Author Topic: 18 hp apposing twin runns bad  (Read 8900 times)

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Offline Workmanf150

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18 hp apposing twin runns bad
« on: March 31, 2009, 05:02:58 pm »
need some advice from anyone that has any ideas im new to these motors i have a stock 18 hp flat head apposing twin with new coil but stumbles bad off idle and surges at full throttle i tried adjusting enrichment screw but doesnt help it is a gravity feed set up no pump it does have a custom built header that is two into one straight pipe. it also backfires alot i do know that on our kart motors the single cylinder flat heads thats normal but dont know if normal on this motor any help would be greatly appreciated

Offline tonykummrow

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Re: 18 hp apposing twin runns bad
« Reply #1 on: March 31, 2009, 05:56:03 pm »
did you clean the carb. sounds like it is dirty i would start their.
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Offline THawley08

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Re: 18 hp apposing twin runns bad
« Reply #2 on: March 31, 2009, 06:08:51 pm »
I would suggest using the fuel pump
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Offline sparks

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Re: 18 hp apposing twin runns bad
« Reply #3 on: March 31, 2009, 06:16:15 pm »
dose it have a stock carb ? if so it the fuel  pump is on the carb.  the carb may need a good cleaning. spark
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Offline crapsmen

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Re: 18 hp apposing twin runns bad
« Reply #4 on: March 31, 2009, 06:53:49 pm »
just clean the carb and if that dont work clean it again, then try and get a fuel :censored: if that still dont work, allso check the gap on ur lifters

Offline amr5080

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Re: 18 hp apposing twin runns bad
« Reply #5 on: March 31, 2009, 08:01:36 pm »
check the plugs also
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Offline Workmanf150

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Re: 18 hp apposing twin runns bad
« Reply #6 on: March 31, 2009, 09:01:53 pm »
yea gonna try cleaning carb and this carb was one that was not originally setup with a fuel pump thought about adding a fuel pump. what should the gap be for the between coil and fly wheel. a local repair shop told me just slide a business card inbetween coil and flywheel and tighten it down it runs but wondering if thats to tight?

Offline amr5080

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Re: 18 hp apposing twin runns bad
« Reply #7 on: March 31, 2009, 09:03:56 pm »
that's what I do and what they taught in my small engine repair class
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Offline birdman_express

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Re: 18 hp apposing twin runns bad
« Reply #8 on: March 31, 2009, 09:04:10 pm »
He told you right, trust your mechanic.
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Offline Workmanf150

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Re: 18 hp apposing twin runns bad
« Reply #9 on: March 31, 2009, 09:06:44 pm »
Is there an aftermarket carb that i can put on this motor to boost the performance and if so where can i get it i have another one of these motors and am getting ready to tear into and rebuild.  been to the G-Team website and thinkin about goin that route with the motor any advice would be greatly appreciated

Offline amr5080

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Re: 18 hp apposing twin runns bad
« Reply #10 on: March 31, 2009, 09:08:59 pm »
If you have another one of them try swapping the carbs. Also, the G team cam really wakes these things up and also the dvd is very helpful
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Offline birdman_express

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Re: 18 hp apposing twin runns bad
« Reply #11 on: March 31, 2009, 09:09:56 pm »
Depends on the class rules set up by your racing organization, on changes to the motors.
some must be original parts.
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Offline Workmanf150

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Re: 18 hp apposing twin runns bad
« Reply #12 on: March 31, 2009, 09:15:33 pm »
well not really have any class rules this one is not on a mower we dont have mower races around here yet they are talkin about next year at the local kart track but for now this one is on a barstool racer that i built the other motor i want to build as wild as i can and if they bring the mower races here then im gonna build on to race here. i looked at the G-team web site and done see how that carb would bolt to my intake unles a get 90 degree elbo

Offline amr5080

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Re: 18 hp apposing twin runns bad
« Reply #13 on: March 31, 2009, 09:17:42 pm »
i have another one of these motors and am getting ready to tear into and rebuild.  

I mean try swapping out the carb on this motor for the one that you are having problems with
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Offline Rooster

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Re: 18 hp apposing twin runns bad
« Reply #14 on: March 31, 2009, 09:32:40 pm »
As far as a 90 degree elbow, you can use an intake off of a verticle shaft engine, it has a 90 degree intake. With that you may be able to get a side draft carb on it.
EC does build the carbs for the opposed engines. I have been looking for awhile and haven't found anyting thats a direct bolt up.
These engines are made to run rich, you want a fuel pump. They do not cool well and will overheat quickly if run lean.
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