Chrylser 125 not pulling max revs on a Bayliner 1900

So, here is my dilemma...

I have a 'new to me' 1984 Bayliner 1900 with the Chrysler/Force 125 O/B but at full throttle I'm getting 42mph (GPS) and 4200rpm.

I am going to replace the fuel pump but everything else looks great - new plugs, carbs seem to be in tune, need to check timing advance but I don't think it's adjustable (is it?)

The boat came with 3 props so I need to get the numbers off them but at what point do you start changing props around and how do you know that the engine is producing it's intended hp - I don't want to change prop to mask a poorly tuned engine.

So I guess what I am asking is what speed should I be getting from a 19' Bayliner with a 125 OB?

If 42mph is fair then I can guess that then engine is producing the goods - and then I can tweak the prop - if it's a bit low then maybe I should have the motor tuned first.

I'm trying to decide what the next step should be. Not having a lot of spare cash for boating, this is a DIY job.

Re: Chrylser 125 not pulling max revs on a Bayliner 1900

42 is quite decent. However, there may be room for some improvement. 4200 is just a little low --the WOT operating range is 4500-5500. SO: First, you need to know what pitch prop is on the engine. Then, you can try a lower pitch to bring up RPM. Hole shot and acceleration will be better BUT with a lower pitch, top speed may drop a bit.

Now, if you are not running a stainless prop, and if money becomes easier, then switching to a stainless prop in the same pitch will give you 200-400 RPM more and a couple of MPH more.

Timing is indeed adjustable and should be 30-32 deg BTDC at WOT. Chrysler used to time their engines at 32 but becaise of low octane m,arina fuel, they reduced full advance to 30 deg. If you consistantly run gas from auto stations, there is no quality issue and you can run the engine at 32 deg BTDC.

Basically, there is no tuning to do. Don't take it to a mechanic. All he will do is change the plugs and fiddle with the carbs a bit. The engine has electronic ignition and surface gap plugs. The only thing necessary is to change plugs if it becomes hard starting or stalls at idle.

Of course, there are regular maintenance items like change water pump impeller, change fuel pump diaphragm, change oil in lower unit, and install a fuel filter between the pump and carbs.

Re: Chrylser 125 not pulling max revs on a Bayliner 1900

Thanks Frank

I'll put the timing light on it - gonna be a bit tricky as I don't fancy leaning over the back of the boat at WOT as I don't want to run at max revs on the hose - unless that's ok to do?

I have 3 aluminum props and a damaged 4 blade 23" from a friends boat so I might go and try and do a trade at the local prop shop

Plugs are new, impeller replaced, fuel pump being done, lower unit oil changed, carbs cleaned and I'll add in a small filter between the pump and carbs - I think I am good to go!

I'll check the pitch of the prop when I pull her out of the water later today and try the next size down for a few more revs but it looks as if low 40's isn't a bad number - I checked more modern 18' and 19' boat tests with 90-135HP and they were all in the mid 40's and that's brand new with modern outboards.