How to build a new set of VM34's and then UFO's on an H2

I suggested to Niche Cycle, somebody should build a VM kit, I see they have one as of yesterday with UFO’s on Ebay………..these will need to be-re-jetted.

I bought NOS H2 manifolds (from Mid Atlantic $150) as they angle down and match the ports properly, mine were cracked and old, your stock ones should work but may stiff and cracked………….
NOTE: I had manifold leak issues after warming up, I got rid of the Phenolic Spacers and Gaskets, three bonded the manifolds right to the cylinders, no leaks anymore…….kind of permanent though.

I had good results with the UFO’s, they were a bit finicky to get tuned, once set, then forget………..They give a good strong signal at lower RPMs and flow more up high, real crisp throttle response………..there is a chart that shows them flowing better than a flat slide, whether true or not, who knows………..I do know the bike always felt “In the Zone”, better low end, lot more range, 33.6 MPG too

Building and getting the Parts

I would find a set of (3) soft springs for VM 34’s, I saw them at something like Mikes Cycle or Mikes something but I already had them, Niche has them………some have used the VM30 springs, but they are a smaller diameter.

Order 3 of all items below from Niche Cycle about $580

VM34-275 Mikunis, (3)
-come with 2.5 slides, these have a vent on the bottom of the float and a second one used for vent tube in the top left by the slide. (They have a flipped carb VM34-168, I did not use one, no need to)
-they also have a “Boss” area that could be tapped for a banjo bolt to drop oil into the float bowl on a B\C 4-line pump………this would have to be machined and tapped………….or, one could use an inline “checkvalve” from the pump……..and feed into the tube on the other side just fine………..I actually ran with no-check valve for a year………..no problem for me, but the correct way is to use a carb check valve………..
-I have heard many guys say “I can get a set for $300 ready to go”……….my thought is………you can buy 3 new ones for $99 each…………and you probably have to buy jets anyway
NOTE: the VM34-275 have the Big 58mm Bell mouth and will not fit a stock 3 into 1 snorkel, use Ram-Air or UNI filters………..VM34 older sled carbs will fit 3 into 1 (they probably need new float needle’s and seats, bigger 3.5mm or something like that)

Cable operated choke kits (3)
-they may be the same as VM30, something tells they are not
-I am using the VM34 cable chokes on my TMX38’s fine……….not positive on that though, best to get the kits

UFO’s  (3)
-Thunderproducts…………Jim Hobbs is making them also, and in different cutaways
-I think the reason they have a 3.5 cutaway (on purpose) is due to how they flow and have a high signal strength
-I have never used anything less cutaway than the standard 3.5 UFO’s (1/8 to 3/8 throttle), who knows, maybe somebody has tried the lesser cutaway with success


Jetting

The jetting below has worked well on a few guys H2’s with chambers and should be close, jetting is up to you though to dial in, a hot rod motor may be a bit different, mine was warmed up a bit………this is what I experienced…………..so don’t assume this is perfect for your bike

-230 (3 of each) main HEX jets (carbs have 260’s in them, 220 was on the edge of lean on my bike, 240 was rich………..always good to have a set of each)

-6DH4 needles, they come with the carbs, 2nd clip down……….. (I ran a 6DH3 but had some Mod’s, Zeeltronic)………this is probably fine for your bike

-P2 needle jets (3), (they come with P-6…….too rich and sluggish) turn the carb upside down; tap out with a drift easily towards the slide area above…………..P-6 was fair without squish heads, P-2 was much better, and with squish heads (made it rich at 3/Cool……..P-2 was a must I (I even went to a P-0 with zeeltronic)

-17.5 pilot jets (3 of each) perfect, get 15’s (lean and peaky on takeoff), get 20’s fat and sluggish

-Airscrews are 1 3/8 turns on my bike………..the idle procedure is different than the book, just try it

(You may want 240 and 250 main jet‘s just in case you have a hopped up motor, always good to have some pilots and mains, they are cheap, needle jets are not)

These carbs have a big mouth and my stock UNI’s would not fit, I ordered a set of 15 degree angle, part number 234185 (don’t remember the Uni model) from Exceptional Motorsports , these fit $40……..but now I prefer the Ram-Air from the UK as they look good and work well, expensive though.

Go to the local Auto Zone, they have fuel proof yellow/transparent weed eater Tygon fuel line about 7’ for oil lines, they also have a small box of 10 small round clamps………this is what I used on the B\C………..as mentioned, a check valve should be used………..not needed on an H2\H2A

I have a Pingel Petcock 5/16” ID again, I used Tygon, 4’ worked for me as the carbs have a bigger 5/16” fuel inlet………...you may need to adapt these to a stock ¼” fuel petcock

Carb Mounting

The VM 34’s will not fit on the bike, they hit the brass tube in the new carbs bottom float bowl on the left and right cylinders, the center carb hits the Neutral switch barely. I got a fine hack saw and cut all three tubes off of the float bowls flush, then get a dremel with a round sanding drum (or file even). Radius where you cut the tubes off about 3/8 of an inch and check them, remove enough so they don’t hit the cases L and R. On the middle carb, grind a small relief where the Neutral switch hit’s on the float bowl itself.

Mount the carbs, make new oil lines from the H2B or H2C pump (I did one at a time so the pump port match’s the proper cylinder), I filled mine with oil and put a stick in each end so they would be bleed till connected, go into the left side of each carb (and an inline check valve), use the small clamps on each end. On a 72 or 73 just leave these tubes for a second float vent. You may want to mix a bit of premix in the gas tank till the oil gets passing through the carbs and you are done jetting.

I set my idle screws with the slide low looking at the back of each carb before I put them on the bike and got them the same, and then I could do each the same exact amount of screw turns later to set the idle. Hook up the Choke and Throttle cables (mark them with masking tape when taking apart L, C, R,. I had some issues with not enough slack and for now had to remove the nut off of the L and R slide adjuster’s, will fix soon (Fixed !), and using black tape temporarily and the boots cover that. I did the pencil trick where you put 3 sharpened pencils in each carb, as soon as they start to lift, you will see them move, get them to all move at exactly the same time. Then use a UniSyn to get them perfect, both idle and a 2500 RPM. Adjust the oil pump cable to the scribe on the pump (I do a little less to cut back on oiling)…………….
NOTE: an H-1 throttle cable is 2mm longer at the carb end than an H2………….works well with VM34 and TMX 38’s (you must tap the side cover for the H-1 oil pump adjuster)…………or, I pulled the 4 way junction apart on the H2 cable, pulled each carb cable out, used a dremel with a saw blade and took two turns off each winding, or you may want to dremel a bit off of the carb caps where the adjuster sits, I did this on my TMX 38……….you want a little slack when at idle

UFO Installation

-I installed the UFO’s which use a 3.5 cutaway slide, I ground my slides to match the UFO’s.
-UFO kit comes with a plastic drill guide and instructions, I recommend using “2” screws, not “1”.
-You will need a 9/64 and a 9/32 drill bit, a dremel with a 60 grit sanding drum, and 6 of 6X32 longer screws.
-Wrap 2” masking tape a few times around each slide and put them in a vise gently when needed.
-Be very careful with the UFO drill guide as you can have it incorrect and drill the hole in the wrong spot, triple check it, drill the 9/64 thru the slide.
-Counter sink with the 9/32 bit, note that the new bit is very sharp, best to drill some holes in a piece of aluminum first to dull the bit, or it will grab on the soft brass slide, get it so the screw head is flush or slightly below the slide needle area.
-Mount the UFO with the self-tapping screw’s in each slide. Make sure no black plastic is visible in the engine side of the slide or they are not seated all the way.

-Put the slide in the vise with the cutaway away from you and with the dremel and sanding drum carefully remove and match the slide exactly to the UFO, this is very easy to do, don’t hurry.

-Clean up the sanded area of the new 3.5 cutaway with some 220 sandpaper by hand and bevel or radius slightly.

I, by mistake, had taken the UFO’s apart a few times and noticed the screws were not long enough (pulled one down when the engine was running, it can get digested in the motor). I got some 6X32 screws, these are the same screws used to mount an electrical box or light switch in your house. IDEAL makes a tool that you put the screw in the cutter and cut to length a “very” small bit longer than the UFO screw’s. Later I am going to use some adhesive on the UFO’s.
NOTE: You need to take them apart from the slide, when ready to put them on the bike, install the throttle cable under the slide, then install the Two UFO screws and UFO until gently till snug……..I did use a little glue on the thread on one…………you do not need to remove them once installed to change needles or clips, only when replacing\removing the cable

Also, make sure you hear the “Thud” when closing the throttle, hitting the idle screw………if not, I had to use some grease and close the UFO onto the base of the carb (idle)……….and remove a tiny bit off of the “V” in the UFO to come down all the way for low idle……..I have talked to other people, nobody else had this issue…………I scraped it with a pair of phone man’s scissors

Stainless Allens and lock washers are a nice touch from ACE hardware (12) for the float bowls

ENJOY…………THX…………Phil Mosher (BBP)