Boyesen reeds occured drop in rpm's

[Galeon]

Mounted Boyesen two stage power reeds on my Mercury 55 Sea Pro on a Gemini Zapcat. I tested performance before going from stock reeds to Power reeds. I got 61,1 mph at 6100 rpm's. This is a often seen performance with this setup. Motor is stock only rpm limiter cut. I was spinning a Merc. 12X18 TH cleaver.

The test results with Power reeds were disappointing. I achieved 57,5 mph at 5700 rpm's.

Further more I had a idle rpm raise to 1100 rpm's. And I had a motor stop when going from full throttle to idle. The engine would start immediately Again.

I'm about to go back to stock valves again but would give it a try for a good advice here.

Regards Brian

[filthy phill]

sounds like something wrong here.
first off the gear ratio is 1.64 to1 so 18 pitch at 6100 so yeah that is possible with a nice slip percentage of around 3.5%. great speed.

57mph at 5700rpm is giving same slip type figures, so you just got a bit of rpm limiting going on.

the reeds from boyesen have been known to do this to bikes years ago. it could be a bad set and your just the unlucky one.

This is why smaller firms like CCMS get real food reviews as they are not into 2 mile long mass production lines just pumping it out and not talking to the customer 1 on 1.
More chance of getting a set of "not exactly good" reeds from this type of company.


So what exactly did you change ?
did you change just the reeds and put everything else back as per normal ? what about reed stops etc.
did you leave anything out or add anything else ?
have you checked for any air leaks on the housing/gasket surfaces.
to lose 400 rpm top end is a big deal, have you had a good look at them to see if they are the correct ones for your motor that is not a tuned race prep motor ?
the reeds you have might be for a hydrotec type of tune up ?

what did they look like compared to the stock reeds ? any shape change ? or just the material ?

I know some of this might seem a bit simple, but often its the simple things we miss out on .

.

[Galeon]

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[Galeon]

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This is how it looks. I have used new gaskets and bolts are torqued properly and as specified in a circle from inside to outside on the manifold.

I have don nothing else. And I don't know how to check for leaks.

[filthy phill]

there is no pictures coming up !!!

[Galeon]

Sorry about the pictures. I doesn't work

[Galeon]

can be seen here: https://youtu.be/FX4J3YYHgog

[hydrospeed77]

What model yer is your motor?

I have a 1996 60 (850cc, 1.64:1 gears) and installed Chris Carson Reeds this past winter. I notice no change at all in performance in any way. No more power up top; no better idle. The engine behaves the same as far as I can tell. Although my application is not very high performance. I see 5100rpm max regularly and maybe 5400-5500 when I really lighten the load and trim up for a top speed trial.

[Galeon]

Its a 2004 model 967 cc 1.64:1 gear.

[filthy phill]

How did you remove the limiter ? if it was a wire simply disconnected , could you have accidently put it back on ?
I am thinking of simple reasons why you lost the extra rpm .
Was the reeds a nice fit when you put them in ? daylight test etc.
I am not in any way saying your daft, doing it wrong or anything like that, I am looking for a reason that can be easy rectified.
I have often been in a rush and made a complete *** of myself . ha ha

[Galeon]

They seemed to be ok. And they fitted nice and easy as seen on picture. The cut wire has been isolated both ends but I will check it. It's placed at away from the manifold so I don't think it's been touched. The reeds were checked after mounting that they were movable not blocked by the gasket.

[fs5]

I fitted boysen on my sea pro years ago . Got a bit better excelleration topend pretty much stayed the same.
Currently running carbon reeds from hydro tech in mine , had Carson reeds in it prior to them couldn't really tell any difference.
Run 3 gaskets between the reed plate and manifold , gives the a bit extra.
Also I found running.060 jets instead of the .058 gives you a mile or 2
Were the weather conditions pretty similar. You loose a bit of performance in summer compared to winter.

[Galeon]

I fitted boysen on my sea pro years ago . Got a bit better excelleration topend pretty much stayed the same.
Currently running carbon reeds from hydro tech in mine , had Carson reeds in it prior to them couldn't really tell any difference.
Run 3 gaskets between the reed plate and manifold , gives the a bit extra.
Also I found running.060 jets instead of the .058 gives you a mile or 2
Were the weather conditions pretty similar. You loose a bit of performance in summer compared to winter.

The test conditions were about optimal and the comparable to the last test with Stock reeds. This last test was only short time ago so no difference in temperature.
Why is it that you run three gaskets ?

[fs5]

Helps them breathe a bit better , one of the guys on here put me onto it.
Some guys make a little spacer plate up for them.

[filthy phill]

if people go to the trouble of making spacers, then it must be the way to go.
got to be worth a try with the gaskets.

[hightide]

I don't really care for Boyesons as I feel the 2 stage design can limit flow

[filthy phill]

I have often wondered about 2 stage reeds, to my mind it must restrict certain amount of flow at stage 1 ?
but not ever having 2 stage I dont realy understand them.
I will stick to single