Running/Idle RPMs
- Thread starter amentac
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Yup, I did that and it still does makes that popping sound. I'm afraid you might be right and I need a valve job or maybe it's a worn out cam. Though I don't understand why it runs smoothly at times for a few minutes, usually at the higher RPMs.
I found the valve lash setting to be a bit high around 0.008 so I reset all of them to 0.005. Engine now runs smoothly and backfiring stops. However once the engine gets warm and under load, backfiring starts again, thought much reduced. I don't understand this, when the pushrods get hot they become longer, so the valve lash will get smaller, shouldnt I set it to a higher value to compensate?
shadetree#1
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Had a new to me Briggs twin Intek that was spitting, acted like valves. Checked valve setting and then thought maybe valve seats or ????
Could not get valve/valves to leak using leak down test and manually pushing open the valves with the push rods off. finally went to the Nikki carb.
I have seen Nikki carbs have those symptoms. Very strange that a carb will spit back and act like a valve. Sometimes on the dual throat Nikki's you can watch down the throat of the carb's intake and see which throat is doing the spitting. I've also seen them dual throat type cause one cylinder on a twin to be completely dead.
Is your Nikki a dual throat type or the single throat type?
I bought a replacement Nikki clone carb to replace a spitting Nikki awhile back (less than $20 and the clone did not spit back, just would not idle smooth. I used parts from the clone into the OEM Nikki and got a good run, mainly used the internal O rings, gaskets and the two little jets with the o rings. During testing the non-spitting clone carb indicated to me that it was the OEM Nikki carb that was causing the spitting and not the valves on the Briggs Intek OHV so I went to carefully checking and replacing the internals inside the bowl section ONLY on the OEM carb using parts from the clone. BUT do not expect to take two Nikki carbs that appear same on the outside but be different on the inside. I just got lucky that day. Not all Nikki's are the same internally for transferring parts and pieces.
I've also used some of the lesser priced clone Nikki kits from flea bay and repaired OEM Nikki carbs. Here is couple of links on flea bay just to give you an idea of the lesser priced kits for single throat and dual throat Nikki's. I noticed that some of the needle's in the kits would cause a high float level when installed but the Nikki carb still worked ok (float would not set level when the kit replacement needle was installed) I purposely tested just to see if carb worked ok with the high float level and got a good run test.
Summary: From hands on experience. Nikki carbs will cause sputtering and spitting back on Both single cylinder and twin cylinder Briggs engines. (and both the single throat and the dual throat Nikki's)
and it's usually the rubber gaskets and o rings inside causing such.
The OEM Nikki kits are quite expensive. As compared to the old Walbro carb's Nikki carbs SUCKS BIG AIR. I think ethanol gas PROBABLY also reduces their life span.
Carburetor Rebuild Kit Master Overhaul For Briggs & Walbro LMT 5-4993 698781 | eBay
797890 Carburetor Overhaul Kit For Briggs & Stratton 791230 799230 699709 499804 | eBay
Here is a single throat Nikki kit on Amazon
Could not get valve/valves to leak using leak down test and manually pushing open the valves with the push rods off. finally went to the Nikki carb.
I have seen Nikki carbs have those symptoms. Very strange that a carb will spit back and act like a valve. Sometimes on the dual throat Nikki's you can watch down the throat of the carb's intake and see which throat is doing the spitting. I've also seen them dual throat type cause one cylinder on a twin to be completely dead.
Is your Nikki a dual throat type or the single throat type?
I bought a replacement Nikki clone carb to replace a spitting Nikki awhile back (less than $20 and the clone did not spit back, just would not idle smooth. I used parts from the clone into the OEM Nikki and got a good run, mainly used the internal O rings, gaskets and the two little jets with the o rings. During testing the non-spitting clone carb indicated to me that it was the OEM Nikki carb that was causing the spitting and not the valves on the Briggs Intek OHV so I went to carefully checking and replacing the internals inside the bowl section ONLY on the OEM carb using parts from the clone. BUT do not expect to take two Nikki carbs that appear same on the outside but be different on the inside. I just got lucky that day. Not all Nikki's are the same internally for transferring parts and pieces.
I've also used some of the lesser priced clone Nikki kits from flea bay and repaired OEM Nikki carbs. Here is couple of links on flea bay just to give you an idea of the lesser priced kits for single throat and dual throat Nikki's. I noticed that some of the needle's in the kits would cause a high float level when installed but the Nikki carb still worked ok (float would not set level when the kit replacement needle was installed) I purposely tested just to see if carb worked ok with the high float level and got a good run test.
Summary: From hands on experience. Nikki carbs will cause sputtering and spitting back on Both single cylinder and twin cylinder Briggs engines. (and both the single throat and the dual throat Nikki's)
and it's usually the rubber gaskets and o rings inside causing such.
The OEM Nikki kits are quite expensive. As compared to the old Walbro carb's Nikki carbs SUCKS BIG AIR. I think ethanol gas PROBABLY also reduces their life span.
Carburetor Rebuild Kit Master Overhaul For Briggs & Walbro LMT 5-4993 698781 | eBay
797890 Carburetor Overhaul Kit For Briggs & Stratton 791230 799230 699709 499804 | eBay
Here is a single throat Nikki kit on Amazon
Last edited:
Hammermechanicman
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If digging into a nikki carb always replace the tiny o ring(s) on the main jet(s). Number one problem with those carbs
shadetree#1
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Hammermechanic says:
If digging into a nikki carb always replace the tiny o ring(s) on the main jet(s). Number one problem with those carbs
Very true and keep a heads up when removing the bowl and then placing the carb up right. I've see the little jet missing, just evaporated. It's laying in your lap or on the floor because the itty bitty o ring is bad and let the jet fall out of the plastic emulsion tube..
Some of the kit's do not even have these little o rings. Some of the Nikki clone kits lately have the little jets and may even have the little brass jets.
Some places have just the little Nikki o rings by themselves for like $4 or more each. I try to look carefully at pictures of the kit on-line to see if I can locate them as being in the kit.
If digging into a nikki carb always replace the tiny o ring(s) on the main jet(s). Number one problem with those carbs
Very true and keep a heads up when removing the bowl and then placing the carb up right. I've see the little jet missing, just evaporated. It's laying in your lap or on the floor because the itty bitty o ring is bad and let the jet fall out of the plastic emulsion tube..
Some of the kit's do not even have these little o rings. Some of the Nikki clone kits lately have the little jets and may even have the little brass jets.
Some places have just the little Nikki o rings by themselves for like $4 or more each. I try to look carefully at pictures of the kit on-line to see if I can locate them as being in the kit.
Hammermechanicman
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I bought a 20 pack of the o rings
I fix most 2 barrel nikki carbs with a kit like this.
I fix most 2 barrel nikki carbs with a kit like this.
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I been getting these from Kawasaki under pn 92055-7013 for 0.62 ea (packages of 5 ea) until the last price update (10/30/22) were they just went to 0.70 ea. Either way they are very tiny and you work where the air isn't moving as they are easily lost.
Also one other thing is when removing the fuel make sure you don't the jet in the first place.
Also one other thing is when removing the fuel make sure you don't the jet in the first place.
shadetree#1
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Hammermechanic and StarTech:
Have you guys seen a Nikki produce the spit back in the Briggs Inteks that makes one think that valves are not seating?
I've isolated the Nikki engine spit back right down to the carb internals on more than one engine. (not the engine or external manifold leaks.
Strange: How them Nikki carbs can act sometimes.
Also seen them dual throat type produce a completely dead cylinder on the twin engines.. No fuel at all getting to one cylinder. (each throat of the dual throat Nikki is isolated from the other so if one side clogs not fuel)
Good info about source for Nikki o rings and twin kit you guys posted. Them Nikki OEM kits and OEM carbs are too expensive for me to put on a old engine.
Thanks for the info
Have you guys seen a Nikki produce the spit back in the Briggs Inteks that makes one think that valves are not seating?
I've isolated the Nikki engine spit back right down to the carb internals on more than one engine. (not the engine or external manifold leaks.
Strange: How them Nikki carbs can act sometimes.
Also seen them dual throat type produce a completely dead cylinder on the twin engines.. No fuel at all getting to one cylinder. (each throat of the dual throat Nikki is isolated from the other so if one side clogs not fuel)
Good info about source for Nikki o rings and twin kit you guys posted. Them Nikki OEM kits and OEM carbs are too expensive for me to put on a old engine.
Thanks for the info
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I know a lot people say these carbs very hard to repair. To me they are not. I even have install bushing where the throttle and choke shafts have badly worn the carb bodies on the Kawasaki engines on JD ZTRs.
The last one I installed a bushing in was so bad that it took me using a schedule 80 1/8" brass pipe to make the bushing out of.
For cost it all depends on the customer here and the equipment condition. I can have in the shop a 22 yr old machine that looks like new and then a have 1 yr old ZTR that looks it been in a war zone.
The last one I installed a bushing in was so bad that it took me using a schedule 80 1/8" brass pipe to make the bushing out of.
For cost it all depends on the customer here and the equipment condition. I can have in the shop a 22 yr old machine that looks like new and then a have 1 yr old ZTR that looks it been in a war zone.