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Dumas Hot Shot 3.5

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Dumas Hot Shot 3.5

Old 09-15-2007, 09:13 AM
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kyle_yokomo
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Default Dumas Hot Shot 3.5

Hi I just got a used Dumas Hot Shot 3.5 off Ebay. The boat came in OK condition right now Im stripping it down, block sanding it, and plan to fix all the little imperfections and put a fresh paint job on it. My question is the plastic cowl looks like it brand new and so i trimmed it to fit, now whats the best way to mount to cowl to the boat, I have no instructions with the boat so Im not sure on the right way to mount the cowl, I know theres alot of ways to mount it, I just want to know what everyone else has been doing? Thanks
Old 09-15-2007, 09:26 AM
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Default RE: Dumas Hot Shot 3.5

I used velcro patches in back to hold the cowl down. Worked good for awhile but then the adhesive let go on it but all I did was finish removing it with lighter fluid and using epoxy to stick it back on. You can buy a velcro "patch" kit and I bought the 1" square type.
Old 09-15-2007, 09:45 AM
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sleepy306
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Default RE: Dumas Hot Shot 3.5

Velcro here too at the bottom back corners. Nitro and adhesive are not a good combo over time. I have used small wood screw in the middle on the velcro patch on the hull and machine nut/bolt on the cover. Just make sure the heads on the velcro are not too large that you don't have a good hold of the cover. It will last longer than the adhesive and it little bit more secure. I'd suggest stainless steel or those snazzy anodized aluminum screws if need to accent the color on your cowl.
Old 09-15-2007, 09:59 AM
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kyle_yokomo
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Default RE: Dumas Hot Shot 3.5

Yeah I thought of the Velcro method, but was wondering if theres any other methods? Also here are some pics of the boat I got it sanded and primed ready for paint. It looks like it was set-up for three servos, two for steering and one for throttle is this a good method, or should I stick with one servo for steering and one for throttle to save weight?

Oh one more thing the sponson bottoms were sanded smooth to the non-trip chine, there isnt a edge running the full length of the sponsons, is this bad? will it make the boat hard to keep tracking in a straight line?
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Old 09-15-2007, 10:00 AM
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Default RE: Dumas Hot Shot 3.5

I have a set of the construction instructions. This is what Dumas suggest (Jerry Dunlap)

The cowl is held on the boat with a pair of 4-40 screws, one on each side that screw onto 4-40 blind nuts in the cocpit sides. The actual palcement isnt too critical. On our box label boat, the screws are 1/2" ahead of Frame 3. On the next boat I built, I move the screws closer to the balance point to make the boat easier to pick up when it's wet

Place the cowl in position on the boat and drill #32 or 1/8" holes through the cowl doubler and cockpit sidesat the same time. Cut a couple 1/2" x 1" pieces of 1/8" ply scrap and install a 4-40 blind nut in the middle of each. Cement one of these nut plates to the inside of each cockpit side over the cowl holes
Old 09-15-2007, 10:40 AM
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Default RE: Dumas Hot Shot 3.5

The three cut-outs were probably for steering, throttle and mixture control. Two steering servos wouldn't be a bad idea if using just standard plastic gear servos. There is quite a bit of torque and vibration involved with running an outboard. Most people I've seen with one use a single heavy duty servo for the steering task.

I have a spare 1/4 scale servo I plan on using in my Hot Shot IV when its built and instead of using two cables or rods. I'll be trying a single-sided tiller arm with rc car type ball joints to get rid of the binding associated with un-equal length servo arm/steering bar setup and easier trim changes. It might be something to consider. I don't want to lay out the money for a high torque metal gear servo and trying to use what I have, but thats the kind I think I would buy for it.
Old 09-15-2007, 05:45 PM
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Jerry Dunlap
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Default RE: Dumas Hot Shot 3.5


[quote]ORIGINAL: kyle_yokomo

Yeah I thought of the Velcro method, but was wondering if theres any other methods? Also here are some pics of the boat I got it sanded and primed ready for paint. It looks like it was set-up for three servos, two for steering and one for throttle is this a good method, or should I stick with one servo for steering and one for throttle to save weight?

Oh one more thing the sponson bottoms were sanded smooth to the non-trip chine, there isnt a edge running the full length of the sponsons, is this bad? will it make the boat hard to keep tracking in a straight line?
[/quote

You might want to consider glueing a piece of 1/16" plywood to the bottom of the the sponsons and keeping a sharp edges on both inside and outside edges. One steering servo w/at least 60 oz. of torque should work fine. Another method of attaching the cowling is to use body clips and posts like they use on r/c cars(also the TS2 uses this method)>

JD

JD
Old 09-22-2007, 09:08 AM
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kyle_yokomo
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Default RE: Dumas Hot Shot 3.5

Thanks for all the help guys! Im going to use the velcro method to attach the cowling to the hull and I think Im going to use two steering servos instead of one because I just have standard servos.

I just got the boat painted and will post some pictures of it later today.

Some bad news though when I was putting my K&B 3.5 outboard on the boat I dropped it[] and one of the skags broke off, so I am in search for a 3.5 lower end with or without the internals, If you know anyone that has one to sell please let me know. This is the standard K&B 3.5 not the SS or SX

Thanks everyone
Old 09-22-2007, 09:13 AM
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Default RE: Dumas Hot Shot 3.5


ORIGINAL: kyle_yokomo

Thanks for all the help guys! Im going to use the velcro method to attach the cowling to the hull and I think Im going to use two steering servos instead of one because I just have standard servos.

I just got the boat painted and will post some pictures of it later today.

Some bad news though when I was putting my K&B 3.5 outboard on the boat I dropped it[] and one of the skags broke off, so I am in search for a 3.5 lower end with or without the internals, If you know anyone that has one to sell please let me know. This is the standard K&B 3.5 not the SS or SX

Thanks everyone
oooouch!! try ebay, might get a good deal,,,,,hope u'll have good time with the boat,,,,i have a real great time with mine.
Old 09-22-2007, 09:23 AM
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kyle_yokomo
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Default RE: Dumas Hot Shot 3.5

Here are some pics of the boat, also the K&B is pictured and you can see the skag is broken, I sprayed the the boat with sikkens autbase+ and sikkens autoclear III.
Old 09-22-2007, 09:28 AM
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kyle_yokomo
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Default RE: Dumas Hot Shot 3.5

OK having problems right now with the upload of the pictures will keep trying
Old 09-22-2007, 09:48 AM
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Default RE: Dumas Hot Shot 3.5

i bought the lower part of my 3.5 from K&B, and just a word of advice, put foam on the cowl underneath, i lost one with the velcro, came flying off and sank like a rock, had to wait a month for a new one from dumas.

http://www.mecoa.com/kb/89/8907-exp.pdf
Old 09-22-2007, 10:08 AM
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kyle_yokomo
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Default RE: Dumas Hot Shot 3.5

Yeah I plan on putting some foam on the cowl, I put it in the bath tub and sure enough it sank to the bottom. Thanks for the link to K&B I have looked there and they want $40 for the lower halves, just thought someone here might have a scrap set laying around they dont need anymore.
Old 09-30-2007, 09:35 AM
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Default RE: Dumas Hot Shot 3.5

Still wont let me upload pictures? After taking the K&B completely apart and inspecting it, Im not sure this motor has ever been run or broken-in? Everything looks super-clean. The flex shaft looks like its brand new with no signs of use and the piston and sleeve look the same. Any suggestions on where to start on the high-speed needle, and does anybody know the proper break-in procedure for the K&B 3.5 outboard?

Also I picked-up a Octura M437/3-blade is this a decent prop for the motor and boat, I know alot of people are saying the 440 is good to.
Old 09-30-2007, 09:43 AM
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kyle_yokomo
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Default RE: Dumas Hot Shot 3.5

Here we go
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Old 09-30-2007, 09:43 AM
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Default RE: Dumas Hot Shot 3.5

Just keep it to the rich side and don't over-rev it and stay away from synthetic oils is my advice. Use all castor oil at least 20% and a light prop. It will probably die on you the first few tries. Thats what I experienced with mine.

K&B has a website with all of their manuals and parts listing here:


[link=http://www.mecoa.com/kb/parts.htm]K&B / Mecoa[/link]


Here is a clip from my 3.5 Air Cooled manual:

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Old 09-30-2007, 04:39 PM
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Default RE: Dumas Hot Shot 3.5

Great looking paint job Kyle.
Old 09-30-2007, 05:13 PM
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Default RE: Dumas Hot Shot 3.5

Needle around 4 to 4 1/5 turns out (this is with 65% nitro) Quality fuel with at least 18% oil. One gallon, add an ounce or two of good castor oil. The 440 or 437/3 props are good to start with. I'd suggest a x1440 b/c from Props-4-U.. Motor will sound rich on shore. After a few laps it should pick up. After a couple of tanks, lean the needle in 1/8 turn. After each tank, bring the needle in 1/8 to 1/4 turn. Should end up somewhere around 3 1/2 turns out. This again depends on nitro%, sea level and a host of other nature settings.

While you have the lower apart, is there a oiling hole on either side of the lower halves? This would be on the lip where the power head is attached to the assembled lower. If one is not there, drill one in. If you don't plan on racing "sport" tunnel, drill/tap this hole, mount a 4-40 nipple on and place a remote oiler somewhere.

On my boats, each are held down by 6-32 nylon thumb screws. The front of the cowl is attached by a lip hold down of some sorts. Cowl lower lip goes underneath the tunnel floor or there is a block (wood / metal) that is mounted front of the radio box that holds the cowl bottom in place. The 6-32 screws are used back by the transom...

Lip at the front:


Screw holes in the back:

Old 09-30-2007, 09:18 PM
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kyle_yokomo
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Default RE: Dumas Hot Shot 3.5

Thanks for the info everyone, its helped me out alot.

Its funny how a hull (hot shot 3.5) thats been out for a long time is still so competitive against the likes of the top speed 2 and others. Where I race there are a couple of hot shot 3.5s that consistently beat the other newer designed hulls, plus I like the looks of the hot shot compared to others it looks just like the real tunnel boats.

ob nut whats with the two fuel tanks? just curious if you know something I should know about

Another question how much better is the K&B 3.5ss compared to the basic K&B im running? I know its not water-cooled has a bigger carb on it has a better exhaust system, is it alot faster? and what about the K&B 3.5sx Im not sure thats the name but it looks just like the SS but has a red head on it I believe and a different colored exhaust.
Old 09-30-2007, 11:12 PM
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Default RE: Dumas Hot Shot 3.5

I've used a little CA to hold the Velcro on. Another trick is ot run a wood dowel or a plastic equivalent through the sides and use body clips from the RC cars and trucks to hold the cowling on.
Gary Preusse is expecting an order from K&B soon and mentioned that there is supposed to be a run of 7.5's for those looking for them. You can call him at630-279-2451 or try Joe Monohan at 707 Specialties.
Old 10-01-2007, 12:10 AM
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Default RE: Dumas Hot Shot 3.5

The top tank is a "hopper" tank. It helps feed the carb with the higher exit point on the hopper tank. Some boats don't need them. The twin tanks have now been replaced with a Grimracer 7oz thank that was around.

My wood Sprint was radar'd at 46.3mph, K&B SS (purely stock - no mods), Wildcat 65% fuel, Props-4-U X1440 B/C.. It has taken a few local IMPBA races, even one where I loaned it out to a fellow club member who beat me with it

The SS motor is a leap over the motor you have. The SX is close to the SS, from what I've heard. It's just a water cooled version of the SS. It has a black head, not red.
Old 10-05-2007, 04:31 PM
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Default RE: Dumas Hot Shot 3.5

Dear Ron, i dont know if MECOA still making K&b outboard, can you know if i order a OB 7.5 from mecoa.com?, thanks and sorry my bad english
Old 10-05-2007, 11:14 PM
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Default RE: Dumas Hot Shot 3.5

I was talking ot Gary Preusse a week ago when I ordered some parts from him and K&B is going to start producing the 7.5 OB's again really soon if they aren't doing it now. He is still waiting for them to start making the inboards.
As an aside, if anybody is using the K&B glow plugs, buy them now as the price is going up next year with a $1.00 increase.
Your English is fine, never worry about it.
Old 10-06-2007, 08:46 AM
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Default RE: Dumas Hot Shot 3.5

What other glow plugs will work with the 3.5 K&B?
Old 10-06-2007, 08:54 AM
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Default RE: Dumas Hot Shot 3.5

It will depend on how much nitro you shove into it. The 3.5's love the stuff so they really perform well with 45-65%.

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