Mikuni Carb Re Fit

Hello All,
I'm new to this site, and would like to intro myself. My name is Neil, I've been riding since '65, and am still currently riding. Not really knowing this site, and how vehement some might be about keeping these Norts stock, I'll give you all some background. In '74 I bought my beloved 850. It came out of the box as a High Rider. At the dealership I switched out the tank, bars & seat and pretty much made a a Roadster. ( tank & sidecover swap for color preference )
Anyway, I havent been putting any time on the bike for the last couple of years, and it needs a going over. My son has alway's coveted the bike, and he just graduated college, and turned 24 years old. Well, I was 24 when I bought it, so what could be more appropriate than to give it to him for his 24th? And.... so I did. ( with a heavy heart, but I still will have riding privledges, and it will even remain in my garage.... read between the lines. BSEG )
So, being a young buck, and having differnt tastes, he is more interested in a cafe type set up. ( he will keep all stock items ) His first big question is carbs. He is thinking instead of putting the money into re building the Amals, he'd rather go with a Mikuni VM34 single. I guess I'd appreciate any input you folks have about that. Is it a good fit? Any issues con? His thinking, youngster that he is, is why invest in old technology, when for a like $ outlay, he can have new. I'm somewhat ambivilent at this point... plus, it's his bike now.
Also, if anyone reading this is from the Minneapolis area and is a good wrench, or knows of one, I'd appreciate a heads up. The kid has cash, just not a ton of it.
I may have jumped the gun here, and some of these issues may have already ben answered and available on this site. I will be doing some exploring for sure.
Nice to meet you guy's.
Stay Well & Ride Safe
ZenSPIKE

Your name looks familiar.Do you also have a roadstar?
I'm pretty new here too.I picked up a 72 commando project a few months ago.From what I have been reading you will get two sets of opinions on this .Some swear by the mikuni while others say amals are just as good when done up right.Some think mikuni's are an eyesore on these bikes.
Mine came with a mikuni and amals so I need to make the decision myself. My guess is the simplest thing would be mikuni.

ZenSpike said:

Not really knowing this site, and how vehement some might be about keeping these Norts stock

Click to expand...

You won't find any of those types here. In fact it's pretty rare to find a Commando owner who has a bone stock bike, let alone the balls to tell someone else not to modify theirs. You might be thinking of those Triumph owners. :mrgreen:

Welcome Zen and Danor
Swoosh has got it right. Do whatever rings your bell although modifications that change the sweet handling of the Commando probably frowned upon.

I personally took a 72 Combat (read up on it), lowered the compression from 10 1/2 to 1 to 10 to 1 with spacer under barrel.
Replaced 2S cam that really comes on at higher revs with a brand new stock one I found on E-Bay for $75. Had lifters resurfaced.
Replaced my two 32mm Amals with a new Mikuni VM34 I found on EBay for less than what I sold the Amals for.
Put in a Pazon Sure Fire electronic ignition.

Sure I took some of the teeth out of her but she starts one/two kicks and pulls like a train for a guy 63 years old.
I opted form minimum running problems, easy start and lots of Mothers aluminum polish.

Rather than looking for someone to work on the bike most of the guys on this site handle their own wrenches although I opted to have a shop do the head work. Valve seal failed so no sure if that was a good move.

I think we find as much fun building and maintaining as we do riding, especially in winter.
If you opt to do that get Norton repair Manual and Parts catalog.
Parts are pretty available and not too pricey.
Quite a few suppliers but I personally like OldBritts. Great site and personal service.

We always like pictures.

Bob

The Mikuni VM34 is great allround carb. Couple of things to note - the jetting is not always correct out of the box, invariably the Pilot is too small and on a 850 a 35 or 40 is neccesary. The manifold pushes the carb right up against the frame junction, usually the airfilter back plate has to come off. A K&N filter is normally fitted, but try and get the biggest one to allow better breathing. The carb will pull like a train from idle strong up to about 5,500RPM in top gear, but that's around 85MPH on 22 teeth gearing and anyways it the peak of torque and power so going further doesn't do much.

Compliment the carb with a electronic ignition, Pazon Sure Fire direct from the maker is probably the best deal going and a nice product.

The front disc is pretty ordinary for today's traffic and you can get a master cylinder re-liner kit that improves pressure as well as steel braided hose to firm up the brake performance, or add on a better caliper and bigger disc. Lots of choices there.

Those are pretty much the basic mods I made to my 850 a few years ago and I've had no issues whatsoever on many many miles of happy riding.

Mick

danor said:

Your name looks familiar.Do you also have a roadstar?
I'm pretty new here too.I picked up a 72 commando project a few months ago.From what I have been reading you will get two sets of opinions on this .Some swear by the mikuni while others say amals are just as good when done up right.Some think mikuni's are an eyesore on these bikes.
Mine came with a mikuni and amals so I need to make the decision myself. My guess is the simplest thing would be mikuni.

Click to expand...

Yes Sir.... I do in fact have a Road Star. That is what I drive on a daily basis. Gettin' old, and it's pretty easy to just jump on and go. They are so ;ow mainteance, and that is a huge plus for me now-a-days.
Thanks for the imput, and nice to meet ya.
Stay Well & Ride Safe
Neil
Ps. how do I reply to a specific post with out the quote option?

swooshdave said:

ZenSpike said:

Not really knowing this site, and how vehement some might be about keeping these Norts stock

Click to expand...

You won't find any of those types here. In fact it's pretty rare to find a Commando owner who has a bone stock bike, let alone the balls to tell someone else not to modify theirs. You might be thinking of those Triumph owners. :mrgreen:

Click to expand...

Good to know. I used to be pretty hard corp about keeping these thing's stock... till I put in an electronic ignition back in'80. What a difference that made. They are such sweet bikes, but certainly modern technology is pretty cool to incorporate.
Stay Well & Ride Safe
ZenSPIKE

rx7171 said:

Welcome Zen and Danor
Swoosh has got it right. Do whatever rings your bell although modifications that change the sweet handling of the Commando probably frowned upon.

I personally took a 72 Combat (read up on it), lowered the compression from 10 1/2 to 1 to 10 to 1 with spacer under barrel.
Replaced 2S cam that really comes on at higher revs with a brand new stock one I found on E-Bay for $75. Had lifters resurfaced.
Replaced my two 32mm Amals with a new Mikuni VM34 I found on EBay for less than what I sold the Amals for.
Put in a Pazon Sure Fire electronic ignition.

Sure I took some of the teeth out of her but she starts one/two kicks and pulls like a train for a guy 63 years old.
I opted form minimum running problems, easy start and lots of Mothers aluminum polish.

Rather than looking for someone to work on the bike most of the guys on this site handle their own wrenches although I opted to have a shop do the head work. Valve seal failed so no sure if that was a good move.

I think we find as much fun building and maintaining as we do riding, especially in winter.
If you opt to do that get Norton repair Manual and Parts catalog.
Parts are pretty available and not too pricey.
Quite a few suppliers but I personally like OldBritts. Great site and personal service.

We always like pictures.

Bob

Click to expand...

Hey Bob,
Thanks for the info. I do in fact still have my old manual. I actually still have the original wallet that came with the bike and all the original paperwork. About as deep as I've ever gotten was pulling the head and bringing it into a shop and getting the vavles done. I'm not a real motorhead, but do enjoy turning a wrench. I would never attempt to tear into the Amals. Too many small parts. I'd have springs and crap flying all over the garage.
I'm also not to adept at the inter net. I don't know how to post pics. We actually took a bunch last week in the driveway, so they are not too artsy. If I figger it out, I'll post some.
Stay Well & Ride Safe
Neil

Well Swooshdave - I think most stockness afficionados would rather not express that opinion very strongly on this forum. There is no need to anyway. Good technical ideas are presented and teaching occurs here and each of us has the option to incorporate some of these ideas in our thinking even though we may disagree with other ideas.

I have mods but they keep with (only my idea of) the spirit of a stock bike and most are hidden. A couple things - maybe not so hidden, but I like it the way it is. I tried to make it work is the main thing.

Lets drink beer and discuss at the rally.

Keep the stock Amals but fix them.

Russ

ZenSpike said:

how do I reply to a specific post with out the quote option?

Click to expand...

It isn't possible to reply to a specific post (except the last one) or to insert messages between others on this forum-however the members are used to the quote system and you can always insert multiple quotes from the topic review (below the reply box) in one message.

>>I don't know how to post pics. We actually took a bunch last week in the driveway, so they are not too artsy. If I figger it out, I'll post some.<<

Under the Topics column there is a link to Techincal Info and how to post pictures.
Uses Photobucket which is free.
Once you get it figured out pretty easy.

Bob

Welcome aboard guys,
Here you will learn about your bike, tools and your computor in no time at all.
You need to take the photos off the camera and onto your computor, then onto "Photobucket" ( your son will probably know ), then on here.
Read up how to achieve the correct size for posting and pick a good one for an Avatar.....
that picture over there...>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

hello and welcome!

i want to show you another possibility.

and if you are thinking about changing carbies why not changing to something that brings also a little bit more punch and power into the bike?

and side-effect.....need less fuel!

on the pic below is my bike fitted with mikuni 34rs flatsliders with accelerator pump. and the pump realy brings fun!



have a nice day!

chris

Take a look at the carbs from JS Motorsport http://www.jsmotorsport.com/default.asp I have a set on my bike and I was impressed by the easy starting.

Jean

Welcome to the Site,

After years of fairly constant fiddeling with the Amals and never really getting them to work ideally, I decided, somewhat reluctantly, to put a single Mikuni on my 74 Roadster. best decision I ever made with this bike. I had to lower the needle valve because I live at 5,000 feet, but now she starts first kick, even when cold, and idles perfectly at 6-700 rpms. As far as performance she pulls every bit as hard as before and starts to plateau before redline. I suppose I could install a main jet bigger than 240 for better upper end performance, but I'm not really that.

I say, modify away. Get the bike to run well and reduce your maintenance and that way you'll be able to enjoy it more than before. Just keep all the original parts....a museum might want them someday.

Good Luck, Bob