Briggs 5hp i/c help. Need valve lash & it won't turn over more than once per pull

drenchedgremlin

drenchedgremlin

Member
#1
#1
Working on a 5hp I/c. first thing I noticed when I got it is that the pull cord only turns it over once & it is very hard to pull & it has way too much compression. Ive delt with that before on a predator but it was the compression release on the cam. I don't think these briggs have that. I pulled the valve cover & I need to check the lash. Anyone know what the lash is for these motors? Also I pulled the head cover & noticed that at tdc, the intake valve starts opening before the exhaust valve closes fully. Is that right? Needing some pointers so I can figure out what is causing the problem.

Ps this is unrelated, but I have been wondering: What makes a briggs motor a flathead? does that just refer to the style or is is that term used to describe a specific motor only (like a raptor?).

Pics will be posted tonight when I get home
 
TheDullCarbide

TheDullCarbide

Active Member
#3
#3
drenchedgremlin said:
Working on a 5hp I/c. first thing I noticed when I got it is that the pull cord only turns it over once & it is very hard to pull & it has way too much compression. Ive delt with that before on a predator but it was the compression release on the cam. I don't think these briggs have that. I pulled the valve cover & I need to check the lash. Anyone know what the lash is for these motors? Also I pulled the head cover & noticed that at tdc, the intake valve starts opening before the exhaust valve closes fully. Is that right? Needing some pointers so I can figure out what is causing the problem.

Ps this is unrelated, but I have been wondering: What makes a briggs motor a flathead? does that just refer to the style or is is that term used to describe a specific motor only (like a raptor?).

Pics will be posted tonight when I get home
Click to expand...
The intake and the exhaust can be slightly open at the same time. This is called overlap and it helps with scavenging and more power and yada yada yada...not a problem.
 
drenchedgremlin

drenchedgremlin

Member
#4
#4
thanks guys. I measured the lash today. I think it may be pretty far off. the engine model # is 132432 i found the lash specs for the 130000 series. (130000 L-Head Aluminum/Cast Sleeve Single Cylinder intake .005 / .007 exhaust .009 / .011)
i measured it at 1/4" past tdc ( someone told me thats how its done but i could be wrong)
intake is about .013-.014 and exhaust is about .012-.013. This seems way off, Maybe i am doing something wrong. If i measured it correctly and it really is that far off, what can i do to fix this, if anything? And would this possibly cause the compression problem if so?
 
TheDullCarbide

TheDullCarbide

Active Member
#5
#5
drenchedgremlin said:
thanks guys. I measured the lash today. I think it may be pretty far off. the engine model # is 132432 i found the lash specs for the 130000 series. (130000 L-Head Aluminum/Cast Sleeve Single Cylinder intake .005 / .007 exhaust .009 / .011)
i measured it at 1/4" past tdc ( someone told me thats how its done but i could be wrong)
intake is about .013-.014 and exhaust is about .012-.013. This seems way off, Maybe i am doing something wrong. If i measured it correctly and it really is that far off, what can i do to fix this, if anything? And would this possibly cause the compression problem if so?
Click to expand...
1/4" past TDC sounds reasonable depending on how you measure. I think you're golden after you get it right. A trick I do to set lash: for example, the intake, get your 0.005" and 0.007" gauges and keep adjusting until the small gauge fits but the big one doesn't. The "feel light resistance" method screwed me over when I couldn't get the gauge straight onto the valve.
 
F

funky ole

Member
#6
#6
that amount of lash is too much. .012-.014 is just about how much the easy spin rests the valve off its seat.

I also set lash at tdc compression power stroke,but as long as you checked yours on the power stroke you'll be fine.
 
drenchedgremlin

drenchedgremlin

Member
#8
#8
since it is a regular briggs flathead style and not an ohv, will i have to start with new valves since the gap is too much? I know there are other ways such as seating the valve a bit lower, but i think that may be beyond my capabilities so i would like to go the easiest route. If i can go the reseating route, could i simply do it with a lap tool and grinding compound?
 
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drenchedgremlin

drenchedgremlin

Member
#9
#9
TheDullCarbide said:
1/4" past TDC sounds reasonable depending on how you measure. I think you're golden after you get it right. A trick I do to set lash: for example, the intake, get your 0.005" and 0.007" gauges and keep adjusting until the small gauge fits but the big one doesn't. The "feel light resistance" method screwed me over when I couldn't get the gauge straight onto the valve.
Click to expand...
Thanks, I used to think that it was supposed to be directly at tdc that you measure the lash. The way that i measured was from the top of the piston to the top edge of the cylinder using the slide out part of a caliper tool. & that makes sense, i will have to give that a try next time.
 
F

funky ole

Member
#10
#10
drenchedgremlin said:
since it is a regular briggs flathead style and not an ohv, will i have to start with new valves since the gap is too much? I know there are other ways such as seating the valve a bit lower, but i think that may be beyond my capabilities so i would like to go the easiest route. If i can go the reseating route, could i simply do it with a lap tool and grinding compound?
Click to expand...
yes, unless you know of a way to make the valves longer!
 
drenchedgremlin

drenchedgremlin

Member
#12
#12
Great, I got the motor Up & running last night, just threw in some valves off another 5hp & started right up after cleaning up the carb & bit & replacing the gaskets as well. Thanks for your helps guys. I am really learning a lot
 
TheDullCarbide

TheDullCarbide

Active Member
#13
#13
drenchedgremlin said:
Great, I got the motor Up & running last night, just threw in some valves off another 5hp & started right up after cleaning up the carb & bit & replacing the gaskets as well. Thanks for your helps guys. I am really learning a lot
Click to expand...
In that case it wouldn't hurt to lap those new valves and check the lash. But hey if its good enough it good enough?:shrug:
 
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