I need carb help?? bigger or not? HELP!!

[1promodfan]

Allright guys I need some help here. I just bought the new ESR 310 and I (think) I have a 34mm. I know its a Kiehin, but I have to measure to be sure what size. If I do have a 34mm do I need to go bigger? Will a 36mm be a change for the better?

I've talked to a couple of people, but I haven't got a clear answer. If I go to a 38mm will it work with my stock boot and my Boyesen Rad Valve? Or will I need to make any changes? I don't want to loose my bottom end, and I don't want to have too much of an "hit" for riding on trails. I just want a good all-around motor.

So, I guess my question is should I change? And if so, to what a 36 or 38mm???

Sorry, I didn't give enough info....
I ride trails most of the time, most of the trail is in the open, sometimes in the woods....a little drag just for kicks

I got the 310 TRX-9 porting non-PV with the ESR TRX-9 pipe & silencer, dome size is for pump gas

no timing advancer.....stock airbox with-out the lid, K&N filter

[dunatic]

are you:

Riding Trails ?
Riding the Dunes ?
Drag Racing ?

What porting did you get ?

what pipe are you running ?

Is it a power valve or not ?

What compression are you running (dome cc size)

Do you have a timing advancer ? if not, do you intend to do that in the near future ?

Are you running an air box lid ? or an air box at all ?

to answer you question above tho.........YES, a 38mm Keihen carb will fit in a rad valve boot. You may have to boil it first to make it really soft, but it will go on and work just fine.

[1promodfan]

Revised^^^^^^^!!!!

[matt250r21]

Get yourself a 38 airstriker Keihin carb.

[wilkin250r]

A 38mm carb would probably be a good all-around fit, and yes, it will fit with the stock boot and Rad Valve (I've actually done it). It's not easy, but a few tricks can help.

If you were looking for all top-end power, a 39 or 40.5 would give you more peak power, but it would sacrifice the lower end a little. With a 310, I'd never go less than 38mm.

[1promodfan]

What type of tricks do I need to know about? If I go with a 38mm, would I still have that low end grunt? So, I guess a 38 will pull more through the mid-range and also on top-end too??!!

[jhtrx250r]

Dont go any smaller than 38mm, pwk or air striker will work fine they should have told you that when you bought the cylinder.
I used to run the same set up esr ported 310 cylinder, I used a rad valve the rad valve boot will easly fit a 38mm the stock one can be made to if you heat it up with a hair dryer, or you can buy one to fit the stock reed cage to a 38mm
If you have run the rad valve befor you should know that you need the reed cage spacer to make any torque with a rad valve ( the reeds dont fully open if you dont have one)
the set up will work great for woods, I ride dunes now and switched to a sphinx 310PV and miss the low end of the NICS based cylinder

call sudco they can hook you up with a pre jetted carb for that cylinder, I am suprised ESR dident set you up already.

[1promodfan]

Originally posted by jhtrx250r
Dont go any smaller than 38mm, pwk or air striker will work fine they should have told you that when you bought the cylinder.
I used to run the same set up esr ported 310 cylinder, I used a rad valve the rad valve boot will easly fit a 38mm the stock one can be made to if you heat it up with a hair dryer, or you can buy one to fit the stock reed cage to a 38mm
If you have run the rad valve befor you should know that you need the reed cage spacer to make any torque with a rad valve ( the reeds dont fully open if you dont have one)
the set up will work great for woods, I ride dunes now and switched to a sphinx 310PV and miss the low end of the NICS based cylinder

call sudco they can hook you up with a pre jetted carb for that cylinder, I am suprised ESR dident set you up already.

O.K., I don't mean to sound like an idiot, but whats the difference between a PWK and a Airstriker? I haven't really talked to Eddie about what I have. I was going to try and call him tommorrow.

[jhtrx250r]

No problem, the air striker is the same a PWK with more air vents
some say it has a improved idle circut, It the 38mm size I have only used a standard PWK and I currently run a 40mm PWK
I have a stock bore 89trx I run a 35mm PWK air striker on, and it has 2 fins in the back of the carb to direct air at low throttle openings it was a huge improvement over stock very crisp throttle response.
I think the 38 PWK air striker also has the fins in the back of the carb but am not sure, I know the standard PWK dose not have the fins and extra vents they are both D slides.

I recomend going to a carburetor web site and looking up the difrences

[superevil]

minumum 36mm is what i was told when i bought my 310,but like these guys said 38mm air stryker all the way

[wilkin250r]

Originally posted by 1promodfan
What type of tricks do I need to know about? If I go with a 38mm, would I still have that low end grunt? So, I guess a 38 will pull more through the mid-range and also on top-end too??!!

O.K., I don't mean to sound like an idiot, but whats the difference between a PWK and a Airstriker?

The PWK is Keihin's top-of-the-line two stroke carb. A few of the sizes (38mm for sure, I think also the 36mm or 35mm) also come in an Air Striker version. The Air Striker is identical to the standard version, but it has a few extra fins to channel air over the jet at low throttle positions. This improves low-end performance and throttle response. You'll see them often referred to as a PWK 38AS.

As for "tips" to get it to fit, it's not that hard. It should fit the RAD valve no problem. To get the stock airbox boot to fit on the other side, pull both carb and boot off the bike. Boil some water, and dip the end of the boot in to heat it and soften it up, and muscle it on the carb. Let it cool, and it should hold that size long enough for you to pull them apart and get them installed on the bike.

[86 Quad R]

if you run the compression up there around 180-185 it will give you plenty of bottom torque with a 38mm pwk/a/s. i personally would run the 36pwk for added bottom end.

[dunatic]

As for "tips" to get it to fit, it's not that hard. To get the stock airbox boot to fit on the other side, pull both carb and boot off the bike. Boil some water, and dip the end of the boot in to heat it and soften it up, and muscle it on the carb. Let it cool, and it should hold that size long enough for you to pull them apart and get them installed on the bike.

thats what i have done too, but I immediately put on a hose clamp and let the carb/boot sit over night.....or a couple of days.

Then you can easily take it apart and put it back together on the bike.

[1promodfan]

O.K. guys, I found out what I have. Its a PWK 36mm quadvent. I was told that may be sufficent. I don't want to sacrifice too much bottom. I guess I'll have to try this and just see what happens. Thanks for all the help from everybody. There is a lot of helpful guys up here.

[wilkin250r]

Yes, a 36mm will work. In my opinion, the 36mm is more suited to a 250 or 265cc, it's a little small for a 310, but it's not unreasonable. It will run just fine.

Carb size is always a trade-off. Larger carbs can flow more air, so they give better peak horsepower performance, that part is obvious and easy to understand.

To understand the benefits of a smaller carb, you need to look at HOW the air flows through the carb. To flow through a smaller carb, the air has to flow FASTER. The higher airspeed helps atomize fuel better, and also helps the carb respond to changes (like throttle position). This gives better low-end and much better throttle response.

[fulltiltrider]

IMO you dont have a very good setup for bottom end anyways. 9 porting, 9 pipe? If you really wanted to get all you can, usable power wise, out of this setup I wouldnt try to sacrifies for somethin ya aint got. Put a 40.5 pwk a cr250 ignition, set your squish at .040 with about 190psi and 110 fuel, and let'er zing lol.

[1promodfan]

Originally posted by fulltiltrider
IMO you dont have a very good setup for bottom end anyways. 9 porting, 9 pipe? If you really wanted to get all you can, usable power wise, out of this setup I wouldnt try to sacrifies for somethin ya aint got. Put a 40.5 pwk a cr250 ignition, set your squish at .040 with about 190psi and 110 fuel, and let'er zing lol.

Well thats true somewhat. I'm not looking for mainly bottom, just a good all-around motor. I like a good pull on the bottom end, but also I want it to sing on top end as well. I don't mind sacrificing a little bottom for more top. Reason I got the 9porting and pipe is, I didn't want it to fall on its face after 5th gear. I want...(hopefully)...to pull away from a few 450's!!!:D

[custom R]

I run a 310 with the 38 air striker and a trx 9 pipe and a upper mid range port and I do alot of trail ridin and it works great in the woods I run 13 / 38 sprockets for woods and 14 / 38 for open trails or sand and it will smoke some 450's a few of my ridin buddies have 450's that are piped and a few other things and one has alot of work done to it by rage racing and i can beat them all in a drag race

[1promodfan]

Hey Custom, how do you like that TRX-9 pipe? I just got mine on Thursday....I can't wait to get it on my bike and try it out. Thanks for the info on the 450's. I know I won't beat them all, but at least a few of them.

[custom R]

So far I love it but I only have one ride on it I had a paul turner 98 eliminator on before and so far the trx 9 feels alot stonger all over esp down low the pt had hardly no low end in the trails the esr pulls really hard esp from 1/4 to 3/4 so yeah I like it alot for my riding style

You will be surprised if you get your carb jetted right i havent been beat by anything other than drag bikes and one guy had a yfz that was really pumped up, I dont do alot of drag racing but when I do I usually win

[fulltiltrider]

Originally posted by custom R
So far I love it but I only have one ride on it I had a paul turner 98 eliminator on before and so far the trx 9 feels alot stonger all over esp down low the pt had hardly no low end in the trails the esr pulls really hard esp from 1/4 to 3/4 so yeah I like it alot for my riding style

You will be surprised if you get your carb jetted right i havent been beat by anything other than drag bikes and one guy had a yfz that was really pumped up, I dont do alot of drag racing but when I do I usually win

I just traded a guy my eliminator for a ct pipe just for that reason. When I had it on my oem cylinder that was ported to about 192 deg of ex duration, it was awesome. Now on my 310 p/v ported by C-Leigh Racing it just fell on its face. I want that low end grunt for spitting sod at all those 4 pokes I ride with lol. I had borrowed a pt race pipe from a local shop and it really woke it up. I know this cylinder would walk all over my old one in a race in the woods or on the strip. The best of both worlds lol. Should be a stump puller once I get the ct pipe on there

[Honda 250r 001]

yes u shouyd a bigger carb than a 36.