# hopping up johnson 25hp jet



## blazer02 (Aug 17, 2014)

I have a 2002 johnson 25 horse motor with a jet on it running on a 18x48 blazer sport that I'm trying to get a bit more speed out of.motor has had carb upgrade to a 30 horse.I'm currently running arounnd 20-21 top end down river and 17-18 up river with me and one other person in boat.not looking to blow anyone off the water just looking for around 26-27mph down river top end.auger been sharpend and sanded.anyone know of something else that can be done to motor or jet unit for alittle more gain.any knowledge or advice be greatly appreciated thanks.


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## Jeeper (Aug 17, 2014)

the best person to talk to would be lil blue rude he knows that stuff darn good have to just wait till he gets on and sees this thread he should be able to help you greatly...good luck


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## Lil' Blue Rude (Aug 18, 2014)

Thanks Jeeper.
You can cut the leading edge of the liner so that it meet the edge of the impeller blades. It makes a smoother transition from the shoe to the impeller. You can also polish the inside of the pump. Doesn't have to be a mirror just need to remove the casting flaws and make it all smooth. You can do the same thing to the shoe too. I always sharpen my impeller from the top side of the blade bringing the leading edge down so it will catch more water, seems to give better bite coming out of the hole.
You can play with your motor height. You want the motor as high as possible without it cavitating coming out of the hole. You can also mess with your trim angle. You don't want a lot of weight up front. makes more of the boat ride in the water and creates a lot more drag. 

Those are some of the simple easy gains, from there you have to start diving into the motor. First I'd get some fiber reeds like Chris Carsons or TDRs, after that you can shave the head and build a exhaust tuner for it, if you want to get wild with it you can port the motor too. You have to know what your doing but that will get you some big gains doing all the motor work.
So are you here in Missouri?


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## blazer02 (Aug 18, 2014)

Yeah I'm in Missouri over here in shannon county lil blue.we have sharped the auger already on the top like you said motor height is good as far as tilt I'm running in my best over all setting.I can gain about another mph top end by adjusting it one more hole but have no reverse with two of us in boat and it is very slow out of the hole but does get up on top alittle better if you have enough of a run to get it there.we have done some sanding on the jet itself to remove some of the casting marks but i have some pitting on the intake side from sand and rocks going in i guess.can a stainless auger go in this motor and if so will it help any.i also had a guy tell me for$125 he can shave my auger down from 4lbs to around 2.he has done this to one other motor and said he saw a noticeable improvement..does shaving the head shorten the motor life in the long run and how do you go about working the exhaust over on one?I'm not looking to be the fast guy on the river i run mostly on 11pts and this time of year water is dropping i would like to be up out out of the water a little more.a new mega 25 tohatsu would solve my problem but at close to 7 grand its just not gonna be possible in the near future .if i could make some changes here and there for 1000 to 1500 and get. close to the performance I'm wanting that will be good enough for this ol boy.ultimate goal is to get around 30 with just me in the boat.


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## Lil' Blue Rude (Aug 18, 2014)

Hey I'm a Shannon county boy too. If you've run on the Current any you've probably seen me around. I use to run the 2 cylinder evinrude in my sig but now I run a short shaft 60hp evinrude Blue and white on a polished Blazer SS. Both of my motor are built to the hilt and run like a scalded dog. Lighter impeller will help them spin up a little quiker but a stainless would be better. Don't think they make a 5 7/8 stainless but pretty sure you could have a 6 1/8 cut down to a 5 7/8. I think 30mph with your budget is doable as long as your boats not really loaded down and the bottom is in good shape. 
Gonna send you a PM


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## blazer02 (Aug 18, 2014)

Don't make current river much anymore haven't even had time to run boat in the last 2 years intill last month and had it out every weekend now.boat has a good bottom but a few dings here and there nothing bad though cost of running down at turners and whitten.boat not loaded to max but is carrying alittle weight has satellite floor rod box and big livewell and around 100 lbs of gear in it.would anding power trim gain me much i thought it might be consider i could keep motor down for fishing and get the most out of it then when I'm running.if so are the cmc units any good i think i found a decent buy on them.the boat ideally needs a 40 on it for its size but 25limit on 11pts can't give up my trout fishing and the bigger boat nice if i fish 3 outta boat or take the wife and kids riding.might be down on current river one of these days if i can get her lined out and running a bit harder.what is the story on sharping your grates i had one buddy do it and he said it helped and another that it hurt.


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## blazer02 (Aug 19, 2014)

Lil blue got your PM and sent you one back.thanks


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## rktman (Aug 22, 2014)

I am very interested in your results since I have a similar setup (1648 blazer/2000 Johnson 25 jet). 
Keep us updated on your progress


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## airbornemike (Aug 26, 2014)

I'm running a 30hp Johnny jet and would be interested in the results as well. Blue Rude, what's your take on "diving into the motor" ? What are the mods I need to do for more ponies? Sorry for the hijack


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## Lil' Blue Rude (Aug 26, 2014)

When I talk about diving into a motor normally I mean something like some intake work, reeds, port work, maybe shave the head depending on the compression, exhaust, maybe a lightened fly wheel depending on the motor. Pretty sure you can get close to 40hp or so out of one of these motors.


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## airbornemike (Aug 26, 2014)

Thank you sir.


[url=https://www.tinboats.net/forum/viewtopic.php?p=364550#p364550 said:


> Lil' Blue Rude » Today, 15:32[/url]"]When I talk about diving into a motor normally I mean something like some intake work, reeds, port work, maybe shave the head depending on the compression, exhaust, maybe a lightened fly wheel depending on the motor. Pretty sure you can get close to 40hp or so out of one of these motors.


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