Anyone done a 4mil stroker with a stock cylinder on like a 68mm bore??? If so how did it run? I just did a number on my 330 cylinder and im looking for a way to make my stock cylinder make some Horsepower!!

There was a guy not to long ago that posted very detailed results of his setup and the steps to get it there. I believe he was making about 56rwhp on gas. I think he goes by the user name butters, im not sure if hes a member here or not though.

 

Anyone done a 4mil stroker with a stock cylinder on like a 68mm bore??? If so how did it run? I just did a number on my 330 cylinder and im looking for a way to make my stock cylinder make some Horsepower!!

i done one a couple of years ago using a 86 2nd over bore cylinder. the power/torque was amazing to say the least. i had it set up to run about 215 psi and was running a 39pwk. if you so chose to go through with it i strongly suggest that you get someone that knows what they're doing as it is very critical to get the port timings right. otherwise you wont be happy.

 

Ok, thanks for the info

 

I've gotten some decent power out of the OEM jug. I've got a writeup and several dyno charts on atvriders.com in the dyno section. Look under my screen name of Buttermilk...

I think it's entirely possible (although I didn't get there yet...) to get ~60 hp or so on gas out of the OEM jug.

I left some HP on the table with mine, but finally called it quits with the OEM jug as I was having other issues that were costing too much money to fix....

I never got to play with ignition timing, and I am certain that there was at least another 2-3 hp in the little motor by re-mapping the ignition curves....





Regards,

Rog

 

Just the guy I was talking about. He really lays it all out for ya, definately an informative read.

 

out of the 5 years of stock (I am including the 85 ATC 250r in this for the 5th year) cylinders, what cylinder does everyone feel has the best power potential? I personally like the 86 year jug but I know others think the later years are better. I have people tell me they like the 87 year better because they think the transfer area is more superior, and some like the 88-89 years as well.

Give me your thoughts, I have my combo figured out for this just looking for opinions.

 

out of the 5 years of stock (I am including the 85 ATC 250r in this for the 5th year) cylinders, what cylinder does everyone feel has the best power potential? I personally like the 86 year jug but I know others think the later years are better. I have people tell me they like the 87 year better because they think the transfer area is more superior, and some like the 88-89 years as well.

Give me your thoughts, I have my combo figured out for this just looking for opinions.

I prefer the later years with the intake bridge because ive had the older ones crack the bottom of the sleeve off. When you start porting on them, it can get pretty thin in those areas. The rest can pretty much be ported the same imo.

 

I had an 86' top end at .080 over with an 89 bottom end. I didnt get thru the break in period but I definately felt some good kick compared to the motor before(86' .060 over) I recently prchased the 89' cylinder with it's first over bore from Ebay. I'm trying to get my motor as close to stock as possible with the exception of a FMF fatty and Boyeson rad valve.

 

I don't have a lot of experience with the different year cylinders. I did however, spend a LOT of time opening up the transfer port volume on the '87 cylinder I started with. I think the transfer tunnels "could" be an area that might be a problem, depending on what you're setting the motor up for.

On the '89 cylinder I also opened up the transfer volume as well. The '89 starts out with more volume than the '87.

Rog

 

This dyno is the '87 cylinder I did.

Rog

 

This dyno is the '87 cylinder I did.

Rog

what do you use for dyno tires? around here the dyno owners all use american racer 10/10/18 sd33's at 10 psi and the only thing i have seen break 60hp are big banshees(425-525) and the highest of them was 78 hp

 

The place where I dyno has designated dyno tires. They are basically Jr. Dragster slicks.

www.sandtrax.com is the place.

Rog

 

The place where I dyno has designated dyno tires. They are basically Jr. Dragster slicks.

www.sandtrax.com is the place.

Rog

i wondered how people got such high numbers. that would make more sense. what are the dimensions of the tire and what pressure do they run??

 

The dyno tires don't "inflate" the numbers. They simply eliminate tire slippage due to the knobby's lack of contact patch with the dyno drum.

The tires I used are 19" diameter, ~8" wide and typically run ~ 15 psi.

When I did my first dyno pull, my 250R barely broke 40 hp. Several months later, and a whole lot of changes, testing, and tweaking, and a lot of dyno time, I hit 56 hp. All using the same dyno tires.

My Banshee first hit the rollers at 74 hp on OEM cylinders, then later made 91hp (421 Cub), and now should be in the mid 90's (421 Cub on gas). Around here, mildly modded Banshees will do 60hp (It don't take much to get 60 out of a Banshee...)

Rog

 

This dyno chart shows what my first attempt at porting produced vs. what I finally ended up with before other issues brought the project to a halt.

Porting was just one of the things changed to finally get there. A whole bunch of things were changed, etc. It was a good learning experience for me.

The place I dyno at does not have a "generous" dyno either. It falls into the more conservative side on producing numbers.

Rog

 

This dyno chart shows what my first attempt at porting produced vs. what I finally ended up with before other issues brought the project to a halt.

Porting was just one of the things changed to finally get there. A whole bunch of things were changed, etc. It was a good learning experience for me.

The place I dyno at does not have a "generous" dyno either. It falls into the more conservative side on producing numbers.

Rog

i understand what you mean. but if you have ever had a set of american racers on your quad they are very soft and ply-able. at 10 psi they squat alot when you roll on the throttle. i don't think they slip they are very tacky.i would think the narrower tire would have less rolling resistance as well. i am not trying to take anythig away from you or anyone else. i saw a picture of a pipe shoot out on a 450 and they were showing mid 50s power out of a stock motor with just pipe and jetting. seemed very high to me. both my 330 motors on the local dynos are mid 50s motors and it takes a very healthy 450 to run with them. i have only seen about 5 in the last 4 years that can.

 

i understand what you mean. but if you have ever had a set of american racers on your quad they are very soft and ply-able. at 10 psi they squat alot when you roll on the throttle. i don't think they slip they are very tacky.i would think the narrower tire would have less rolling resistance as well. i am not trying to take anythig away from you or anyone else. i saw a picture of a pipe shoot out on a 450 and they were showing mid 50s power out of a stock motor with just pipe and jetting. seemed very high to me. both my 330 motors on the local dynos are mid 50s motors and it takes a very healthy 450 to run with them. i have only seen about 5 in the last 4 years that can.
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That's all fine and dandy, but irrelevent at the most. Don't take this wrong but the dyno is just a tool for tuning, nothing more. Run the same setup, tires and gearing, everytime you make a pull, thus eliminating inconsistencies. One dyno to another is not comparable. I will admit its nice to have a good sheet, but don't sweat the numbers too much, as long as your makin progress your good.

 

jadleybray
i understand what you are saying. i have been on 3 different dynos. the info i forgot to post was that in the pipe shootout it looked like on the back of that 450 they had a narrow set of groved car tires. the dyno i have chosen to use regularly actually reads the lowest Numbers. i use it because the fastest quads i race against use this dyno,then i know where my motor stacks up. you can have a good chassis set up but when someone drives around you on a long straight it sure does piss you off!!! not often that that happens.

 

Just my $.02 on dynos and tires:

I know on street drag bikes we see up to 8 hp difference between a normal street tire and a Shinko ultrasoft drag tire. This is with the same bike on the same dyno - you just gotta take that into consideration when talking dyno numbers. Oring vs non-oring chain makes a tiny difference too.

 

Just my $.02 on dynos and tires:

I know on street drag bikes we see up to 8 hp difference between a normal street tire and a Shinko ultrasoft drag tire. This is with the same bike on the same dyno - you just gotta take that into consideration when talking dyno numbers. Oring vs non-oring chain makes a tiny difference too.

What do you mean by take it into consideration, the street tire was slippin on the drum, and the motor made the same hp just couldn;'t get it too the dyno. As long as your tire stays to the drum, no slippin, its doesn't matter what tire your using.

 

What do you mean by take it into consideration, the street tire was slippin on the drum, and the motor made the same hp just couldn;'t get it too the dyno. As long as your tire stays to the drum, no slippin, its doesn't matter what tire your using.

Nope, neither tire was/is spinning - we strap them down. The heavier and softer drag tire has more parasitic loss than the harder street tire. I would think that's pretty easy to understand.

If you want apples to apples you need the same tire and the same dyno.

 

Run the same setup, tires and gearing, everytime you make a pull, thus eliminating inconsistencies. One dyno to another is not comparable.

So right here you agree with me but two posts later you don't? :blink:

 

what do you use for dyno tires? around here the dyno owners all use american racer 10/10/18 sd33's at 10 psi and the only thing i have seen break 60hp are big banshees(425-525) and the highest of them was 78 hp

big banshees only making 78hp? def something wrong there.. 421cc shees are easily breakgin the 100hp mark on alky.. and more than a few are gettign there on gas.. .

 

(It don't take much to get 60 out of a Banshee...)

yep yep.. i've gotten it done with fmf fatties, a midrange port, and left everything else stock.. the guy was short on cash and didn;t even do any headwork... still had the stock carbs and airbox too.. pulled 62hp..


60hp is a trail banshee around here..