LTD B engine upgrade

I have a 1980 LTD B4 engine with some 34 Flat slide carbs and I have been told they are too big for this motor and I need some head work for them to run on this bike. Or go back to stock carbs since the motor is stock.

What do i need to do to make the head match up with the carbs? But I want to keep the bike street.

Are there any other engine mods? Air box, cam, exhaust, etc? How is it running now?

If the rest of the bike is stock, it might be easiest to go back to the stock BS34s.

RS34s can be made to run well but if you're just looking for a stock performance setup, the stock BS34 carbs should work fine. Might be the easiest and cheapest solution.

that bike came stock with 28mm carbs,find a set of 28-29s

Yeah. Sorry. BS34s not stock till 81

Well heres the deal i bought the bike with 33 smoothies on it and had them rebuilt and the guy screwed me on the job. So I asked a local shop what should i do and they said why not just put some new flats on it and be done with it.

So I did and the bike ran ok but keeps running through pluggs and now got a brand new set of Mikunis that i can't return because i used them.

Now back to local shop and they say Oh we didn't know the bike was stock Sorry we should've asked you that before telling you to buy new 34mm carbs. Now they want $2000 grand to build the motor up to match the carbs. I like the throttle response of the 34's. I tried a buddys 29mm and she was kind tame.

Don't give that shop any more money.

What has been done to the bike aside from the carbs?

texaskz1000 wrote:

I tried a buddys 29mm and she was kind tame.

If the 29's are tuned right they are anything but tame.

Nothing as far as I know, the guy I bought the bike from said he had done some work but when i did the compression test it came back stock.

So I'm assuming pods (the stock air box boots won't fit over the RS34s) and stock exhaust. Correct?

If you have good throttle response, that's half the battle. What's the jetting? Main jet size and needle position?

Keep in mind that RS34's only need about 1/4 turn open on the idle mixture screws. Make sure they're not turned out 1 1/2 turns. This is a common mistake and will lead to carbon fouled plugs.

Also, the carbs should have come with a set of main jets ranging from 110 to 125.

I think I did 1 full turn on mixture screws and i have the 110's still in bag.

Man! What you really needed to buy was some cr29 or 31s not 34s but that you have invested that much in to the carbs and obviously like speed save your pennies and dimes and build the motor but it won't be cheap. And then before all of that the chassis needs to be 100%
I have some 29 smoothbores I just took off of my bike and would be willing to make a trade plus give up the differnce cash to make up the difference for what you paid because I have an engine in my 79 that I plan on going big with. I have them with chromed tops and bottoms and almost new K&N filters that have 130 main jet in them but could get them jetted to run for your bike. They are not tame carbs on a stock motor. When I put them on my bike I completely noticed a difference like tire smoking action at take off. They work great with stock motors. I also have a set of 28s from my 80ltd that came from california with my bike that had 7000 miles on them when I took them off. PM me let me know if you are interested.

Put a 1075 kit and cams in it and you will be glad you have those carbs.