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Discussion Starter #1
I was hoping someone can give some clarity. I am a new vintage racer,(71 Cb350), using stock CV carbs, rebuilt - but fussy. I am on the fence of making the purchase of TH Racings 34 mm Mikuni Kit with the velocity stacks. Any suggestions or heads up I will need.

Am also on fence of revamping exhaust (2-2, 2-1 ??). I have read past Tech postings and spent hours going through the many views. What I need is a basic starting point and I think I can work it from there. I know each bike is different. I have Dyna 3 ohm Coils, which I will probably install and for the time being - running points.
 

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if we knew where you lived or what club you'd be racing with the question might be easier to answer. Most classes that you will run on a cb/cl/sl350 require you use the stock CV carbs. If you want to spend big $$ building up your engine into a near 50hp 350gp bike you will need carbs (and a LOT more), if you just want to race the bike keep the engine stock.

By the way, those carbs aren't specific to THR. Check sudco.
 

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Discussion Starter #4
I live in Mass and will probably spend a majority of racing @ NHMS. That being said, most everyone that saw my bike told me to get rid of those carbs and run the mikuni's.

Speaking with TH Racing, they advised me that they have the correct set-up and don't waste my time buying the carbs from another source (sales-pitch?). Any advice on this. I have a connection to Sudco parts (and a discount), but am not sure of the correct jetting or where to start.

Also, should I try 34 mm or the stock 32mm? You guys seem much more knowledgable.
 

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Here's some free advice and keep in mind you get what you pay for. The people that told you to get rid of the CV carbs and get mikuni's have no idea what they're talking about. If you keep the engine stock with the stock carbs you'll have a lot more classes you're eligible to race in. Which is especially important with a new racer. Track time and a good handling motorcycle are more important than hp.

Clean the CV carbs out well and they won't be fussy any more. And I mean really well. Don't just spray carb cleaner through it and call it a day.

If you really have you're heart set on Mikunis the velocity stacks that THR sell are very nice. But the carb prices are very high. You can get Mikunis from Sudco with the correct set up. THR is trying to sell you carbs set up for a full race motor and those things won't work very well with a stock motor. And also keep in mind that if you end up buying mikunis that will work with a stock motor and you decide at some point to build a full race motor those mikunis will no longer be what you need.

Bottom line, keep the stock carbs and get them running well. Get more seat time.

Craig
 

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craig you smart man
Are you coming next week to light fireworks with us?
 

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Scott,

It's not looking too good right now. I'm going to be sending a transmission out to be undercut today. I really doubt I'd get it back by next Thursday. And I don't want to just put another stock transmission in there until I figure out what's causing my transmission problems. But I'd really like to go.

But there's the whole getting beat by a girl thing that I'm not looking forward to.

Craig
 

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Discussion Starter #8
I like your advice. Seat time is most important. I may still go with the mikunis. A minor upgrade, considering.

Thanks
 

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This might be redundant, but don't eliminate your option to run the FCB class by jumping to Mikunis right from the get-go. USCRA FCB grids are large with a varied ability levels and if you are new to racing you'll be surprised how well a stock engine/stock carbed race bike can get around a technical track like Loudon.

Check out the rulebook:
http://www.race-uscra.com/forms/USCRA.2005.Rules.FINAL.pdf

See you out there.
 

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more redundancy-

if your first mod is to add the mikunis, then you've immediately put yourself in a class (lightweight supervintage)with fully built honda 350 (and other bigger) race bikes. only the stock carbs are legal in the honda 350 only class (Formula CB). but in LWSV your bike will immediately be at a huge disadvantage to those bikes with hot cams and big overbores and fancy vavles and sculpted ports, etc. so basically, if you just add the mikunis, you've put yourself in no-mans-land in regards to the two Honda350 classes...illegal for the Formula CB class, and very slow for the Lightweight Supervintage class. so yeah, it's a minor upgrade that only puts your bike in a bad place.

everything these guys above are saying is right, stick with the stock engine and carbs, work on your suspension and chassis, then when you're ready to go faster, do the carbs and engine. there's plenty to keep you busy before adding the mikunis.

good luck and keep posting-
tt
 

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+1 on everything here.

and lets not forget, a good rider on a well sorted stock 350, can do really well in lw at louden. if youre looking for cheap racing, fcb is where its at. and before you dump a boat load of cash into the bike, then realize racing is scaring the shit out of you, or you spend the first year of racing with broken bones, and think maybe its not for you, you should take the first season a little slow. after that, build your motor and frame. plus, you wont find a better grid of people than the fcb grid. (no slight to the other guys, but we must only be second to the 50'd or the sidecar teams.)

jc
 

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Discussion Starter #12
I like all your advice ($$ -wise). My main issue is the left carb seemed to need to get "primed" before it would give me the power from that side. I need to rev up the motor, then and only then - if I manually work throttle lever @ carb end of cable, it seemed to keep the vaccuum. Does this make sense to anyone. I am running a two into one and am seriously considering dropping for fear this is may be contributing to an inconsistent carb response from the left side. Any ideas or sound a bit messed up? Maybe I'm not explaining it well enough - but this is what i have. Carbs have been rebuilt pretty throughly. 105/ 70 jets. Runs clean sparks
 

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Your carb is not clean or your carb slide has a tear in the rubber.

If your carbs are like most they've been sitting for quite some time. That plugs up the idle and slow speed circuits first. Yours is working at full throttle because that's running on the main jet and that's the easiest to clean.

Unless the exhaust is plugged up that's not the problem.

Craig
 

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Discussion Starter #14
I managed to get those jet slides out and cleaned as well. Vaccuum passages to top slide reservoir are free flowing (with air blowing through nicely). Could be the rubber, although I cannot see a tear to the naked eye - I can try another one from an extra set I have access to.

Anyone else, ideas?
 

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yep.

could be a plug wire, or coil too.

does sound like a totally plugged idle jet though.

jc
 
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