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Predator 212 e85 running weird

E

emmeres

New member
Hey all,

I am trying to build a cheap decent power engine for a yard kart. I removed the governor and have had no problems for about 6 months. I decided i wanted some more power from it and saw a few threads about running on e85. I got a set of precision jets and drilled out the jets. The pilot jet is at 0.6 mm and the main is 1.2mm. First start up it idled really well, I propped the rear wheels off the ground and revved the engine about 50%. No issues there. Then I put it on the ground and tried to drive around the cul-de-sac but above about 30% throttle it seemed to stall. The rpms went way down with an occasional louder pop. Thinking this was an issue with it being too lean, I drilled the main jet to 1.5mm and put a small hole in the fuel cap to help with air flow. Here's where the engine s*** the bed. Starting the engine back up and it was like it was possessed. The engine at idle was swapping between an excessively high rpm and incredibly low rpm until it dropped low enough to stall.

Can anyone tell me what the problem is? I don't know a ton about small engines/ carbs so any advice about symptoms of running too rich/lean would also be appreciated.
 
emmeres said:
Hey all,

I am trying to build a cheap decent power engine for a yard kart. I removed the governor and have had no problems for about 6 months. I decided i wanted some more power from it and saw a few threads about running on e85. I got a set of precision jets and drilled out the jets. The pilot jet is at 0.6 mm and the main is 1.2mm. First start up it idled really well, I propped the rear
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I'm pretty sure you went to big on the jets! We need to know what size jet you started out with.

E 85 shouldn't require a whole lot of change in jet size.

For instance; .038" to .039" is a 5.3% change in jet hole area. That's a lot.

Drilling jets is not a good idea either. The slightest imperfection in a hole can create a big change in flow.
 
alvin l nunley said:
I'm pretty sure you went to big on the jets! We need to know what size jet you started out with.

E 85 shouldn't require a whole lot of change in jet size.

For instance; .038" to .039" is a 5.3% change in jet hole area. That's a lot.

Drilling jets is not a good idea either. The slightest imperfection in a hole can create a big change in flow.
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Give the guy a break Al. He said he was a backyard guy. You think he should go out a buy a $20 reamer.
 
DynoDon said:
Give the guy a break Al. He said he was a backyard guy. You think he should go out a buy a $20 reamer.
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In 1967 dollars, that would only be $3.95.
I didn't hear him say he was poor, he said he was a backyard racer.
I don't remember telling him to go out and buy a new reamer, just a new jet.
 
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