High EGT numbers, 2.5 245 with WH20 carbs.

**rjdubiel** · 06-06-2020, 06:39 AM

1994 2.5 245 (carb 260) with factory crossdrilled intake, WH20 carbs, EGT probs in the bottom exhaust divider plate bolts, adapter plate is a 2.4 that has been opened up to match the 2.5. On my vking with the interior, still on the light side for boat weight.

First run, 26 yamaha, .0937 mains, .056 idle, ran up to 7700 rpm and was reading about 1250 degrees on both sides

Second run, 26 yamaha, .090 mains, .056 idle, ran up to 7700 rpm and 1350 on both sides.

Third run, 24 yamaha, .0937 mains, .056 idle, ran up to 8400 rpm and 1350 port and 1270 starboard.

.0937 is the biggest I have right now on mains, plugs are dark and piston tops black. I gotta be reading flames?

Looking for some opinions and comments. I will get some 96 mains but I do have 90's and down to try. Was going to try 88's quick to see if EGT comes down or stays.

**FORBESAUTO** · 06-06-2020, 10:24 AM

Tune it reading plugs and piston wash. Havnt had much luck trying to tune with EGT on these things, I’ve always seemed to run a tad high on temps. They are good to note what is your particular engine/ setup happy place, and be able see when something is going wrong. Personally don’t like em to tune with, wide band a/f would be a much better way to tune if ya could make it work reliably with the water.

**rjdubiel** · 06-06-2020, 01:30 PM

Plugs wet but not black. I need bigger idles. But piston tops all wet and black. 130 psi on all 6

**rjdubiel** · 06-06-2020, 01:32 PM

will do some runs right to the trailer and see how the burn is on the piston.

**Merc 2.5** · 06-06-2020, 01:59 PM

Originally Posted by rjdubiel

will do some runs right to the trailer and see how the burn is on the piston.

If u can dont even let it idle for 1 sec. Kill it as high as possible can u post pic of plugs

Also. Usually gotta run em for a couple min wot to settle in on a color

**eli** · 06-07-2020, 09:36 AM

130 psi might need more compression for complete burn or try non cross ported intake

**Chaz** · 06-08-2020, 10:52 PM

Get it to idle happy. The idle feed restriction stays active until you turn the key off. Consider it in your overall jet area.
Late ignition timing will tend to "run it out the exhaust" . The jetting could be spot on , but as you say reading flame .
In a perfect world you would be @ 1150* .. If it likes 100 more and everything looks good and safe , let it ride.
A spark plug reading tool to look down inside , bore scope , egt , O2 ( works great with isolator ) are all "just another 9/16" wrench in the tool box" .. each provide valuable info .. a man gotta have tools to work ..

Chaz = thinkin, sometimes too much info can fool ya into going down the wrong road .. I know my hand is in the air .. lol

**rjdubiel** · 06-09-2020, 09:16 AM

Thanks for all the posts. One thing I did not say was my compression test was done with the carbs closed so may be a bit lower than actual, it does have the 1.2 mm gaskets. When we assembled it I put some .75 mm gaskets on and it was in the 155 psi before it was ever ran. I think I need one of those bore scopes that hook to my phone as it is a pain looking in the park plug hole! I think I am chasing my tail with these big jets, need to go down to the mid 80's and see if it comes down on EGT and I need to do a chop and read plugs and heads. Just a quick rip and shut it off and watch out for the wave over the back into the back seat.

**Capt.Insane-o** · 06-09-2020, 09:12 PM

I'm running 82's in wh-20's in a very similar motor. Started out with 90's and it was way too fat. Most of the time I run a 31 and it will pull 7400 easy with 125 psi.

**rjdubiel** · 06-10-2020, 09:22 AM

Originally Posted by Capt.Insane-o

I'm running 82's in wh-20's in a very similar motor. Started out with 90's and it was way too fat. Most of the time I run a 31 and it will pull 7400 easy with 125 psi.

I have read your posts before helping people with the same setup I have, and thank you for your input here. I got the engine with it down on 2 cylinders and it had .0937 mains with no water diverters and I am guessing that may have been one reason it took out 2 pistons. So now 2 sleeves with diverters installed and US1 cooling mods for the 1 pc adapter. So as you can see above I ran 90 mains and the egt went up so I need to go down to 84-86 I think and try there and see how it goes. I did run a 30p and it would only get to about 7100 rpm with the .0937 mains. just pig rich!

**Capt.Insane-o** · 06-10-2020, 02:08 PM

Mine is steel sleeves so im running a promax cooling set up on a 1 piece. With 90s in it everything was black as coal.

**rjdubiel** · 06-15-2020, 08:27 AM

I did not have six 86 or 84 main jets, just 4 of each so getting those sent this week. Did get out Sunday in very windy conditions but ran 88 mains and still rich with a 26 yamaha, but starting to get some brown color on the plugs. Piston heads still black and wet. Was not able to do any sort of testing except some quick WOT runs and then back to the trailer as it was rough out on the river. Port was 1351 and starboard was 1287 so still reading flames.

**Baker343** · 06-16-2020, 12:25 PM

Myself and several others have ran Modified 2L's crossed drill 5 and 7 petal with WH46's or 22's with around 145psi.
We run 96 or 98 mains to keep them happy when running the Parker Enduro. I don't run a EGT so I don't have those numbers.
Drill out some mains for testing. I would keep going up on mains until you see a change in top end numbers.

**rjdubiel** · 06-16-2020, 01:22 PM

Baker343, how long are the enduro races? I am guessing it is lots of WOT all day! I have some 96 jets that will be here this week so will run them this weekend. But with how wet everything, piston tops and plugs, I cannot believe I need more fuel. But like you said, keep going up till I start to slow down. I started with the biggest jets I had so It will be interesting to see what the 96 mains will do.

also, from reading lots of TRex posts the 260 blocks are much more efficient than piston port motors. Is your 2L a behind the liner motor or piston port? If piston port, like a BP, I fully expect to have very large jets, but with this 260 block it is much more efficient and does not need as much fuel, so I have read.......

**Baker343** · 06-16-2020, 01:43 PM

Yes, mostly WOT for 4hrs with 3 mile straight away's.
T-Rex and several others who commented know there stuff probably through trail and error. I've been trying to distance my self from the error part for awhile.
You said your motor had to bad pistons.
Did they melt or grenade with 94 mains