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Old 01-04-2009, 03:47 PM
  #1  
speedy.d
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Default engine troubles

i have a cy 28.5 that just doesnt want to stay running. i have good spark(replaced the coil),and i have good compression. if i try starting it inside it will star as soon as i thionk im good to take it out and run it it wont start. i have walbro 668 carb both needles are set at 1 1/4 turns out(the high speed is closer to 1 5/8). i was suffering from a weak spark. so i put the coil off of an unused fs engine on it. that gave me agood spark. i have noticed that my carb (exterior) is slightly damp. i am leaning towards a new carb. i would be greatful for any suggestions any of you would have thanks guys
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Old 01-04-2009, 04:04 PM
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Lars from Norway
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Default RE: engine troubles

Try to use some start gas or something similar (did someone mention WD40?) around the carb where the gaskets are to see if the rpm's are changing,if it does you have an air leak somewhere
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Old 01-04-2009, 05:23 PM
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speedy.d
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Default RE: engine troubles

ive used the wd-40 on the solex on my karmann ghia to trace air leaks, but i cant even get this thing to start and run. the last time we ran it (yesterday) it ran thru pretty much a whole tank. it died as i was reaching for the kill switch. the tank was almost empty. hmm maybe i sucked a piece of dirt or something into the carb? a buddy is going to bring me a new crab to try.
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Old 01-04-2009, 05:29 PM
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Default RE: engine troubles

Do you have a bright blue spark coming from the plug? When you replaced the coil did you check and set your air gap? Is the plug getting wet with gas when you try to start it?
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Old 01-04-2009, 07:44 PM
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speedy.d
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Default RE: engine troubles

the coil gap was "set" at the thicknes of a match book. i am getting a nice blue spark, and yes my plug is wet. i have pulled the plug and heated it and put it back after doing this i have been able to get it to fire but not run. does anyone have some baseline needle settings, and an exact coil and plug gap so i can double check these.
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Old 01-04-2009, 08:53 PM
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Default RE: engine troubles

Not sure this well help but take a look.
http://www.rcuniverse.com/forum/m_72...tm.htm#7217622
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Old 01-04-2009, 10:10 PM
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speedy.d
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Default RE: engine troubles

46u and lars thanks for taking the time to come up with some ideas to help me out. i found my problem, i blew the head gasket. luckily innovative hobby products is just a few miles away. i made one out of a baseball card and gave it a try and i am running again! i will get the right gasket tomorrow and fix it right .


AGAIN THANKS TO 46u AND Lars FOR YOU HELP!!!!!
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Old 01-05-2009, 10:11 AM
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Default RE: engine troubles

No#1 reason why a engine won't start? Air leak. #2 wrong oil mix. #3 left choke on.
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Old 01-05-2009, 12:05 PM
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speedy.d
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bsrman14,
hey... uh... thanks... couldnt have done it whithout you. oh wait yes i did.
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Old 01-05-2009, 12:19 PM
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ORIGINAL: bsrman14

No#1 reason why a engine won't start? Air leak. #2 wrong oil mix. #3 left choke on.
You must elaborate more. Dont just give very simplistic answers that everyone already knows, you must give details on how to correct these. Details such as:

#1) Air leaks: Check the carb fitting to the manifold-intake block, check the gaskets in between, always replace the gaskets whenever you take off the carb and its intake block, Check the exhaust pipe/canister, make sure it is bolted down all the way, always replace the gasket between the block exhaust port and the pile manifold, Check the cylinder head and make sure it is bolted down to the lower crank case pieces, etc.

#2) Wrong oil mix: Fore break-in go with a 1:32 mix, then progress to a 1:40 mix for everyday running once the engine is broken in, etc.

#3) Choke left on: Aactually, I would have made this #1, it is probably the most common simple mistake we all make in starting any 2-stroke gasser.


Dont give simplistic answers, you must give more details and actual solutions. You only gave problems, no solution on how to fix them. Giving too simplistic of an answer unfortunately makes you sound noobish (No offense intended). Give your knowledge on how to solve the problem.
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Old 01-05-2009, 12:43 PM
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Default RE: engine troubles

thanks savagejim, i was hoping you would catch my post last night. my homade gasket definatly worked but it wont work indefinatly. i will have a new set of gaskets in an hour or two. your advise is very helpfull i would love to sit down and have a beer with you and do some bench racing!
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Old 01-05-2009, 09:53 PM
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Default RE: engine troubles

SAVAGEJIM why does the Baja SS manual say 25 to 1? Is this to much oil or does it depend on the oil you are using?
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Old 01-05-2009, 11:14 PM
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Default RE: engine troubles

they recommend 25:1 for max engine life and for the lowest running temps.

i personally think that 32:1 is better because you get better performance but you need higher quality oil to do this safely. i use [link=http://www.davesmotors.com/s.nl/c.885035/n.1/it.A/id.3312/.f]this[/link] oil. i am running the rest of my first gallon of fuel in my km baja. i used 25:1 for break-in but once i finish this gallon, i'll switch to 32:1. there are plenty of people at my LHS who have 5th scales and most run 32:1. one guy even runs 40:1 in his fs king kong. that klotz techniplate oil is very good and has 80% synthetic and 20% castor.

if you want to stay on the safe side (especially during hot summer days) run 25:1 but if you want a little more power, run 32:1 as long as you have high quality oil. 40:1 isn't too bad as long as it's not too hot outside and the oil is VERY high quality. For winter use, i think that klotz oil should do just fine in your baja at 40:1 as long as you don't tune it too lean. it is hard to tell when you are running lean when running gassers. with nitros, it is very easy to tell if it's lean. i was running my baja lean until one of the 5th scale "veterans" told me to turn the HSN 1/8 turn to the left and i got more power by richening. Gassers will happily run too lean without many symptoms so spark plug reading is one of the better ways to tune. I just run the factory carb settings to be safe. (for a km baja's engine, factory setting is dead-on. no tuning needed after that. not too rich or lean. the only problem is that it usually comes way out of whack from the factory and needs to be set to the specific settings. the HSN is supposed to be 1 3/8 turns out and mine was 4 turns out.)
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Old 01-05-2009, 11:35 PM
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Default RE: engine troubles

do you know what the std LSN setting is supposed to be?
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Old 01-05-2009, 11:39 PM
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Default RE: engine troubles

I am sure I will not have a problem as with 35 plus years as a motorcycle mechanic and machinist I am pretty good at reading plugs. I have a bottle of Golden Spectro I will be using till it is gone. When I had my shop Klotz and Golden Spectro was my best sellers. Many of your team Honda riders use Golden Spectro or they use to any how. Thanks for the info.
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Old 01-05-2009, 11:55 PM
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Default RE: engine troubles


ORIGINAL: Bainbo

do you know what the std LSN setting is supposed to be?

that setting i was talking about is for the KM engines. i can't remember what the stock settings for CY "fuelie" and Zen are.
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Old 01-05-2009, 11:57 PM
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Default RE: engine troubles

Factory settings Hope this helps
http://www.rcuniverse.com/forum/m_72...tm.htm#7217622
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Old 01-06-2009, 01:12 AM
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Default RE: engine troubles

i have the km also, had it for a couple of months. the mixtures were out when i got it HSN was nearly two LSN was 1 1/2 so i set it to std hpi settings its ok but right settings for the km motor would be better
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Old 01-06-2009, 09:46 AM
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Default RE: engine troubles

[sm=cry_smile.gif][sm=cry_smile.gif][sm=cry_smile.gif][sm=lol.gif][sm=lol.gif]
ORIGINAL: speedy.d

bsrman14,
hey... uh... thanks... couldnt have done it whithout you. oh wait yes i did.
[sm=cry_smile.gif][sm=cry_smile.gif][sm=lol.gif] Oh no you didn't untill later.
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Old 01-06-2009, 11:02 PM
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Default RE: engine troubles

try not to worry about needle settings, especially since you cannnot remember what the factory settings are.
Instead, tune the engine by sound and running cues (I am assuming your engine is already broken in)

For tuning a gasser, (even a KM engine), wtach this vid. If you tune to the sound and performance cues like on this vid, you will have the correct needle settings for your running conditions. Be sure to listen to the noises of the engine in the vid as the guy explains. It is an excellent intsurctional vid.
http://www.youtube.com/watch?v=6tMUfbQCzI8
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