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Need help reading plugs for oval port wiseco piston

2K views 15 replies 4 participants last post by  Kngdomkroz 
#1 ·
I seem to be carbon or oil fouling plugs on the trail. I did a fresh wot pull on a new plug with the engine warmed up.
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Heres what the new one looked like after a 4 hour crawl (not same a above)
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155131


It def looks like my main needs to come up a size. Not too comfortable with the hot white.
 
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#4 ·
That was not a test - the plug should have been white - it was still new

Forget everything you saw on you tube - the proper way to do a plug check is to run at a steady speed for about 5 minutes, cut the ignition, hold the throttle steady while the engine dies and come to a stop - pull the plug and check the coloration - with no lead fuel and especially alcohol blended fuel, the inner porcelain should light tan or mostly white on the flame front side with discoloration on the shielded side - the ground electrode should should be tan to dark brown at the tip and get progressively darker to black where the electrode is welded to the shell. You can only do plug checks at throttle settings between idle and WOT

For top end jetting, increase the main jet in 2 size increments until at the top of the rpm range it falls on its face like the choke is on then back down 2 to 4 sizes to where it might flatten out at the top of the RPM range without losing power - if it flattens out and then loses power, it's still too rich.

Curious about what the Wiseco oval port piston has to do with the question? Changing the bore, stroke and piston has no to little effect on jetting. Exhaust has some effect, but changes to the intake has the greatest effect. Also, oil to fuel ratio messes with the jetting. The less oil you mix with the fuel the richer it runs - the more oil to gas leans the mix. The more oil you can run without fouling plugs the more power the engine will produce and the longer it will last. You did not mention what type of fuel, kind of oil or what ratio you chose to run with. They all play a factor in performance and if you are using alcohol blended fuel, you have to use an oil that will mix with water (alcohol is closer to being water than it is to being gasoline).

No let me know what you figure out.
 
#5 · (Edited)
The reason i mention the oval port is because i previously had a circular wsm piston in it and until the overhaul i had never had a new spark plug foul so quickly when trail crawling. The oil pump was reset to the correct marks. I have since switched to klotz snowmobile 2 cycle oil in the injection system. I did ditch the airbox and have a 2 stage uni foam filter on the end of the carb. The fuel i run is always ethanol free fuel from the pump. I always try to get 91 but also have access to 87 ethanol free. No vp race blends ect.

Heres whats in my vm34 275 catb
30 pilot
200 main
480 needle jet
6cey6-3 jet needle 2 slots down from top on clip
Cutaway 1.5
Pilot air is 1.0 out

I have 1 br8es left and some time tomorrow i will start your check list


EDIT: Usually it takes about 4 hours or low speed rock crawling to build up enough gunk to get the plug to start missing. If i try a high speed acceleration shortly after it will chugg and die under load or act like a rev limiter until i put a new one in
 
#7 ·
Heres whats in my vm34 275 catb
30 pilot
200 main
480 needle jet
6cey6-3 jet needle 2 slots down from top on clip
Cutaway 1.5
Pilot air is 1.0 out

I have 1 br8es left and some time tomorrow i will start your check list
That's just wonderful - you have all that information and I have nothing to go on - I don't know what type of vehicle you have and most of the information you have provided is meaningless unless you are a carb tuning guru tuning for optimum performance and vying for first the championship of the series you are racing in. More important than what you have is provided is what you removed from the carb and why

The VM34-275 comes with a 260 main, 35 pilot, 159 Q-2 needle jet, 6DH4 needle, 2.5 slide cut,2.0 air jet and a 3.3 float needle valve set. Now I just need to know what the VM34-275 replaced and I will get that from the stock specs once I know that the vehicle is.

Why use snowmobile oil in an ATV? Would you use Weedeater oil in a Mercury Marine?

91 octane non ethanol is good, but what brand? Every brand has their own formulation as all gas is a blend of aromatics, detergent and a host of ingredients that looks like a bomb makers shopping list.
 
#10 ·
Engine fully warmed 5 minute ride at a steady speed this is my result
Looks perfect in the mid-range for a two stroke.


OK - now that you have explained I may be able to help.

First, the VM34SS was manufactured by Mikuni exclusively for Polaris - the VM34-275 is somewhat similar, but requires different jetting - carbs are jetted at the factory for the flow characteristics and not for the engine it is to be installed on. You should put the original parts back into the VM34-275 and try it. Fine tuning should be done from there. Since you are utilizing the oil injection jetting will be simplified, but the jetting in the SS was for the SS and the jetting that came in the 275 was for the 275 - when you go mixing parts out of two different carbs there is no telling what the result will be.

You are lucky Casey's has any non ethanol fuel where you are - we got a new Casey's about a year ago and since we are located near a large recreational lake, the had one pump with 91 non ethanol to cater to the boaters. Late last year they removed the non ethanol - they now have E88, E85, 10% 87, 89 and 91. I was having to drive 20 miles to get to a Hy Vee's that has 91 non ethanol so I bought a 300 gal overhead tank at a farm sale. I now buy in bulk and save about .60 a gallon over buying at the pump.

No - no brand list the ingredients of their fuel blend as it is proprietary information and that is why some fuels provide better performance than others. You have to pay attention to the labels on the pumps. Some say MAY contain up to 10% ethanol and others say contains AT LEAST 10% ethanol. I have found some brands with as much as 15% ethanol and others with as little a 8% ethanol. Last time I checked Casey's here; 87 was 12% ethanol, 89 was 13% ethanol and 91 was 9% ethanol. Our BP station is 87 10%, 89 10% and 91 8%. Our Circle K is the worst at 87 15%, 89 15% and 91 17% and customers at Circle K regularly get 25% water mixed with alcohol when they fill up if the tanker is putting fuel in the tanks at the time they get gas. One guy filled up his Harley at Circle K which is about 3/4 mile from my shop. He made it from there to about 300 feet from my place - his bike died and he coasted in to my drive. I drained his carb (100% alcohol/water) and drained his fuel tank until I got gas. I handed a half gallon milk bottle that was about 1/2 full of water/alcohol and told him to take it to Circle K along with his receipt from when he gassed up and my bill for cleaning his fuel system. They gave him a refund for the fuel and paid his repair bill.

Anyway, Castor oil is a vegetable oil and will mix with alcohol, but it is not to be used in an injector system - it will gum up the pump and could cause it to fail. I cannot say the are no oils with castor that are injection approved, but I do not know of any, I am a stocking Klotz dealer and am not aware of any Klotz oils with castor that is injector approved. but there is no reason you cannot use castor oil in your motor. It is a superior lubricant to mineral and synthetic oil, but is produces a high amount of carbon which will rob power if left to accumulate. Mineral oils produce carbon, but not as much as castor oil. Synthetic oils do not burn in the combustion process and therefor smoke less, but the exhaust will run wet and might drip. It's called splooge an some people hate it - they want their exhaust dry.
 
#11 ·
Okay, so i am on the right track. I just wanted to be sure i wasnt gonna burn anything up. So would you think rock crawling is loading the plug down with oil. Its a lot of slow speed low to medium rpm riding with periods of intermittent revs. I like using the 2 stroke on the trail for the simplicity and power. This machine wheels in the hills surprisingly well even maintaining idle and performing at near dismount angles. You say your a klotz dealer? Do you ship too? Whats your price on a gallon of snowmobile oil?
 
#12 ·
You could go a heat range hotter on the spark plug (you are probably using a B8ES - try a B7ES) for the low speed rock crawling.

You using the TC-W3? Gal $55 - no minimum, but shipping is less in multiples - would have to have your street address, residence or business and zip code to check shipping charge.
 
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