and Kohler were the exceptions) Lied or exaggerated their HP.
If tecumseh said it was 4 HP that was what they were rated EPA wise. In reality the earlier 3.5 made the same "pollution" but also had a lower threshold.

Hope that made some sense.

Bottom line, if the exhaust won't melt anything and the carb isn't hanging out in space, The 3.5 would be the better choice.
Top speed will not be affected. Both engines run @3800 RPM top no load speed. The acceleration difference will be minuscule.

Accepts:
Expert:	Deere Dr
Pos. Feedback:	96.3 %
Answered:	10/18/2009

Small Engine Technician

John Deere service mgr for 18 yrs. Briggs, Kohler, Kawasaki, expert level for all

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