mailman

You may want to think twice about contacting Dr. Q. Here is a post on a guy who had some serious issues with this guy. Q Ripoff post If you are intelligent and want the best for your LT500 then give Jerry Hall a call. His results speak loud and clear. The man has spent more time than any builder on the planet trying to get more hp/tq out of the LT500 motor. He does it on gas with no "big bore" or stroker options, either. 623-931-8132 Here is the detailed dyno report on the pipe shootout for the LT500's. LT500 Pipe Shootout Mailman

I know exactly what you are referring to. Port chamfer is definitely a possible cause. Although I have seen this issue first hand even though the port chamfers were excellent as well as the port shape. An overly square vs. oval port can cause that also. Other possible causes could be excessive heat and or rpm. How much rpm does the motor turn? The acceleration forces of the rings get exponentially greater when the rpms are high. There is a huge difference between say....turning 9K rpm vs. turning 11k rpm for a trail bike. This combined with too much heat and/or a poorly designed piston could all be possible causes. Sorry I don't have any definite answer but can only offer suggestions. I know the cost of those pistons can require a 2nd mortgage on the home. Take a look at the underside of the pistons for any charring. That can be a sign of too much heat. Where did you get the domes? A poorly designed dome can cause detonation and some strange symptoms. Mailman

Thanks man.

No, it would be impossible. There is no ignition source and not enough compression for that to happen. Keep in mind that blow by is the burnt mixture not the fresh mixture and the motor (rings actually) is not sealing with the cylinder. When it is sealing then all the burnt charge, or mixture, goes out the exhaust pipe as intended. Blow by does not mean all the burnt mixture is lost through the rings. It means some of the burnt mixture is lost. Most will still make it out the exhaust.

Blowby is a term used when the rings are worn to the point that they don't seal well enough against the cylinder and some of the exhaust gasses "blow by" the rings. This is evident on the pistons when the motor is torn down by black or brown residue seen on the piston. When the motor is running there really isn't a way to tell if there is blow by or not. It is just a sign of a worn motor. The more worn a motor gets, the more blow by it gets until compression starts to suffer. Don't be fooled into thinking a compression test will tell you about blow by; it won't. A really worn motor will lose compression but at that point the motor is pretty gone, performance wise. Your erratic idle is most likely due to a lean condition caused by an air leak. Air leaks can show up in many different places like base gaskets, crank seals, intake gaskets, etc. etc. Your bog could be caused by many different things. I would start by finding the air leak and repairing that or your top end could suffer damage. I would then try to address the bog. Most likely the bog is carb related but not always. Hope this helps.

I have pods but no outerwears.

You can run filters with an angled flange which will route the filters away from the pipes.

It is no big deal. It always sounds much worse than it is. Take the front shocks off. You can actually just remove the bottom bolt if you want to be lazy. On the bottom of the shock where the bolt slides through, there is a metal pivot pin. It looks like the pin that hold the piston to the rod on your motor. Slide that metal pin (about the size of your thumb) out. Clean it and grease it. The area where it rides on the shock is probably also dirty and dry. Clean and grease that area as well. Put it all back together and the squeak will be gone.

Bought a chain tensioner from him. Fast shipping. Perfect product. Thanks!!!!

Who cut the trans? Any idea on why it failed? Hard back loading or downshifting without clutch?

I just received the clutch basket today from kolb02 today. It looks great! He shipped it right away. No worries with this guy.

Thanks for all the help guys! I just found a set of aftermarket ones from a member so I will grab those.

Are there any Honda hubs that fit on the banshee axle? I have a friend who has a bunch of Honda 110 pattern wheels but is running a banshee axle. I know he could drill the rims for the 110 pattern but is there any Honda hub or a hub he can get that will fit the banshee axle and have a Honda bolt pattern? He did find an aftermarket set of hubs that will do the trick for $150 but if there is a cheaper way to go then let's here it. Thanks guys, Mailman

Just wondering what the time frame is at this point. How soon will these pipes be available? What pipes will be available? Any idea on cost? Any more dyno runs you would like to share?

Those are Vforce 2 reeds and cages. You can still find replacement reeds for those. Check with some of the site sponsors.

I think those numbers are way too low. There are many different derivations of the formula but here is the formula I use. HP X 6500 / L X RPM where hp is max horsepower, L is the engine displacement in liters, and of course RPM is the revolutions per minute where the engine produces max. hp. For my gas engine: I have 492 cc's or .492 Liters (1000 cc's = 1 liter), I put out 105 hp at 10700 rpm so my bmep would be: (105 X 6500) / (.492 X 10700) or about 130 for a bmep which is actually not a very good number for a twin two stroke motor. I see bmep as a function that relates the hp you put out with the cc's you have and at "what rpm". The easy way to make hp is just to spin the motor faster. If a person, and most do, just compare max. hp numbers then they would never understand why two motors with the same hp would not be equally fast in a race if the two motors have different bmep's or in other words make the max hp at different rpms. The one with the higher bmep or making the hp at a lower rpm should always win assuming all other things being equal. BMEP is a more effective measuring tool than just comparing max hp since it takes into consideration the rpm where the max hp is made and of course the cc's. I like to think of bmep as "how highly developed" a motor is. Hope that makes sense, Mailman

The smallest part of the divergent section of the exhaust is what I was actually referring to. This is often smaller than the end of the pipe. On my Shearer sb/sf oof silenced pipes, the OD is 1" at the smallest part of the convergent section and only about .905" ID there. The silencer fits over this and therefore has a measurement of 1" ID at the end of the pipe. When we had the inframe Shearer big bore and small bore pipes, the big bore did have a larger ID measurement. If you think about it, the big bore is designed for larger cc motors because they flow more exhaust due to the larger displacement. If they had the same id as a small bore then the heat would back up in the motor and cause some undesirably high piston crown temps. I don't know what CPI is running for IDs on big bore or small bore.

The best answer is "It Depends". You really need to try a set of both on your setup and take the bike to the dyno, hill, or drag strip to compare. Every motor is a little different and there are a lot of factors that would influence your choice between small bore and big bore pipes. With that said, I have tried both on a few different motors up to 521 cc's and the small bores always did best in my comparisons. I have known a few people that say the big bore worked better for their 421 cubs so again, it is something that really needs to be tested. If you had to guess and could not test then I would say that for a 421 the small bore will be the best most of the time. The big difference between the two is the size of the stinger opening. The big bore is larger and doesn't hold as much heat in the motor. I think some builders put these on their customers bike just to be on the "safe side". I have yet to see a pipe out perform Matt Shearer's oof sb/sf pipes on the 4 mils and 10 mils that I have tested them on. I don't think the big bore pipe has a strong enough return pulse for the smaller motors and therefore doesn't push as much of the charge back into the motor. I have attached a dyno sheet of three pipes that I tested on a 4 mil. The two best runs are essentially the same pipe and are inframe small bore shearers. The weaker run is with big bore inframe shearers. You can see that "in this case" the big bores were weaker from about 8800 to 10500 rpms when they recovered. The big bore was clearly not the best choice for this motor which was 472 cc's. Many feel that 500 cc's is the magic number when a motor should switch from small bore to big bore pipes. Well, it is not a bad guideline but there really is no magic number. Testing is your best bet but if forced to make a decision with a 421 then go small bore. I hope this helps, Mailman

I think 150 is too high for pump fuel but some will argue. How old is the fuel? Where did you get the domes from? If you are looking for a quick fix, try to run some av-gas or race fuel in the motor and see if the plugs still back out? What carbs and jetting are you running? TexasBansheeMan had a good point that it could be lean jetting also.

No oring behind that gear. The stock clutch uses orings between the plates.........maybe that is what you saw in the diagram.

Assuming the plugs were installed correctly, then yes, it is detonation. There are a number of things that can cause this like; old fuel, too high compression, over advanced timing, and poor dome design to name the most common ones. Tell us a little bit about your bike like compression, the fuel you are using, timing advance if any, stock head, cut stock head, or head with domes. Mailman

Hey Peddro, The angle cut on the Trinity domes is not always accurate which can cause a convergent squish angle and wreak havoc on the msv and combustion process. It caused me to go through a lot of money, time, and dyno testing to find the root cause. On another note, do you have the DM shell or the older style Cheetah shell? I feel there are some issues here as well. PM me for the details. Mailman

Hey Peddro, Nice clear pics. I have been running my Cheetah 4 mil cylinder for a few years and have not seen this issue. I would call Calvin Pollet at CP industries, the maker of the cylinder, and get his input. You could also send him an email. You may also want to post this on atvdragracers.com to get their input. As a side note, why are the water passages so rusty? Are you running water straight from the garden hose in your bike? Mailman

Most people mount them to the foot pegs. Some bolt right up and some need a bracket that attaches from the foot peg to the pipes.

Here is a post about a similar question. I think Calvin would know best how big you can safely go. I hope this helps. http://forums.atvdragracers.com/topic/8727-421-cheetah-question/