Power Reeds Air Bleeds Tuning and Other Tales

" I recently found myself quit

" I recently found myself quite adventurous and decided to add Boysen Power Reeds to my dual ?4 1.6l Sea Drives. As with most of my projects this one quickly spun out of control!
The starboard motor of the installation was rebuilt (At rebuild all 4 cylinders hoovered around 125 - 130) with currently about 30 ?40 hours on it. It? anybody guess on the port motor, although compression checked out @ 120 on top 2, 110ish on bottom 2). It should also be noted, I have a relatively new fuel pump on the starboard motor (20 hours?), I believe the port fuel pump is orginal.

While upgrading to the power reeds I also rebuilt all 4 carbs, replaced intake manifold recirc check valves, replaced all fuel lines, filters, and plugs. In addition I replaced exhaust cover gaskets on the port motor due to an inlet water leak, and also the stats (I thought they may be stuck, and needed to remove to get at exhaust cover. You know the story....might as well, might as well, might as well!!!

So the story goes, Boyseen recommends several options (motor dependant) to prevent backfiring (they explain the reeds can be damaged, I guess the carbon fiber reed material will burn up!)

From their installtion instructions ?ACKFIRE, a lean condition in the idle circuit, sometimes described as lean pop, coughing, or sneezing?

The items applicable to my situation are (as per their installation instructions): 1) Down size idle air jets 5 sizes (.005) 2) On some worn or modified engines, no adjustment necessary.

After rework I ran both engines on a flush with cowling off. The port motor fired right and ran silky smooth (set idle to about 1000 rpm), never could ask for better..... smooth, smooth, smooth!!!

The starboard motor of the installation was a little stubborn to start, but also fired right up (also set idle to about 1000 prm). The sound of the motor was quite different. It seemed to run strong (seemed to have good fuel, and spark, no hesitation or wanting to stall), but had what I? call a ?onsistent consecutive pop? The pop was consitent at idle, and seemed to remain consistent with throttle.

Not being an expert (believe it or not, this is my first in-depth expierence with motor tinkering of any kind)I? not sure if this popping is indeed a lean condition and I? at risk of burning up my prized power reeds? Or can the significant ?ound?differences be attributed to higher compression of the rebuild, or newwer fule pump? Should they sound more alike, or would you expect a "stark" difference.

I would really hate to burn those reeds up after all the $$$$, toil and trouble. I picked up a set of downsized jets to try but haven? had a chance (had "33"'s was able to get "26"'s). Any harm or foul with a richer idle condiiton?

(Sorry to be so winded!!!!)

RW "

Reed valves do not really aff

Reed valves do not really affect compression as the exhaust ports are open to atmosphere at the same time as intake ports. The exhaust ports are the last to close and then compression starts.

" I would suspect the air blee

" I would suspect the air bleed jets or the carb syncronization to be the problem. The decreased size of the jets actually allows more fuel to be used at idle, and when it is too much, an exhaust pop will be the result. This is because the extra fuel mixture occasionaly fouls a plug. Try using the old jets(temporarily) to see if the pop disappears, then try a slightly smaller jet. "

"R. Wood.... My line of though

"R. Wood.... My line of thought goes along with Tom's. You say at one point "but had what I? call a ?onsistent consecutive pop? The pop was consitent at idle, and seemed to remain consistent with throttle".

This would lead me straight to the carburetor section. Usually this is caused by one of three things (or all).

1 - Having the linkage adjusted wrong between the carburetors would result in having one throttle butterfly closed, and one slightly open.

2 - A idle air bleed jet being the wrong size would cause the engine to run lean.

3 - The throttle butterflies are opening too soon. They should just start to open when the scribe mark on the cam lines up with the center of the carb roller.

The idle air jets can be checked easily by having the carburetor face plate removed so that you can look right into the carburetor throats. Run the engine at idle, and while doing so, one carb at a time, stick two fingers into the carb throat. This of course enrichens the fuel flow. When you hit the carb that eliminates the popping, the rpms should increase somewhat. This pinpoints the carb(s) that will require the idle air bleed jet change. In the case of a "air bleed jet" downsizing the jet increases the fuel flow.

Joe "

" I appreciate the feedback. I

" I appreciate the feedback. I struggle with my lack of expierence in this matter. I'm not sure if I'm diagnosing a lean condition or it's the way the motor runs. I can say the two motors really had a different sound to them. Should they sound more alike?

Sorry to confuse but I have not stuck in the down sized idle air jets. I plan to fool around with the toothpicks tonight (if it does change, I'll install the downsized jets). I don't think carb synch is the issue, but I'll check tonight also.

I may also try to record the motors sounds tonight, and maybe email to those intrested to help but me @ ease.

Either way I'll let everyone know what I find.

Thanks

RW "

" I ran both motors tonight an

" I ran both motors tonight and fooled around with the carbs at idle. I tried toothpicks in the jets, and it just bogged it down to stall. Fingers in the carbs really didn't seem to make it run any smoother (often stalled out).

In retrospect I'm not sure if there is an issue or not. Both ran well, hopefully I'm just being paranoid.

Would you expect a recent rebuild with low hours to run / sound different than 1 with many hours on it (100+)?

I do have mpegs of both motors starting and idling, you can notice a difference, port engine seems smother, but both just want to run after their warm.

Would you expect a recent rebuilt to run / sound different?

I'm not sure how to post the mpegs, but I can email em. Let me know via email and I'll send em.

I would greatly appreciate a few veteren ears to take a listen.

Thanks to everyone for their continued support of my "hobby" ! "