[tooseevee]

I just checked the Niche Cycle website, Mikuni air jets ARE a thing, in addition to the pilot jet.

        Yes, I know there are Mikuni air jets.

         My question to Steelaway was just mostly about terminology.

[Steelaway]

      I didn't in any way mean to compare my TM 32 to the VM.

       My comments were only asking or answering in general terms how carbs work & I think we'll get into a morass of semantics & terminology down the line.

         I wish Steelaway would answer because it sounds to me that the air/fuel mixture screw is being called something else. I'd never attempt to help Steelaway dial in the VM. They're totally different animals (or fruits)  Just general stuff.

     Anyway. I was just curious 'nuff sed -  they are apples & oranges - I'll steal away now 

Thanks for all the input again it is really appreciated and I do realise I am pushing the envelope a bit.

The pilot air jet was definitely not drilled - Chinese quality control?

I was going to drill a 1mm hole in it initially to see what difference it made. But while I was trying to think if some way of holding it while I drill it I thought ---- I wonder if the original vacuum carb has one fitted. Amazingly when I unscrewed that one it has a jet with a 1.5mm hole through it.

I fitted that one to my new Mikuni carb and its lot lot better- Still not good but better. .
It seem to be mega rich but it has a 200 main jet which seems to be the optimum.

I suspect that the slide which seems to be around a 2.5 is too rich it could well need a weaker slide a 3 or 3.5
I could still drill a 2 - 2.5mm hole in the blank jet and see if its better

Onwards and upwards.

I'll try some other stuff tomorrow.

[Steelaway]

I was at the Classic Motorcycle Show at Stafford yesterday and saw this.

The new 2024 model?

[Adrian II]

I can't un-see that... 

A.

[Steelaway]

I can't un-see that... 

A.

Don't you think?

I wonder how well it runs on that flat slide carb?

[Adrian II]

The PWK carbs were offered by the former US importer (whose forum this once was) as an aftermarket goodie for the old style Bullets and Electra-X models, or rather Taiwanese clones thereof. If jetted correctly they work fine on 4 stroke applications. Of course this particular er... thing is a show bike, so I'm not convinced it actually runs much at all.

A.

[Steelaway]

The PWK carbs were offered by the former US importer (whose forum this once was) as an aftermarket goodie for the old style Bullets and Electra-X models, or rather Taiwanese clones thereof. If jetted correctly they work fine on 4 stroke applications. Of course this particular er... thing is a show bike, so I'm not convinced it actually runs much at all.

A.

Even more from that mine of information.
I do know about the PWK flat slides but I felt a step too far away from the classic look I'm trying to maintain.
Where would you feel it's possible to attain the maximum torque with the EX?

Which carb are you running?

I need to cover some mileage as soon as can now.

[tooseevee]

Thanks for all the input again it is really appreciated and I do realise I am pushing the envelope a bit.

The pilot air jet was definitely not drilled - Chinese quality control?

I was going to drill a 1mm hole in it initially to see what difference it made. But while I was trying to think if some way of holding it while I drill it I thought ---- I wonder if the original vacuum carb has one fitted. Amazingly when I unscrewed that one it has a jet with a 1.5mm hole through it.

I fitted that one to my new Mikuni carb and its lot lot better- Still not good but better. .
It seem to be mega rich but it has a 200 main jet which seems to be the optimum.

I suspect that the slide which seems to be around a 2.5 is too rich it could well need a weaker slide a 3 or 3.5
I could still drill a 2 - 2.5mm hole in the blank jet and see if its better

Onwards and upwards.

I'll try some other stuff tomorrow.

      This is really confusing & don't get me wrong. I'm just confused & curious. Here is an exploded view of the VM. Remember, I do not have this carb. I have a TM 32 flat slide which I'm VERY happy with & could take apart & put back on blindfolded.

       https://mikunioz.com/vm-round-slide-carbs/vm32-carb-parts/?v=13b249c5dfa9

       The exploded view shows that your carb has a Pilot Jet (21) exactly like my TM with holes in it; a hole through the center & holes 90 degrees into that center hole.

                   Maybe that's what's confusing me.

         I don't see how they could be selling thousands of the carbs like the one that you have with components that need to have holes drilled in them.

         If it's running way rich that's the Pilot Jet that's too big (or the needle's too high) & that jet in your picture isn't the Pilot Jet. Do the Main Jet after you do everything else; air/fuel mixture at idle, pilot jet, needle height at 1/4, 1/2, 3/4 throttle.

          I think that Air Jet you show is one that I have never even had out of my TM 32 since I put it on.

         Anyway. Sorry I ramble on. Good luck with your tweaking 

         & yes, I agree the VM "looks more better" on the pre-UCE engines.
       

[tooseevee]

Reference my Reply #53: I found it! The "Air Jet" in my TM 32. It's Part # 53 in the link below, right under the intake throat:

https://mikunioz.com/flat-side-carbs-non-pump/tm32-parts/?v=13b249c5dfa9

     I was never concerned with this jet (never had it out) when I was dialing in the TM 32. Just Air/Fuel Mixture Screw, Pilot Jet, needle height, needle # & Main Jet. Whatever slide came in it is still there.

      Next time I can I'll pull it & see if there's a hole in it. Everything hurts too much today.

       I learned something from this back & forth. Thanks.

[Adrian II]

The pilot air jet was definitely not drilled - Chinese quality control?

More on those pesky air jets, I see genuine Mikuni items come drilled to different sizes, starting at BS30/97/0.0 and going up to BS30/97/2.0, with 0.0 actually being a blank, i.e. a plug! Maybe your Chinese supplier sells the holes separately? You could try Allen's Performance or Motocarb who are Mikuni suppliers in the UK and see if they'll sell you just an air jet, though of course they might not be too happy if you tell' em it's for a Chinese copy VM. 

You were asking about what carb I'm running. My old Electra-X started off an a PHF32 Dell'Orto new from the dealer, then I swapped to the rather bulkier Mikuni TM36-31 carb, whose picture I posted previously, but here it is again for convenience.



My current AVL hybrid has a Dell'Orto PHF36.



I was also working on another AVL hybrid engine project for which I was experimenting with a variety of carbs. That bike is now getting a different engine, buy I hope to get back to it at some stage. If a (genuine) Mikuni VM38 or an ex BMW R90s Dell'Orto PHM38 don't float your boat,





does an Amal 1.5" GP provide the classic look? 



As for torque, I think that will be down to the seat-of-the-pants dyno. Being of the pie-eating persuasion I found my Electra-X was over-geared with the standard 18T gearbox sprocket, dropping down to a 17T in line with a normal 500 Indian Bullet made the bike more fun to ride in city traffic (I was commuting on it for a while) with no loss of top speed. Get the carb sorted to match your Goldie loudener and the gearing right for the sort of riding you want to do, and I think you'll be pleased with the results. Top-end performance is limited by the AVL cams, but that's another story.

A.

[Steelaway]

      This is really confusing & don't get me wrong. I'm just confused & curious. Here is an exploded view of the VM. Remember, I do not have this carb. I have a TM 32 flat slide which I'm VERY happy with & could take apart & put back on blindfolded.

       https://mikunioz.com/vm-round-slide-carbs/vm32-carb-parts/?v=13b249c5dfa9

       The exploded view shows that your carb has a Pilot Jet (21) exactly like my TM with holes in it; a hole through the center & holes 90 degrees into that center hole.

                   Maybe that's what's confusing me.

         I don't see how they could be selling thousands of the carbs like the one that you have with components that need to have holes drilled in them.

         If it's running way rich that's the Pilot Jet that's too big (or the needle's too high) & that jet in your picture isn't the Pilot Jet. Do the Main Jet after you do everything else; air/fuel mixture at idle, pilot jet, needle height at 1/4, 1/2, 3/4 throttle.

          I think that Air Jet you show is one that I have never even had out of my TM 32 since I put it on.

         Anyway. Sorry I ramble on. Good luck with your tweaking 

         & yes, I agree the VM "looks more better" on the pre-UCE engines.
     

The pilot air jet 18 is to atomise the fuel in the emulation tube (needle Jet) or you would just get neat fuel and probably too rich.
I was about to drill out the blank one when I thought what's in my old CV carb. When I removed it I measured it with a drill to ne about 1mm. I fitted this to my new carb and it was better not great but better.
I then drilled it out to 2mm thinking that that I still have the blank jet if its too big --- even better -- but it still kept cutting out and sooting up the plug occasionally.
Then I noticed fuel leaking from the float chamber.
I took the float chamber apart and found a piece of grit in the float needle jet ----- That would be it -Flooding occasionally
Now it behaving so good that I took it for a ride.

Eventually when I arrived at the by pass I revved it hard through all the five gears and it was clean all the way up to 85mph with still some to come.

I'm happy with the initial performance through the gears but I still need to check the main jet for richness/weakness.
The slide that it came with is a No2 and I'm told it should be a No3 or even No3.5. so there is still some experimenting to do.

Do I need to fit an air filter - or not bother?

I'm going to the Newark Auto jumble on Sunday to see what they might have to suit.

[Paul W]

My personal experience of putting old bikes (and cars) together, more than fifty years since I rebuilt my first bike, taught me never to run an engine for long without an air filter. A suitable one is very cheap insurance against top end wear. The amount of dirt that washes out of a reusable filter never ceases to surprise me.

[Steelaway]

My personal experience of putting old bikes (and cars) together, more than fifty years since I rebuilt my first bike, taught me never to run an engine for long without an air filter. A suitable one is very cheap insurance against top end wear. The amount of dirt that washes out of a reusable filter never ceases to surprise me.

You are right.
I've sent for a performance filter - that should fit now I've taken the old air box out.

Thanks for the reply

[Adrian II]

Depending on what size your filter is there might be clearance issues with the side cover.

If so, don't junk or chop the old cover, get the cover from an Electra-EFI which has a bigger cut-away in the affected area but is otherwise the same.

e.g. this one, or maybe a less kicked-about version?

https://accessories.hitchcocksmotorcycles.com/33500?cont_page=Toolboxes-Air-Filter&page=2



Mikunis don't have their own fuel filter where the petrol feed enters the carb (unlike Amals and Dell'Ortos), so you might also want to treat the bike to an in-line fuel filter.

A.

[Steelaway]

Depending on what size your filter is there might be clearance issues with the side cover.

If so, don't junk or chop the old cover, get the cover from an Electra-EFI which has a bigger cut-away in the affected area but is otherwise the same.

e.g. this one, or maybe a less kicked-about version?

https://accessories.hitchcocksmotorcycles.com/33500?cont_page=Toolboxes-Air-Filter&page=2



Mikunis don't have their own fuel filter where the petrol feed enters the carb (unlike Amals and Dell'Ortos), so you might also want to treat the bike to an in-line fuel filter.

A.

Brilliant idea. I'll order iinow
Has it been modified by previous owner?