tohatsu 40

I have a tohatsu m40d2 1998 engine.<br />What can i do to get more power?<br />Is it possible to make it a 50 HP ?

Re: tohatsu 40

Not cost effective.

Re: tohatsu 40

Very cost effective, drill the carbs to 25 mm (about 1") now 22mm and change the main jet, clean the middle port in the cylinder and you will have over 50 hp.<br />Cost= headgasket!<br />On a heavy boat the differene is only 1 knot<br />but on a lighter boat several knots!

Re: tohatsu 40

The 40 hp two stroke was a very strong 40. I have used the 40 and the 50 and there seemed to be a negligable difference. <br /><br />Just out of curiousity why do you feel you want more power? Is it having trouble getting on plane? Does it seem to lack low end out of the hole or high end speed? Is it too much boat for the motor? Or are you like me and just simply want every ounce of power that the motor is capable of making?<br /><br />I know these seem to be stupid questions, but many times people have problems that can be rectified by moving the cavitation plate, better trimming, or better proping to max RPM etc. Many times we can make your current set up more efficient without tearing apart your engine yet still get the performance you desire. <br /><br />If you have already tweaked the performace through proper set up, then you either need to modify your current engine or move up in HP. Elvin is by far the most knowledgable on these boards when it comes to Tohatsu/ Nissan engines.

Re: tohatsu 40

As I said...it is not cost effective to turn a 40D2 into a 50D2. That engine has a different block, crankshaft, exhaust tube , etc. The cubes are the same, but the block has different porting and the crankshaft has different bearings.

Re: tohatsu 40

VERY SAGE ADVISE,here..<br /><br />think you'd get more BANG from a diffirent prop size..<br /><br />( i always thought the 40 & 50 were the same ..as in most brands..) <br /><br />magin' that,, i learned somthing..!!

Re: tohatsu 40

Theese engines are exactly the same exept the carb.<br />On some models they used different crankshafts but this was only because they had a problem with a loose fitting (the crank did not stay staight, twisted very easily) the stronger crank was first used on 50 hp. but later all models used the stronger crank. However no problem you can weld the crank so it doesn´t move. I have changerd several 40 hp engines and they are stonger that any 50 hp. in the store! Despite very cheap to get some extra 15 hp. but you have to do the work by yourself otherveise it can become expensive. for normal use there is absolutely no reason to do the job but if you have a light boat and want to go fast........

Re: tohatsu 40

My head is really hurting now. In mid year 2003 Tohatsu made a change to the production process where they detuned the 50 down to the 40. That was done to save production costs. Those engines do share the same block and crankshaft. However, you would still have to change out the tube and the carbs. From the first half of 03 and earlier you still have to change out everything else. Also, the Tohatsu 40 D has never had a problem with crankshafts twisting. The few cases where a 40 D has twisted a crankshaft can all be traced back to inflatable boat racers who have run them way over the top rated RPM and damaged the cranks or to people who have had high speed impact(running in to things) stops on the lowerunit.

Re: tohatsu 40

I think Bolaget's idea of cheap is if you have a fully equipped machine shop at your disposal. . . free, and the skills to use the equipment.<br /><br />If you want more reliable performance go to a bigger engine.<br /><br />If you want to race in a displacement class then get Tohatsu to give you exact dimensions and instructions for modifications for competition version of your engine. Then go find a sponsor with deep pockets to pay for it all.<br /><br />Oh, and build a second and third engine to use while the grenades are being repaired.

Re: tohatsu 40

Yes JB is so right!<br /><br />Everyone tampering with those engines needs a complete workshop + a lot of know how, it is not possible to get the know how from the factory, I have played around with those engines for about 20 year and learned everything by trial and error. Another point is that why do you want to go faster, want to burn more fuel? Are you in a constant hurry? Or is your neighbour driving 8s around you?<br />When I modified my 18 hp tohatsu it took me about 3 years to get it working properly, the poweroutput is about 25 hp. But the best tuning trick was to put on a 9.9 decal set which I got from Japan. Later on I put the engine aside and took a bone stock 9.8 and was very satisfied with the lighter and cheaper to run engine, so think twice, what is the general idea???

Re: tohatsu 40

I may have a 1991 50hp. Tohatsu with controls, and cables for sale. I am going to do a trade for it.<br /><br />Regards,<br /><br />Steve..