Tried searching but found nothing. Think the swap to new server has search function limited. But anyway...........One tuning question. Tried to adjust the little black air/fuel adjustments but there is a slight bog when mashing the throttle from a dead stop. Is this normal with the stock carb with custom heads and an open exhaust? All jets are stock. I haven't cut the black tabs off for more adjustment just trying to adjust within the limits. plan on getting a HSR42 at later date, but for now, the stocker will have to work. Any tuning tips?

anybody ever answer you?

Bog should be less and sould be able to be tuned out by adjusting the idle circuit.

First- you can search on Google and find posts older than August '12.

On your question, try giving it more air flow. Air in/Air out = performance. Some simple things to try:

-If you haven't removed the foam pre-filter, toss it.
-Install a K&N E4665 air filter- its a higher flow lifetime replacement for the stock filter able to be cleaned and re-oiled
-Open up the carb shield to help eliminate the hard 90 the air has to take flowing into the carb
Stop there and see if it improves enough for you.



I did a recent experiment with one of these that I hacked out of c-channel and it seems to work really well:


If you want to go more, then try porting the intake manifold to soften the hard turns the air has to take, on Horizontals I have added a carb spacer to mix the fuel before entering the manifold with a knife edge port (other benifit is you can adjust either main jet to give it more fuel as the two chambers are combined).



Porting and polishing the other pieces is possible, just depends on how far you want to go and what your time is worth.


You can also replace the cheese head screws/lock washers on the throttle and choke plate with lower profile button head screws (you must use Red loctite if removing the lock washers). Going further would be to shave the carb shafts to make them more aerodynamic for flow through the carb. Someone even more anal than I am measured the increased area for flow through the throat as 14%. This is really labor intensive but has been measured on the dyno a while back for a ~0.8HP gain. If you plan on the Mikuni it may not be worth the time for temporary gain.

Really appreciate that. Did plenty searches but never saw that one. Very detailed. It's actually running alot better with the premium fuel. But I will definately try the air filter and cut the plate. If I need more, then I'll keep going. But as you said, I do plan on getting the mikuni later.

where can you purchase the carb spacers

Adjusted my first reply.

do as the others said. high flow air filter to go with yur exhaust. adjust for more fuel to air ratio. and check yur plugs often to see if yur runin lean or rich. good luck

So you're saying adjusting the ratio will not cause a plug change or you need to cut one up to see what it's actually doing?

So if you have a stock carb with a K&N and an open exhaust and it is bogging going from idle to WOT does that mean it is running rich and needs more air? In that case I figured it would be running lean and need more gas because the K&N and exhaust help air flow. Don’t the idle mixture adjustment screws only affect idle performance or will adjusting them help over the entire throttle range? How do you know if the air/fuel mixture is correct at WOT? How do you adjust high speed (WOT) mixture? Is the only way to get more fuel at high speeds to port the jets?

Thanks. So if you have a K&N and an open exhaust and it is bogging going from idle to WOT does that mean it is running rich and needs more air or lean and needs more gas? I would think it would be lean and need more gas because of the K&N and exhaust but not sure.

Make the air eaiser to flow in and then adjust the idle air mix screws to get rid of the bog.

Last post- the bog is caused by the idle/off idle ckt of the carb. If you have air restriction it will bog, if you have a lag in fuel it will bog- what I am saying is to tune it out.

The mains come into play at WOT and these motors are jetted fat coming out of the crate. Having more air flow will give you higher RPM on the top end. Clear?

cb is right. run the motor with load for 10 to 15min wot and kill it right away without letting it idle for more then a few seconds. do this with a fresh plug and you will get an idea if its runnin rich or lean at wot loaded. deadbirds right on them runnin a lil on the rich side out of the crate. just a lil insurance for the companies makin them. rather rich then lean and blowin them up. id still venture to say yur runnin lean. check out some of the gokart sites like agk and nr racing. some good info right there.

I heard another way to check it is run it under load at WOT and inject propane into the hole on the air filter cover. If it bogs down then its about right or running rich and if it speeds up it was running lean and needed more fuel.

What is the length x height x depth of the c-channel u made

That is interesting. That would mean that the 35's were the opposite of the 23's and 18's which come running lean from the factory these days because lean means less emissions to comply with EPA regulations.

Looking for a little more info for cleaning up the intake. I have an older model motor and it has a black plastic spacer that is in-between the intake manifold and the 90 that comes from the carb. Are guys getting rid of these or opening these up too? I see most are doing a nice edge on the intake manifold, but it wouldn't seem to work out that well with the black plastic spacer in there.

Look here at the spacer towards bottom of page and that is what you need!!

http://www.alphacarts.com/vanguardperformance1.asp

Thanks. I saw that some were using those, I was trying to avoid that. May try to open up the plastic one, if that doesn't work I'll see if I can find one of the others, that place says there out of stock.

Make on out of 3/16 r 1/4 aluminum flatbar

with cut carb shield and k&n filter, gutted exhaust will a/f need to be adjusted?

yes


Sent from an Apple Tree..

where is the adjustment located? Read different threads saying theres no adjustment and then some that say there is.... got a 35 marine vanguard

there's pictures on top this page....bout second to last one...2 brass screws with springs, stock they will be covered in black plastic...


Sent from an Apple Tree..

What's a good starting point? How far out to turn with just the air filter and cut shield?

notice any improvement?

Good read

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