Budget d-mod build up

[Morris85C]

I know the last ones i got from Dudly were 1450 each I got 2 of them New towers are about 450 500 bucks for a new D mod power head every thing new But the block an crank 4500 an that is all the good stuff.So for a new D mod moter with all the goodies your looking at 6,450.00 Not bad for a race ready moter. AN yes they are faster then the moter you port with a file.

[form-e one]

mmm well we building d-mods now as we chat,,, got 44xs style stock motors latest ignition from e-bay 200$,,, port job from john meyers around 125$,,, stacks about 600$ kc carbs,,30$ each,,, the specs keep the limit down on porting sooo ..unlike our unlimited v-rudes,,and with this combo and a little fileing to match mateing surfaces up we can see 90mph or about 85mph short course,,,,,, nothing to special.... to me lee tietz makes the best towers and they short ,, spendy but i figure that my life if that mid section brakes ... i blew my feh over and the tower is just fine .. from tietz... so i spend the money there,,, the bass mid sections good also ,,just taller... d mod gear cases can run about anything since not alot of torque there,,, alky cases etc,,, they handle better than merc cases,,, i run bass just cause they proven,,all this and we will have a starter on it soo just push the button to start it ,,,like my v-rude

[PRO-MOTIONRACING]

Phase Two

Phase two, The filler block. with the porting done I rough up the surface around the ports (as seen in previous pictures) so when I bed the filler block in the epoxy sticks better.
I have seen the filler block done many ways, from mounting it to the cover plate and running it dry to bedding it in with silicone sealer,. I am not saying this is the best way, but this is the way I do it...
First I fit it to the filler block to the engine block, there are always differences in the castings so there is often grinding on the filler to be done. Make sure that the face of the filler block is at least level with the block face, when in doubt a little loose is better to allow for expansion. Expansion of the filler is a bad thing, it will push on the cylinder wall distorting the cylinder and damage could occur.
To counter expansion I run the filler block wet. First I drill holes between the ports in the filler block to allow water to run through it, usually two in the center and two in the other two bridges and nothing on the ends. Then I drill the water tubes in the block, the ones that look like bolt holes. I try to angle them so that they will be like sprinklers spraying on the filler block. I allow the water to exit by drilling holes in the cover plate so that they will cool the elbows also. While I am at it I also drill out the second layer in the water inlet in the bottom of the block. As a final part of the cooling I drill very small holes in the water jackets on the fuel pump side just to be sure we have circulation and no stagnant hot spots. One last thing, this block did not have the fitting in the top for the pee tube so I drilled and tapped it.
I use Marine Tex epoxy to mount the filler block. I drill and tap small holes in the filler block, then mount angle iron to it to hold it level with the gasket surface. I then coat the blocks with a layer of epoxy and squish it in place. Then using a finger I smooth it around inside the ports and around the outside of the filler block. After it sets up I dress the epoxy withe the die grinder, often a second coat is in order to assure proper sealing.
With the filler block done I install the cover plate and port match that to the filler block, then remove the plate install the elbows and port match those ta assure smooth flow through the exhaust. Lastly I chamfer the ports with that cut off file that other guy mentioned and give the bores a honing.
Well that's it for block preparation and just in time, the weekend is here and it's motocross season so time to shift gears and keep my focus (currently 3rd in points in my class). Be back in a few days.

[Dave M]

Nice

What I like best about this D Mod build is you are not asking questions, you are doing and posting what you are doing. It is great to see someone still willing to put together a race engine like this, and learn. To many times people ask advice and they get a ton of suggestions and arguments from various builders about what works and what does not. Each build is not the same. What works for one builder might not work for another, depends on the block, and other things done.

The MOST expensive part you will find on just about any Mod engine for you DIY builders will be the tower housing and gearbox. Most of the towers now are not the old pipe style and the costs are now well over $1000.00 for one. And gear boxes are now $1500.00 or more new. You will spen dmore on these two items than your whole engine.

One other item that is expensive if you don't have them already are the elbows and pipes. I still feel the best design out there is the old Bayer style. I think these might run you near $500 - $1000.00 for brand new depending on what brand you do end up with. This can add up I guess if you are new starting from scratch.

Thanks Pro motion for detailing your project.

Lonnie, I can say that those hand filed engines can be just as fast or faster than those milled engines... I can say thoguh, we have had machine shops mill ports in and such, it is just faster to get the material removed.. hehehehe.

[blueskyracer]

Very interesting. I had to look at the pictures and read the description a lot to figure out where all the holes were put.

[blueskyracer]

Dave M you are so right. It is nice someone is willing to share there secrets to promote the class like Dale. You are right about the rest of the motor costing more than the powerhead. And dont forget those 4 blade props, ouch!

With all the other posts going on it is nice to have a boat build one and a motor build one with out all the &*$%^% That new folks can enjoy and maybe get interested in the sport. Anyone want to start one on getting started and boat set up????

[Morris85C]

Yes Dave you are right. I used to do all my ports by hand.Then i got the mill WOW much better.But if you dont have one then doing them by hand works too.BUT what i can tell you is the closer you get all the ports the same the better your moter will run.an that is hard to do by hand. But it can be done.OOOO I was going to tell you that your ride in cail is all most ready for ya cant wait to test it.See ya soon.

[B Walker]

This post has inspired me to do a step-by-step for Stock Yamato 302 in a similar format as we have a new powerhead coming soon.

Inspiration is good! We need more of it!

BW

[Morris85C]

If there is any one out there that needs help or parts for a Dmod motor I would be more then happy to help them out.

[blueskyracer]

This post has inspired me to do a step-by-step for Stock Yamato 302 in a similar format as we have a new powerhead coming soon.

Inspiration is good! We need more of it!

BW

Thank you we need more helpfull and positive posts fore sure.. And Lonnie I hope folks will take you up on any help. Should they contact you with a private message or do you have more contact info?

[Morris85C]

They can do it here.There is nothing to hide.Or if they want they can call me 209 629 0811 We need to per mote the sport an i will help any way i can.

[Dave M]

See U in April

Yes Dave you are right. I used to do all my ports by hand.Then i got the mill WOW much better.But if you dont have one then doing them by hand works too.BUT what i can tell you is the closer you get all the ports the same the better your moter will run.an that is hard to do by hand. But it can be done.OOOO I was going to tell you that your ride in cail is all most ready for ya cant wait to test it.See ya soon.

I can hardly wait for April. I am ready to see if all this hype is ready to be driven like a red headed step child ! You have some West and wood in the shop ? In case some mods need to be done ?

[modhydro]

Cost of parts

I'm not sure what others are getting price wise for towers, but my cast one is still at the same price it has been for nearly 10 years. They are $575 including the lower unit adapter plate, the thrust socket assembly and steering bars. That is mounted up on bronze bushings when you supply the center section. It is also designed so that you don't need an upper adapter plate for the powerhead. That just never made sense to me.

That is quite a bit cheaper than $1000. Lets not scare people away by ambitious rounding. That being said, I have the pattern at a new foundry for a batch to get quoted. I may have to have the first price increase since I started making them, but I will do my best to maintain the current pricing.

I'm not sure what Cliff Johnson is getting for his current rentition of the O'brien towers, but I think it is not that expensive either. There are options out here to help guys that want to race.

Steve Roskowski

[blueskyracer]

Steve are you also the one who makes a killer ignition system for these motors??

[modhydro]

Mod Mercs

One of these? That is me. One is headed out your way incidentally.....