Wildcardracing

I agree with Jared that a cub is not likely what you are looking for. I would need a very detailed description of the riding that this bike will see. But, you are probably going to be the most happy with a nice ported stock cylinder or Serval.

Bought some misc. parts from Tony, parts showed up quick and were as described. Was a great transaction, wouldn't hesitate to do business with him again. -B

Well, you have a pretty good package of supporting mods to do up a nice stroker dune motor. My advice is to go with a longrod crank and to use cut domes instead of a spacer plate. This will give you the best reliability. I would suggest ditching the timing key in favor of a plate, I've seen the offset keys shear and damage flywheels/crankshafts in the process. The 4mil with stock cylinders will displace between 373cc and 396cc with Wiseco's 795 series pistons available in 64mm-66mm in .020" increments. I would suggest getting the parts from the builder you plan to use for the portwork that way you won't endup buying items you don't need or that don't work the best with his particular setup. If you want you can give me a shout and I can put a package price together for you. Our engines are custom tailored to the rider not just generic "kits". -Brandon

Where are you riding at that you need 21's for pump gas? you should be able to get away with 19's on pump fuel at all the areas you ride. I have a set of 21's on the shelf I'll swap you if you want though. Might have some 19's as well.

Pat, Just give me a call when you have time and I'll get you set up. Those new cylinders are going to require very different jetting than your stock ones. -Brandon

The 4mil is only worth a few extra ponies up top, but it's the added torque throughout the curve that is a huge benefit. I encourage anyone to go for the stroker setup if their budget allows for it. The 4mil stock cylinder makes a great motor for trails or dunes. -Brandon

If it was ported for a 4mil crank I suggest you sell the topend and bottom separately. Advertise the topend as a 4mil and the bottom as a 10. The porting won't likely work well with the extra stroke and a spacer plate will make the problem worse. I would hate to see you end up with an unhappy buyer.

What size are your dumps and mains drilled out to? If the dump tubes are too small it can cause the kinds of issues you're describing. What pilots and needles? What is your elevation? Sounds like you are lean for sure. Your pilot circuit will enrichen as you turn your air screws in. Should start tuning with the power jets open all the way, but you're not drawing on them in the lower rpms. There is a great writup on atvdragracers on how to read alky plugs that will help you with tuning once you get this issue addressed.

I use a light coating of motor assembly lube or oil on the crank seals inner lip where it contacts the crank.

Porting is stroke and rod length specific. If the porting is aggressive ie: drag ports and most dune/aggressive dune ports they can't be re-ported for a longer crank stroke. Drag ports wouldn't suit your trail riding very well. If your looking to do a trail freindly 4mil you will want to run cut domes and no spacer plate. Have the cylinders ported to match the stroke. It's really the only right way to do a stroker setup. Virgin cylinders with a low bore go all of the time for $200-$250. I have 2 sets for sale if you need some of them. If you plan to stay with a stock stroke the oem cran with some good bearings and true/weld job is the best bet you have for reliability. I will have a good used OEM crank for sale in about a month for sure maybe sooner if you're still in the market hit me up. Other than that, buyer beware when puchasing used rotating assemblies. Be sure to check into the sellers reputation before you purchase a used crank. -B

If you have the cylinders being ported, you need to discuss the dome size and setup with your builder...If he can't make a suggestion for you then you really need to get your parts back NOW and send them to a builder who can help you set it up. -B

Nice to see everyone help the guy out. zmania you're going to have to answer a few questions before anyone can really help you out though. What is currently done to your bike? What kind of a budget are you looking to spend? What kind of riding do you plan to use it for?

If you're doing a 4mil or smaller and have the choice of Wiseco, Vito's or Hotrods....Hotrods would be my first choice. TDR offers a pretty decent forged crank for your 7-10mil applications, if you're looking at billet I prefer Crankworks over Twister personally. -Brandon

Will need to know a few things: What fuel do you plan to run? What crank and piston combination? Are you having it built or building it yourself? Are you planning to have it cleaned up, fully ported or running as cast? Most common base gaskets for a 421 are a .012 and a .020, selection is really builder preference. As for you question on the domes, 17cc is way too small. Dome size is really up to the builder as well. We typically use 21cc domes for 110 octane. The domes have to be sized for a 68mm bore or they will NOT work. Your absolute best bet is to contact a reputable builder and have them help you get the right parts. -Brandon

They are for 65.5 and below. You can also buy big bore gasket kits for larger bores. But, you have the right gasket kit. -B

The 795 series pistons are only available in .020" increments. There are spacers available to run longrods with standard pistons but is not recommended. Your cylinders are pretty much used up at .090 over, you could resleave them with big bore sleeves and use blaster pistons with that longrod crank or replace them with lower bore cylinders and use 795's. I recommend porting it for the stroke and using cut domes. -B

Youre machinist will need the actual piston going in the bore to match the bore size to, if he's willing to bore without it go somewhere else. Also make sure they know the ports need to be chamfered. The last thing you want is someone who doesn't know what they are doing messing around in your cylinders. If you are on your stock bore now, do yourself and your jugs a favor and only go up one oversize not a full mm. You will have just taken half the lifespan off those jugs boring them from 64 to 65 if it isn't absolutely necisary to bore that far. You will end up saving money in the long run even if the pistons are on sale now. A new set of jugs on a low bore aren't cheap.

You are going to need intakes, filters or airbox and ofcourse the carbs. Tell us about your setup and we will be able to get your jetting specs close

CP Industries builds them, not trinity. Any CP dealer such as myself can get you the head and/or domes...blanks if you want -B

They use the same throttle cable as the TORS eliminator kit. I want to say they are aound $25 shipped from us. I'll have to check for sure.

Can get you one piece base gaskets in just about any thickness you need. An other option is to make some adjustments to the domes you have. I'd do as Dave said and degree it out to see where you are; if your timings are good cut the domes, if they could be raised some go for a thicker gasket.

I'd start off with a lower bore set, you'll get more life out of the money you've spent on porting. And, there are always good virgin cylinders here and on other sites for sale. Chances of getting screwed are less buying from a reputable seller here than buying from someone on Ebay.

My vote also goes to Tim at Stellar!