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Charger25

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Hey if I repalce the high speed jet in a 25 with one from a 28hp .would I go faster? Or is just not worth it
 
You will lose power by installing the 59D
The number roughly corresponds to thousandths although it is actually a "flow rate" number according to Engineering.
The letter designates direction of flow through the jet. There were "D" series and "C" series jets.
 
Thanks Pappy, guess its best just to leave it alone. The reason I was thinking about it is cause a bud of mine had a 14' Lund with a '95 25 hp Evinrude. I rebuilt his carb and ran it on the Lund, best speed I could get was 26/27 mph according to my GPS. I adjusted the trim and load and that was the best I could get at WOT. I thought it would run faster. Well now he wants to race :LOL2: Mine will run a solid 30 mph. Both boats are semi-V and basically just row boats, no decking or anything. He has no idea that I've clocked both boats with the GPS . What I did notice is that his motor sits lower than mine, guess its creating more drag.
Didn't mean to get long winded, but I'm gonna enjoy the case of cold ones......... :beer:
 
Don't know how many posts you have read but have been noticing for the last couple years that jets have been eroding. You may want to get a new 51D or even a 50D and pop it in there and see what the changes bring. Have seen them erode up to 4-5 jet sizes with ethanol fuel. Don't have a clue why yet. Not all are doing it and have seen some engines where they are all eroded so something is going on.
 
Not to interrupt the conversation, but are you talking about brass jets eroding Pappy? I hadn't heard anything about this so it's got me curious about my motor because I'm pretty sure it's not running like it did the first few years of it's life. I bought it from a friend and remember how well it ran when he got it.
 
That's exactly what I am talking about.
Get yourself a good # drill set and check them. Sometimes they are not exact to what the # on the jet is but always very close. Lately I have seen these jets erode to several sizes larger. Questioned the customers in almost every case and none have been drilled out and cannot find any marks that would indicate this to be happening. My next door neighbor had all four in his looper V-4 replaced by me. The engine was running super rich and very sluggish.
By all means give it a try and let us know what you find.
 
Well guys now that I think about it, I've got a older CJ-7, I cannot run "modern" lubricants in the transmission due the additives eating up the bronze bushings. Older Jeepers call it the yellow metal transmissions. I can only run G-4 or Valvoline syn. That being said,it doesn't surprise me that some additive, either in the fuel or the oil that would be responsible for eroding the jets. If you think about it, a LOT of fuel mix goes through that tiny orifice in the jet.
 
Pappy have you been able to confirm this in engines that have been running ethenol free gas? I'm wondering if its the new oil insted of ethanol
 
That I have been able to confirm. Some have been using both. None seem to run the same lubricants so far.
Have looked high and low in the net for information on brass jet erosion with very little success. Have seen a lot of references but no hard science to back it up.
Learned a lot more about bronze bushings along the way though! Thought I was back in metallurgy classes again.......ugh!
 
Hey Pappy, from what I can find out it's the type sulfates in the oil that are eroding the bronze // brass bushing in the transmissions.

https://www.jeepsunlimited.com/forums/showthread.php?486783-T-176-Manual-Trans-Why-was-old-oil-red-in-color&highlight=yellow+metal


https://www.jeepsunlimited.com/forums/showthread.php?536877-t-18-Oil&highlight=yellow+metal


https://www.jeepsunlimited.com/forums/showthread.php?420335-Lubricants&highlight=yellow+metal

These links are from JeepsUnlimited that I frequent as I have 2 Jeeps

I'm wondering if the 2 stroke oil has the same type of sulfates?
 
Didn't find anything conclusive in those links.
I don't ever put much stock into a bloggers statement that he has run "X" for some amount of time with no ill effects so therefore "X" must be good.
We see that here and in other outboard oriented forums a lot.
However when you do a search for "sulphur in TCW3 oils" you begin to get meaningful results.
Here is one blog outlining the chemical make-up of Pennzoil TCW3 oil. Note the high levels of sulphur in the overall package.

https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=475055

Interesting to note (when looking at the results for the above search parameter) that the diesel truck guys are now starting to add TCW3 oil into their fuel to make up sulphur content in the newer low sulphur fuel they have to burn.
 
I have a 28hp carb. The jet numbers for omc carbs are in thousands of an inch. (Ex. 59D = .059" 51D = .051"). To answer your original question no you will only burn more gas and be a little slower with the 28hp jet. The throat size (venturi) is 1-3/16" which is smaller than the 25hp carb. The 28hp carb came with bigger jets because they allow more airflow (air/fuel mixture).

In regards to the erosion, my .059" jet measured .061" on a 20yr old carb which may be a little more proof.
 

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