Running bad and stalling

[sbest]

I did not follow that break in on my present Grubee GT5A, I used 20:1 oil and moderate loads (with VERY brief occasional WOT) just to follow manufacturer's recommendations for the first 3 tanks. By then it fouled the plug and oil was dripping out the exhaust. Bore looked good but rings took the 3 tanks to wear through the black coating. Next cylinder I will run harder.

A note of warning, I had detonation with the stock head during hill climbs. That could be devastating to a new engine if you kept it going. It sounds like a random metalic popping sound. Head temperatures rose quickly, piston and rod bearing damage would be quick to follow. A very good reason to have a quiet muffler.

Steve

 

[Neufcruz]

Yeah, I'm not hearing anything with this pipe! Lol
I saw on some site, some silencers. Not sure if they would work or even fit for that mater.

 

[HeadSmess]

they dont have much in the way of chrome, and even less in the way of cylinder honing on these engines... so im a bit iffy on the whole break-in topic. ive had some rings last 5000km without losing that blackened surface... but they are machined with "record finish"...machined in record time, and sorta similar to an edison "toilet paper roll" phonograph...rough!

meh, i always agreed with everything mentioned by this guy,http://www.mototuneusa.com/break_in_secrets.htm even up to making ports SMALLER when i work on my 4 stroke pitbike... lifan 140, racing hi-lift cams, and the thing knocks peoples socks off... pretty funny when you catch up with a yz450f and you tell em you were backing off cus you dont wear a helmet... or maybe they just cant ride their yamaha-ha properly?


but thats 4 strokers, not everything is the same. though the air doesnt know any different, it still operates just as physics demands it behave!


did i mention, let it warm up... THEN ride it like you stole it? i have never been one to take off with a cold engine.

 

[Neufcruz]

Well, at it again. Had a #7 gapped at .30 and a .64 jet. She's been running way better, not close to perfect but wasn't bogging and could at least ride around. Now yesterday it died/ plug wet, piston wet. Even wet around too if head where plug sits. Ordered new #7 iridium plug. Going to change gas to 93, mix up 24/1 ratio and jet down and then see. Might open up Cdi and increase spark.
Also, is the plug garbage once it's been fouled or can it be cleaned and reused? Best way to clean??
Mike

 

[merlinfire]

Well, at it again. Had a #7 gapped at .30 and a .64 jet. She's been running way better, not close to perfect but wasn't bogging and could at least ride around. Now yesterday it died/ plug wet, piston wet. Even wet around too if head where plug sits. Ordered new #7 iridium plug. Going to change gas to 93, mix up 24/1 ratio and jet down and then see. Might open up Cdi and increase spark.
Also, is the plug garbage once it's been fouled or can it be cleaned and reused? Best way to clean??
Mike

I'm interested to hear the answer to this as well. Let us know how it works out.

 

[Neufcruz]

Haven't had a chance to take it out. Tomorrow. I relieved the plug but not going in till I get the jetting close. I hear plugs on these are toast after a hood foul so at $10 a plug, Im not gonna just throw it away. Going to do a throttle chop and see how it is with the .62 jet. Seems lean up top but will check.
Wish I knew the tight way to really tune this thing. I have so many vatiables to adjust/change and test. Not sure what to do and in what order. Wish there was a DIY for timing a set up like mine.
66cc- high compression head- expansion pipe- reed valve-windowed piston- jaguar CDI- dellorto carb-.93 octane @32.1- currently ngkb6hs (have ngkb7hs as well and the ngk #7 iridium plug.)
So many things to adjust.
Carb jetting, CDI, #plug, plug gap.
I love tinkering but want to get it so I can go out and have fun instead of worrying if it will foul etc... Plus I really want to see what this thing will do once running right.
Mike

 

[sbest]

Plug fouling - Yes, you can rescue a fouled plug often, but just as often it will let you down again. Chuck it.

Tune new set up. Pick your best guess, aim for: Tame timing, Cheap hot-ish standard plug, slightly rich jetting, standard gap.
Warm up engine on a used plug.
Install new plug and give it as long a blast at WOT as you feel safe (watch head temp and detonation)
Check bottom of plug insulator (cut it if need be) for mixture and correct jet. Repeat until right.
Adjust needle for crisp running from idle to WOT.
After WOT run adjust plug heat range based on top of insulator (will be evident on above also).
Adjust timing for WOT power and no detonation.
Adjust plug gap for max power at WOT or tinker with plug type.

That is your order Mike. Jetting, Needle, Heat range, timing, gap.

Understand:
You cannot read jetting on a cold plug.
Start rich and retarded and go more so if you hear detonation or see white plugs.
Main jet, then needle (because our plot jet is fixed) is the order to jet.
Jetting has huge effect on timing but timing has little on jetting, do jetting first.
Heat range will only be apparent at WOT when everything else is perfect.

My take, any suggestions?

Steve

 

[HeadSmess]

fouled plugs can be cleaned just by poking them into an engine that runs REALLY hot, or calls for a fairly high number plug...ie, if it asks for 11, it will "self clean" a 5...just dont run it so long the electrodes start to melt! good luck finding one that can accept a B thread plug though got any friends into go-karts, perhaps? one lap oughta do it.

other method is to hit it with the blowtorch hey, the things are "immune" to heat! just concentrate on the bit that goes in the engine, wait for it to stop smoking

ive only ever seen one or two engines "killed" by the plug, usually cus some turkey has dropped it! (possibly the same turkey that stripped out the thread too!) though some brand plugs are also useless... i avoid champion(but do use the CJ8, standard brushcutter plug), and chinese muck is instant bin model stuff. plugs are cheap. get a collection happening.

iridium is a bit pointless but then again, its your money...do whatever you want

ignore plug gaps, anywhere between half to 1 mm is fine, these are not high performance engines! the CDI can easily jump twenty mm in open air...

low octane fuel produces MORE power, but is an issue if you run high gear ratios and lug the engine at low RPM. my recent experience (seizing my nsr150 at 130km/h in a corner) has left me with a decided bias against ethanol fuels. ( though i think the issue was pre-existing...i will never try E10 again!)


when doing the "plug chop", USE THE KILLSWITCH! ie, at WOT, kill it!. do not idle, do not back off! just hit the killswitch, as even one or two revolutions (with the ignition running, at a different throttle setting) will mess up the plug reading...


you can check mid and idle settings with plug chops as well, but same deal...you need to stay at consistent throttle setting for at least a minute, and use the killswitch to stop the engine. you adjust mids with the needle, and one these engines, with slide carbs, adjust the idle mix by filing the angled section of the slide... can only go leaner, cant go richer. leave that bit alone unless you really know what you are doing...

oh...its a dellorto...they have a low speed mixture screw... leave slide alone


and, you still wont notice much difference... except for the tuned pipe/expansion chamber...if its a decent one.


remove exhaust altogether, make custom intake manifold, tune that in for max power at same RPM the exhaust kicks in(start with it fairly long, keep trimming til it hits the peak), then you really start to boogie may require earplugs and a remote location, doing that...