hello new boat and glad I found the forum

daryl2cb · Jun 22, 2006

well, finally my registration is final and I can post. On friday I bought a boat used. it is a boat tech tunnel hull with a 8701 k and b 7.5cc out board. I am having some issues with it. I ordered some parts after doing some research for a while. I wont bug you guys for newb q and a with out researching via the search first so I am going to do some research now. if you want to give me advise great. Knowing what I know from nitro cars, I noitced several things. one gaskets were leaking so I took the motor apart brake cleaned every thing and reaasembled with after run oil. the carb was gummed up got it rolling again. I ordered a flexshaft rebuild kit, engine screw set, gasket set and head shim set, comes with .03 and .10 shims I believe. I got it on the water yesterday, and it rips, some observations idles great, noticed chocking out at full throttle, also gas spary comes out of the carb, is this normal, also I removed the motor from the outdrive and noticed the rear main bearing has no race is this normal? I am thinking that this could be causing irratic performance, also I moved the fuel tank because I figured the pick up tube was coming out of the fuel. so I will try these setting and install the new parts. besides that I bought the boat with remote, starter and glow plug strater for 100 bucks so I figured I did alright. the front bearing is good no leakes, any advise. right now there is no head shim in the motor, I thought I would try the smaller head gasket then try the other.

RaceCraftBearings · Jun 22, 2006

If it is spewing fuel from the carb it sounds way rich and that will stall the motor when you open the throttle. What motor K&B 3.5? The Boatech hulls are decent boats for thier day, they have been out of production for better then 10 to 12 years. However any boat properly setup can be fun and possibly be made into a respectable race boat. If tthe motor was gummed up it has been sitting a while without proper storage maintenace having been done and will need gone through. The rear main bearing without a race is not good and I would suggest you stop running the motor until the bearings are replaced.

Good Luck and have Fun!

Ron

daryl2cb said:
well, finally my registration is final and I can post. On friday I bought a boat used. it is a boat tech tunnel hull with a 8701 k and b 7.5cc out board. I am having some issues with it. I ordered some parts after doing some research for a while. I wont bug you guys for newb q and a with out researching via the search first so I am going to do some research now. if you want to give me advise great. Knowing what I know from nitro cars, I noitced several things. one gaskets were leaking so I took the motor apart brake cleaned every thing and reaasembled with after run oil. the carb was gummed up got it rolling again. I ordered a flexshaft rebuild kit, engine screw set, gasket set and head shim set, comes with .03 and .10 shims I believe. I got it on the water yesterday, and it rips, some observations idles great, noticed chocking out at full throttle, also gas spary comes out of the carb, is this normal, also I removed the motor from the outdrive and noticed the rear main bearing has no race is this normal? I am thinking that this could be causing irratic performance, also I moved the fuel tank because I figured the pick up tube was coming out of the fuel. so I will try these setting and install the new parts. besides that I bought the boat with remote, starter and glow plug strater for 100 bucks so I figured I did alright. the front bearing is good no leakes, any advise. right now there is no head shim in the motor, I thought I would try the smaller head gasket then try the other.

MarkScott · Jun 22, 2006

RaceCraftBearings said:
I would suggest you stop running the motor until the bearings are replaced.

Direct from the man that will sell you those bearings

Ron, got the MAC bearings today.. Rebuilds will be this weekend... Thanks for the quick shipping.

daryl2cb · Jun 23, 2006

I figured as much, I dumped some after run oil down her throat, and it made its way out by the prop, so bearing must be no good. the motor is a 7.5, I believe it to be a 8701 model as it has the square carb and no remote needle valve, I ordered the new screw set and head gasket as well as the flex shaft rebuild and gaskets. As of right now the needle is set to 3 turns out, thought that should be about right, guess it is still rich, can you get me bearings? If so let me know I definately need them. at least the two for the pto drive, the front bearing seems to be holding well, but I figure if I replace the pto bearing, guess what, the front will leak, so might as well do all at once. another discovery, the fuel tank was junk, this guy had the exhaust pressure tube(sullivan 12 oz tank) sitting in the middle of the tank, not all the way up to the roof of the tank bent at a 90 degree angle, thought it looked wrong. so I just finished putting in a new 14 oz sullivan tank, plus a fuel filter and new lines, also I new servo horn for one of the streering servos. I should be in good shape after the bearings are in. I also made a gasket for the radio box via one of the posts one here I read yeasterday. Registering is paying off already. I will hold off putting in the new gaskets and screws as well as the head gaskets till I hear from you guys. Any thoughts on the head shims? should I go .03 or the .10? let me know on the bearings

topfuel443 · Jun 23, 2006

We usually run the head clearance on the K&B 7.5 motors (8701 or 8702) at 11-12 thousandths. Use whatever shimming nesscesary to get to that clearance and you will be good. Definately replace the bearings. Ron is the man for bearings, he willget you the right stuff.

~James

RaceCraftBearings · Jun 23, 2006

I have the complete set of bearings in stock that being 2 for the motor and 2 for the PTO. Check out my site at RaceCraftbearings.com

I chimed in to help you in the right direction, please feel freeto buy bearing where you prefer and if you choose me then both of us will be happy.

Good Luck!

Ron

daryl2cb said:
I figured as much, I dumped some after run oil down her throat, and it made its way out by the prop, so bearing must be no good. the motor is a 7.5, I believe it to be a 8701 model as it has the square carb and no remote needle valve, I ordered the new screw set and head gasket as well as the flex shaft rebuild and gaskets. As of right now the needle is set to 3 turns out, thought that should be about right, guess it is still rich, can you get me bearings? If so let me know I definately need them. at least the two for the pto drive, the front bearing seems to be holding well, but I figure if I replace the pto bearing, guess what, the front will leak, so might as well do all at once. another discovery, the fuel tank was junk, this guy had the exhaust pressure tube(sullivan 12 oz tank) sitting in the middle of the tank, not all the way up to the roof of the tank bent at a 90 degree angle, thought it looked wrong. so I just finished putting in a new 14 oz sullivan tank, plus a fuel filter and new lines, also I new servo horn for one of the streering servos. I should be in good shape after the bearings are in. I also made a gasket for the radio box via one of the posts one here I read yeasterday. Registering is paying off already. I will hold off putting in the new gaskets and screws as well as the head gaskets till I hear from you guys. Any thoughts on the head shims? should I go .03 or the .10? let me know on the bearings