i bought a tower 75 last year after reading lots of info on these forums about the quality and power of these motors. I followed the running in process given in the instructions to the letter. i had reasonable results with full throttle power output being quite good, but the mid range was really very poor to the point that it would load up and spit fuel out the carby with in a couple of seconds and then quit. i tried everthing to fix the problem but had no luck. i was told that the carb may be suspeck so i got onto tower but they said that I was not adjusting the carby properly, (i have been tuning for quite a few years now)!, any way after much frustration i emailed Just Engines in England and bought a "TN2" 9.5mm carby to suit a 15mm bore , it arrived and looked good. anyway today i started the tower 75 up again and to my surprise the tower 75 behaved like a....... perfect motor! i was amazed idle, transition, top-end, were fantastic, i am very pleased now with the tower 75. i was about to give up on my tower 75 and off load to the auction site, im now glad i didnt, it did cost me an extra few $ but im now very happy. i will include some updated rpm figures in the taco/rpm forum soon.
Greg

Glad to see you got it fixed.

I think there are at least two different carb designs that were used on this engine. The carb that came on my .61 is a completely different design than the one illustrated in my manual.

Mine has always worked well, so maybe it's the type shown in the manual that gives problems.

I can scan my manual and take a pic of my carb if anyone wants to see the difference.

David

Greg,

I also believe the one carb you have is suspect. This weekend I fixed my SK-90 by using my TH-75 carb. My SK tuned up perfectly with the TH-75 carb.

Like David's carb, the design of the TH-75 carb I have is not like the one shown in the manual that comes with the engine. How to detect a bad one, that is still a mystery, I guess. In my carb, you never see the LSN because it is inside a tube sleeve that runs all the way across the carb throat. If you see it from the side of the venturi that goes into the crankcase (carb bottom), you see a square hole in the middle of such tube. There, you can see the LSN moving as you come close to WOT.

My problem now is I need a new carb, either for the SK or for the TH engine. David (rainedave) pointed me to the Perry carb. I always have the choice of buying another from TH when parts are available because I am not using the TH-75 engine right now. So, what's the cost of the carb you bought from Just Engines?

Pedro

Greg,

I had the same problem with the first Tower .75 I bought-totally rich and spitting out fuel droplets in the mid range. I caught a big ration of you know what from Tower users that said I didn't know how to adjust engines. I plugged in an SK 90 carb and it ran perfectly. Tower did send me a new carb, which runs OK.

I think they had a run of bad carbs. Whether it was the grind angle on the low speed needle or the angle of the groove on the rotating barrel, I don't know. I just know it was unusable in the mid range.

Unlike the experience Pedro has had with the SK 90, I have 2 of them, which I run on 15-6 props, and as far as I am concerned, the carbs run as well as my OS carbs. So far, I have fixed a Tower .75, Evo .61 for a friend, and an Evo 1.00 by installing an SK 90 carb. The big Evo 1.00 I bought for $50 because the owner couldn't get the Evo carb to work. I installed the SK 90 carb, which has a slightly smaller thrat, so the top end rpm is down some, and it runs fine. To fit the Tower, I did have to sand off about 1/16" off the bottom of the carb on a belt sander. What can I say, they run good and are only $29 last time I checked.

At this time, I believe there are few bad samples in every brand. Frustration arises when we circle the wagon because we don't have the resources to prove what or where the problem is. The next challenge is dealing with the sellers and warranty claims. Some companies honor warranties until they are presented with evidence, for other companies the word of the customer is enough evidence. The later are companies that promote and develop loyal customers. While some people persist and find solutions, others give up and never purchase again from a particular brand/model.

Anyways, I am sure this has already been the subject of other threads.

In regards to my sk carb, I will call Kangke and will try to get a warranty carb for my engine. On the other hand, I own an SK-50 that ran perfectly out of the box. Anyways, I am buying another SK-90 for another model. I truly believe this one will perform fine out of the box.