Non-Mikuni Parts from MikesXS

[kvanderploeg]

Just received my order from MikesXS. I ordered the following:

48-0119 #135.0 Main Jet (Pr.) Lg. Round type
48-0120 #137.5 Main Jet (Pr.) Lg. Round type
48-0607 #45.0 Pilot Jet - (Pr.) - BS30/96
48-0662 Needle Jet - 336 YO
48-0663 Jet Needle - 5IX11

While the Needles and Needle Jets are Mikuni parts, the Pilot jets and the Main jets clearly are not. I sent Mikes an email stating my dissatisfaction this evening. So I guess in Mikes speak, "Mikuni Type" = Knockoff. Are these jets any good? Everything I've ever heard is, if it's not Mikuni, throw it out.

Kent

 

[xschris]

They work fine. I have been using them for years

 

[hooktool]

Replacement jets have a bad reputation in the 2-stroke world. You can get real Mikuni jets from Reproduction Decals.

John

 

[5twins]

I don't use them. I did in the past when they were cheaper than genuine Mikuni jets, now they're not so why bother? I never had a problem with them but I just feel better with the real deal in my carbs. If you compare the beveled part that leads into the metering orifice, you'll see it tapers differently than a genuine Mikuni jet. I've just got to think that affects flow.

 

[grizld1]

Right you are, 5twins, that chamfer does indeed affect flow; it's where the correction is made after the jet is bored.

 

[kvanderploeg]

I'm thinking I can use the small body diameter jets the same as the large body. Anyone have any experience with doing this?

Kent

 

[5twins]

I guess they flow the same but Mikuni used that large style jet in your '80 carbs for a reason - it anchors and holds the needle jet into the carb body. The large headed version is probably better at doing that than the smaller one would be. If you have a collection of the small ones, you might use them for testing and dialing in your carbs then buy the large style in the size you finally settle on.

 

[kvanderploeg]

Thanks for the advice, guys. Still not very happy with Mikes, as I don't think they make it clear that these are not OEM Mikuni jets.

Kent

 

[5twins]

With Mike's, you need to become an educated consumer. Ask first on one of these 650 lists about ANYTHING you consider buying from them. They have many good products but also have some absolutely worthless trash.

 

[kvanderploeg]

Another lesson learned about Mikes...

Kent

 

[grizld1]

Kent, just to confirm, flow is the same through large round and small round Mikuni mains.

 

[kvanderploeg]

Thanks, Griz. I figured it was as I know the V-Stars take the small body and guys will use the large body with no problems.

Kent

 

[YL82]

What's wrong with this picture?

Main Jets recently ordered from Mikesxs.

They indicate that they will take care of it. I'm glad this was a spare set, or I would be PO'd.

 

[kvanderploeg]

Real high quality control there, eh?

Kent

 

[Davep]

On the Mikuni topic, I have Mikuni VM carbs on mine and am not that impressed really. My bikes just been on a dyno at a very well respected race and drag bike tuner and he said "they're the worst carbs I've had to set up in years!" It still makes 52hp at the back wheel but................

Has anyone got experience of the Dellorto pumpers on here?

 

[grizld1]

If you want to spend that kind of money, go here and look at a pair of modern 4-stroke flat slide pumpers: www.mikuni-topham.de .

You didn't mention what motor mods are on your machine. Bear in mind that the horsepower spec given by Yamaha is gross horsepower--power measured at the crank, with no drive train or alternator. What your tuner measured on the dyno was net horsepower--power delivered at the wheel. If your engine has modified exhaust and VM carbs and is otherwise stock, 52 is a very respectable number.

 

[Davep]

Thanks for that I'll have a look a some carb options, no hurry though just yet. Not stock motor, 45mm exhaust headers and reverse cone silencers, VM carbs and power filters, fast road gas flowed head with modified combustion chambers. I know the filters are a little restrictive even though they're not supposed to be but it misses out on some HP due to no acelerator pump and it's a bit flat up to 3000rpm, after that it flies.

 

[racerdave]

Thanks for that I'll have a look a some carb options, no hurry though just yet. Not stock motor, 45mm exhaust headers and reverse cone silencers, VM carbs and power filters, fast road gas flowed head with modified combustion chambers. I know the filters are a little restrictive even though they're not supposed to be but it misses out on some HP due to no acelerator pump and it's a bit flat up to 3000rpm, after that it flies.

Your 52 rear wheel hp is at full throttle load. A accell pump in the carb would not change that as it would only pump gas as the throttle is moved.

 

[Davep]

Yeah I get that it's just more to do with lower rev range really, leaving road junctions etc and for being more usable in the future should I do some more tuning, it would also help with getting the fuel in faster rather than just rolling the power on, although I've no complaints, it's set up and running lovely. it's an illness really!

 

[Tomterrific]

Its the 45mm exhaust being too large. A 1 3/4" is known to be too large for the XS cylinder. Michael Morse at 650central has a fix or use 1 1/2" diameter pipes.

Tom Graham