Custom/Hybrid Schmidty's BOB build

[Schmidty721]

Time for a long overdue update.

Pump:
Got my 10/16 hooker installed with 5mm spacer to push it out to a -2mm cutback. Jetworks recommended this to let my engine spin up a little quicker and to relieve some load right of the bottom. I also bored my reduction nozzle to 84mm and re-visited my trim system to get a few more degrees of throw out of it. Pump is installed with all cooling lines run, pump seal in place and midshaft mounted/sealed.

I had a brand new WSM steering cable that had a bunch of free play in it. I called up WSM and told them about the issue and he gave me his UPS account number to ship it back. They warrentied it without question, the the new cable still has freeplay. Not sure what the deal it. I'm going to run it for now, if it bothers me I'll bite the bullet and by a new OEM.


Handpole:
Finished up the fat bar mount, got all cables, electrical, hot hands plumbing and breather tubes run. Modified the original 'chin pad' on the WDK pole to work better with my fat bar pad and setup. I'm also running a set of Mt. Bike levers I picked up for $12. They provide a little more throw to use off of the available trim. Had to modify them to accept the calbes, but I think they will work out jus fine.

 

[Schmidty721]

Engine

While I was waiting for my cylinder to get back from Jetworks, I worked on filling the crossover and port matching my 760 intake to V-Force reeds I picked up. Cross over filling was simple. I used some two part epoxy putty. Matching the V-Force reed cages took a bit more time. I had to fill in part on the outside of the oval where the stock port was wider than the V-Force cage and then open up the corners to match the more square design.






I also painted my cases and had a few parts powder coated while waiting for my cylinder.

Got my cylinder back and assembled the engine. After putting the head on I realized I needed to recut my domes for the larger bore size. The squish band diameter was not wide enough anymore. I'm running a 5mm stoker without cylinder spacer so my domes are cut to accept the positive piston deck height. I got in touch with a co-worker and made plans to meet the following day to cut the domes. Cut the diameter larger and reinstalled the head to check squish. It wasn't even close... about .022". Went back to the lathe cut more material out of squish band to get squish to ~ .045". After squish was set, we cc'd the heads assembled. 23cc total netting a static CR of 17:1. Time to cut some material out of the domes. Took us awhile to figure out how do recut the domes and ended up using a 3/4" ball end mill. I took 4.5 cc's out of each dome. This puts me at about 15:1 and hopefully right around 200psi cranking. All said and done, about 7 hours of dicking around with the head. But it's done and everything is back to speck.

 

[Schmidty721]

More engine

After all the fun with the head, the engine was assembled and ready to pressure test. I ended up having a few leaks on my base gasket so I tore the engine back down, put a thin coat of 1211 on the gasket and reinstalled torquing the girdle studs to 33 lb-ft instead of 26. Then when I was putting the head on, I snapped the last head bolt in the pattern while torquing to to spec. Pulled the cylinder back off, extracted the bolt and repeated the process. So after about 25 hours of engine assembly, it's finally together.




Next I tried to install the billet couplers I purchased used. Got the engine side coupler on about half way and it started getting difficult to turn. I used a pry bar and got it on about 3/4 of the way before it became too difficult. I think the coupler itself is out of round from using what looked like pipe wrench marks to remove it. I posted a WTB add for some couplers and the 615 boys came through and had me a set of new ADA's in two days. The new coupler went on like butter!

Next step was to drop in the hull. The engine lined up nicely side to side, but it was sitting too high. I contacted the Ski Clinic and Derrick informed me that the first few hulls they produced were setup to run without any shims. Needless to say, there is some variance in bed plates which they soon found out. I messed with my motor mounts and spread them as far as I could to let the engine settle a little lower. This helped a bit, but not all the way. Next I loosened the mid shaft and held it upward to eliminate any play between the bolts and holes in the mid shaft. This also helped slightly. I'm now within about 1/16" from being perfectly aligned. I am going to try to run it like this and keep and eye on mid shaft temps. Obviously if I experience severe vibrations or other issues I will pull the engine and machine the bed plates to drop the engine.

 

[Schmidty721]

bilge pump and EPIC

I wanted to run a bilge pump on top of the versa-plug on my ski. With the engine setback as far at it is getting a bilge pump down by the couplers looked like a hassle. I ended up mounting mine in the right rear corner using the rear exhaust tube and a brace and made an aluminum strap to clamp around it. It's not optimum placement to remove all the water, but it will still help when I need it most; when the engine bay if swamped. The scooper will take car of the rest.




Tonight I built my Ebox including a new EPIC cdi. I had two set of 61x electronics and a set of 62t from a couch. I used the best looking parts out of each to build what I hope will be a trouble free setup. I got my stator and flywheel installed and everything wired. Hit the start button and she turned over nicely! Also have nie strong spark so I'm keeping my fingers crossed that I won't fight any of the issues others have had after installing the EPIC. Tomorrow I'll work on getting the box closed up and mounted as well as putting together a couple of ignition curves.

 

[Sanoman]

Awesome write up and great work man! l hope you get it the water soon.How are your water temps?

 

[Schmidty721]

Ice on the river just went out this past weekend. We are in flood stages right now, so everything around here is no wake. I would guess water temp is mid 30s.

 

[Sospikey]

I wanted to run a bilge pump on top of the versa-plug on my ski. With the engine setback as far at it is getting a bilge pump down by the couplers looked like a hassle. I ended up mounting mine in the right rear corner using the rear exhaust tube and a brace and made an aluminum strap to clamp around it. It's not optimum placement to remove all the water, but it will still help when I need it most; when the engine bay if swamped. The scooper will take car of the rest.

View attachment 149264View attachment 149263



Tonight I built my Ebox including a new EPIC cdi. I had two set of 61x electronics and a set of 62t from a couch. I used the best looking parts out of each to build what I hope will be a trouble free setup. I got my stator and flywheel installed and everything wired. Hit the start button and she turned over nicely! Also have nie strong spark so I'm keeping my fingers crossed that I won't fight any of the issues others have had after installing the EPIC. Tomorrow I'll work on getting the box closed up and mounted as well as putting together a couple of ignition curves.

By placing the bilge like you did you will have no issues with cavitation in the bilge if the water starts to rise. I keep one pump in that position and one under the coupler along with my Versiplug scupper. Works like a charm!

 

[yamahahaha]

dang.. im in minnesota and I cant find a bob anywhere.. I want one so bad but I dont have the money to order a complete ski or the knowlege to build one. My only choice is to find a new one and there are NONE around here hahaha.

 

[Matt_E]

dang.. im in minnesota and I cant find a bob anywhere.. I want one so bad but I dont have the money to order a complete ski or the knowlege to build one. My only choice is to find a new one and there are NONE around here hahaha.

Order a new hull from Skiclinic?

 

[yamahahaha]

dang... Im in minnesota and I want a bob so bad but I dont have the money to order a complete ski or the knowlege to order a hull and build one.. my only choice is to buy a used one but there are NONE around here hahaha

 

[AZRIDER]

dang.. im in minnesota and I cant find a bob anywhere.. I want one so bad but I dont have the money to order a complete ski or the knowlege to build one. My only choice is to find a new one and there are NONE around here hahaha.

This stunt has been forsale forever in michigan
http://www.x-h2o.com/threads/81899-stunt-for-sale&highlight=custom+hull+forsale

 

[Schmidty721]

You have a SJ to use as a donor? Shipping is pretty reasonable on a bare hull this size and weight, espically if you have access to someone with a shipping account. This one came from the Ski Clinic through our fed ex freight account for $144. Where in MN are you? Check out the TC Jetpilots www.TCjetpilots.com I'm sure you could get help putting a BOB together.

 

[Big Kahuna]

After all the fun with the head, the engine was assembled and ready to pressure test. I ended up having a few leaks on my base gasket so I tore the engine back down, put a thin coat of 1211 on the gasket and reinstalled torquing the girdle studs to 33 lb-ft instead of 26. Then when I was putting the head on, I snapped the last head bolt in the pattern while torquing to to spec. Pulled the cylinder back off, extracted the bolt and repeated the process. So after about 25 hours of engine assembly, it's finally together.


View attachment 149259View attachment 149260

Next I tried to install the billet couplers I purchased used. Got the engine side coupler on about half way and it started getting difficult to turn. I used a pry bar and got it on about 3/4 of the way before it became too difficult. I think the coupler itself is out of round from using what looked like pipe wrench marks to remove it. I posted a WTB add for some couplers and the 615 boys came through and had me a set of new ADA's in two days. The new coupler went on like butter!

Next step was to drop in the hull. The engine lined up nicely side to side, but it was sitting too high. I contacted the Ski Clinic and Derrick informed me that the first few hulls they produced were setup to run without any shims. Needless to say, there is some variance in bed plates which they soon found out. I messed with my motor mounts and spread them as far as I could to let the engine settle a little lower. This helped a bit, but not all the way. Next I loosened the mid shaft and held it upward to eliminate any play between the bolts and holes in the mid shaft. This also helped slightly. I'm now within about 1/16" from being perfectly aligned. I am going to try to run it like this and keep and eye on mid shaft temps. Obviously if I experience severe vibrations or other issues I will pull the engine and machine the bed plates to drop the engine.

View attachment 149261View attachment 149262

Did you re-align the pump to the midshaft? If not, you will strip the splines on the drive shaft. Been there, done that........... Not fun nor cheap!!!!!!

 

[Schmidty721]

Did you re-align the pump to the midshaft? If not, you will strip the splines on the drive shaft. Been there, done that........... Not fun nor cheap!!!!!!

The midshaft only moved upward about a 1/16" so I didn't mess with pump alignment at all.

Got the ebox all sealed up last night and mounted in the hull. Starting running some of the cooling lines and trying to tidy up all the electrical wires. It looked so clean before the ebox went in!

I want your guy's opinion on a bilge fitting location. I'm debating on placing the fitting on the inside-side of my front foot hold. It is easily accessible to plumb in and would be out of the way. My only concern is with it being close to the water level. Would I have issues with water entering the engine bay through the bilge pump, or do they only allow water to flow one direction?

Got my pipe chamber back from ceramic coating last night too. I think it turned out nice. Was done by a shop in a small town about 30 min away. He charged my $75 for the chamber, but said he'd do the whole system for $125 plus any shipping charges. I have is contact if anyone is interested. I thought this pricing seemed pretty reasonable.

 

[Big Kahuna]

If you were already a smiggen off, and you added 1/16" (Which is huge) then you may really be asking for trouble. Take the time and align your pump with your midshaft. Then if your motor is still way out, then machine your bedplates to compensate for the mounting points being off by the builder. How much money do you already have invested? Is it worth destroying a drive shaft and midshaft.

I stripped mine at the 05 Lanier ride 15 minutes after I got there. I ordered a new intermediate shaft and got another drive shaft, It was fine for a year, then same thing. I did not consider why it stripped. Took my ski to the Myrtlebeach race in 2006 Paul Lehr met me there with a used drive shaft and intermediate shaft, while I was working helping setup the race site he and PancakePete snatched my motor and driveline, swapped parts and found out what had happened. My Bedplates had shifted some, that is all we can figure out. It was at least 1/8" on the low side (Motor).

 

[Schmidty721]

Almost done

Well, the end is in sight! I would say the build is about 98% complete at this point. I think all that is left is to wire my bilge pump, make and install a limit rope, install fuel filters, and finish arranging cables, wires, hose in the engine bay.

The rest of assembly went pretty smooth. I did run into an issue with my fuel tank and steering cable. I had to build up one side of the engine bay with turf so the tank wasn't resting on the steering cable. I also put a couple layers of turf under the waterbox for a little extra clearance between the pipe chamber and bedplate.

I ran a compression test on the engine once everything was installed and had 210 front, 208 rear. I'm happy with these numbers and very pleased the front/rear are so similar. We kind of took a shot in the dark with what amount of cc's to cut out of the domes.

I also put the ski on one of our shipping scales. 255lbs complete, ready to ride, no fuel with light weight battery (6 lbs I think). I picked up a couple gallons of race fuel tonight and will hopefully get this thing in the water if we have a nice day this week. The river I typically ride is flooded right now and debris everywhere in the water, so I'll need to find a lake to put in for the madden voyage. I checked water temp in the river today, 44 degrees!

 

[Jr Freestyle]

turned out nice, where did you find the black fuel lines?

 

[Schmidty721]

The fuel line is just some low pressure stuff we use on our carburated bikes here at work. Not sure who makes it.

 

[Schmidty721]

It's Alive

Fired it up tonight. Idled smooth and fired right off. Hopefully ride it tomorrow.


[video=vimeo;22270348]http://vimeo.com/22270348[/video]

 

[Schmidty721]

Got my first ride in tonight. Water temp was somewhere around 50 degrees so not too bad. Air temp was low 60's. The ski ran OK. I have some tuning to do as is expected when you change around a bunch of components as I did. Seemed a little rich off the bottom. Mid range up ripped pretty hard. The 10/16 hooker has plenty of speed for this little hull. I put together a toned down ignition curve for the EPIC and lowered the rev limit to 7500 for the break in. I'll begin to add some timing back into it slowly as the tune gets closer. I'm also new to B-pipes, so have lots of experimenting to do with the screws. I started with 1/2 turn bottom, 1/2 turn top, middle closed. I need to get a tach and set my flow control valve too. Judging by sound I think it is pretty close. I developed a rattle in the engine towards the end of the ride. I think my bendix may be hanging up and I'll have to look into it before the next ride.

The BOB hull is going to be a fun ride. I was pleasantly surprised with how it rode. After a few minutes I was able to cruise around, corner somewhat aggressively, do some slide 180's, etc. High speed stability seemed OK as well, all though it does get a little sketchy when you let off the throttle after cruising at higher speeds. I'll have to experiment with my steering position some. Next ride I'll go to my forward mount position on my steering plate which will shorten my overall length by about 1.25". I think I may like the position a little more as I start to ride more aggressive.

I also had the chance to ride a pretty mint 300sx some guys had just picked up for $50. He was there with his sun and daughter with two sit down's and the 300 just trying to get everything to run. 300 ran great and they are a fun little ski to ride.