34 or 36 mikuni vm

rbt11548 · Oct 23, 2009

I am thinking of changing my carbs from amals to a single mikuni, reading the forum they nearly all mention fitting the 34mm, however Allens Performance state
" The single carb configuration does give slightly less top end power but the improvement in midrange delivery and fuel economy is a better compromise for most owners, We recommend the 34mm kit for 750's, the 36mm kit for 850's and the 38mm kit for those who really need to get their top end back!"

Would it be better to stick with a 34mm which most of those who have fitted Mikuni seem to use?

highdesert · Oct 23, 2009

I have had a 34 for over 20 years. Starts first kick, idles like a rock,and runs the bike just fine.
Top end? I could care less. I hardly ever ring its neck, or go over 4500rpm, or over 75 mph.
Mine is a 73 850. I have ridden another 850 with a 36, I could not tell any difference.

arc · Oct 23, 2009

I have had a 34mm Mik for about a year now and it has proved to be excellent(Got mine from Stan at Rockypoint USA) although i have fitted the biggest KN filter that would fit(pancake) as i felt the one with the kit was a bit small.Some say they are a bit tricky to set up but mine runs excellent as supplied by Stan and i have changed the choke from lever to cable.Most people say the 34mm is the way to go if your fitting a Mikuni...............hope this may help ........ Andy

pelican · Oct 23, 2009

My 850 came with a 36.

rbt11548 · Oct 23, 2009

arc said:
I have had a 34mm Mik for about a year now and it has proved to be excellent(Got mine from Stan at Rockypoint USA) although i have fitted the biggest KN filter that would fit(pancake) as i felt the one with the kit was a bit small.Some say they are a bit tricky to set up but mine runs excellent as supplied by Stan and i have changed the choke from lever to cable.Most people say the 34mm is the way to go if your fitting a Mikuni...............hope this may help ........ Andy

Thanks guys,Was going to give rocky point a try, but don't know if import duty would be prohibitive, was already stung by her majesty's best , then royal mail on top of that!, when I got my Tri-spark last year! Andy what set up was on yours when you got it
Cheers
Robert

arc · Oct 23, 2009

Hi Robert,Yes you have to watch for the dreaded VAT and import duty but at the time it was still cheaper from the States(about £60) good exchange rates!!! As for jetting I told Stan model ect and he jetted accordingly as a starting point (you get spare jets with kit) it just so happens that the settings worked perfectly for me,but they vary from machine to machine.Mine used to be an 850 Interstate but now wears a Highrider tank and Le pera seat!..I'll post a pic if i can remember me Photobucket password?????????.........Cheers Andy

splatt · Oct 23, 2009

Have you thought about going to a TM 34 you may get a minor performance improvement :?:

rbt11548 · Oct 23, 2009

splatt said:
Have you thought about going to a TM 34 you may get a minor performance improvement :?:

No I hadn't to be honest, any views on it guys?

tpeever · Oct 23, 2009

I have a 36 mm Mikuni on my 74 850 and it runs great. I don't have anything to compare to other than the twin Amals that were on the bike when I got it. The Mikuni beats the hell out of the Amals (couldn't get them to idle) but to be honest I haven't tried sleeving the Amals which would probably take care of most of the problems. A single carb is just way easier to tune and is far more tractable than twin carbs. I have heard that midrange response is better with the 34mm Mikuni on both 750s and 850s but that top end may be limited. I imagine that if you are a regular rider, the 34 mm should be just fine.

rbt11548 · Oct 25, 2009

Just looking through some older posts on Mikunis, is there a clearance problem with the cable inlet and the back spine of the frame? Also would a TM 34 be a better bet, if so what would be the best jet settings to start with?
Thanks

highdesert · Oct 25, 2009

Stan at rocky point will send it to you jetted and set up perfectly, these things have been around for ages for Nortons and anyone here can
give you the stock correct jets and needles sizes, but you should not need to be concerned as they come set up to just bolt on.

There is no issue with fitting under the frame, order a 34 and be done worrying about carburaton ever again.

rbt11548 · Oct 25, 2009

highdesert said:
Stan at rocky point will send it to you jetted and set up perfectly, these things have been around for ages for Nortons and anyone here can
give you the stock correct jets and needles sizes, but you should not need to be concerned as they come set up to just bolt on.

There is no issue with fitting under the frame, order a 34 and be done worrying about carburaton ever again.

Had thought about getting it from Rocky Point,and I would have liked to get it from there, as I've heard nothing but good stuff about Rocky Point on here,I mailed Stan, but have just spoken to HM Custom & Excise about , import duty and tax, and it would put just over 23% onto the price that's without including postage from US and our Royal mail's extortion ,sorry "fee" for collecting the tax!, which probably makes buying it from U.S. prohibitive. so I'll have to try and source one from here in U.K., a friend said Moto- carb have the kit on sale here so I'll have a look!,
Upgrade to TM , any ideas?
Thanks
Robert

jughead · Oct 26, 2009

I got a 34 on my 750, had a little port work done and took the inlets from 30mm to 32mm same as combat. Bike runs great up to 90+ mph but runs out of carb after that. Got 27.5 inter and 240 main jets and running at sea level.
Hope that helps. BTW I see you got one of Jim's hydro clutches, I just ordered that setup from Matt CNW, how does the master cylinder feel at the bars, does the lever come into the grip or does it stop short, sorta lika a brake feels?? I got a Baker hydro clutch fitted to my Shovelhead. :mrgreen:
JUG

Gino Rondelli · Oct 26, 2009

I run a 36 on my early 850 and a 34 on both my Mk3 850 and 750. The 36 def gives more overtaking grunt in my opinion and on the 850 slightly better fuel consumtion funnily enough. Try Motocarb in the UK just used him and he is first class, he's advertising a 34 kit for the Commando for under £200, I used to get my stuff from Stan but HM Government took a big slice and its not worth it now. http://www.motocarb.co.uk/

rbt11548 · Oct 28, 2009

Gino Rondelli said:
. Try Motocarb in the UK just used him and he is first class, he's advertising a 34 kit for the Commando for under £200, http://www.motocarb.co.uk/

Hi Gino, just mailed Moto carb, they told me that the ad was a temporary site page at least 18 months old and the price was £236 and £65 extra if I wanted to change it to a TM 34 and an extra £10 for a VM36 without filter as they said the filter for the 36 is a tight fit but the would supply one if needed for £34.50. I think one of my friends is going to be heading to his holiday house in Florida about Christmas, might arrange for one to get delivered there and he can bring it back for me!
Thanks again
Robert

pete.v · Oct 31, 2009

72 Commando 200xxx
Combat Head with compression plate
1.5" big bore exhaust
36mm Mikuni

Inhale - Exhale

Don Tovey · Nov 14, 2009

Hi there,
I put a 36VM Mikuni on my 1972 750 commando & noticed the acceleration was down quite a bit from twin standard Concentrics.
I have to say its easier to keep it running smoothly now after 15 years with a mikuni.
Not sure about top end speed as it never did over 110mph from new anyway which it still does with the mikuni( ive owned it from new). Although I would not reccomend riding a commando at 110 mph.
If your not bothered about it being a real roadburner I would reccommend the Mikuni VM36.
ps, ginos a tiop geezer in the NOC, he knows a lot of things about Nortons.
Cheers
Don from Yorkshire Branch.

ps if anyone want a Yorkshire Branch Norton calendar for 2010 they are £7 each including postage .
Mail me at toveypress@yahoo.com & I will forward the address for cheques to be sent to.
POSTED TO UK ONLY I'M AFRAID.

jughead · Nov 14, 2009

rbt11548 said:
Just looking through some older posts on Mikunis, is there a clearance problem with the cable inlet and the back spine of the frame? Also would a TM 34 be a better bet, if so what would be the best jet settings to start with?
Thanks

There is a bent top adjuster, 45deg I think, that you can order from most suppliers that fixes the cable clearance problem.
I got one fitted to my bike and no problem at all.
JUG

71Norton750 · Nov 14, 2009

im right in the process of doing my 34mm mik conversion, the kit looks so nice I dont want to put it on, but I payed $300 for it and its gotta go on, ill let you know how it runs when im done!

34 or 36 mikuni vm

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