GX630 almost dies before returning to idle

[mattrourke]

I am working on a freinds G16 that has a Jake's big block kit with a Honda GX630 and the engine fires nicely and idles nicely and seems to cruise well but where i'm having trouble is if i quickly drop the revs, either to slow down or if you spike the throttle with your foot, the engine stumbles hard and almost dies before returning to a smooth idle. I'm guessing this is governor related. Any suggestions of how i can smooth this out?

thanks,
Matt

[slonomo]

I wouldn't think it's governor related. The governor on the Honda vtwins are typically a rev limiter set somewhere around 4000 rpm or so. It's electronic and doesn't limit engine rev at any other rpm except at the preset high limit.

If you are having drivability issues, I'd be looking at the carb and/or fuel delivery. It could be either starving for fuel or flooding. Could have some gunk in the carb in the low speed passages. Could just need a basic tune up/maint, has that been done?

How old is the engine? How many hours? Have you inspected the spark plugs? Has the air filter been changed?

[mattrourke]

Originally Posted by slonomo

I wouldn't think it's governor related. The governor on the Honda vtwins are typically a rev limiter set somewhere around 4000 rpm or so. It's electronic and doesn't limit engine rev at any other rpm except at the preset high limit.

If you are having drivability issues, I'd be looking at the carb and/or fuel delivery. It could be either starving for fuel or flooding. Could have some gunk in the carb in the low speed passages. Could just need a basic tune up/maint, has that been done?

How old is the engine? How many hours? Have you inspected the spark plugs? Has the air filter been changed?

It drives nicely, its just when the revs drop quickly they almost drop to the point of stalling and then even out to idle. So if i sit in it and tap the gas pedal it will rev nicely but almost die completely. If i rev it up and then reduce revs slowly it will return to idle just fine. Air cleaner is fine. Spark plug looked fine. The engine is about 10 years old but probably only about 20 hours on it. I could check the carb next if that is a likely culprit.

[raydhd]

It really has the signs of a lean mixture

[slonomo]

What you are describing is what I call "drivability issues" since it stalls when you drive it. Typically this is usually solved by going over the basics.

[slonomo]

I'm betting it's carb related and needs to be tuned/adjusted.

What kind of air filter are you running, stock?

How did you tune the carb?

[Cartmaster]

If this is not a brand new engine, i might suspect the link between the governor and carb may have some play in it and allowing the revs to drop slightly until the governor settles down. There is usually also a long spring that can be too loose and allow a bit of movement.

I may be completely wrong but I have seen it on a few Toro workmans and they had either a worn plastic bush at the throttle butterfly operating arm or a stretched spring.

I could also be completely wrong LOL.

[mattrourke]

Originally Posted by slonomo

I'm betting it's carb related and needs to be tuned/adjusted.

What kind of air filter are you running, stock?

How did you tune the carb?

Stock air filter. I have not tuned the carb yet, just adjusted idle. I will get a service manual and do that.

[mattrourke]

Originally Posted by Cartmaster

If this is not a brand new engine, i might suspect the link between the governor and carb may have some play in it and allowing the revs to drop slightly until the governor settles down. There is usually also a long spring that can be too loose and allow a bit of movement.

I may be completely wrong but I have seen it on a few Toro workmans and they had either a worn plastic bush at the throttle butterfly operating arm or a stretched spring.

I could also be completely wrong LOL.

It's worth checking. I will take a look.

[slonomo]

So many things to check. "Tell me what's good, I'll tell you what's bad" famous quote.