2021 and the XS650

I'm thinkin' the air holes aren't needed on the later 38's like you have, but I'm not the expert on 'em. I expect 5twins will be along to set us both straight.
True - I'll see if he chimes in. Checked mikesxs and I believe their vm22/210 have the breather holes. I think if I order a new set a size up, I'll probably order a set at 27.5 spec as well to test if they do have breathers. Not sure if it'll solve my problem but could be a contributing factor.
 
I wouldn't get 'em from Mikes. I don't trust their aftermarkets to be sized correctly.
I order jets from Niche Cycle. They have the repops and OEM Mikuni. I stick with OEM.
 
I wouldn't get 'em from Mikes. I don't trust their aftermarkets to be sized correctly.
I order jets from Niche Cycle. They have the repops and OEM Mikuni. I stick with OEM.
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This is interesting. I got a box of parts from Dime City today. Dime City is part of Revival Parts that includes MikesXS. The bag with that tag on it took me by surprise and I’m not sure what to make of it.
 
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Your no-hole pilots (VM22/210 type) are correct for your '78-'79 type BS38 carbs. The pilots flow only fuel so no air bleed holes are needed on the sides. The air is added to the fuel above the jet after it comes out of it. I guess Yamaha was able to strike a deal probably and get the jets cheaper without the side holes. The larger replacements you get will have side air bleed holes but that's OK, they'll still work just fine. If you wanted to find larger no-hole replacements, your only option would be to scrounge them from a different Yamaha carb set, a set from the XS500. It came with #30 no-hole pilots. Yamaha doesn't sell these jets anymore so, like I said, scrounging is your only option.
 
Here's a little help for when you start wiring.

Thank you - an excellent tutorial.

I usually employ Japanese-style 3.9 mm bullet & socket type connectors but the stripping and crimping method is very similar. If and when I get around to re-doing the wiring, will try and identify places where being able to pull a connection apart is not normally needed and will use the non-insulated butt connectors you showed.
 
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Your no-hole pilots (VM22/210 type) are correct for your '78-'79 type BS38 carbs. The pilots flow only fuel so no air bleed holes are needed on the sides. The air is added to the fuel above the jet after it comes out of it. I guess Yamaha was able to strike a deal probably and get the jets cheaper without the side holes. The larger replacements you get will have side air bleed holes but that's OK, they'll still work just fine. If you wanted to find larger no-hole replacements, your only option would be to scrounge them from a different Yamaha carb set, a set from the XS500. It came with #30 no-hole pilots. Yamaha doesn't sell these jets anymore so, like I said, scrounging is your only option.
Thanks 5twins. That at least narrows my issue down. Going to reclean the carbs tonight, but also ordered a #30 pilot to help alleviate some of my carb issues - I think my unifilters might be part of the reason it's running too lean and needing the choke at idle, along with any potential debris.
 
Anyone have a recommendation for coil replacement? - I intend on keeping points, not really looking to upgrade ignition system.

I still have stock dual coils and condenser, and i'm thinking this may have weakened over time. Not too certain though.
 
I'm having a heck of a time finding a grab bar for the '79 Special II (1979 xs650 2F). The bar that the previous owner had on doesn't reach the fender mounts. Not sure what grab bar fits - probably needs the mounted signals with the bar too. Any ideas?
 
Anyone have a recommendation for coil replacement? - I intend on keeping points, not really looking to upgrade ignition system.

I still have stock dual coils and condenser, and I'm thinking this may have weakened over time. Not too certain though.
My stock coils work fine 60,000 miles and 38 years. OTOH, I put Dyna coils on my XS1100 and they work very well, also expensive.
 
My stock coils work fine 60,000 miles and 38 years. OTOH, I put Dyna coils on my XS1100 and they work very well, also expensive.
Thanks Jet - I didn't think there was a reason why they would go bad - but did notice left one getting pretty hot. Will browse forum about diagnosing.
 
but did notice left one getting pretty hot. Will browse forum about diagnosing.

Being a 360° twin, invariably one of the cylinders will stop on the compression stroke when it shuts down. Because no two cylinders have identical compression, it will tend to favor one cylinder over the other. The cylinder that stops on compression will have that point set closed, which will have that coil charged for spark. The other point set will be open... meaning no current flow through it. That's a long way of saying one coil will get hot if the key's on and the engine's not running. The other (open points) will be cold.

They will both get hot with the engine running... and both should feel about even heat to the touch.

So what condition are you at, running or not running?
 
Running. Cam tension set, points are new and gapped, and timing set using a light. Carbs are cleaned and rebuilt: jetted pilots a size up, new gaskets, floats set to 25mm, new diaphragm. Carbs are also synced using vacuum gauge (although I will be using a manometer this week to get them more precisely dialed in). Idle mixture screw set to about 2.25 turns - I believe that is close to the spec. Also did valve adjustments: .006 exhaust, .003 intake.

Bike kicks over so-so on a few kicks, and the starter is pretty intermittent. Thinking starter is pulling too much and the spark is weak at the plug. Bike idles OK at about 1500 rpms (a hair high) but will dies after a few minutes. Worked out any backfiring and idle is smooth. Leaning more into thinking it's an electrical issue. Starter sucks the life out of the lights as well when using it?

Also wanted to add - vacuum petcocks are supplying fuel.

Bike is 1979 XS650 2F (special II)
 
Just quick and dirty... you could swap coils between sides and see which one runs hot. You don't need to physically swap 'em, just swap the lead that goes to the points and swap the ht leads at the plugs. If the same one still gets hot, it might be getting close to the end of it's life. Check and see if the primary rsistance is low.

Too much dwell on that point set will cause a coil to run hot also. You have a dwell meter?
 
Just quick and dirty... you could swap coils between sides and see which one runs hot. You don't need to physically swap 'em, just swap the lead that goes to the points and swap the ht leads at the plugs. If the same one still gets hot, it might be getting close to the end of it's life. Check and see if the primary rsistance is low.

Too much dwell on that point set will cause a coil to run hot also. You have a dwell meter?
Thanks Jim - I'll give it a try tomorrow. No dwell meter (I don't think my multimeter has it - but not sure off hand).
 
any chance the intake rubbers have a split or cracked, also being hard they don't squeeze tight so easily just a thought concerning running lean :)
 
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