Looking at the cheap jet sets for Mikuni VM crabs on the EvilPay, like $8 and free shipping for #200 to #290.

Anyone messed with these before?

Probably stick some genuine Mikuni jets on the optical comparator at work one day to see what is up.  

Seems risky

4 minutes ago, mnstang said:

Seems risky

That thought has crossed my mind, but Mikuni's jet numbers are a measurement of flow, apparently.

Hole size is hole size and flow is flow.  

Q = V x A

I'm thinking a spreadsheet formula will decipher if the cheap shit from the big rock candy mountain is as good as the genuine stuff.

11 minutes ago, racinfarmer said:

That thought has crossed my mind, but Mikuni's jet numbers are a measurement of flow, apparently.

Hole size is hole size and flow is flow.  

Q = V x A

I'm thinking a spreadsheet formula will decipher if the cheap shit from the big rock candy mountain is as good as the genuine stuff.

Yes the numbers are flow.  Like 290 would be 290cc per minute or something like that.  But that's also at specific controlled conditions that the manufacturer controls like under a very certain vacuum and pressures and even the fluid they're running through them etc.  I think it would be in direct relation to the hole size but it is the flow where the number comes from.  Flow could be different if the length of the jet is different even if hole size is the same.  But how much do the China children really care about getting it exactly right?  You're into old turds I'd think you'd have a piles of jets around.

5 minutes ago, mnstang said:

Yes the numbers are flow.  Like 290 would be 290cc per minute or something like that.  But that's also at specific controlled conditions that the manufacturer controls like under a very certain vacuum and pressures and even the fluid they're running through them etc.  I think it would be in direct relation to the hole size but it is the flow where the number comes from.  Flow could be different if the length of the jet is different even if hole size is the same.  But how much do the China children really care about getting it exactly right?  You're into old turds I'd think you'd have a piles of jets around.

I don't have anything in the smaller 200's other then what I ordered with my VM34.  I have mainly high 300's, 400's, and low 500's since that is what the old race sleds took.  

Have a 210, 220, and 230, but for $8 shipped, I think it could be interesting.  Not sure I'll ever use them.

I ordered the finest, cheapest jets EvilPay has to offer.  

$4.62 shipped and tax.

Sizes 200-290.

Going to do a little number and spreadsheet crunching on some OEM stuff and these to see how they compare.

 Bought OEM... Not sure I want to be a guinea pig testing my sled.

 

1 hour ago, ICG said:

 Bought OEM... Not sure I want to be a guinea pig testing my sled.

 

Here are my general thoughts on this.

They may or may not go in a Enticer 250 with a Mikuni conversion on it.  The Facespace says a 210, 220, or 230 main jet should be the ticket for MN racing/riding.  I have those 3 sizes from Mikuni.

If I were to use these, I'd be putting it on a 1 crab 1 cylinder sled.  If it is a "214" instead of a 210 or 220, is it that big of a deal on a sled like that?

It gives me a reason to fuck-off in the engineering and QA labs for a while.

At this point, it is an exercise in futility, but I've wasted $4.62 way worse then this.  I'm mostly curious at this point.

Probably still have the new jets from the 198o's....never changed them for temp changes.

My order of the finest, cheapest, most questionable jets arrived after 8 or 9 days in the mail from Kentucky.

Note: I forgot to bring my Mikuni jets with to compare.  Next time I run to work I might remember them.

Here is my brief rundown:

On initial inspection, they seem decently made.  Brass, bright, laser marked size, well machined threads.

Under inspection using a basic microscope, they do begin to fall apart a bit.  The external machining work is good, the marking is good, but several of the orifices in the jets appear to be machined off center.  Some were dirty inside while some looked clean.  I didn't notice any bad burrs.

Once I stuck them under one of our high end scopes, found a couple things I suspected, one I didn't.  First was our super expensive microscope measurement software does not recognize the the lenses installed in it, so the measurement on the screen may not be what the actual measurement is.  Orange arrow is a machining mark that follows to the top of the hole, so the concentricity isn't there, but may not be a big deal in this instance.

Size marked isn't consistent.  Some may be mis-marked?

Marked size vs. Measured "size"

200 = 2.37359mm (larger then both 210 and 220)
210 = 2.28310mm (should be 200?)
220 = 2.35575mm (should be 210?)
230 = 2.49449mm
240 = 2.53387mm (should be 250?)
250 = 2.50634mm
260 = 2.54915mm
270 = 2.56316mm
280 = 2.63920mm
290 = 2.65792mm

Would I buy them again?  Maybe? 

Trust them to be consistent?  No

Chart them out compared to Mikunis and use them as "odd" just sizes?  Maybe?

8 minutes ago, racinfarmer said:

My order of the finest, cheapest, most questionable jets arrived after 8 or 9 days in the mail from Kentucky.

Note: I forgot to bring my Mikuni jets with to compare.  Next time I run to work I might remember them.

Here is my brief rundown:

On initial inspection, they seem decently made.  Brass, bright, laser marked size, well machined threads.

Under inspection using a basic microscope, they do begin to fall apart a bit.  The external machining work is good, the marking is good, but several of the orifices in the jets appear to be machined off center.  Some were dirty inside while some looked clean.  I didn't notice any bad burrs.

Once I stuck them under one of our high end scopes, found a couple things I suspected, one I didn't.  First was our super expensive microscope measurement software does not recognize the the lenses installed in it, so the measurement on the screen may not be what the actual measurement is.  Orange arrow is a machining mark that follows to the top of the hole, so the concentricity isn't there, but may not be a big deal in this instance.

Size marked isn't consistent.  Some may be mis-marked?

Marked size vs. Measured "size"

200 = 2.37359mm (larger then both 210 and 220)
210 = 2.28310mm (should be 200?)
220 = 2.35575mm (should be 210?)
230 = 2.49449mm
240 = 2.53387mm (should be 250?)
250 = 2.50634mm
260 = 2.54915mm
270 = 2.56316mm
280 = 2.63920mm
290 = 2.65792mm

Would I buy them again?  Maybe? 

Trust them to be consistent?  No

Chart them out compared to Mikunis and use them as "odd" just sizes?  Maybe?

Off center would be some concern as to what it will do with flow around the needle in 1/2 to 3/4 throttle.  That much variation in diameter would the big concern primarily if there're measuring smaller than what there're marked,

It would be interesting to see what the Mukuni jets measure out to for size and concenticity.

Mikuni jets are more, but not that much more and then you have them for a lifetime.  It's good you have the capability of measuring them but most people 99.9% do not so I feel vindicated in choosing to advise against them.  Plus their chinesium brass grade is highly likely to be poor which could lead to more problems.

Imagine being lean and going up two sizes and ending up more lean!   Unbelievable.  It usually pays to spend the money upfront on the quality parts.  At my work I always see customers trying to save money with cheaper parts or cheaper labor and they always end up paying way more in the end and that's not including their time.

23 minutes ago, mnstang said:

Mikuni jets are more, but not that much more and then you have them for a lifetime.  It's good you have the capability of measuring them but most people 99.9% do not so I feel vindicated in choosing to advise against them.  Plus their chinesium brass grade is highly likely to be poor which could lead to more problems.

Imagine being lean and going up two sizes and ending up more lean!   Unbelievable.  It usually pays to spend the money upfront on the quality parts.  At my work I always see customers trying to save money with cheaper parts or cheaper labor and they always end up paying way more in the end and that's not including their time.

I could have one of our techs shoot them with the Niton gun to see what the different in grades is.

More out of pure interest at this point.

I have had a number of aftermarket jets never trusted them, none of them had the same taper as the Mikuni tested by inserting a Mikuni needle end of the jet.

 

Comparing the Mikuni to the cheap shit.

Only had 210, 220, and 230 to compare to.  210's were the closest match to one another.  

210:

230:

On 3/8/2024 at 6:29 PM, racinfarmer said:

Comparing the Mikuni to the cheap shit.

Only had 210, 220, and 230 to compare to.  210's were the closest match to one another.  

210:

230:

Not sure if it's just the picture but the threads looks a little different too.

 

Those cheap ones are probably only about good for smoking your drugs out of