Carb question for modified 120hp looper.

**NWolf** · 04-01-2018, 11:46 AM

While setting the timing on my motor last night I noticed a strange issue. When I run it up to 4500 in gear it stays there for a second then starts to slowly fall off like its running out of fuel. Holding hard preasure on the bulb made no difference. If I let off for a couple seconds, then hit it again it goes back up to 4500. Do you guys ever have to open up your float valves when you modifie these motors?

**Motv18** · 04-01-2018, 02:45 PM

How was it set in gear dunk tank or free, the load will play with things.

**NWolf** · 04-01-2018, 02:59 PM

Not sure I understand the question. But it was strapped to the trailer on the boat ramp.

**Motv18** · 04-01-2018, 09:46 PM

Sounds close.

Not it really a omc guy myself but bump into a few. Possibly the power(is it called power on omc) valve it will squirt extra fuel and then bleed away.

Thats is just one possible and maybe wrong. I’m on a loose streak lately.

I will I’ll say if you can turn 4500 with the 24 raker it’s a strong v4.

**powerabout** · 04-01-2018, 10:13 PM

whats modified?
Did you have the timing light on it when it slowed down?
Did you check all cylinders

**NWolf** · 04-02-2018, 05:02 AM

Ports have been opened up slightly, all casting marks polished out. CCM reeds, and the heads have been shaved. Yes, the timing light was on. Nothing changed there. I used the light to watch the fuel spray coming from the carbs. All looked great, except number 4. I took that one apart when I got home to see if something was in it, it was clean. It may have looked bad because the timing light was still hooked to 1. I didnt think of that until I got home. If the weather is better today Im gonna take it to the ramp with a spray bottle full of gas to check it.

**powerabout** · 04-02-2018, 05:05 AM

Originally Posted by NWolf

Ports have been opened up slightly, all casting marks polished out. CCM reeds, and the heads have been shaved. Yes, the timing light was on. Nothing changed there. I used the light to watch the fuel spray coming from the carbs. All looked great, except number 4. I took that one apart when I got home to see if something was in it, it was clean. It may have looked bad because the timing light was still hooked to 1. I didnt think of that until I got home. If the weather is better today Im gonna take it to the ramp with a spray bottle full of gas to check it.

you will get a different picture from the timing light in each hole unless you keep moving the light pickup
so its stock 120 intake and reeds and stock carbs jetting for that engine?
how much cranking compression with the shaved heads?

I would be hitting the choke when it dies just to check for a lean condition

**NWolf** · 04-02-2018, 05:22 AM

Compression is 135 and its all stock jets. I actually had it jetted up on the mids and Idle but had to take them back down. It idles pretty rich. I may put the mids back up, just to be safe in case I ever decide to run at part throttle. The highs are stock. Ill hit it with some fuel when I take it out this time and see what happens.

**powerabout** · 04-02-2018, 05:25 AM

Originally Posted by NWolf

Compression is 135 and its all stock jets. I actually had it jetted up on the mids and Idle but had to take them back down. It idles pretty rich. I may put the mids back up, just to be safe in case I ever decide to run at part throttle. The highs are stock. Ill hit it with some fuel when I take it out this time and see what happens.

more comp, airbox off and full load on the trailer, its going to be lean to risky...