Weather affecting engine performance?

FurryOnTheInside

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In general, just from what I have read on this forum, the forum threads concerning jetting that seem to go around and around getting nowhere, and contain a lot of weird counter-intuitive nonsense,
are those carburettor jetting threads where the dude has no cap on his muffler.

You might try some mods to help with the flow of your stock muffler, so it can have its end cap on and have some minimal or moderate back pressure, but not too much or none at all. Then jet the carb.

IMHO of course, and I hope this is helpful.
 

Tyler6357

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I'm using somewhere between 16 and 32 to 1. I will work on it tonight and keep up updated. My spark plug was black and completely saturated. I assume that is what the problem is. In about 3 hours I'll have a good idea. Thanks for your help and tips Tyler. I think ill order that jet kit tonight. I'm using a micargi clone carb ... at least I think thats it. It looks cool and was 16 bucks on Amazon. I guess even with throttle control to keep it from 4 stroking I still need to adjust the.ratio for a dependable ride.
32x1 is fine as long as it's a high quality synthetic or semi-synthetic 2 cycle oil. Also, if the plug was black that indicates a rich condition, again, you need a smaller jet. Aren't you using a Dellorto clone carb? I bet 65 would be about right---> https://www.ebay.com/itm/Racing-Car...550801?hash=item1ccebc9951:g:p5YAAOSwZcZcqsYG
 

CrazyDan

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My question before I toss my $0.01 in, is the plug dry and black, or oily and black? It could be too much fuel to air mix, or too much oil/fuel mix.
 

JerboaJohn

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i think he meant a mikuni knockoff, but even those are $30 I think. id put money on a dellorto/sha clone for $16 bcs that's what I have.
you can go one step hotter on the plug if it's black n wet, but best to jet it. bandaid fixes are good in a pinch
 

Tyler6357

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i think he meant a mikuni knockoff, but even those are $30 I think. id put money on a dellorto/sha clone for $16 bcs that's what I have.
you can go one step hotter on the plug if it's black n wet, but best to jet it. bandaid fixes are good in a pinch
But he posted a pic of his bike in another thread, it sure looks more like a Dellorto clone than a Mikuni clone---> https://motoredbikes.com/threads/my-first-high-i-mean-build.54828/#post-488011

It's kinda important because they have different types of jets.
 

JerboaJohn

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yep. good catch. same as mine,, it's the SHA also known as HP carb, 5mm jets. I think I got the 5 packs of jets for $8 each from BMW. not sure how much they r now
I think many of 'em are made by Runtong
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JerboaJohn

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yeah for what they r, they're decent. esp when you want to be cheap. but sometimes I wish it could tune it better.
 

Tyler6357

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yeah for what they r, they're decent. esp when you want to be cheap. but sometimes I wish it could tune it better.
Yeah, I kinda got lucky and found the right jet, the #60 seemed to just wake up my engine perfectly. I went from the stock #70 to a #65 but it was still 4 stroking so I tried the #60 and it was just perfect.
 
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