Briggs & Stratton 18.5 twin gurus

[Bob_VT]

Okay I have this 18.5 hp twin horizontal in my rider. Today when I started it I could not get it above an idle. Last week it was okay....

I have had it for 10+ years and it no longer has the power it used to. I checked that mechanical govenor and everything is in place (no broken springs/cables everything is connected). If I peer (peek, look, glance, stare) into the carb I can see the butterfly closed while it is running. I can manipulate the butterfly and over-ride the governor and it will rev right up. (an evil thought crossed my mind to stick a rod into the carb to keep it running faster but I did not go there )

I sprayed good old sea foam into the carb and got the confirming white smoke.

I am just stumped at what controls my high speed? I guess I will pull the carb and do a impromtu rebuild...... any ideas?

Stumped?

 

[JustJason]

Re: Briggs & Stratton 18.5 v twin gurus

Re: Briggs & Stratton 18.5 v twin gurus

Its probably the carb. But have a look at your air filter, and as with any engine obviously spark and compression. A lot of B&S OHV engines want valve adjustments every 100 hours or something like that, so It may be just an adjustment. I'm surprised that it has a governor and just doesn't have a throttle control.
A governor limits speed/over reving. The govna's job is to close the throttle plate as rpms increase. So if your not over reving then typically (but not always) the Gov'na is doing its job. Depending on how its all set up. There may be a rod that connects the govna's arm to the throttle arm. Alot of times the linkage has about a million different holes so mark the ones you take the rod out of. With the rod out/or the gov'na disconnected the carb's throttle should go to wide open. If you started it like this then obviously the motor would rocket off. If it doesn't i'd suspect a broken or got broken and is now missing spring(this is the freaking worst, when you know something is missing but you don't know what it is or where it's missing from).

 

[Bob_VT]

Re: Briggs & Stratton 18.5 v twin gurus

Re: Briggs & Stratton 18.5 v twin gurus

Oh it has a throttle lever on the dash and that connects by cable to this conglomeration of springs and levers which ties into the butterfly plate.

Yup I am probably going to rip the carb off and do some real maintenance to the thing. I have to say it has been darn dependable over the years.

 

[thefairlaneman]

Re: Briggs & Stratton 18.5 v twin gurus

Re: Briggs & Stratton 18.5 v twin gurus

Make sure you havent got trash in the gas(bad gas ) and also make sure you drain and clean the float bowl . Then if it doesnt run a carb kit should be next.

 

[Bob_VT]

Re: Briggs & Stratton 18.5 v twin gurus

Re: Briggs & Stratton 18.5 v twin gurus

Yup, a new inline fuel filter is on the list..... since I am the only owner..... I tend to take care with the gas.

 

[JustJason]

Re: Briggs & Stratton 18.5 v twin gurus

Re: Briggs & Stratton 18.5 v twin gurus

So it has a throttle lever and a governor? Little weird.
When you start it up and push the throttle to rabbit... does the throttle plate on the carb open? May want to double check the compression, i'm not on my laptop with all my manuals on it but i'm pretty sure those engines need valve adjustments.
That would explain

it no longer has the power it used to

 

[JustJason]

Re: Briggs & Stratton 18.5 v twin gurus

Re: Briggs & Stratton 18.5 v twin gurus

If you can post a model ## for that engine i'll check my manual stash on monday when I get home and see if i've got one for it.

 

[Howard Sterndrive]

Re: Briggs & Stratton 18.5 v twin gurus

Re: Briggs & Stratton 18.5 v twin gurus

I agree with those above mentioning valve lash adjustment.
Video of how to adjust valves on the V twin:
http://www.youtube.com/watch?v=hGkn0jR9RJM

 

[Bob_VT]

Re: Briggs & Stratton 18.5 v twin gurus

Re: Briggs & Stratton 18.5 v twin gurus

Thank you I will look.

Yup just returned from the parts store..... no carb kits till wed-thurs next week

 

[dolluper]

Re: Briggs & Stratton 18.5 v twin gurus

Re: Briggs & Stratton 18.5 v twin gurus

Sounds like a linkage problem.....since you have it apart check your air gap or if you have a rust build up on the flywheel

 

[Bob_VT]

Re: Briggs & Stratton 18.5 v twin gurus

Re: Briggs & Stratton 18.5 v twin gurus

Okay UPDATE

First I am dumb. It is a horizontal twin not a v trin..... it is NOT OHV.... I did not have the patients to pull the carb toady...... I did the fuel filter, air filter, oil change and more sea foam. No real change. I am probably going to bite the bullet and do the carb soon.

Oh yeah plugs are fine too.