Hi guys, cool site. I just started a mini project and got a free engine a 3.5 horse eager 1 Tecumseh from a sears edger. I really dig these little engines. Even though they aren't the best for making power, I want to use it anyway. I'm doing a budget build and free is good when you aren't working. Anyway, has anyone here built up one of these? Any good performance parts for them? For now I was thinking about fabricating an intake that is less restrictive, I was thinking a strait one. Anyone done this? I am definately building a header for it, just wondering what would be a good overall length and diameter? I thought about a better carb down the road, porting and a cam. Any reccomendations are appreciated! Thanks
Advice on power mods for a Tecumseh 3.5
YouTube - SPECTRE K&N GO KART thats my 6 hp sraight pipe and new filter to get started on power it could give it .5 if done good and new spark plug good gas good oil:thumbsup:
Due to the overwhelming response I recieved from that thread I'm getting the impression the 3.5 HS engine is unpopular. Suprised with as many of those engines that are around that more people aren't trying to crank a little more power from them. For everyone that read this thread, I'm still going to keep looking for info in the 3.5. My plan for the HS 3.5 is as follows; New motorcycle carb, around 19mm or so and I'll make a custom intake for it, remove governor, nice exaust header, head porting, and lastly I'm going to try and find a thinner head gasket for a fuzz more compression without having to cut the head. I'll start posting up pics of the bits I make for the engine.
In other news, I got my hands on a frame for the project and a tec 3.0 horse engine! Got that yesterday. The frame will be completely altered! If anyone reads this thread and has any info on the smaller engines I would appreciate it if you put down what you know!
Thanks!
In other news, I got my hands on a frame for the project and a tec 3.0 horse engine! Got that yesterday. The frame will be completely altered! If anyone reads this thread and has any info on the smaller engines I would appreciate it if you put down what you know!
Thanks!
Thanks minibikedude! Ya, 15mm sounds like a good size, I think 19 may be abit big. I now have a better Tecumseh carb off the 3 horse, it's at least a powersport carb. I'll probably make a new strait alum intake for it today and fit it to the HS engine. I have some tubing I'm gonna use for the header, but I think I'm gonna leave that til last when I've got the frame done.
As far as clutches go, what is a good reliable clutch for these motors?
I also wanna ditch the governor today. Looks like I can get to everything from removing the side cover, not sure yet but I'm gonna find out! If anyone has info on dumping the gov on an hs35 let me know.
Thanks:thumbsup:
As far as clutches go, what is a good reliable clutch for these motors?
I also wanna ditch the governor today. Looks like I can get to everything from removing the side cover, not sure yet but I'm gonna find out! If anyone has info on dumping the gov on an hs35 let me know.
Thanks:thumbsup:
Excellent! Nice pic. It's nice to see one done that way! I'm gonna also look for a stock Honda 50 carb. Lots of those floating around and it should work good. Should be cheap too, which is a major goal for me, spend as little as possible! So far my total investment for a 3 and a 3.5 frame, wheels and a few other bits is 32 bucks! I think I'll be getting a good condition 6.5 powersport too. I'm taking it out of a yerf dog and putting a rotax sled engine in it's place. Thanks for the pic minibikedude!
i Shaved the head on my 3.5 HS removed the Governor ported it and put a Mikuni VM Series 22 MM Round Slide Carburetor with a 4inch strait intake.built a header out of 1inch tubing and the steeped it out to 1.5 inches.I dont now how much hp it has but its fast it bogs a little bit with the 22mm carb. I what to try to run a alcohol some time
Way cool. So on your head milling, how much did you have removed. I've been wondering if there are thinner head gaskets available. As far as running alcohol, I've never ran it, I've always used high octane fuel. One fuel choice that is real popular around here is a avgas/91 blend. We are duners, and we have a bunch of high hp banshees that run real well on it. We mix 4 parts 100LL av fuel to 1 gallon 91 or 93 if you can get it. The reason for the blend is av fuel is meant to be run at high altitude. As you increase altitude the boiling point for fuel decreases. Av is blended to overcome boiling point issues so fuel won't boil and vapor lock the fuel system. I think at sea level av boiling point is 260. Mixing pump brings the boiling point back down making this an inexpensive high octane fuel. It's about 1 dollar more per gal than pump and you end up with a 97/98 octane fuel for half price of race fuel. Maybe try that before alcohol because your carb won't need to be modified to run it. No purging the system like alcohol either. If you decide to try it I have found it likes to be run a little richer due to the oxygenates in the fuel. I'm sorry, got way off topic there!
Cool, thanks man. So, did you happen to do a before and after measurement on the head? Just curious. Did you shave the head yourself or take it to a shop? As far as the fuel goes, it's easy to get. I drive to the local airport, drive right onto the Tarmac to the pump, swipe card, pump fuel, done. Last week I think it was 4.35 per gal. Compared to the cheapest race gas @ 7.95, its a deal. It has lead in it though, bad for the environment, but the engines love it!
Just thought I would try to generate intrest in this topic one more time before I abandon it. I figure with as many of these engines that were built, and with as many mini bikers using this forum, I would be able to find more info. I'm moving forward with mods regardless, just hoping for a better direction first. If there are any old school guys with some info, I'd love to hear it. Thanks Robbie for the info on your bike. Today I removed the governor from the case. Although I plan on running a small mc carb, I have fitted a powersport carb and manifold for now. I got it all tuned in. Idles nice, good throttle response and revs pretty far. I have to put it aside for a week or so though, I have customer bikes to repair. Next I will be milling the head and porting the cylinder. If anyone knows how much should be removed in mils that info would be great as I plan on having that done at a machine shop. Anyway, thanks for any info. As I move forward I'll post up what I'm doing so others can use the info.
