[pushrod]

Thanks in advance for any help. I bought a 2000 military Bullet and would like to know if this is the original carberator, it looks a little different than the drawing in the owners manual I got with the bike.

[ace.cafe]

No, that's not the original carb.
It actually is an upgraded carb.

From the looks of it, I'd say it's a Mikuni VM34.

To operate the enrichment circuit(some people call it the choke,but it's actually not) on that carb, you pull up on that knurled knob, and that opens the enrichment circuit for cold starting.
To close the enrichener on that carb, push the knurled knob back down.

The stock carb has an identical system, but it has a lever on it, so the direction of actuation of the lever arm is exactly opposite, and you need to know which way to make that knob move to work it properly.

Pull that knob UP to open the enrichener on your VM34, and push it DOWN to close the enrichener.

[Cabo Cruz]

"From the looks of it, I'd say it's a Mikuni VM34."  ace.cafe

Ditto.

[pushrod]

Ok thanks, my owners manual shows a VM28. Looks like the previous owner changed the carb, air cleaner and exhaust but the bike only has 23 miles on it, at least thats what the odometer says by the looks of the bike I think it's true, but the guy I got it from bought it from the guys family along with 26 other bikes so he doesn't know the history. The owners manual has Motorcycle Warehouse written on it so I may try and contact them and see what history of the bike I can find. I'm not in any real hurry, I want to get it sorted out properly before I start breaking it in. Thanks again

[ace.cafe]

Ok thanks, my owners manual shows a VM28. Looks like the previous owner changed the carb, air cleaner and exhaust but the bike only has 23 miles on it, at least thats what the odometer says by the looks of the bike I think it's true, but the guy I got it from bought it from the guys family along with 26 other bikes so he doesn't know the history. The owners manual has Motorcycle Warehouse written on it so I may try and contact them and see what history of the bike I can find. I'm not in any real hurry, I want to get it sorted out properly before I start breaking it in. Thanks again

It's not too unusual for people to put upgrades on the bike when it's brand new.
It could very easily have been put on by the dealer, when the bike was first purchased, at the customer's request.

[ace.cafe]

I would change the oil and filter immediately.
Go to a good motorcycle shop that knows what they are doing, and get a good quality motorcycle oil, like Torco, which is rated for flat tappet engine break-in.
That will have sufficient zinc and phosphorous additives to break the engine in right, and not put too much wear on the cams.
Modern car oils do not have these additives anymore, in sufficient quantities for breaking in flat tappet engines.

Get some extra bottles of that oil too.
Change the oil again at 100 miles, and again between 250 and 500 miles.
Alot of oil changing in the first few hundred miles is good. It gets the metal bits out that were in the engine from the build, and that came off the edges during early break-in.

Don't use any synthetic oil during the break-in period.

[Blltrdr]

I would replace the nuts/washers on the intake flange with some new stainless fasteners. Good luck with your Military, it looks like a real sweet ride. Give yourself extra time while riding it places because you will be approached by many people wanting to know all the particulars about your bike.

[pushrod]

 Thanks Ace, This is getting interesting, I have a Classic Motorworks accessories catalog from that time period and they list a Mikuni VM34 Carburator kit with includes the carb, intake manifold, spacer and pancake performance K&N filter. Now this is where it gets interesting, it also states that "To get full use of this carburator we recommend that head porting be done, a high performance cam, and a high compression piston should be considered, and a performance exhaust system be installed. The 34mm carb is a big carburator for the Bullet engine and performs at it's best when the engine has been modified by these changes. Check local emmission laws before ordering."  I'm wondering if any of that has been done to this engine or just the carb kit.

[Blltrdr]

Thanks Ace, This is getting interesting, I have a Classic Motorworks accessories catalog from that time period and they list a Mikuni VM34 Carburator kit with includes the carb, intake manifold, spacer and pancake performance K&N filter. Now this is where it gets interesting, it also states that "To get full use of this carburator we recommend that head porting be done, a high performance cam, and a high compression piston should be considered, and a performance exhaust system be installed. The 34mm carb is a big carburator for the Bullet engine and performs at it's best when the engine has been modified by these changes. Check local emmission laws before ordering."  I'm wondering if any of that has been done to this engine or just the carb kit.

I would think with the mileage you state just the exhaust, carb and air cleaner have been modified.

Blltrdr

[ace.cafe]

Thanks Ace, This is getting interesting, I have a Classic Motorworks accessories catalog from that time period and they list a Mikuni VM34 Carburator kit with includes the carb, intake manifold, spacer and pancake performance K&N filter. Now this is where it gets interesting, it also states that "To get full use of this carburator we recommend that head porting be done, a high performance cam, and a high compression piston should be considered, and a performance exhaust system be installed. The 34mm carb is a big carburator for the Bullet engine and performs at it's best when the engine has been modified by these changes. Check local emmission laws before ordering."  I'm wondering if any of that has been done to this engine or just the carb kit.

The only way to tell is to check the parts.

However, in the vast majority of the purchases of these larger carbs, it's just the carb, manifold, and filter, that are added. Along with a better exhaust system.
But, some people did go into the engine to do stuff like that, and it's possible.

Here's the thing about the big carbs.
They are at their best at higher rpms, where more air/fuel mixture is required.
At lower rpms, the normal 28mm carb does just as well.
Only when the throttle is opened on the big carb, to the point where the carb opening is larger than the fully-open 28mm carb, will the extra carb size really do any good.
But, at least you know your carb will be good for any revs you plan on getting out of a Bullet.

A simple compression test will tell you if you have a high compression piston in there.
A normal Bullet will give compression test readings around 110 psi.
If the compression reading is up around 145 psi, then you have the high compression piston. Compression tests are done with the throttle full-open, and require at least 5-10 kicks in very rapid succession, to get a good reading.

[pushrod]

Thanks again Ace, to tell the truth I hope the carb is all thats done, I'm not looking for high performance at this stage of my life. I havn't put a mile on this bike and I can't stop smiling

[dogbone]

pushrod, I would recommend going back to the 28 mm micarb, or maybe a 30mm flatslide.
this is not a rootin tootin hi rpm engine, it's a low compression late 30's design, torquemaster.   The 34mm will be a detriment, not an asset.
It has to do with velocity. A smaller venturi will work much better at lo rpm's, where the Bullet engine is at most of the time.

[clamp]

Its a Mikuni.

      Yes it is, you can tell because it has Mikuni in the alluminium casting on the body.

       This is a dead give away.

       A lot of oil changes in the first 100 miles?   your joking?

     Please explain why phosphorous and zinc oil helps break in engines.    I have never heard of this before.  Does it assist in grinding the parts or something yet not the cams.

    What are flat tappets?

[ace.cafe]

Its a Mikuni.

      Yes it is, you can tell because it has Mikuni in the alluminium casting on the body.

       This is a dead give away.

       A lot of oil changes in the first 100 miles?   your joking?

     Please explain why phosphorous and zinc oil helps break in engines.    I have never heard of this before.  Does it assist in grinding the parts or something yet not the cams.

    What are flat tappets?

Phosphorous and zinc(ZDDP) are oil additives which help resist scuffing of surfaces, particularly cams and lifters, on solid lifter valvetrains. It is not as important with hydraulic lifter valvetrains.
Since solid lifter valvetrains are not in use much anymore, and the phosphorous and ZDDP shortens the life of catalytic converters, the new API standards call for reduced phosphorous and ZDDP content in the new oil formulas.

It is particularly useful to have at least 1000ppm of ZDDP and phosphorous in the oil during break in, and it does make for reduced cam and lifter wear.
Once they are broken-in, it is less necessary, but it does help to use oil with high ZDDP and phosphorous periodically to keep some on the metal parts, especially the cams and lifters.

"Flat tappet" is just a generic name for a tappet that is not a roller type tappet or a radius-type tappet. We have flat tappets in the Bullet, of "mushroom" type, that have a wider foot than the shaft.

I didn't really call for "alot" of oil changes in the first 100 miles.
I recommended an immediate change, so that he knows what is in there, and when it was changed, and that the condition of the oil is good.
Then, again at 100 miles to drain out any swarf or bits that may have not come out in the initial change. And this does usually yield some bits coming out.

At 250 and 500, it's draining the last bit of break-in material coming off, and I think it helps, particularly since oil is cheap, and getting any bits out can help.

He doesn't "have" to do this,
It's just what I think can be helpful.

[clamp]

Some strange terminology here from over the pond.

    A tappet to me is the rocker arm and adjuster screw   ( the tapping bit )

    A cam follower is what you call a lifter.

     Why does phosphorous in oil not needed for hydraulic followers / lifters?

     If I was a cam lobe and I looked up I would not be able to tell if I was pushing a flat base follower or a hydraulic one. Its job and appearance is the same except that the hydraulic adjuster takes up the slack.  So I dont understand you comment that the phosphorous oil will not be necessary on hydraulic followers?

     

[ace.cafe]

Some strange terminology here from over the pond.

    A tappet to me is the rocker arm and adjuster screw   ( the tapping bit )

    A cam follower is what you call a lifter.

     Why does phosphorous in oil not needed for hydraulic followers / lifters?

     If I was a cam lobe and I looked up I would not be able to tell if I was pushing a flat base follower or a hydraulic one. Its job and appearance is the same except that the hydraulic adjuster takes up the slack.  So I dont understand you comment that the phosphorous oil will not be necessary on hydraulic followers?

    

I'm not sure about why the hydraulic lifters don't need as much of it.
It's just something that is mentioned by the oil companies as an explanation.
Maybe it's because most of the hydraulic lifters these days are rollers.
There have been numerous examples of heavy cam and lifter wear on solid lifter classic machines, which bear out the problem associated with the new oil formulations.

There are warnings all over the internet on all the classic car websites about it.
It's a pretty well known thing now.

But there are oils which still have sufficient amounts of these additives. You can still buy older oils from previous formulations, or you can buy "off-road" oils that are formulated for vehicles that don't have catalytic converters.
And some racing oils too.

The supposed threshold is about 1000-1100ppm or more, of ZDDP and phosphorous content for the older vehicles.

[Kevin Mahoney]

I agree that the issue is roller versus flat bottomed lifter. You can ruin a new cam with flat bottom lifter by not using the correct lube the first time you start it up. I don't think it is a big deal with a roller cam. ( I could be wrong here).

[clamp]

I have seen some special grease made for fitting cams into American iron engines.

    As an apprentice in the early 70s there were many engines with crap cams in England. The new Range rover would knock out cams in a few thousand miles and was a common job in the workshop. The followers failed also with crack thrust faces on the hydraulic followers which were a vovelty on English cars in those days.  Only RR would have those and they taped like hell on cold start ups
 
 The Ford overhead cam in the mark 3 Cortinas were similar and most accessory shops sold cam kits for these early engines.

      Not one cam job ever had any break in grease applied to it. If I fit cams today I use STP

     Thinking of my apprentice days reminds me of an American car we had in the workshop. It was a very powerful machine and would come in for repairs to the chassis. It would rip anti tramp rods from the chassis, the exhaust made me laugh as it was huge.   It was a soft top car and made a lot of noise.

       It was eventually traded in and stood in the back of the workshop for years till one of the mechanics bought it.

      I did not know what it was just a huge American car,---I know now what it was

       It was a soft top Shelby Mustang.

[Chasfield]

Clamp: regarding strange terminology.

I wonder if the blurring of the way the term "tappet" is used came about when engines transitioned from side valve to overhead valve operation. What few simple parts where there on side valve motors were all set low in the timing chest, and the cam following bit would incorporate the clearance adjuster. So, the term tappet kind of covered everything.

[clamp]

Side valve engines  had no push rod or anything really. The cam follower with its adjustable screw pushed directly on the valve stem. Consequently the clearances could be tight 4/6 thou as not much metal to expand.

      The terminology for adjustment of that configuration in my book would be just as simple as in adjust valve clearance.

      But  they too can tap and should.

       The 6 cylinder Rover engines in the 70's were both,-- overhead inlets and side exhaust.

        The foreman David Eastwood  said that tappets were made to tap and insisted on hearing them all gently tapping.  They did sound nice when they were done right and could'nt be heard in the car.

     If it took 2 days to do then it took 2 days . Cars were washed and delivered when finished.

    Sorry --long post.